Pressure relief valve leaking

So Ive replaced the valve twice now on my oil fired boiler. Works fine for about a year then slowly leaks. Checked my expansion tank on the boiler and theres NO air in it. Funny thing is though, its not taking any air at all either. No water leaks out of the shrader valve on the bottom so Im not sure that the diaphram is bad. I even used an airline from my big air compressor and still no air will go in the tank. What should I look at?

 

I believe the tank is full of water by tapping on it. But I dont think the bladder is ruptured due to no water coming out of the valve. So my question is, how come I cant get air into the tank?

 

What pressure are you running in the boiler ?

 

15 psi I think???????????

 

I think most Boiler Relief Valves are pre-set at 30 PSI.

What are you using as a gauge to estimate the 15 PSI ?

You must be running at something above the estimated 15.

Depending upon what the actual pressure is, that may explain why you can't add air.

You may have to find a vent and open it to allow for air to enter . . . . or drain off some water in order to allow for air to enter the Expansion Tank.

And set it at ≈12PSI for a one floor dwelling, maybe ≈15 for a two story. Then close the Vent or the Drain, and refill . . . . but the cold or stand-by pressure ought not be much more than the 12 or 15 lbs . . . . rising to 20 or 25 when heating; but never approaching the 30 PSI which sets off the Relief Valve.

I AM NOT a Plumber or HVAC Expert . . . . just an observant DIY observer.

You may want to consult with a professional.

 

It has a vent on the top but not sure how to open it. I even has the pressure relief valve open when I tried to ill the tank but still didnt work. And it has a gauge built into the boiler that shows pressure and temp.

 

What does the Gauge on the Boiler read ?

Do't you have a little Bleeder Valve upstairs on one of the baseboard radiators ?

And a drain faucet at a low spot near the bottom of the Boiler . . . . with a hose nipple ?

 

Your bladder is either ruptured or simply deflated. Water doesn't have to be coming from the shrader valve to have a defective bladder.

If you tap your tank with a screw driver the top should sound solid and the bottom hollow because of the bladder being filled with air. If both top and bottom are solid the tank is water logged and your heated water has no place to expand and will at 30 psi release your relief valve.

Remove the tank and replace. Once removed from the system you can try to drain and recharge if you want but they are cheap enough to just replace.

Check air pressure in new one before installing to make sure it's charged. Should be about 12 psi. If you run your system higher match the tank pressure to your cold system pressure.

If you don't have one already you might want to install a shutoff valve between the tank and its connection for future maintenance.

One thought here if you are removing a full waterlogged tank. A #30 extrol holds about 4.4 gals of water when full and at about 8.3lbs a gallon that tank will be about 35 lbs. so be careful.

Hope this helps a little.

 

Yes the tank if full of water. I just think its wierd that NO air will go into the tank and that no water will come out of the shrader valve if the bladder is ruptured

 

Im going to replace the tank but heres a question. How do I know what size I have if there no markings on it? Its not very big.

 

Im also guessing I need a potable water tank?

 

If you push in the stem of the shrader valve you should get some water if the bladder is ruptured, if not it might just be delated.

The customary size is a #30 unless otherwise specified. Pics of the tank would help if not sure.

You have a closed system with no where for the water to go by adding air to the bladder. Your system is full with no release except the relief valve. The tank has no place to expand.

A potable tank has nothing to do with your problem. If you need one that's another situation and will not help your problem here.

Try this sight to get an idea of what you need. Click on HEATING and the EXPANSION TANKS and you'll see what's there.

SupplyHouse.com - Plumbing, Heating & HVAC Supplies

 

Thanx for the link. Unfortunatly I dont know the size of my boiler as its really old and hard to read the tag. But the tank is 8" wide and 12" tall which looks to be a 2 gallon tank. Also since the hot water goes to the shower and rest of the house wouldnt I nead a tank for potable water?

 

Your boiler water only goes to your baseboard heaters or whatever emitters you have. Your faucet water comes from a different source. You may have a tankless coil in your boiler so you think it's the same water but it is a separate coil inside your boiler.

If your system is that old I doubt that you would have a #15 on there just because back then everything was always oversized and #15 were hardly heard of. Is there a chance your tank was changed and someone put in the wrong size.

If the tank is too small it will not take the volume and will release the pressure from the relief valve.

Pics would be good.

