Creeping Boiler Pressure! Too High Help!

[dedonderosa]

Ok well let me start off my story by this. i went into the basement and noticed the floor was wet and the relief valve had popped off. so i initially thought it was time for a new one cause it was fairly old etc.

I decided to turn off the switch for the boiler and drain the water and let it cool for a few hours. Went to home depot and decided to replace a few things just as i didn't know the age of them on the boiler. i picked up a new relief valve, hy-vent, and expansion tank (which i found out was from 1996 and only had about 2 psi in it). Anyway i went home replaced all 3 items on the boiler, opened the fill valve and fired up the boiler. Psi was bout at 20psi when fully hot, has been fine for a few weeks now no pop off or anything but i kept checking it and noticed that the psi keeps creeping up higher and higher. Now given my heat is off the season as i have baseboard heating but the boiler still heats my water for showers etc. Anyway it slowly creeps and now has been sitting steady between 25-28 psi which i know is not right at all. Shouldn't it be at about 20psi full operating temp around 180 degress? Only thing left by what i was reading it could be would be faulty internal leaking water reducing valve. mine is currently a B&G.

Let me know what you guys think of my situation, also is there anyway to tell if the pressure reducing valve is leaking internally? i read one thing saying if you touch the "bell" part of it and its stone cold that water is getting through and that is leaking internally. this should be warm or hot to the touch ?

thanks guys let me get some of your opinions.

 

[BillTheEngineer]

when you replaced the relief valve and went to refill the system, sediment got into the reducing valve or the reducing valve has crapped out since using it. You could try opening the relief valve or a drain valve on the system and opening and closing the fill valve quickly a number of time to see if you could get it to seat, but most like it will need to be replace. This is not an uncommon occurrence.

 

[Sponsor]

 

[dedonderosa]

also when i replaced all 3 of these items i had shut off all the water valves, let the boiler cool and drained the boiler, then proceded to replace the items. after all were replaced i slowly opened the valves to fill the boiler then fired it up, i was told there should not be a need to bleed the system. is this true ? i did go upstairs to all the baseboards and bled them but nothing but constant stream of water no air came out.

 

[Dana]

It's not a "pressure reducing valve" it's an "auto-fill valve", and it's not really necessary. Once the system has been filled to the correct pressure and purged of air it's fine (usually preferable) to turn off the system isolating shut off valve between the auto-fill and the potable water distribution. Many older systems don't even have an auto-fill valve.

With the system isolated by a ball valve (or sometimes a gate valve), the system pressure will not change unless there's a leak, and the system loses pressure over time, or there is some other seepage from the potable side to the system side. If the system is losing pressure due to leaks it'll be making lots of noise long before it's a safety issue. If the boiler has an embedded potable hot water coil or a indirect fired hot water with a pinhole leak in the heat exchanger, that too can cause the system pressure to creep up over time.

The fact that the old expansion tank registered 2 psi isn't necessarily an indication that the tank has failed. Did you try re-charging it to the desired system pressure? The air valves are the same as those on car tires, and can be replaced for super-cheap, if that was the failure mode. If the internal bladder was still intact you might have gotten another decade out of it. Did you charge the NEW one to the system pressure? Whatever the pre-set psi on the new tank was alleged to be, it needs to be verified, and if need be adjusted prior to pressurizing the system. Unless it's a building with 3 or more upper floors with a boiler in the basement you don't usually need more than 12-15psi when the system is idling/cool. How high it rises when operating at full temp is a function of the system volume and the tank volume. For high volume high temperature swing systems a 10 psi increase from cool to max isn't unusual, but if it's going from 12 psi to over 25 psi you probably need a bigger expansion tank (or a higher pressure relief valve- but only necessary in taller buildings that need a lot more than 12 psi to get water up to the top story radiators.)

It's rare that you can open up the system to replace it all without getting at least some air in the system, but as long as there is sufficient circulation on all heating loops the system vents will usually take care of it after several hours or days of operation. You really only need to bleed the system to purge air when there's enough air in the system that it is limiting or preventing flow. At the end of a heating season it's sometimes useful to purge crud from the system with a full system purge & water replacement, especially in systems with cast iron radiators and iron pipes, but that's a separate issue. If no air came out of the bleeder valves and all zones are still getting heat you're good to go.

