Boiler circulator pump and wiring


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Old 11-27-16, 10:50 AM
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Boiler circulator pump and wiring

I have a natural gas boiler (Allied Boiler / Super Hot / Saturn Series SG-180) that feeds two zones. The first zone is an indirect hot water tank (Weil Mclain Ultra 40) controlled by the built in aquastat wired to a White Rogers Type 1361 zone valve. The second zone is in floor basement heating and is controlled by a wall mounted thermostat, which controls a Grundfos circulator pump (UP 15-42F / 59896155).

Recently, the boiler started making banging sounds which was the sound of water flashing to steam and at times the relief valve would discharge. I believe the problem relates to the boiler circulator pump (Wilo Star 16) not running while the boiler was firing. As a temporary fix, I hard wired the boiler pump to run 24/7, which solved the flashing problem, but opened up a rats nest of 1980’s wiring through multiple relays. I replaced all the relays, keeping the original wiring intact, but noticed that the boiler pump did not run while the boiler was firing, so I went back to my 24/7 solution. Some questions.

1. Is it normal in this vintage system to have the boiler pump only run when there is a call for heat from either zone, but not when the boiler is firing? The aquastat (Honeywell 40000593 056) on the boiler does not appear to have the control / aux output to control a circulator pump or was wired into the relay system. I would think that there would be times where there is not a call for heat from either the water tank or the in floor heating, but the ambient temperature in boiler / wild loop has fallen below the low limit causing the boiler to fire and the consequential flashing / relief valve going off.

2. If it is not normal, is it safe / in code to wire the gas valve on the boiler to a dedicated SPST relay (no pigtail connections from any other source) such that I can wire the boiler pump to turn on when there is a call from heat from either zones or the boiler?

Sorry for the long post, but thank you.
 
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Old 11-27-16, 12:19 PM
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How old is that "vintage" system ?

I'm no hydronic expert or HVAC Engineer; but I believe that the logic is that the circulator ought to run anytime there is a call for heat AND the boiler temperature is above the low limit (and below the high limit), including that time period during which the burner is firing . . . . it shouldn't cease running while the burner is active.

That's the logic of my 1954 vintage oil fired boiler; but smarter logic may prevail with more modern non-vintage systems . . . . but I doubt it !

I'm always open to new information, and recognize that there are a lot of illogical systems in this world, so we'll see if someone more knowledgeable will correct me.
 
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Old 11-27-16, 12:46 PM
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Thanks for the response.

Most of the system was installed in 1998 with the indirect water tank replaced in 2012. I suspect that some of the wiring was messed with.

The call for heat in a zone or the boiler is each controlled by a thermostat, so the only link between the zones and the boiler would be the water temperature in the closed loop. The boiler will fire when the temperature in the closed loop falls below the lower limit regardless of whether there is a call for heat from either zone (those will either turn zone valve on turn on another pump). So there will be cases where there is no call for heat from either zone and the boiler is firing. Logically, I agree with the idea that the pump should be running when the boiler is firing hence my question. The only options would be.

1. Keep the pump running 24/7
2. Buy a new aquastat that has built in relay / has auxiliary controls
3. Wire it in on the basis that the circulator pump turns on based upon the zones calling for heat and NOT when the boiler is firing.
4. Wire it in on the basis that the circulator pump turn on when there is a call for heat from either the zones or the boiler. But this would involve connecting a SPST relay to the gas control valve on the boiler which gets 24v when the boiler is firing.
 
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Old 11-27-16, 01:20 PM
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I would assume that it was properly wired when it was originally manufactured/installed . . . . and that some component (sensor/thermister/thermal switch) or a relay has begun mis-behaving and allowing the burner to continue firing even after the high limit has been achieved.

If you replaced all of the relays, them I'd suspect some cheap heat sensor has shorted out internally and continues to give false information to your aquastat, which in turn, instructs the burner to continue firing.

Running the circulator 24/7 (and I've done likewise) serves to dissipate the heat and apparently, prevents the boiler from "boiling"; but isn't it getting HOT inside the living quarters ?

That's my read; but I'm just a Real Estate Broker applying logic. Someone with real knowledge will come along to help out soon . . . . meanwhile, do you have access to the original wiring schematic ?
 

Last edited by Vermont; 11-27-16 at 01:45 PM.
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Old 11-27-16, 02:29 PM
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Thanks for the response.

The boiler is not firing past the high limit. Nor is the temperature not properly regulated in the living areas as the wall thermostat properly regulates the temperature by turning on / off the Grundfos pump, which circulates water into the in floor heating system. Mechanically the system operates properly with the exception of the circulating pump. I'm just trying to determine what is normal.

If the wiring that I am seeing is close to original, I just can't see how they would only have the circulating pump running when there is a call from heat from one of the two zones and leave the chance that the boiler is firing when there is no call for heat from the two zones.

I want to wire in the boiler into the logic loop for the circulator pump and I know that I have to isolate the SPST relay, but just wanted to make sure I wasn't missing anything.
 
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Old 11-27-16, 04:05 PM
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It sounds as if you're saying your boiler is maintaining temp. all year round when nothing is calling which you don't need if you do not get your hot water from your boiler. You have an indirect hot water heater which is essentially another zone so your boiler should be set as a cold start or on demand which means when the burner comes on so does the pump whether it be for heat or hot water. I would look at your control to see how it's wired.
What control due you have on there. You are running off the low limit to maintain boiler temp needlessly. There may be a way to bypass that.
 
