Pressure relief valve keeps leaking on Weil McLean Ultra 230 boiler


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Old 11-22-22, 04:43 PM
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Pressure relief valve keeps leaking on Weil McLean Ultra 230 boiler

This boiler was installed in 2015. The pressure relief valve keeps leaking. It begins with a slow drip and progresses from there to a rapid drip. Iíve replaced it 4 times in the last 12 months.
Iím using Watts valves with ratings of 30 PSIG and max 510 000 btu hr.

Iím on a well and the pump is set at 60 psi. There is a pressure reducer installed on the makeup water set at 20 psi. The gauge on the boiler reads 20 psi.

Three weeks ago I called a service company who installed the system. They replaced the valve at that time and its leaking again already. They wanted to simply shut off the makeup water, but that seems like an inadequate solution.

Supply House sells a Weil McLean pressure relief valve for this boiler. SCU 385 500 095. But they donít provide any of the ratings for the valve. The photo looks just like the watts valves.
Would appreciate any thoughts to help trouble shoot this issue.

Iíd really appreciate any thoughts to help trouble shoot this issue.

Thanks!
 
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Old 11-22-22, 05:49 PM
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The boiler gauge is not always accurate.
I carry a separate gauge that screws onto a standard 3/4" bib somewhere in the boiler system.
I recommend the 100psi model.......... Water pressure test gauge.

What is the system temperature. That is called a T and P valve and opens by pressure or heat.
Has the pressure tank been checked for air charge ?
A tank pressure of approx 12psi is needed to balance the system.
Auto fill valves do leak....especially on well water with high sediment conditions.
 
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Old 11-22-22, 06:18 PM
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I suspect that your system pressure is running too high. What is the pressure as shown on the boiler gauge?
 
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Old 11-22-22, 06:56 PM
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OP has stated 20psi but that may be incorrect.
The valve shouldn't start dripping until 27-28 psi.
 
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Old 11-22-22, 07:56 PM
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If I'm understanding you correctly with the boiler off everything is fine then as the boiler heats up the relief valve starts to drip and the hotter the water gets the more the relief valve leaks.

To me it sounds like your extrol tank may have lost its charge so the tank is full of water so the expanded heated water has no place to go so the pressure builds in the closed system and at 30 psi the relief valve lets go.

What you can try is to tapping the tank as a quick check. The top of the tank should sound solid due to water being there. The bottom of the tank should sound tinny due to the rubber air bladder in the bottom. If the whole tank sounds solid then your air charge is gone so you much either try to recharge it or replace the tank.

To check your extrol's pressure it must be completely divorced from your system or else you will be reading system pressure so you must either remove the tank or drain the boiler until you see 0 lbs pressure and you can replace the defective gage at the same time.

Your boiler only has a 30psi relief valve. A hot water tank has a T & P valve, generally set to go off at 150psi and 210 deg. Completely different than a boiler relief valve.
 
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Old 11-22-22, 08:11 PM
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I keep trying to post pics and get errors which deletes everything I’ve written. So no pics this time, will try pics separately.

When the service guy came three weeks ago, he did check the pressure independently with a gauge like PJ’s. 20 psi did check out. He said he also checked the expansion tank and said it was ok too. Just now I checked it and it is hollow at the bottom, and full at the top. What should the pressure of the tank be? There is not pressure gauge on the tank, just on the boiler itself.

The display on the boiler indicates the following:

TARGET: 180F
SUPPLY: 173F
RETURN: 155F
OUTDOOR: 29F
DEMAND: FCL
PUMPS: 2 3
ADD’L HEAT DEMAND: OFF

Thanks for all your input!
 
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Old 11-22-22, 08:17 PM
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This is the expansion tank, full at the top, hollow at the bottom. You can see the pressure reducer which is set at 20 psi, left of that is what seems to be a backflow preventer with a relief valve. I think the white handled ball valve would shut off the auto feed? Which is what the service guy wanted to do.

Not sure if this is useful, but this is the domestic pressure on either side of my sediment filter.

This is display from the boiler. Which supplies hot water to my hydro air system and indirect water heater.

 
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Old 11-22-22, 08:19 PM
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System pressure on the boiler gauge is displaying 20 psi.
 
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Old 11-22-22, 08:25 PM
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M,
The tank comes with a 12 psi charge but can be be adjusted if need be but 12 is pretty much the standard for residential. There are no gages, you can use a tire pressure gage on the schrader valve but it must be separated from the system or boiler drained to zero. Technically the extrol should be charged to whatever your cold starting boiler pressure is but it's hardly ever done and they work fine.