 

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Your boiler looks like a Weil McLain P368-WT. The WT is for the tankless coil for you domestic hot water. Your tank is an Amtrol #30 extrol tank.

You already have the isolation valve so you don't have to drain your system to remove the tank. Just shut the valve off and if it holds unscrew the tank and install a new one.

You have 2 pipes coming out of the top of the boiler. The one on the right goes through your air scoop and extrol the way it should to help with the air and expansion. The one on the left does not. Where does that pipe go.

That tapping was made for a vent and not a feed line.

That boiler is older but not ancient. It probably dates back to the late 70's somewhere. Back then they didn't change designs or have so many models as today. That was and is a good boiler. I happened to have the same one in my house that I installed in 1984 and it's still going strong.

I only see 1 pump and no zone valves but 2 supplies and 2 returns so I'm assuming you have a somewhat of a split loop or 2 floors on 1 stat. They should have taken that left supply line after your flocontrol valve (red) near the wall instead of from the boiler.

When your boiler runs for hot water do you get heat where ever that line goes. There's nothing to stop the gravity flow. That's the job of that red valve.

By the way your domestic hot water is coming from that round tankless coil on the upper right hand corner of the boiler where your pressure gauge is. Those 2 pipes are your cold in and your hot out.

Just an observation I thought I'ld. share.

 

Are you saying you beleive the tank is this one? 102-1 - Amtrol 102-1 - #30 Extrol Expansion Tank (4.4 Gallon Volume)

It cant be that size as that one is physically larger. Mine is 8" wide and that one is 11. I beleive mine is 2 gallons. Thanx for that great observation btw even though I have no idea what most of that means, haha.

 

Getting back to the original reason for this Post, somehow your system has eliminated the air cushion. There is no place for heated water to expand, because you cannot compress water.

The fact that you cannot put any air into the Expansion Tank indicates that the bladder is collapsed. We don't know whether it has been ruptured; but if it were, you'd expect water to exit the Schrader Valve.

I have asked what the PSI is indicated on the Boiler Gauge; with no air in the system to compress, the heated water has no where to exit EXCEPT the Boiler Relief Valve. There's nothing faulty about the Relief Valve . . . . it's seems to be doing exactly what it was designed to do - provide safety RELIEF.

Somewhere, you have to remove some water so that replacement Air can again be put into the Expansion Tank. If, in working with the Schrader Valve, water begins to exit, then you'll know that the Tank is bad . . . . but right now, that has yet to be proven.

Is i possible that some unauthorized person allowed all of the air cushion in the Expansion Tank to escape ?

 

First thing to do is to verify boiler water pressure with another temporary gauge. Frequently boiler pressure gauges give wrong readings.

Here is old DIY post on one. http://www.doityourself.com/forum/bo...ure-gauge.html

First before attaching temporary gauge, open drain valve to flush out any debris. I would also recommend using length of hose from hose fitting to gauge so it is vertical and debris will not affect readings.

 

P,
Yes, that is the size tank you need. There are different tank manufacturers and although they are the same capacity they may be different sizes. You definitely need at least the #30 which is what it looks like you have on there now.

Do you have all fin tubed baseboard or do you have any cast iron radiators for heat. I ask because CI requires a larger tank, generally a #60.

Let's solve one problem first and if you have questions on the other things I'll be happy to explain what I meant.

Bottom line if you have conventional baseboard heat you need a #30 extrol tank. Don't worry about the dimensions. Just make sure you match the pressure in the tank to what you run for cold system pressure and you'll be fine.

Although it's important for your pressure gauge to work properly it has no bearing on your current problem at this time.

 

Ok first of all thank you guys for your help so far it has helped me learn more about this system. Yes I only have baseboard heat in an 1260 sq ft rancher. To check water pressure will this gauge work? https://www.amazon.com/gp/product/B0...KIKX0DER&psc=1

To measure pressure I just go outside and hook that gauge into my water connection correct? Then if I have 40, 50 , or 60 psi I set the tank to that pressure or 12psi? Ive read so many conflicting things Im getting confused.

 

Also spott, that #30 tank is 3" wider and 3" longer than what I have now. That seems like a lot larger. Ill gladly buy it since it has a 1/2" connection like mine has but itll hit the copper line behind it so Im not sure it will fit. When I checked the psi in the tank I waited for the boiler to cool, cut the water to the boiler, then opened the relief valve til the pressure dropped. Did I maybe not get the water out enough for the air to go into the tank?