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Old 11-27-16, 05:41 PM
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Thanks for the response.

Yes, the boiler maintains a minimum temperature in the wild loop and is set to fire at about 155F and shut off at 185F. I THINK this is normal for a hydronic heating system and pragmatically not really an issue give how little water there is in the closed loop (maybe 10 feet of 1 inch pipe) and the fact that between the indirect hot water tank and the basement slab heating there is a call for heat every couple of hours i.e. it's not like there is 100 gallons of water being held at temperature for days on end.

To be honest, I had assumed that the boiler was set up correctly so I don't know much about the controller or cold starts. The controller is a Honeywell 40000593 056 appears very basic and I can't find any documentation on it. Just has four electrical connects, two for high limit and two for low limit, with a jumper cable between a low limit and high limit connection. I THINK this jumper makes it a high limit only aquastat. When the boiler is NOT firing I see 24 volts at the aquastat and 0 volts at the gas valve. The reserve when firing.

I wanted to use this voltage at the gas valve to feed a relay that would allow me to run the circulator pump in a more intelligent manner rather than 24/7. I honestly don't think the boiler setup is an issue.
 
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Old 11-27-16, 07:29 PM
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http://alliedboilers.com/

If you copy and paste this in another search bar it will bring you to a sight. Click on Saturn Series and then click Literature and then the last choice in the menu and you should find all the info on your boiler. Wiring schematics and the last part is troubleshooting.
Hope this helps.
 
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Old 11-27-16, 08:12 PM
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Thanks for the response and trying.

Unfortunately, that is the documentation for a new SG-180 boiler and the controls look nothing like my 29 year old unit. Regardless, the aquastat, gas control and circulating pump are generic and can be interchanged, so they may not be original to my 29 year old unit. The issue is the circulating pump and how it should be configured to run with my system.
 
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Old 11-28-16, 12:28 PM
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hk–

I’m just a newbie so take what I say with a grain of salt - lol. I’m not really following the configuration very well but it sounds to me like you have a triple aquastat with the low limit function NOT DISABLED. I think you need to REMOVE a specific jumper wire, NOT ADD a jumper wire, to disable the low limit. I think that’s correct. Maybe one of the other guys would know for sure. But something to check out IMHO.

I think that would explain why your burner fires with no pumps running. Maybe the boiler came with a tankless coil for DHW, and thus a triple aquastat to supply low limit capability, and when the Indirect Water Heater was added the aquastat was never changed. Maybe something like that.

But regardless, it seems to me that running the burner to keep the boiler water temperature above a “low limit” should not cause a problem – other than possibly wasting fuel. I don’t think you need a circulator running because the burner is running – although in your case that may not make sense to have the burner run with no circulator. (My burner runs a lot with no circulator running , I have the tankless coil).But- should that cause a boiler temp/pressure problem and the pressure relief valve to activate? Doesn’t seem so – to me anyway, lol.

Just a few thoughts!
 
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Old 11-28-16, 01:50 PM
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H,
I reread your post and have a couple of questions.
How many pumps do you have. What do you mean by wild loop, and if you only have 1 pump it must run no matter if you're calling for heat or hot water. If you have 2 pumps why the zone valve.
Finally, your aquastat should be controlling both heat and hot water. Your t-stat is only a switch, like a light switch that sends a signal to the aquastat to turn on the burner and the pump. You should have an aquastat on the indirect that sends a signal to the boiler aquastat that turns on the burner and pump.
Any chance of pics of the system.
 
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Old 11-28-16, 06:25 PM
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I found this definition at the link below:

Deadhead avoidance


The infinite loop, also called a “wild loop,” exists so that the boiler’s main pump does not deadhead (i.e. have nowhere to pump its water and burn itself out) when no zone valves are open.
Hydronics Q & A – Coping with cycling - Mechanical Business
 
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Old 11-28-16, 08:36 PM
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Z,
I get the purpose of the loop but I don't understand why he would have that setup. It's only used on constant circulation systems. I have used them on commercial buildings where apartments are fed by individual monoflo systems.
His complaint is the pump doesn't run enough. That's why I was asking his definition of the term.
 
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Old 11-28-16, 08:51 PM
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An one solution to the problem is to use an automatic pressure sensing pump like the Grundfos Alpha. Grundfos ALPHA | Grundfos

Leave it on 24/7. Disconnnect end switches, it will automatically adjust to load as valves open and close. And it saves up to 85% on electricity.
 
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Old 11-28-16, 10:51 PM
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Thanks everyone for the responses.

Sorry about the delay, spent most of the day rewiring the 3 dpdt relays in the boiler system, which was interesting.

To summarize the loops (smallest to largest) and the control devices

Loop 1 – Boiler loop / Wild loop (WAG = 10 feet of 1 inch pipe) – Heat controlled by aquastat on the boiler. There is a Wilo circulating pump on this loop mounted on the return side just before the boiler. How this / the Wilo pump should be operating is the question.