Just saw your boiler pics and comments. You mention you have an Indirect WH. You also have a coil in that WH which may have a pinhole leak, letting cold water into the boiler system.

You should shut your cold water feed off to your tank also for the night if possible.

What you can try is shut your supply and return off from the tank to the boiler which would stop any unwanted water getting to the boiler and see what happens. If that works then the coil in your IWH would need attention.
 
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Old 11-22-22, 08:29 PM
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Even though the expansion tank is hollow at the bottom, do you still recommend removing it to test the pressure. Draining the system is not an option - its a glycol filled system.

I’ll go pick up my own pressure gauge like PJ’s tomorrow and confirm the system pressure as well.

Thank you all!
 
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Old 11-22-22, 08:50 PM
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Your boiler numbers look good. You can either shut the White valve or the Red one near the extrol off but that will only shut the feed off to the boiler and he must be thinking it's the auto feeder because that is all that will be checked by shutting off that valve. Your relief valve is not in the pic. Should be on the top of the boiler I believe. That pipe that is coming down is from your BFP. if it opens. That is not the pipe that's leaking is it.

With your system full of glycol hopefully you have shutoffs between the boiler and the system to drain as little as possible if need be. If you do have to change the tank I would put a 1/2" shutoff in between the hydro vent and the tank for the future. I would try shutting off the IWH before removing the tank.
 
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Old 11-22-22, 10:13 PM
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Spott.
I’ll upload a pic of the relief valve that is leaking and some pics that show more of the plumbing. There seems to be shutoffs “everywhere” on the system. There is a drain at the bottom of the boiler tank that I could use to drain a little glycol and that should reduce the pressure to zero if I shut off the valves for each zone above the expansion tank as well so that I don’t get backflow from the pipes. That is what I did when I changed out the relief valve the last couple times. If I do that so the gauge reads 0 PSI, then can I check the expansion tank pressure with a tire gauge? Or should I remove the tank and empty it to do that?

I’m afraid you are losing me when you use the acronyms like IWH and BFB. Can you elaborate?

Thanks!

 
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Old 11-22-22, 10:19 PM
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Pictures

Here are some picturesÖ

Arrow points to the relief valve that is leaking

View from the back of the boiler

Expanded view of more plumbing.
 
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Old 11-23-22, 12:55 PM
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M,
Sorry for the confusion.
IWH = Indirect Water Heater
BFP = Back Flo Preventer or Backflo Preventer
PRV = Pressure Reducing Valve or Auto feeder to boiler.
PRV = Pressure Relief Valve. Set to go off @ 30 PSI.
Potable Water = All Faucet Water. Hot or Cold
IMO = In My Opinion.
Will try to be more clear in the future.


Pressure to 0 PSI in the boiler is sufficient for extrol check. Looks like Extrol #60. Good size tank that they figure was needed so check the info if you must replace. It looks like you have a 4 zone system. Three heating and one Indirect water heater for your potable water.. You do have a lot of valves and that is good, I love valves and IMO you have a first class install.minus the isolation valve at the Extrol.

I noticed you have 4 pumps but cannot see 4 Flochecks, just 1 Green One with the arrow on side. More pics of Hot Water Tank Supply and Return piping and Supply and Return from boiler. might be helpful.
 
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Old 11-23-22, 01:55 PM
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Thanks Spott.
You forgot: WTF and KMA.

I will take more pics when I get home tonight.

Thank you!
 
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Old 11-23-22, 01:59 PM
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There are actually 5 heating zones. Two on second floor. (There is a separate second floor hydro air heat exchanger in the attic), one zone on the main floor and one in the finished basement. There is also a garage heater that looks and sounds like a soviet era heater. If you count the indirect water heater, then that makes 6 zones?
 
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Old 11-23-22, 04:55 PM
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I figured 4 because of the 4 pumps I saw. Other zone controls must be out of the pics.
 
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Old 11-23-22, 07:26 PM
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Ok. I drained the boiler until the boiler gauge read 0. Then checked the pressure in the tank. It was 4psi. Also- a little bit of liquid came out when I opened the valve with my fingernail. Could that just be condensation? Or does that mean the tank is shot?
I filled the tank up to 12psi with my bicycle pump and checked it again with a reliable tire pressure gauge, then restarted the boiler. I emptied the bucket that the relief valve was draining into so I should know in the morning if it is still leaking.
Will upload and describe a bunch of photos in a separate post.
 
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Old 11-23-22, 07:31 PM
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PicturesÖ.