 

There is no relationship between hydronic heating system water pressure and street water pressure. Pressure regulator valve sets heating system pressure.

Connect temporary gauge to heating system drain valve., Not to something on house cold water piping. Do not see drain valve in your pictures but there should be one around the furnace.

The 12 to 18 psi is based on height of highest heating element in system with 12 psi the usual minimum. It is not critical, just minimum needed.

To measure 12 psi do not use a 200 PSI gauge. Best resolution is 30 psi, but 50 or 60 psi is acceptable.

Here is a 30 psi $4.35 gauge with quick delivery, often next day:
PEM199 - Winters Instruments PEM199 - 2" PEM Dual Scale Economy Pressure Gauge (0-30 PSI)

 

Should i just remove the tank, empty it, then fill it with air to see if it holds? It doesnt need water pressure on the bladder for any reason to hold pressure right?

 

Air won't just wander into the Expansion Tank just because you've relieved the pressure.

You must actively pump air into the Schrader Valve while the system is open, as if you were adding air to a tire.

And 12 PSI would be appropriate since you said your home is a Ranch.

 

Vermont, I had the pressure relief valve wide open while pumping air in. Was that not good enough? Should I have had the drain on the bottom of the boiler open? Doughess, stupid question but where do I mount that gauge? I just cjecked on the boiler and I beleive the gauge reads correct as it hit 30 psi then water started dripping quickly out of the relief valve til it went down to 20 psi.

 

P,
No matter what tank you install they all have 1/2" pipe.

You do not have to remove any boiler water and shouldn't IN YOUR CASE to recharge tank. You will not let out enough water, just compound your problem by letting fresh water back that brings air with it that must be bled.

For the moment forget about the pressure gauge and concentrate on your tank problem. Ignore the post about the pressure gauge. You are getting confused and you're making this more difficult than it has to be.

If you insist on listening to doug then I will bow out and put you in his hands which in your case will only do you an injustice.

I don't know how I can put this more simply.

1) Turn off your boiler
2) Close the valve above your extrol tank
3)Remove the tank being careful of the weight of a full waterlogged tank being about 35lbs.
4) An option is to drain the removed tank after and recharge or buy a new one.
5) If the tank doesn't fit by the piping add a 1/2" nipple and a 1/2"elbow another nipple and elbow to relocate tank and get away from the copper bypass line.
6)Open valve above tank
7)pressurize system if needed and bleed if necessary which shouldn't be if directions are followed.
8)Turn on boiler and test for proper operation.

You are getting street (house) pressure confused with boiler pressure. They are two totally different things.

FORGET ABOUT HOUSE PRESSURE FOR NOW. If your faucet pressure is fine then you have no problem. I see a BLUE tank in the picture which is telling me you most likely have WELL WATER. Forget about that for now.

I hope this helps a little.

 

Spott great writeup thank you . I love learning new **** everyday! You say that all boiler expansion tanks have a 1?2" nipple. I was thinking of buying this one at one point and it had a 3/4" 140N738 - Amtrol 140N738 - THERM-X-TROL ST-8 Expansion Tank

. Is this not for a boiler? I just wanna learn more here.

 

That is an expansion tank for potable water (faucet water) which is not what you need. It is a different tank which you would buy to install on your house cold water inlet of a hot water tank if needed. Those tanks are 3/4" and also are rated for a higher pressure to handle house pressure and also made of different material I believe because the are installed on your potable (drinking ) water line.

You can use them on heat but it is overkill. They are also much more expensive. You do not want that tank. A simple #30 extrol is what you need.

 

Good lord theres a lot of different stuff when it comes to home heating! Thank god for you guys!

 

A few years back it was pretty cut and dry. They were simpler times as they say but like everything else the heating industry has evolved and it is becoming a specialty where knowing what is out and available to best suit your purpose is really a full time job now.

Gone are the days when you can just look at a fire and tell how it's burning or jumping across terminals sometime to troubleshoot. Meters and testing equipment and instruments and the knowledge to use them are the norm rather than the exception in the trade today.

Installing is one thing, troubleshooting is another.

 

Regretfully have to bring this thread back. So I replaced the expansion tank with the extrol #30. Then I sprung a leak on a joint going to the T that the tank is on. Tried desperately tonight to resolder it but that joiont is NOT taking. Also the only way I could get the water out of the pipe was to take the tank back off. No matter what valve I closed or what I drained the joint wouldnt get hot enough. SO, should I just replace the copper or would PVC work? Im not sure pvc would suppert much weight without bracing.