 

[dedonderosa]

yeah no air came out of the baseboards, just constant steady streams of water, and like i said it was fine for a few weeks and was roughly staying at 20psi @ 180 degrees. but i would check it every few days or so and would notice that it went up to 25psi, and stay roughly there steady, then this morning i looked again and it seems like its at about 28psi or right before 30psi. no i have the heat off for the season but it still heats my showers and water etc,
but it could be in fact the B&G auto fill valve correct? being as i have no clue how old it is, we have very hard water. How how else can i test to see if its internally leaking ? the only thing accord to B&G is to touch the bell part and see if its ice cold, if it is then that means water is passing through when it shouldnt be.

 

[dedonderosa]

how else should i try and bleed the boiler first ? is there another procedure besides just at the baseboards? can someone tell me exactly what i need to do or try first?

 

[Dana]

Bleed the system pressure down somewhere near the boiler. Then test the heating system by turning the T-stats up, and verify that all radiators/baseboards get hot. If they all get hot, turn the shut off valve completely off and monitor the system pressure for a few days.

If it's stable it's likely that the auto-fill valve seats aren't sealing.

If it continues to creep up, you probably have pin holes in heat exchanger of the potable water heating setup.

 

[dedonderosa]

so get the pressure down to 12-15psi then shut off the shut off valve lever before the auto fill valve correct?

 

[Dana]

If by "...the shut off valve lever..." you mean turn the ball-valve handle perpendicular to the body of the valve, yes.

(off position)

 

[dedonderosa]

Ok well i messed with it a little tonight. You may think im crazy lol i reduced the pressure cranked the t stat everything got hot etc gauge went from 12-15 up to 20psi and stayed there with tons of heat in the house

And seeming to stay there... for now. I took a flat head screw driver to the fill valve and put it against my ear to see if i could hear water going though it. The gauge was at 20psi and i had the water valve open and could hear water going through the fill valve then stop as i shut the valve shile still listening. My question is if the gauge is reading 20psi hot shouldn't the fill valve be fully shut not allowing any water through it? Or am i wrong?

 

[dedonderosa]

Now someone please answer me this. If i drain the boiler a little to reduce the pressure down to 12-15psi and leave that water valve off the pressure will stay and the boiler will be at 180 deg. As soon as i open up that valve the gauge goes right to 20psi!? Is that because the boiler was hot?

Also isnt it not good to have that valved closed for a long period of time? Isnt that what feeds the boiler no?

 

[Dana]

The auto fill valve should always be fully shut whenever the pressure of the system is at or above it's preset value. If it's seeping a bit, that will overfill the system. That is why you need to close the shut off valve after filling the system- it guarantees that even if the valve seats aren't sealing perfectly on the auto-fill it won't continue to add water to the system.

 

[dedonderosa]

yeah i could def hear water going through the fill valve after the boiler was fully hot at 180 deg. it just sounded like a small amount going through it. so im gonna say it has to be replaced then

 

[Reach4]

yeah i could def hear water going through the fill valve after the boiler was fully hot at 180 deg. it just sounded like a small amount going through it. so im gonna say it has to be replaced then

You should listen to what Dana said.

 

[dedonderosa]

sorry for being a pain, so after the system is fully filled and pressure is at normal 12-15psi, i should leave the shut off valve permanently closed before the auto fill? and not open it at all?

 

[Reach4]

If I read correctly, you would leave it shut unless there is a symptom of low pressure. And if you get such a symptom, you would troubleshoot why you lost pressure in addition to opening that valve for a bit to work around the problem.

You could replace the "auto-fill valve", but it is not needed.

The above is my interpretation of what Dana was saying.

 

[Dana]

Correct, turn it off, leave it off. This disables the auto-fill (which is more of a convenience than a necessity), and stops the bleed-by. You can replace the auto-fill if you like, or you can just leave it there.

If the system develops a leak the auto-fill won't function with the shut off valve closed, but the system will be delivering a lot of audible feedback that something is wrong before that happens. When the system pressure drops there is a lot of sizzle pop & bang happening from bubbles forming on the heat exchangers then collapsing audibly when the flow pushes the bubble beyond the heat exchanger.

 

[Jadnashua]

The autofill valve MIGHT need to be readjusted to provide your desired pressure level. The spring might be getting weak. Safest to just shut off the supply, but if you want to keep the thing open, you need to adjust it to your desired pressure level.

 

[Dana]

There is really no point to leaving it open. Auto-fill valves on hot water systems are for the convenience of the installer, not the homeowner. As the air is purged from the system the pressure drops a bit, the auto-fill makes sure that it doesn't drop too much, so the system keeps working and the installer doesn't get the call-back from the irate customer.

In truth, they are more trouble than they're worth (to the homeowner, that is.) When the valve seats get worn, pitted, or pick up some debris they end up causing this very problem, but that's a decade or two after the installation.