Loop 2 – Zone 1 (40 Gallon Indirect Hot Water Tank) – Heat controlled by the aquastat on the tank, which opens a zone valve allowing hot water from the boiler loop to flow through the water tank heating the domestic water in the tank.

Loop 3 – Zone 2 (1800 square feet of in floor concrete slab heating) – Heat controlled by wall mounted thermostat, which provides power to a Grundfos circulating pump.

Specific answers to questions:

Triple Aquastat – No, I have the complete opposite, mine is basic and looks
like it’s from 1988 and has no auxiliary controls (i.e. B1 or B2 or C1 or C2 or CZ etc).

Number of pumps - 2

Wild Loop – It is consistent with what zoesdad posted. The only difference being that I don’t have 2 zone valves closed. Instead one zone valve is closed and the other is the pump not running, which in essence is the same thing. What’s interesting is that the definition posted seems to imply that it is normal to have the pump running 24/7.

Why the zone valve? – Because I have 3 loops in essence. If not, then I would be either wasting energy circulating through a zone (water tank) that doesn’t require heat or overheating the water in the hot water tank, which has a separate relief valve (temp and pressure).

I am pretty sure that the system setup is normal, just not common in residential homes as it really just depends on what your hot water demands are. So it is not surprising to hear SPOTT say that you see these systems in commercial applications as I have greater demands than the average home. In my area, most homes have a single gas furnace to heat the main floor and second floor with an 80 gallon gas / electric hot water tank (typically less than 40,000 btu) or tankless. Basements are not normally heated. My circumstance is different. I have a tank and 180,000 btu because my needs are different. I don’t’ know much about how the new tankless / on demand hot water systems are configured, but I don’t think they were around in 1988 and I don’t know if they have the throughput for domestic hot water and hydronic heating.

So if anyone knows how the boiler pump / wilo should be configured to run, please let me know. Thanks.
 
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Old 11-29-16, 07:03 AM
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Hi, that does not appear to be a good Honeywell number,can you send a pic or 2 of the control?
 
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Old 11-29-16, 08:07 AM
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Power coming in from the top (24v). White wire goes directly to the gas valve. Black goes into the top right and exits on top left to the gas valve. Bottom two are jumped together. Tried the L4062 number, but nothing.
 

Last edited by hkstalon; 11-29-16 at 08:52 AM.
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Old 11-29-16, 01:27 PM
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hk –

As you said before, it looks like that aquastat is really old. FYI this link-

https://customer.honeywell.com/resou...0s/95-6701.pdf

shows (Table 1 Page 1) the L6081 as the Honeywell recommended replacement for the L4062A . Might be helpful someday.

It seems to me looking at the top pic and the way it’s wired as you described, that the control will keep the water heated around the low limit – as long as it’s supplied power. At least that’s the way it seems to me (you probably already analyzed the operation and may have come to a different conclusion; I’m no expert for sure).

But what surprises me is that the control seems to be operating at 24VAC. If you look at the top pic it says it’s a 120/240 VAC unit. But I guess 24VAC is enough to operate the relays.

Doesn’t answer your question about when should the Wilo pump run. Maybe spott and/or Geochurchi and/or doughess who know more about this stuff can figure it out.
 
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Old 11-29-16, 02:32 PM
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Thanks Zoesdad

At least I know what model the aquastat is now.

So if anyone knows how the boiler pump / wilo should be configured to run, please let me know. Thanks.
 
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Old 11-29-16, 02:38 PM
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What other controls are on that boiler, normally the zone valves will control the main aquastat which in turn will start the boiler and circulator, it could also maintain boiler temp.does that thermostat control the Grundfos pump directly?if so if the boiler would fire on low limit.
 
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Old 11-29-16, 03:33 PM
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Thanks for the reply.

None. The only other things attached to the front of the boiler are the aforemeentioned aquastat, gas valve and pump. The only wires in would be power.

The Grundfos / other pump is controlled by the wall thermostat and NOT by the aquastat on the boiler.

So if anyone knows how the boiler pump / wilo should be configured to run, please let me know. Thanks.
 
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Old 11-29-16, 04:03 PM
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H,
After your latest description you said you have 1 pump for your heat being controlled by a t-stat. Is that stat 110V or does it go through a relay. Your indirect tank has a ZV which is fine but just a ZV will not circulate boiler water to heat the tank therefore since you only have 2 pumps the Wilo pump along with the ZV must come when there is a call for hot water. Does that make sense to you.
Your duel aqustat is wired with 14 g wire used for 110V circuits and yet you say it goes to your gas valve which is generally 24V. How do you get from 110V to 24V or is the aquastat 24V with the wrong wire.
Last question for now. What does that 1" pipe go to and where does it return.
With only 2 zones and 2 pumps why would you need constant circulation.
Any chance of pics of the system to get a better sense of what you have.
 
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Old 11-29-16, 06:51 PM
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Thanks for the reply and trying.

I have attached a simple schematic, which visually lays out what I have described above. The only question that I have is how the boiler / Wilo pump should be configured to run.

Again, logic has it that it should run when either the boiler is firing or when there is a call for heat from zone 1 or 2. But given how simple the boiler aquastat is (no auxiliary controls C1/C2/B1/B2/L1/L2/CZ), it leads me to believe that in these types of systems, the boiler pump was only wired to run when there is a call for heat from the zones (1&2) and not necessarily when the boiler is firing.