 

You can not solder a copper joint as long as there is water in that pipe. You have to be able to isolate that section of pipe to re-solder the joint. Also, if you are trying to re-solder the joint in place, the joint is contaminated and dirty so the solder won't adhere to the copper. There may be a type of acid flux that will work but I would leave that up to a person with a lot of experience in soldering. The best solution would be to remove the piece with the bad joint so the fittings can be cleaned and fluxed properly. And "NO" you can not use plastic! And one last thing, I hope you pre-charged the tank with 12 PSIG of air pressure before installing it.

 

Yea I tried to remove the water but the only way was to remove the tank. Tried turning the valves off and draining from several places but no luck. What is the purpose of the red valve? I turned the knob on top off and noticed it was hardly open.

 

That red valve is not a shut off valve, it is a flow control valve to keep the hot boiler water from flowing by gravity to the radiators when the boiler is supposed to be shut down. Movement through this device is by pump operation only. You should turn it closed, (clockwise) to it's normal position.

 

That is classic sign of water in pipe when heating copper soldered pipe fittings . With plenty of heat ,if solder does not melt there is water in there. I have seen fittings turn purple/blue from high heat and solder still does not melt.

Basic physics: 1,000 BTU needed to evaporate 1 pound of water.

 

pantera –
I don’t want to muddy the waters here, and I’m no expert for sure. I don’t know which joint you are saying is leaking but I see a union in the picture which is there so things can be taken apart. The air scoop to the left of the union is also threaded and that can also be unscrewed if need be.

I don’t know whether removing any of that would help you to keep the joint dry as you solder. But it looks like it might if the joint that is leaking is near that air scoop. You would need to drain the water from that piping before you opened up the union or you will get a big flood. If there are no other shutoff valves around that piping then I think you would have to drain a lot of water from the system to bring the water level down below the piping to be soldered.

In other words I think there is a good chance that even after draining the water from the pipe, it won’t be dry enough to solder unless you open things up and let it all drip out and dry with a rag.

Maybe the other guys would disagree. But I know that just a little bit of water sitting in the pipe and you can heat all day long and you still can’t solder.

I think you probably should support that tank somehow. I wonder if because of the increased size and extra weight it put more stress on a joint and the joint sprung a leak.

 

P,
Can you post a pic of the leak. From the pic I see you do have some options to remove the water.

As Z pointed out you have a union that can be opened to let water drain out and if you removed the tank and open the shutoff above it water would drain out there also

I would start by getting hangers or wire or anything to support that pipe before you start to work. I would put a hanger between the air scoop and union and another between the union and Flocheck (red valve) to take the weight off the pipe and joints. Depending where the leak is you may want another hanger before the air scoop also.

You do not want any weight on the pipe of the joint to be soldered.

The handle on that red valve should be closed all the way to prevent water from coming back to the boiler. It is a one way check valve. By opening it up you allowed water to come back to where you were trying to solder.

Remove your expansion tank to take the weight off of the pipe before you solder.

What kind of torch you have depends on how much heat you produce. Once you open that pipe, either by union or tank you can pitch that pipe a little so the water will flow out of the opening.

Once open, if you heat the pipe you can boil the water out and with the pipe pitched it will run right out.

As you found out you cannot solder with water in the pipe.

Sometime you can resolder a joint but you must clean it completely with sand cloth and flux it real good and if you can get the solder to melt then you can add solder also. An extremely clean joint, all the way around and good flux and enough heat is the key.

There does become a point though where you can overheat the joint and it becomes unsolderable, if that's a word. The pipe changes properties or something and cannot be soldered and must be replaced.

Sometime it's easier to cut out the section and replace with new fitting and couplings.

Hope this helps a little.

 

First of all thank you all for your help so far, its greatly appreciated and Im learning a lot. So Im going to remove all the pipe from the top 90 to the red valve as the pipe and joints are very corroded and i believe thats part of the reason for the leaks. Ive have quite a few copper pipes spring a leak in this house over the years so Im getting good at soldering. SO, Im STILL having water coming out of the pressure relief valve even after replacing the tank. Pressure is fine for a few hours but then creeps up to 30 psi somehow. What would be next to check? Im wondering if leaving on of those valves opened or closed is causing this?