Purge station redesign


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Old 06-27-17, 07:19 AM
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Purge station redesign

Hello again. I have a four-zone boiler system, and nearly all the shutoff valves on the zones were leaking, so I'm basically rebuilding the supply and return headers from scratch. So I have a chance to do it right. What's the best way?

The Honeywell zone control valves were previously on the return side. But it occurs to me that the simplest design would be to put the zone valves on the supply side, and put these guys on the return side:

50613 - Webstone 50613 - 3/4" Sweat PRO-PAL Ball Valve w/ Drain

The simplicity seems attractive -- just two valves per zone, one on the supply and one on the return.

To purge a zone, I would just open up the zone valve for the zone being purged, and flip the return-side valve to direct water out the spigot.

Am I missing something? Would I need any other valves on the zones? Or is it really this simple?

Thanks as always for the great advice!
 
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Old 06-27-17, 08:11 AM
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Or I guess another option would be to put simple isolation valves on each zone return, and then a single "ball valve with drain" on the main pipe after the return-side header.

Do I need anything else?
 
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Old 06-27-17, 09:08 AM
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I'm reading this earlier discussion:

http://www.doityourself.com/forum/bo...mendation.html

In that discussion, a purge valve was recommended on both the supply and return sides. I guess this was for air elimination when filling the boiler kettle. So now I'm wondering if I'm missing something.

I made the following diagram of what I'm proposing. Excuse the crude diagram, but hopefully this gives the idea. For simplicity, I just showed two of the four zones. It's the orange pieces where I'm asking for feedback.

Does this make sense, or do I need something additional to facilitate filling and purging? Note that I only have purging on the return side:



Thank you for any help!
 
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Old 06-28-17, 03:46 PM
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Please, could someone take a quick look at my diagram? I just want to know if I can valve the zones as follows:

* Supply side on each zone: Zone control valve
* Return side on each zone: Isolation valve
* Return side after the zones join: Ball valve + drain

Purging a zone would involve opening the two valves on that zone (zone control valve on supply and isolation valve on return) and closing all others. Then switch the ball valve + drain to direct water to the drain (rather than back through boiler). Force air out the drain by filling with supply water at high pressure (~25 psi) through fill valve.

I think this works? But I'm still totally new at this, and "I don't know what I don't know," as they say. There could very well be something I'm missing, so I'd be very grateful for a quick "that seems fine".

Thanks for any help! And thanks for all the excellent help you've all given me so far. I wouldn't be able to take on this project if it wasn't for all the advice that you've so generously offered. I definitely feel more confident being able to modify and maintain my boiler in the future.
 
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Old 06-28-17, 07:06 PM
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d,
If it were me I would put an isolation valve on each supply line before the ZV, and then on the return I would put a drawoff and then an isolation valve on each zone.

For purging purposes the common drawoff will work but with 4 zone valves I would be concerned if a ZV had to be changed. With the common drain you're going to have to shut the whole system down at least while you drain that zone. With individual drains on each zone you can isolate that zone and keep everything else running. You wouldn't even have to shut the boiler down until you are ready to refill after the repair.

Your way will work but with that many zones and possible problems I like to be able to isolate any problem areas for convenience.

One other thing I like to do is to isolate the pump in case of replacement. With valves on both sides of the pump you don't have to drain the boiler. Just shut off the valves and remove the pump. When done you don't lose enough water to have to bleed anything.

Just my thoughts. The less water you have to remove the more time you save and the better off you are not adding fresh water to the system.
 
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Old 06-28-17, 09:32 PM
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Thank you once again for the excellent advice spott. I hadn't considered the need to shut the whole system down to drain one zone. That does seem like a major drawback.

I guess my limited experience leads me to a "less is better" philosophy toward valves. The original impetus for this project was that I previously had:

* On supply side of each zone: Isolation valve
* On return side of each zone: Isolation valve, zone valve, drain, isolation valve

So 12 isolation valves and 4 drains, and nearly all of them were leaking. We have extremely hard water in my area, which may be the cause. But you talk about the negative effects of adding fresh water, and my system was leaking and filling all the time.

So reducing 12 isolation valves and 4 drains to 5 isolation valves and 1 drain seemed attractive to me just because it's many fewer points of failure. I guess that's what it comes down to: I see valves as possible failure points and want to limit their use. Maybe I just need to get over my negative (but admittedly quite limited) experience and better appreciate their benefits in terms of flexibility.