So if anyone knows how the boiler pump / wilo should be configured to run, please let me know. Thanks.


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Old 11-30-16, 05:39 AM
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Originally Posted by hkstalon
". . . So if anyone knows how the boiler pump / wilo should be configured to run, please let me know . . ."
You're lucky that Allied Engineering/Allied Boiler is still in business.

Did you contact them with the Serial Number for your series SG-180 Boiler and ask if they can supply the applicable schematic ?

These Customer Service are often pretty helpful; and being a Canadian Manufacturer, you ought to have one leg up as a fellow compatriot.

They're in Vancouver at (604) 929-1214.
 
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Old 11-30-16, 06:13 AM
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H, how did this system operate before you started getting the banging you are talking about?could there be another problem with the system? I am not familiar with the plumbing aspect.
 
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Old 11-30-16, 08:35 AM
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Thanks all for the replies

Plumbing - Very unlikely. Been through 3 plumbers on this and they simply either did not understand / could not troubleshoot the issue or misdiagnosed the problem and randomly replaced perfectly working parts (expansion tank and boiler pump). I was getting frustrated and replaced the relief valve and auto air vents myself as a last ditch effort. So mechanically, basically everything is new and working properly. All of which did not solve the original issue. The last plumber noticed that the boiler pump was not running while the boiler was firing and diagnosed this to be the issue. To be fair, this was an intermittent issue i.e. previously we tested all the different loop combinations and the boiler pump was always running. Anyways, he saw the rats nests of wires and relays and said that likely one of the relays had failed. I replaced all the relays myself. Even after this, it allowed the boiler to fire while the pump was not running and no calls for heat from either zone1 or 2. Could this be "normal" and how the system is suppose to run? It doesn't make sense that there would be no circulation in the wild loop while the boiler is firing. I assumed that this was not correct and hard wired the pump to run 24/7, which brings us to today.

I tested the relays and 2 of the 3 had a failure. One coil failed and one "pole" failed. I might need an electrician to see if it is possible with my equipment. I tried and I thought it would be easy, but I am having a load issue with the boiler aquastat driving the gas valve and a SPST relay. Not to mention the safety concern of tying directly into the gas valve.

Customer Service - I will try to call them but I am skeptical.

So if anyone knows how the boiler pump / wilo should be configured to run, please let me know. Thanks.
 
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Old 11-30-16, 09:07 AM
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Originally Posted by hkstalon
". . . The last plumber noticed that the boiler pump was not running while the boiler was firing and diagnosed this to be the issue . . ."
Could it be that he just observed a moment in time when the Boiler was firing to bring itself back up to the standby temperature ?

I can see that most Plumbers would not want to willingly venture into this situation, when so many alterations have already been affected, tested, and already abandoned.
 
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Old 11-30-16, 10:00 AM
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Thanks for the reply.

Sorry, I am not sure what you are saying. I think the boiler firing up to bring it up to standby temperature is normal.

I think some of the confusion and rabbit holes are caused by the fact that this is an older more mechanical system. For example, this is a non condensing boiler, so the return temperature in the wild loop must be kept in the +160F range to avoid condensation and rust. I think this explains the earlier comments about cold starts and maintaining temperature.

http://www.cleaverbrooks.com/uploade...NovDec2013.pdf

Another example would be the basic boiler aqaustat. I think this explains earlier comments about voltages (110v vs. 24v) and wiring from the indirect water tank. All the transformers, relays and control logic are built into the newer aquastats, but not on mine.

Anyways, if anyone knows how the boiler pump / wilo should be configured to run on this older more basic system, please let me know. Thanks.
 
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Old 11-30-16, 08:24 PM
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The return temperature in the wild loop must be kept in the +160F range to avoid condensation and rust.
133F is the condensation/due point temp on oil fired systems. That is why 140F has long been the standard minimum water temp used on hydronic non condensing boilers.

Over 180F scaling produces rust in boiler water chambers. That is why 180F is the widely used max water temp.

At times on some systems, circulated cold return water can bring boiler below 133F. There are various ways to deal with that. I use a control to deactivate circulators below 135F. When the burner brings it up over 135F the circulator restarts.

Control only activates briefly in early morning when thermostats raise room temp to day time levels. Use Honeywell thermostats with Smart Response feature that "learn" response time to bring up room temperature. They accommodate for any lag due to circulator cutout and burner response to bring room temperature up at set time.
 

Last edited by doughess; 11-30-16 at 10:17 PM.
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Old 12-01-16, 06:56 AM
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So, often a heating system with zone valves will have the pump running continuously, and will have a "wild loop" the water circulates through when all zone valves are closed. The wild loop is most often the longest loop in the building, but it can be something as simple as a pipe from the pump outlet back into the boiler inlet. If the wild loop is the longest loop in the building, as soon as a zone valve opens to provide an easier, shorter path for the water to take, the water flows through the zone instead of the wild loop. However, if your wild loop is just a pipe from the pump outlet back to the boiler inlet, then IT'S the shortcut the water will want to take ALL THE TIME regardless of whether any or all of your zone valves are open. So, normally, there will be a gate valve in that short wild loop to pinch off the flow through it enough that water PREFERENTIALLY flows through the zones whenever a zone valve is open.
This is a link from another site,helps to explain the "Wild loop",
 
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Old 12-01-16, 09:28 AM
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hk –

I have a few observations which may be totally worthless –lol, and have to be taken with a grain of salt.

