My PSI keeps increasing after I let water out.

bender1227

I have a Weil Mclain Gold CGT.

It is a gas fired system.

The water pressure is at around 40 psi and the chart on the side of the boiler says MAWP Water 30psi. I assume that means that max the water temperature can be is 30 psi. Every time I let water out of the system and the pressure goes down to 30psi it goes right back up to 40 psi. Any ideas what can be causing this?

Thanks!

Harvey Ramer

Do you have a tank less coil or an indirect water heater connected?

Fred

Do you have a waterlogged expansion tank?

Gordy

Unless your emitters are at an extremely high elevation you should only need 15psi. The boilers relief valve is set to relieve at 30 psi. So a reading of 40psi is either the gauge is not reading right, or the relief valve is stuck shut which is not a good thing.

As Harvey mentioned if your DHW is heated with a tankless coil, or an indirect. It could be possible that the heat exchanger has a leak allowing domestic water which is a higher pressure to fill the heating side of your system.

Another thought is a fouled fill valve for the heating side that keeps the system at a set fill pressure. Again should be set to 15 psi. To check shut that valve off if it is left on. Then drain down the boiler to 15psi see if pressure still climbs. If not it's the pressure regulating valve for the boiler.

Please verify.

kcopp

A Weil CGt is a CI boiler w/ a tankless coil. Prety good bet there is a pinhole in the coil, filling the boiler.... OR the fill valve is letting in water.

Harvey Ramer

I've seen a 30psi relief valve not lift at 50 psi. Sometimes they stick.

Gordy

Potable side could be a well 40-50 psi not unheard of.

4Johnpipe

If not a leak in the tankless coil. it sounds like a combination of a bad auto fill valve and or a water logged expansion tank. I would have a semi major service and replace the boiler relief valve and the gauge as well.

Steamhead

Bottom line: Call a pro. Check out the Find a Contractor page of this site.

ChrisJ

Anyone consider maybe the op has well water? 20 - 40 PSI is a very common operating range.

Just throwing that out there along with possibility the stuck pressure relief which is downright scary. BOOM!

If it was me, I'd shut the boiler off, shut the water feed off to the autofeeder and the tankless coil if applicable , drain the pressure down some and call a professional.

ChrisJ

Hatterasguy said:

ChrisJ said:

Anyone consider maybe the op has well water? 20 - 40 PSI is a very common operating range.

Actually yes. Gordy considered it a few posts above.

Damn that @Gordy

Fred

It's so strange. We always tell people to read their owner's manual but we also make assumptions, like this HO has a HW coil in the boiler that has failed (it may or may not) BUT the WM Troubleshooting section for this boiler says the Gold CGT Uses a bladder or diaphragm expansion tank and if pressure rises, immediately after reducing it to the correct pressure to first check for an under-sized or waterlogged expansion tank. Troubleshooting is a series of steps. I'd look at the obvious (what WM knows about this boiler's characteristics) first and then move on down the line to the next step.

ChrisJ

Fred said:

It's so strange. We always tell people to read their owner's manual but we also make assumptions, like this HO has a HW coil in the boiler that has failed (it may or may not) BUT the WM Troubleshooting section for this boiler says the Gold CGT Uses a bladder or diaphragm expansion tank and if pressure rises, immediately after reducing it to the correct pressure to first check for an under-sized or waterlogged expansion tank. Troubleshooting is a series of steps. I'd look at the obvious (what WM knows about this boiler's characteristics) first and then move on down the line to the next step.

A failed bladder tank will do that with any boiler, not just this one.

The problem is 40 PSI is well above the pressure any normal relief valve should allow. That's bad. What's lying, the relief valve, or the gauge?

Fred

I think the real issue that this HO asked about is what is causing the pressure to rise like that. I agree, along with that, the PRV needs attention but until he finds the source of the pressure problem, a new PRV would just blow. The point of my post was, lets take it a step at a time 1) check the Expansion tank, 2) IF it has a coil, check that but at this point, we don't know that he has a coil and we certainly don't know that he's on a well and it seems he's gone anyway??? More info needed.

ChrisJ

The boiler needs to be shut down and the water source turned off and pressure relieved until it can be confirmed that the pressure relief is working properly.

That is step one in my book.

Once the pressure relief is confirmed good or replaced troubleshooting can continue.