Anyway, thank you again. You've helped me better understand the tradeoffs. I'm not sure yet what I'll do, but I feel like I can make a much more educated decision now.
 
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Old 06-29-17, 10:05 AM
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d,
One more thing to consider is. Fresh water is a boilers worst enemy in any condition. If your water is that bad that it's ruining your valves imagine what the constant feeding due to leaks is doing to your boiler sections. It's a lot cheaper to replace a valve than a boiler.

Gate or globe valves have replaceable parts if they leak as do boiler drains. Ball valves have nothing that can leak and even if a boiler drain leaks, with the right placed ball valves for a couple of bucks they're easily replaced with little or no draining.

You will never be sorry you installed the ball valves if the time ever comes for maintenance.

Good luck,
 
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Old 06-30-17, 08:41 PM
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Thanks for your help spott. Yes, the inside of my boiler is probably not in great shape. It still heats the house, though, and I'd like to keep it running as long as possible, which is why I'm doing this rework project.

Other than avoiding introducing fresh water, do you have any other thoughts on dealing with hard water? We've had so many problems related to hard water, apart from the boiler: dishwasher leak, swamp cooler leak, heavy scale on faucets and shower windows, etc.

We're looking at installing this 3M product on the water supply line coming into our house:

3M™ Aqua-Pure™ Whole House Scale Inhibition Water Treatment System AP430SS

It doses incoming water with 2 to 3 ppm of polyphosphates, greatly reducing the minerals' ability to collect as scale.

I also just replaced my air scoop and Taco vent with a Spirovent Jr to improve air elimination.

Finally, I also plan to clean the boiler and piping with Fernox F3 and then protect with Fernox F1. It seems like many people around here aren't fans of chemical treatments, but our hard water in the Colorado Rocky Mountain foothills is pretty extreme, so I'm willing to try extreme measures.

Thanks again for all of your extremely helpful advice.
 
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Old 07-01-17, 09:39 AM
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d,
I also am not a big fan of chemical treatments especially on older systems. A person experience a few years back was a Housing Authority I was taking care of, against my recommendation let a boiler treatment sales rep treat their 30 year old boilers. All it did was loosen up all the rust and foreign matter inside the pipes and create all kinds of leaks. I didn't know that about the treatment until I got there on a boiler leak call. They decided not to let me know since they knew my feelings about it. Upon discovery of the leaks the chemical company was called and reiterated my concerns about causing leaks in older systems, which the salesman conveniently forgot to mention.

After the damage was done and repairing numerous joint leaks we ended up flushing the whole system and they never used it again. This was used in a highrise commercial system which I'm sure cost them thousands of dollars never mind the cost of repairs.

This all got buried quietly and since it was a federally funded building at the tax payers expense.

Possibly starting preventative treatments on a new system might be worth it, on older systems where the damage has already been done I think it's more of a detriment. If you elect to try this just be prepared in case of problems. Sometimes the rust is the only thing keeping old pipes from leaking.

On a brighter note the Spirovent was a good choice and well worth the money.

As far as filter systems go that's not my field and cannot offer any intelligent solutions. I have run across a few cases in my area and had to do a lot of research on my own which generally started with getting the water tested and then talking to the local water department to get there thoughts and pick their brain about who to call for filtration systems.

Every area is different and only the pros in your area I believe know how to deal with the problems and solutions.

I wasn't trying to suggest a new boiler. If yours is still working then by all means I say leave it alone. I'm not one to go new to keep up with the Jones'. My own boiler is over 30 yrs. old and still working fine and I have the means to change anytime I choose. New doesn't necessarily mean better.

Just one more thought about boiler chemicals. Once the air is removed from the water in your boiler the water it becomes as we say dead water and is no longer corrosive which is why fresh water is bad for boilers. It's because of the air that is in all fresh water. If you can prevent the constant refilling of the boiler, chemical treatments becomes a moot point. At least that's what I find to be the solution in my location, unless you have a different situation.

I know this is long but I hope it helps a little.
 
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Old 07-03-17, 08:06 PM
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Thanks again for all the helpful advice spott. Your first-hand experience with the nasty results of boiler chemicals is especially helpful. I hear what you're saying, about the cure possibly being worse than the disease. I think you just talked me out of it. The boiler does its job, and I'd hate to destroy it.

Thanks again.
 
 

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