I think your point about the aquastat being old and limited in scope is correct, but if you look at the label on your aquastat (post #17 top pic) the label clearly indicates that it is a 120VAC a’stat. Yet you measured 24VAC across the terminals and in addition you say the output goes directly to a 24VAC gas valve. And as spott pointed out in post #22 the wire looks like 14 gauge which you use for 110V. Something doesn’t seem right there.

I think Geochurchi has addressed this but are you sure that is in fact a “wild” loop? I know some systems have a Boiler Bypass where the supply piping out of the boiler has a segment which connects right back to the return side of the boiler and if the pump is inside that loop at the return side, then that is called a Boiler Bypass. I think the idea is that some of the hot water out of the supply returns immediately to the boiler thus increasing the return water temperature to the boiler. That purpose is to maintain an acceptable differential between the supply and return water temperatures as far as I understand.

But I believe there is a valve in that loop which can be adjusted to regulate the amount of water returning through the loop. I was wondering if what you have is actually a Boiler Bypass – but you would see a valve in that loop somewhere so that you could adjust the amount of water passing through the bypass if that’s in fact what you have. Or maybe since the pipe is only one inch diameter, that in itself would limit the amount of return water through the bypass (if that’s what it is) and thus you could actually have a Boiler Bypass without a regulating valve on the pipe.

What good would continuous circulation through only 10 feet of one inch pipe do? In other words, what’s the difference between keeping the boiler water at the low limit WITHOUT circulating through 10 feet of one inch pipe, vs. keeping the boiler water at the low limit WHILE circulating the water through the 10 feet of one inch pipe? It doesn’t seem like that would help much in terms of a capability for a faster response to a demand. spott addressed the purpose of the wild loop in post #13 and it doesn’t sound like it would be anything like a 10 foot pipe.

Not circulating the boiler water when the burner runs should not cause a problem. My system does that and I think so do many others. The aquastat keeps the water at the proper temperature in the boiler, and it looks like because your system was set up to use the low limit, the idea was to keep the boiler water at a minimum standby temperature for the DHW tank demand.

It seems to me that the return water temperature at the boiler by definition only exists when you are circulating water, and you should only be circulating water when there is a demand from a zone. In other words, you wouldn’t circulate the water just to maintain a return water temperature. Instead, you would want to maintain a return water temperature ONLY WHEN you had to and were in fact circulating the water.

So it would seem to me your Wilo pump should normally be OFF and only come on when there is a call for DHW from the DHW zone – and thus the operation of the burner and the operation of the Wilo pump would be independent of each other. The burner would run when the water in the boiler cools below the low limit, and the Wilo pump would run when the DHW zone thermostat calls for hot water.

It would seem to me that when the ZV opens for the DHW tank zone the Wilo pump should run. I think that is was spott pointed out in post #22. Is there some way that ZV was connected to the Wilo pump and you missed it? It doesn’t seem to me to make any sense to continually circulate water through that short loop.

It doesn't make sense that there would be no circulation in the wild loop while the boiler is firing. I assumed that this was not correct and hard wired the pump to run 24/7, which brings us to today.
I think that is probably not correct and the plumber must have never seen a warm start system. Also, I don’t see how to-circulate or not-to-circulate would have anything to do with the relief valve discharging. Didn’t your temperature/pressure gauge(s) show something when that happened?

I think spott in post #6 explains how the system operates. If it were me I would diagram the system with all the components (aquastat, circulators, relays, etc.) and connections and see if it doesn’t match the operation spott outlined in post #6- although I think you are not sure what the Wilo pump was originally connected.

Just some thoughts - from a non-expert to be sure!
 
  #32  
Old 12-01-16, 11:01 AM
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The aquast voltage rating really has nothing to do with it ,other than to state the highest voltage that the control can be used with,14 ga. Wire would be perfectly acceptable for the 24 volts,really doubt the gas valve would be 120volts.
 
  #33  
Old 12-01-16, 12:13 PM
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Thanks everyone for the responses and trying.

Doughness – Yes, I agree 140F return and 180F supply. The article also says 140F. I must have just typed it in wrong. My system maintains this temperature in the wild loop.

Geochurchi – My wild loop is when all the zone valves are closed and it is the smallest loop in my system and flows from the outlet / supply side of my boiler through 10 feet of 1 inch pipe through the Wilo / Boiler pump, which is inches from the inlet / return side of my boiler. What is said about zone valves and preferential flow makes sense logically, but only rationalizes why you would want the boiler pump running when a zone valve is open which I agree with. It does not rationalize why you would want the boiler pump running 24/7 i.e. why would you want to circulate water though the wild loop when all the zone valves are closed and the boiler is not firing?