Fred

Hatterasguy said:

Fred said:

BUT the WM Troubleshooting section for this boiler says the Gold CGT Uses a bladder or diaphragm expansion tank and if pressure rises, immediately after reducing it to the correct pressure to first check for an under-sized or waterlogged expansion tank.

Let's say the tank is fully waterlogged. Not a bit of air space available within the tank.

We reduce the pressure to the required value of 15 psi.

The fill valve is operating correctly and it does not feed at 15 psi.

The pressure immediately climbs back to 40 psi.

What do you think causes the pressure to immediately rise? It cannot be rising due to a temperature change because the boiler isn't operating.

If the boiler isn't running at the time he lowers the pressure and it climbs, I would agree additional water is being added. The unknowns are many. Does he have the boiler running when he reduces the pressure? Will the boiler continue to build pressure beyond the 40 PSI if he didn't intervene? Is he on City water or a well? If on a well, is his pressure in the 40 PSI range and the boiler equalizes or is it his intervention at 40 PSI? Does he have a HW coil? I understand the possibilities, it just seems to me that checking the expansion tank would be an easy first check in the diagnosis. Of course, we don't even have enough info to determine that he didn't already do that.
EDIT: The other question I have is when he reduces the pressure, why is he just reducing it to a level (30 PSI) that should blow the PRV anyway?

Harvey Ramer

We can talk till the cows come home and solve nothing unless the OP shows up again.

My guess is he/she already has the situation under control. Or not...

Tinman

I saw the perfect storm last winter on a TT Prestige. Relief valve locked up tight, fill valve slowly leaking through, system pressure at 49#. First time for me ever seeing this boiler. I brought the customer over to show them everything, explain the dangers, and then shut it down. 2 days later they sent me an email saying they hired a radiant/boiler specialist from southern Wisconsin that said I was being an alarmist and a cheat. They then threatened to sue me. They are very wealthy people and they thought their money would intimidate me. I responded to the email in kind and never heard from them again.

I hope the "specialist" fixed their problem(s).

Gordy

Stephen Minnich said:

I saw the perfect storm last winter on a TT Prestige. Relief valve locked up tight, fill valve slowly leaking through, system pressure at 49#. First time for me ever seeing this boiler. I brought the customer over to show them everything, explain the dangers, and then shut it down. 2 days later they sent me an email saying they hired a radiant/boiler specialist from southern Wisconsin that said I was being an alarmist and a cheat. They then threatened to sue me. They are very wealthy people and they thought their money would intimidate me. I responded to the email in kind and never heard from them again.

I hope the "specialist" fixed their problem(s).

All most makes you want the boiler to blow off the wall after they hit send on their threatening email.....

Alan (California Radiant) Forbes

We have those kind of "specialists" out West as well. They want to make themselves look special and be heroes when a lot of them don't know anything at all.

Gordy

Do to the lack of return info I suspect the relief finally popped, and a phone call was made........pure speculation.

ChrisJ

*Due

Gordy

South

bender1227

Here is a picture of the boiler. Nothing has popped yet but when I tuned off the town supplied water to the furnace and drained the system down to 30 psi it did not raise. But once I turned the towns supplied water back on it went back up to 40 psi.

bender1227

Here is a picture of the expansion tank.

bender1227

Expansion tank

bender1227

Here is a picture of the hot water storage tank.

delta T

You need a new feeder. You do have a tankless coil but it is disconnected (the two pipes coming out of the top near the front that are cut off). You also need a new relief valve if it is hitting 40 psi and not opening. This is a MUST!!! Your relief valve has failed, and it may not prevent your boiler from exploding if it every over pressurizes. You may also need a new expansion tank, it is impossible to tell without actually removing it from the system to test.

Also, your boiler should run somewhere around 12-15 psi. The new feeder will correct this.

delta T

Steamhead said:

Bottom line: Call a pro. Check out the Find a Contractor page of this site.

Agreed.

These are routine repairs for a pro, if you have never done it, these can be time consuming, frustrating and dangerous to do on your own.

bender1227

How do i know what typelse of feeder I need and what is a tank less coil?

Is the installation for the feeder valve just taking the old one off and putting the new one on? Are there any settings that need to be adjusted?

Fred

bender1227 said:

How do i know what typelse of feeder I need and what is a tank less coil?