 
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Old 11-23-22, 07:41 PM
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The first tow pics in the last post show the boiler pressure gauge at 0 after draining and shutting off the autofeed. The second shows the pressure in the tank. It was initially at 4psi. Then I tried to drain the little bit of liquid that was in the bottom portion of the tank. I would say there was maybe a teaspoon or two of water. Smelled like rubber.
When I filled the tank back to 12psi, the level of where the tank sounded hollow rose from about 1/3 from the bottom to about the middle of the tank after charging. D

the rest are different pics of the system.
Will post back tomorrow if I find any more leaks.
You guys are the greatest! So generous!
 
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Old 11-23-22, 08:16 PM
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Your tank being @4 psi is most likely why your relief valve was going off. The bad news is you shouldn't have been able to drain any water out because that valve is part of the rubber bladder. Being able to restore it back to 12 psi I believe is only temporary and my guess is that your bladder has a slow leak and will have to be replaced but as long as it has 12 psi the boiler pressure should be good and the relief valve should not leak.

If it starts to leak again you will know where to look.

Happy Thanksgiving.
 
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Old 11-23-22, 09:08 PM
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OP #1` There is a pressure reducer installed on the makeup water set at 20 psi. The gauge on the boiler reads 20 psi.
Most hot water boilers use 12 psi to two story homes. If home has higher elevation of highest heating element, pressure is raised accordingly.

Boiler gauges are frequently not accurate. See : How to verify a boiler pressure gauge - redux

Rather that focusing on Leaking relief valves, first check pressure reducer/regulator. They are often source of makeup water raising system pressure till relief valve leaks.

A simple test is shut off feed valve to regulator. Drain boiler water to 12 psi. If over xx hours pressure does not rise, leaking regulator is likely cause. Yes, sometimes tankless coil leaks but is uncommon.

Servicing regulators is a lot easier with with unions on either side. A shut off valve on boiler side allows it to operate on cold days when regulator is serviced.

Life of expansion tanks is shortened with Ĺ” pipe nipple on top or side. Nipple on top allows harmful water debris to collect on top of bladder. See manufacturer instructions. Most are have 12 psi pressure
 
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Old 11-24-22, 07:18 AM
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NO LEAKS THIS AM!
My bucket is dry. Seems like the culprit was the low pressure in the tank.
Would you recommend a wait and see if the tank loses pressure again, or just go ahead and replace it?
I will install a valve on the top of the tank if I take it off. Is that as simple as plumbing in a 1/2” ball valve between the the fitting and the tank? Seems simple enough. This will require draining more water as there are some large pipes and some distance to the next valves up the line, but thats not a big deal.

I’m so thankful for your help!
Happy Thanksgiving!
 
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Old 11-24-22, 08:16 AM
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​​​​​​​I will install a valve on the top of the tank if I take it off. Is that as simple as plumbing in a 1/2Ē ball valve between the the fitting and the tank?
This is a better valve for that purpose:


It isolates the tank from the system then allows the tank to be drained without de-pressurizing the entire system.
 
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Old 11-24-22, 09:35 AM
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Since you understand what can happen if you lose pressure I would watch it for now but if it starts leaking again I would change it before it becomes an emergency. I would get the valve to have on hand and see how readily you can get the extrol if you want to wait. You've had the problem this long so you may make the winter but it won't improve with age.

If that bladder completely lets go, that is a big tank and your looking at a lot of weight at approx. 80 lbs if full.
As far as draining to change, you have isolation valves at each pump and to separate zones from boiler and since the tank is above the boiler and water does not flow uphill I would open the relief valve to take pressure off the boiler and drain water in pipe between tank and boiler without losing boiler water.

At 80 lbs the tank may be too much to handle. What I used to do is put a container underneath and drill holes in the bottom of the tank to empty and lighten the load.

Just a thought, hope this helps a little.
 
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Old 11-24-22, 09:47 AM
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mchristo: Rather than fancy $40 combination valve in Post 24. Install expansion tank with nipple on top. Put 1/2 tee on nipple. Put drain faucet on one tee port and other port ball shut off valve

To pressurize tank, shut off valve, drain tank and pressurize. Then close faucet and open shut off.

If bladder eventually fails, those valves make it easier to drain and remove empty tank.

Heating systems often have to be serviced during winter. To keep system running in cold weather, each zone has isolation valves, as does circulator pump, pressure regulator & reducer has unions to easy removal. Expansion tanks has shut off to ease depressurization. To easily see system status and diagnose issues have LED pilot lights on things. On cold winter night want quick solution, not Fix It Challenges.
 

Last edited by doughess; 11-24-22 at 10:58 AM.
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