ZoesDad – See below

Voltage – Yes, I am 100% certain the voltage going into the aqaustat is 24v. I have 120v coming into a junction box, which is hard wired to a 120v to 24v transformer, which feeds the wires that you see in the pictures. Plus I measured and the voltage and it is 24v. The label on the aquastat also has 240v and 24v on it as well, so I think that depending on the input, the aquastat can “drive” different loads. In my case, since I have 24v going in, it can sustain a 2.1 amp load vs 120 volts a 5.1 amp load. It also seems to confirm that the aquastat is operating on high limit only on the picture, there is no 24v and low limit load ratings. I am positive on the voltage, unsure about the meaning.

Sorry not sure how to use the quotes.

“Not circulating the boiler water when the burner runs should not cause a problem. My system does that and I think so do many others”

This video was where my journey started and was exactly what my system was doing prior to rewiring it to run 24/7. This video makes sense to me. With no circulation in a closed loop system, the water in the boiler get’s super hot and flashes to steam. Yes, the aquastat stopped the boiler from firing at 180F, but the temperature continued to rise to 220F since there was no circulation (effect of heat soak on the stagnant water). The system pressure would also rise to above the normal 12 to 15 psi to the mid 20’s and at times would activate the relief valve. This is why I believe it is illogical to have the boiler firing and the pump not running. Could this be another rabbit hole caused by the difference between a indirect hot water tank (closed loop) and tankless coil system (open?)? Again, I know nothing about tankless coil.
https://www.youtube.com/watch?v=lE8gLBUtdzg

Sprott #6 – I think this post assumed that I had a condensing boiler. I do need to maintain 140F to 180F to avoid rust.

“It would seem to me that when the ZV opens for the DHW tank zone the Wilo pump should run.” – I agree.

“It doesn’t seem to me to make any sense to continually circulate water through that short loop.” – I agree, which is why I am asking the question.

“I think that is was spott pointed out in post #22. Is there some way that ZV was connected to the Wilo pump and you missed it? – I think you mean #11? If so, I never responded because it’s not the issue or the question. Yes, I suspect the relays were configured to provide power to the Wilo pump running when the ZV is open. No, the ZV does not provide direct electrical control over the boiler aquastat, this is done indirectly by water temperature in the wild loop when the ZV is open.

The issue is NOT whether the Wilo / Boiler pump should be running when there is a call from heat from either zone (water tank or in floor heating), but whether the Wilo / Boiler pump should be running when the boiler is firing to maintain temperature and there is an absence of a call for heat.

“the plumber must have never seen a warm start system” – It was a warm start

“Also, I don’t see how to-circulate or not-to-circulate would have anything to do with the relief valve discharging” – As described above, heat soak on stagnant water in a closed loop system. I think at around 212F water goes to steam and expands exponentially, increasing the system pressure.

“I would diagram the system with all the components (aquastat, circulators, relays, etc.)” - Everything is on my basic diagram other than the relays, which I am 100% certain would add more rabbit holes.

Anyways, if anyone knows how the boiler pump / wilo should be configured to run on this older more basic system, please let me know. Thanks.
 
  #34  
Old 12-01-16, 01:18 PM
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H,
You seem to have an obsession with maintaining temp to avoid rust. If you were to replace that boiler today, unless you got one with a tankless you would get a cold start boiler which would only run on a call for heat or hot water and would not have a low limit to maintain a set boiler temp.

As far as your boiler making steam. Water turns to steam at 212 deg @ 0 PSI. At 12 PSI it takes around 242 deg to make steam which and I'm just guessing that aquastats have a high limit cut off of 240 deg. I never looked into it, just my own thought.

The issue of the zone valve I still don't understand. Simply put, you have 2 zones. 1 for heat and 1 for hot water. It couldn't be more simple. You have 2 pumps. 1 for heat and 1 for hot water. Without pics of the system I can't say what purpose the zone valve serves. Why was the ZV installed instead of just using 2 flockecks to stop the water going into unwanted zones.

Aquastats. They do work with either 24 or 110 volts. Why I mentioned it was because of the wiring being 14 gauge which is for 110V and then you said it goes to the gas valve which I know is 24V. There had to be a relay in there somewhere which I was trying to get you to post but didn't.

Anybody who would use #14 wire on a 24V circuit is either very uninformed is just lazy to get the proper wire and in either case should not be touching boiler controls. My whole point is the integrity of the whole system wiring and for that matter the piping. If they're doing work like that how can you assume anything is right and is suppose to work the way it is.

Zoesdad made all valid points and makes sense. When I asked about the wild loop I was figuring as ZD brought out, a bypass loop and was trying to get your definition of a wild loop but never happened. A bypass is used on a new boiler replacing an old boiler with a large amount of water in a high water content system for example an old system with large piping and radiators. The new boiler having only about 13 gals. of water. On a call for heat the pump would empty the hot boiler water and cold system water would return to a hot cast iron boiler shocking and possibly cracking the boiler so with a bypass loop and a throttling valve it tempers the return water to eliminate cracking problems.

I realize this is somewhat off point but all relevant to your problem.
As far as the pump having to run when the boiler maintains temp., that is only necessary with these boiler that have minimal water content and only run on demand. There is no need for a pump to run unless there is a need to circulate hot boiler water for heat or hot water.

What you call rabbit holes could be relevant to your problems. My guess is you do not need half the components you have if it was done right the first time.
Without pics or more info these are just my thoughts.


