Taco Zone Valve seat leaking

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Old 11-26-15, 12:09 PM
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Taco Zone Valve seat leaking

Hi,

I recently bought a home with a furnace equipped with 3 taco zone valves and a honeywell zone valve. My previous issue was resolved here: http://www.doityourself.com/forum/bo...aco-valve.html

This time I've run into an issue with my Taco Zone Valves. Two weeks ago, I was in the middle of working on a paper when I went downstairs and found that my basement was flooded with over 5 inches of water. This is what happened:

http://i.imgur.com/h0n8xI4.jpg

Two of these zone valves started leaking in the center. I cannibalized parts from two spare zone valves and replaced the "guts" inside the seat, including the spring and the metal mounting plate. Both of those zone valves work perfectly now.

However, a third zone valve started leaking this morning and the basement flooded again. The Weil-McClain was running at around 30 PSI and 140 degrees(F) when I shut it off due to the leak this morning.

It started leaking from the same place as the other zone valves. After I cut off the water supply and removed the head/metal plate, you can see what I'm talking about:

http://i.imgur.com/Zkg7Zbf.jpg

I have a feeling that if I buy a zone valve tomorrow, I can again, cannibalize the parts and fix it. However, what worries me is that all three zone valves failed in the same way, and in quick succession. Before I replaced 2 of them, none of these were new.

What could be the cause of this problem? Boiler overheating? Water quality/hard water?

I'm getting a bit stressed out about this, since I have a long workday and I'm afraid that one day the leak is going to start when no one is home to take care of it.

Thanks in advance, and happy Thanksgiving to everyone!
 
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Old 11-26-15, 03:08 PM
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I've seen a few Taco zone valves leak a little bit, but never anything like that. Are you saying that 3 of them have failed in succession, in exactly the same manner?

If the boiler TP relief valve is functioning properly and you are not getting any discharge of water from it, then boiler overheating is not your problem. What does the gauge on the boiler read when the boiler is a its temp. high limit?

There is an arrow on the Taco zone valve body which shows the way it should be installed, relative to the direction of the water flow. Are the valves in your system installed properly?
 
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Old 11-26-15, 05:18 PM
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That is really strange. I'm not the boiler/hydronic system pro but I have worked on a lot of systems and have never had a single leaking valve like that. Usually they just get stuck.

Maybe NJT or Larossa can shed some light on the subject.
 
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Old 11-26-15, 05:59 PM
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To answer your questions:

1) Around two weeks ago, two of them failed simultaneously. This morning, the third one failed. When I replace this third one, I will have essentially replaced all of the old Taco valves on the system, except for the bronze seat attached to the pipes.

2) It was at 30PSI and 140 degrees(F) when I shut the system down due to a leak. I'm not sure if this is normal for a Weil-McLain CGa.

3) The arrows are pointing in the right direction(down).

Also, before either time the zone valves failed completely, the house has been getting great heat. The system works, but the zone valves have just kept failing, and I don't know what is making them fail, which is stressing me out. I think I'm going to stay away from Taco products in the future, since the Honeywell seems to be taking whatever the others can't handle in stride.

----------

I also have a bit of an unfortunate update to make:

Shortly after I removed the taco valve and restarted by boiler so that the remaining 3 zones could get heat, my boiler began to make a loud clicking noise. I went downstairs and realized that the circulator light was flashing(with the clicks) and the circulator was not starting. I couldn't figure out why, but after checking the Argo relay box, one of the relays(the one on the right) was soaked from the water coming down from the zone valve. The copper strips inside were corroded beyond recognition, and it's the only thing I could find that was seriously out of place, so I'm figuring that it's also the reason why the circulator is refusing to start, and the boiler keeps clicking. I've shut the entire thing down.

I'm starting to feel a bit in over my head at this point. It has been a long thanksgiving
 

Last edited by plc59; 11-26-15 at 06:01 PM. Reason: more information
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Old 11-26-15, 06:03 PM
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30psi is a wee bit high. You should be around 15-20psi. At 30psi you risk the T & P (temperature and pressure) valve opening.

It would appear that the relay/control box is going to need to be replaced too.

Ah...yes..... it never rains... it pours.
 
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Old 11-26-15, 06:16 PM
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Any idea why my pressure is getting that high?
 
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Old 11-26-15, 06:40 PM
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Most likely not enough air in the pressure tank.