Is the installation for the feeder valve just taking the old one off and putting the new one on? Are there any settings that need to be adjusted?

It is clear you are not familiar with this kind of work. Please find a good contractor (look for one under the "Find a Contractor tab) on this site and let them check out the feeder, the expansion tank, the Pressure Relief valve (PRV). It's better and easier to get this fixed now than in the dead of winter, not to mention the risk associated with excessive pressure as well as flooding damage, should you be fortunate enough to just have the PRV finally blow, especially with a faulty water feeder.

rick in Alaska

OK. Just to satisfy my curiosity, and at least one others, try turning off the water feed and drop the pressure to zero on the gauge. My guess is it won't go that low because the gauge is broken. Until we know if the gauge works, we are just guessing at the problem. My gut tells me there is no problem, except bad gauge.
Rick

Gordy

It appears from the boiler pic the tankless must have developed a leak some time ago being nicely disconnected.

It is quite possible the gauge may be reading a higher than actual psi. The differential of 10psi when drained down to 30 psi, and going back up to 40psi after feeder was turned back on with out relief popping could be.

Try draining down to 0 psi as Rick suggested. If it will, however don't get carried away if your draining after you hit 30 psi, and the gauge does not drop anymore it's the gauge. If you keep draining you will drain the whole system.....

bender1227

What is the best way to go about checking the gauge. Should I just drain the system by releasing water and watch the gauge drop. If I can drain the gauge down to 0 wouldn't that be emptying the entire system? Is this what I should or and is this healthy for the boiler? Are there any other things I should be doing when draining the system?

Thanks again everyone!

Brendan

JUGHNE

If he had isolation valves at the boiler to not drain the emitter/system, this could save him some grief. Any pictures of the boiler and piping?

bender1227

So I shut off the in coming water and drained about a quart of water which lowered the gauge to 0. Then when I turned the incoming water back on it raised the PSI reading back to 40 psi. It also sounds like when the gauge hits 30 psi that the system is still receiving water and doesn't stop till it hits 40 psi.

Does this mean my feed is bad?

How can I tell if my expansion tank is bad?

Thanks

ChrisJ

If it was my system I'd order a new quality gauge, a new pressure relief, new auto feed and a new expansion tank. Tear it apart, replace all of the questionable stuff at once and refill. Done.

Some will disagree I'm sure, but that's what I'd do if this was in my house.

If the expansion tank is bad it will be full of water. Hard to tell with it hooked to the system though. I suspect if you try to let some of the air out, it would spray water if the diaphragm is ruptured.


My beef is it's been several days and you still possibly have an extremely dangerous situation in your house (stuck pressure relief).

Is the burner disabled?

bender1227

The burner is not disabled but I have all the zones turned off.

I also am leaving the psi at 30 ish as I shut off the incoming water and let out enough water to leave it at 30 psi?

How is this like a bomb, what can explode?

How can I fully shut off my boiler?

ChrisJ

bender1227 said:

The burner is not disabled but I have all the zones turned off.

I also am leaving the psi at 30 ish as I shut off the incoming water and let out enough water to leave it at 30 psi?

How is this like a bomb, what can explode?

How can I fully shut off my boiler?

I would rather a professional such as @Steamhead or @Charlie from wmass give advise on this.

Tinman

https://heatinghelp.com/find-a-contractor/

Gordy

bender1227 said:

So I shut off the in coming water and drained about a quart of water which lowered the gauge to 0. Then when I turned the incoming water back on it raised the PSI reading back to 40 psi. It also sounds like when the gauge hits 30 psi that the system is still receiving water and doesn't stop till it hits 40 psi.

Does this mean my feed is bad?

How can I tell if my expansion tank is bad?

Thanks

I was looking to see if the gauge would drop to zero psi. It did so to me that points to the auto feeder needs replaced. however I think a pro should handle this, and verify gauge accuracy also.

The system will take water until street psi equilibrium is reached, or the relief valve on the boiler pops. So just because it sounds like the system is taking water after 30 psi does not mean it needs it.

You need to get this fixed asap before you use it. The danger is in the unknown of your pressure relief valve operating properly which it's not if the system holds 40psi. the valve should be opening letting out excess pressure.

When the boiler gets used from heating the warmer water takes up more space in the system so pressure will climb more yet. Especially if the expansion tank is water logged,