Good luck,
 
  #35  
Old 12-01-16, 02:15 PM
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just saw spott made a post, didn't read it yet

hk-

It looks to me from what you described as the aquastat wiring in post #17 -

Power coming in from the top (24v). White wire goes directly to the gas valve. Black goes into the top right and exits on top left to the gas valve. Bottom two is jumped together. Tried the L4062 number, but nothing.
and the label in pic 1 in post #17 which says -

both HIGH limit and LOW limit contacts -

“OPEN ON TEMPERATURE INCREASE”
- then you are definitely running off the LOW limit.

Once the water temp climbs above the LOW limit, the LOW limit contacts open and the path to the gas valve is broken and the gas valve shuts OFF.

In other words, the path:
[top right->bottom right->bottom left->top left-> gas valve] is broken between [top right->bottom right] when the LOW limit contacts open.

I just now noticed that your LOW limit in the pic is set to 180. I think that may in fact be the problem. Usually that’s a HIGH limit on most systems. I could see how that is playing right on the high margin and could at times cause overheating.

I’d lower that for a while and see if you have any problems.
 
  #36  
Old 12-01-16, 05:02 PM
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Thanks for the response and trying

Zoesdad – I have to think about it because regardless of how it is wired, the boiler has ALWAYS stopped firing at 180f and starts at 155f, which is what I want. Not to mention that only licensed plumbers and gas fitters would have adjusted that in the past 29 years. Certainly, I wouldn’t have. There is a differential as well on the right hand side, which you can’t see from the pictures, but again, I think it’s doing what I want it to do. What you have described to me “Once the water temp climbs above the LOW limit, the LOW limit contacts open and the path to the gas valve is broken and the gas valve shuts OFF” is in my mind the high limit setting. Are you saying this only in the context of how my system is wired? If so, does that mean that my high limit setting does nothing or does the gas shut off at the lower of the low limit and high limit settings?

Spott – See below

Maintaining water temperature – I am not obsessed with it. I am just suggesting that this is the way that it was originally setup, been running perfectly for 29 years and based upon what I have attached and what I have read is the norm for older NON condensing boilers. A new boiler would probably be setup for cold start but isn’t that because it is a condensing boiler, which uses the colder return temperatures to absorb any residual heat (prioritizing efficiency of new over longevity of equipment of old)? A new boiler is thousands of dollars, running a $100 pump 24/7 that consumes 60 watts is incrementally probably $40 a year. Something has got be right with a boiler that has lasted 30 years.

Boiler making steam – As I indicated, the high limit is 180F and the boiler is NOT firing when the temperature increases from 180F to 220F. Put another way, if the boiler isn’t firing and the temperature is continuing to rise, what option could there be other than a lack of circulation? Whether that is caused by a bad pump (youtube video), not running pump (my case, I think), rust / debris or calcium buildup? Hard wiring the boiler pump to run 24/7 fixed this / the original problem, so you can rule out rust / debris and calcium buildup as the problems.

Zone valve – Again, it allows hot water from the wild loop to circulate into the heat exchange that is built into the indirect hot water tank. I believe this is how an indirect hot water tank system works. “You have 2 pumps. 1 for heat and 1 for hot water.” - I’m not sure about this statement. One pump definitely provides circulation to the in floor heating system or heat. The other pump doesn’t just provide circulation for the hot water tank but the wild loop as well. If the only purpose of the pump was hot water, then you wouldn’t need the zone valve, you would just run the boiler pump and circulate water through the indirect hot water tank every time the boiler pump was running whether it needed it or not. I think this is where you are going, but it goes back to what I said in #15 “Because I have 3 loops in essence. If not, then I would be either wasting energy circulating through a zone (water tank) that doesn’t require heat or overheating the water in the hot water tank, which has a separate relief valve (temp and pressure).“

Wiring – I understood where you were coming from originally. I didn’t want to make it a point of debating it as using a slightly thicker gauge wire than required seemed to be a very minor issue and more importantly irrelevant to my issue. I obviously can’t stop you from extrapolating this minor issue into something more. Yes, simple mistakes can at times lead to more. I just don’t think it’s the case of 14 awg wire and a system that has worked well for 29 years. Just noticed that Geochurchi, who appears to be an electrician, said something similar.

Bypass Loop – As you say this is common on NEW boilers. Mine is 29 years old and I don’t believe I have one or how it would be related to my issue. I defined what I believe to be the wild loop, from what I can tell 3 times between words and pictures (#15, #23, #33).

Until recently, the system has been running perfectly well for the last 29 years and has passed muster with all the licensed plumbers and electricians and inspectors that have ever touched it. Yes, the indirect hot water tank was replaced, as was a sticky zone valve, the pilot gas tube and about 5 thermocouples, but the bones, being the boiler, water pipes, aquastat, gas valve, the wiring / relays and how it operates are all 29 years old original. So to start asking questions / raise concerns about how the copper pipe is connected or the voltage / gauge wire used on the aquastat or the temperature settings on the aqaustat or cold start vs. hot start just leads me further from the answer to what is a very simple question and an extremely long thread. The 2 plumbers I have talked to and who have visited my house and the youtube video have indicated that it is not normal that the circulator pump is not running when the boiler is firing. Again, my 24/7 running of the pump fixed the problem and confirms that the pump should be running when the boiler is firing. What I wanted was a confirmation that this is right from others that have a boiler / hydronic heating system and indirect hot water tank. The only thing that even makes me ask this question is because based upon my simple aquastat (no aux outputs B1/B2,C1,C2 etc, no transformer), I don’t know how, using 3 DPDT relays they could have told the boiler / circulator pump to run when the boiler is firing. I'm not an electrician, so my lack of understanding probably isn't relevant, but there were also no wires other than power connecting the boiler aquastat or gas valve to the rest of the system, so how could they have wired the pump to run when the boiler is firing? This leads me back to the question of whether it is normal for the pump to not run when the boiler is firing on my old closed loop, non condensing boiler, indirect hot water tank, hydronic heating system.