The following thread is a sticky that covers the problem.
http://www.doityourself.com/forum/bo...sion-tank.html
 
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Old 11-26-15, 07:25 PM
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yes check psi in tank ( exp)... I will read this thread to see what advice I can give...
 
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Old 11-27-15, 04:17 AM
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Heating boilers do NOT have temperature and pressure safety valves, the safety valve is actuated by pressure only.

While most heating boilers have a maximum allowable working pressure (MAWP) of 30 psi some boilers are rated higher. Running 30 psi on a boiler rated for 45, 50, 60 or higher pressure is perfectly acceptable. The important thing is to be about 10% below the MAWP at the highest pressure. Check the boiler nameplate for the MAWP and check the safety valve for that set pressure. Never use a safety valve with a set pressure higher than the MAWP.
 
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Old 11-28-15, 08:20 AM
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Hi, I wanted to give you guys a bit of an update. The PSE&G repairman came this morning and replaced the expansion tank with a new one we bought yesterday, partly because I couldn't find an adapter that would connect my bike pump to the air release. We put in a new zone valve and just reconnected the old relays(including the corroded one), and the boiler is working fine.

I also realized that I gave you guys some bad information, namely, I was reading the top numbers of the pressure gauge, not the bottom one. My boiler never exceeded 20PSI, even with the old expansion tank.

This explains why the pressure release valve never opened, but what it doesn't explain is why the seats of all three taco valves failed within the span of a week. The repairman who came by told me he'd never seen the seat fail before, even though he had replaced plenty of powerheads.

If there was no overpressure in the boiler, why was water leaking out of the taco seats? When I engaged the manual open lever, it would push the center ring in and the leaking would stop. So then I thought that it might be that the powerhead itself had gone bad and the wax piston wasn't exerting enough force on the seat to keep it closed. But it's not supposed to leak if I remove the powerhead.

We fixed the problem, but as I feared, I still don't know what is causing this issue.

A big thanks to everyone who offered input.
 
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Old 11-28-15, 11:28 AM
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The repairman who came by told me he'd never seen the seat fail before, even though he had replaced plenty of powerheads.
If there was no over pressure in the boiler, why was water leaking out of the taco seats?
I've seen the seats leak.... a little drip.... not a stream. If no one replies with a reason I'd fire off an email to Taco technical services and ask them.
 
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Old 01-04-16, 09:54 AM
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plc59,

did the PSE&G tech replace the whole Zone valve or just the powerhead?
 
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Old 01-04-16, 10:29 AM
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In this case the power head was fine.... it was the valve itself that was leaking.
 
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Old 01-04-16, 11:16 AM
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thanks. was just wondering if they had to cut pipes or just replace the guts
 
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Old 01-05-16, 10:09 AM
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Safety First

Whatever the cause of the problems here it could be very dangerous.

The first thing to do is put a second pressure gauge on the system to verify what the actually pressure is. A gauge can be temporally attached to a boiler drain valve fitting.

Most zone valves are designed to work at 12 psi on systems with a 30 psi safety release valve. Yes they can leak, but 3 at the same time is a good indication of over pressure.

The pressure regulator is the first thing to check. A second is incremental pressure build up, especially on cold start systems, it can generate high pressures. It occurs when the water temp cools dropping the system pressure and causing the regulator to allow more water in. A few cycles of cooling, make up water and heating to boiler temp can increase pressure to where the safety valve should open.

A quick check of the regulator and temporary solution is to turn off the boiler water feed valve. After heating and cooling cycles it should stay in the same range. Then, if you leave the valve open and after cycles the high pressure keeps increasing then the regulator diaphragm or washer is leaking.

Expansion tank issues obviously impact water pressure and that is another related subject to consider.
 
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Old 01-30-16, 01:37 PM
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This is an old problem but I wanted to give everyone some closure on what ended up happening.

We cannibalized the parts from new Taco zone valves and put them inside the seats, then replaced the powerheads. For the past two months, the system has been working fine.

We replaced the expansion tank as well, just in case, even though upon closer inspection the old expansion tank as only a year old.

My best guess is that the system was damaged when the pipes in this home froze several years ago before we bought it. However, this still doesn't explain to me why the zone valves decided to fail when they did(several weeks after the system had been running for a while).

The HVAC spec PSE&G sent over had no idea what caused this either. In fact, because he had never had to replace the insides of a Taco Zone Valve, I was better than doing it than he was.
 
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