Given so much evidence pointing in both directions I’m not sure. As I indicated, I get the sense that much of the debate has to do with operating differences between new equipment (tankless coil / condensing boilers / aquastats with outputs) and old equipment (non condensing boilers / aquastats without aux controls).

Again, no issues and happy to pay the $40 to run 24/7. Thanks and hopefully someone has some insight on how my / these older systems should work.
 
  #37  
Old 12-01-16, 05:53 PM
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H,
I wasn't suggesting a new boiler, just saying anyone buying a gas boiler today would not get a duel aquastat but a cold start or on demand if you prefer the term. That is with a condensing or noncondensing boiler. My previous statements were made with noncondensing boiler in mind.

To simply answer your question about running pumps, I have a boiler that I put in back 1984 that supplies heat and also an indirect hot water heater of the same age and my boiler happened to come with a triple aquastat meaning it operates to maintain boiler temp even when nothing is calling and my pump does not run when the boiler comes on to maintain temp. I can adjust the maintaining temp to whatever I want or eliminate it altogether but whatever I choose to do if the heat calls the heating pump comes on, if the indirect calls then that pump comes on. Other than that they are silent which is what they should be.

As for older boilers still being around I believe it's because of quality. By todays standards not as efficient of course but the overall quality of the product was better. A good example is Burnham Boilers. A few years back they decided to have there cast iron sections made overseas and ended up with massive leaking problems. I put 2 steam boilers in a house and had to replace them under warranty the next year. The castings were so thin they just didn't hold up. The same thing happened with Utica. I would never suggest changing a boiler just because of age.
 
  #38  
Old 12-01-16, 06:36 PM
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Thanks Spott.

Since you have installed a system similar to mine and configured the pump to NOT run when the boiler IS firing to maintain temp I will wire my boiler pump / relays accordingly to test it out. Hopefully I don’t get the flashing and the relief valve discharge. As unintuitive as it is, I’m just a lay person applying logic and am happy to try it out.
 
  #39  
Old 12-01-16, 07:59 PM
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H,
I agree a 40 deg override in temp is ridiculous and I've never seen it before so it's hard to imagine but that being the case it does sound like something is amiss. If you have a regular gas fired boiler with approximately 13 gals. or more of water and no flochecks in the lines to stop the water from at least moving by conduction through what you call the wild loop or any of the 2 loops it sounds like there is a problem. It will not flow pass the zone valve.

This is just a thought. Do you know if there is a check valve built into your Wilo pump. You can get pumps with or without check valves installed. That would not allow the water to circulate even by conduction but the 40 deg swing would still be excessive. I mention this because that pump must have been changed because that brand was not around 30 yrs ago or at least not in my area.

One more thought about the aquastat settings. I realize you're comfortable with the settings but they are made to be adjusted and honestly 180 seems a bit high for slab heating and if you tried say 160 and 140 to see how it goes you would save some fuel and maybe not even notice the difference. If it doesn't work out you can always put it back or try lowering it by 10 deg first. Just be sure to keep them 20 deg apart and adjust your differential to 10 so there is not that big a swing in temp.

Just my thoughts.
 
  #40  
Old 12-01-16, 09:02 PM
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Thanks for the response.

Check valve - I don't know. The wilo pump was installed in 2012 when the indirect hot water tank was replaced. The system has not changed at all since then and has operated perfectly for 5 years until recently. When the wilo pump was replaced recently (last two weeks), the plumber just removed the housing with the motor and left the "valoot" (sorry about the spelling) / plumbing in place. The pump really didn't need to be replaced, as the motor was spinning, the impeller was turning and ultimately did not fix the flashing problem. But he thought the lack of circulation was causing the flashing and it was a reasonably cheap fix, so I was okay paying for it and having a spare part. Plus it matched the Milan HVAC youtube video as an explanation that made sense to me.

Aquastat - Yes, in slab heating is heat sensitive. A thermostatic mixing valve was installed as part of the original installation 29 years ago on the supply side of the pipes going into the floor. Again, I did not mention it because I don't think it has anything to do with the flashing issue and the question of how the circulating pump should be configured to run on the wild loop.

Thank you Spott. I can tell that you are thinking hard about my question and trying to cover all the bases and genuinely trying to help me.

Just outta curiosity, why do you think my definition of the wild loop is incorrect? I only know and started to use the term because the plumbers that have come to my house and seen the pipes refer to it when they are explaining it. Also seems to match what Zoesdad posted as well. The only rub was whether it is the smallest or longest loop. Mine is the shortest loop.

Anyways. Thanks again
 
 

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