System pressure going too high why??

[mpilihp]

Last week I found my basement floor wet and I found it coming from my oil boilers over pressure vent tube, it was dripping out. Looking at the boiler pressure it was at 20psi, kinda high but shouldnt be leaking at that pressure. I released some water from teh system and got it back to 12-15psi and I put a bucket under the vent tube and waited. Next day, it was full and the pressure was at 20 again.

Well I was going away for a couple of days this weekend (Red Soxs game) and I figured I would change both the boiler's pressure vent and the supply water pressure regulator.

After changing and turning the water back on the system pressure went to 20 psi, the supply pressure regulator is brand new.... I left it as it was holding at 20 and not leaking..

It was cold when we got back today and I fired up the wood boiler to warm the house up. Going back and looking at the pressure gauge and its at 30psi now! All I can think of is one of the expansion tanks bladders has burst and now the system doesnt have enough room to expand when the system water temp rises and it expands. Tapping on them they sound the same and dont appear to be water logged.

Any thoughts??

 

[Tarmsolo60]

new fill valve, new relief valve, doesn't leak when cold...sounds like nowhere to expand to when hot. my money is on the expansion tank. you sure its a bladder type and not one that can be drained and refilled?

 

[mpilihp]

Yes they are both bladder type, they hang from the air seperator scoop devices. I will probably try pulling the expansion tanks and verify them tomorrow night. Thanks

 

[ohbie1]

After changing and turning the water back on the system pressure went to 20 psi, the supply pressure regulator is brand new.... I left it as it was holding at 20 and not leaking..

Any thoughts??

If you think about it, this statement seems to indicate a faulty pressure reducing valve. If the valve is working, the pressure should not immediately go to 20, whether the expansion tank is working or not. It should stop at 10-15, and rise some more when heated, but not before. The expansion tank comes into play after the water begins to heat up. No?

 

[North of 60]

Do you have a single wall DHW heat exchanger on your system? What is the air charge in your expansion tank bladder when the waterside is open to atmosphere? Also have you isolated your feed water once it stops feeding?
N of 60

 

[mpilihp]

Hello I will have to shut things down and drain out some water to check the air charge in the bladders, will try that tonight thanks I will check that.

I have a boilermate unit 40 gallon. Im assuming your suggesting that the coil in it has gone bad and allowing water pressure to sneak in through from the DHW side of the boilermate into the system water? I can check that as well by isolating it good idea. Last night I turned the feed water off and drained some water out to get the pressure down. Will look and see what its done/at tonight. Thought there was to verify the pressure is or isnt increasing because of the feed but I hadnt thought of where else it could come from... Boilermate! THanks

~ Phil

 

[Tarmsolo60]

Hello I will have to shut things down and drain out some water to check the air charge in the bladders, will try that tonight thanks I will check that.

I have a boilermate unit 40 gallon. Im assuming your suggesting that the coil in it has gone bad and allowing water pressure to sneak in through from the DHW side of the boilermate into the system water? I can check that as well by isolating it good idea. Last night I turned the feed water off and drained some water out to get the pressure down. Will look and see what its done/at tonight. Thought there was to verify the pressure is or isnt increasing because of the feed but I hadnt thought of where else it could come from... Boilermate! THanks

~ Phil

I've seen this happen once before and it was a Amtrol Boilermate.

 

[Tarmsolo60]

After changing and turning the water back on the system pressure went to 20 psi, the supply pressure regulator is brand new.... I left it as it was holding at 20 and not leaking..

Any thoughts??

If you think about it, this statement seems to indicate a faulty pressure reducing valve. If the valve is working, the pressure should not immediately go to 20, whether the expansion tank is working or not. It should stop at 10-15, and rise some more when heated, but not before. The expansion tank comes into play after the water begins to heat up. No?

If he had 20 psi with both feed water valves after filling the system my thought would be more likely just a inaccurate pressure gauge. Also with a bad feed water valve or bad heat ex in the boilermate I don't think the pressure would drop back down that low when cool. A very quick push on the expansion tank air inlet valve while the system is under pressure should show water if the bladder has failed. When taking off a waterlogged expansion tank just remember they get really heavy quickly when you get the last thread out.

 

[Tarmsolo60]

After changing and turning the water back on the system pressure went to 20 psi, the supply pressure regulator is brand new.... I left it as it was holding at 20 and not leaking..

Any thoughts??

If you think about it, this statement seems to indicate a faulty pressure reducing valve. If the valve is working, the pressure should not immediately go to 20, whether the expansion tank is working or not. It should stop at 10-15, and rise some more when heated, but not before. The expansion tank comes into play after the water begins to heat up. No?

The expansion tank does take some water in when cold and the system is filling, so immediately going to pressure when filling tells me there is no where for the water to expand to. I've been wrong before though... just ask my wife. :-S

 

[flyingcow]

Hello I will have to shut things down and drain out some water to check the air charge in the bladders, will try that tonight thanks I will check that.

I have a boilermate unit 40 gallon. Im assuming your suggesting that the coil in it has gone bad and allowing water pressure to sneak in through from the DHW side of the boilermate into the system water? I can check that as well by isolating it good idea. Last night I turned the feed water off and drained some water out to get the pressure down. Will look and see what its done/at tonight. Thought there was to verify the pressure is or isnt increasing because of the feed but I hadnt thought of where else it could come from... Boilermate! THanks

~ Phil

Kind of a separate note. I have an amtrol on my oil system, but its off line because my storage tank heats my DHW. Are you heating your DHW with the boilermate? I did for a few weeks after start up, than my installer came back and hooked up the coil. I used a lot more energy out of the tank trying to heat thru the boilermate. Just curious, probably missed something.

 

[Vtgent49]

Just tap the exp. tank(s) with a fingernail. If there is air inside it kind of rings, if full of water, then it will be a thud.

 

[North of 60]

Just tap the exp. tank(s) with a fingernail. If there is air inside it kind of rings, if full of water, then it will be a thud.

How does that tell you what the charge in the tank is?

 

[mpilihp]

Well I isolated the expansion tanks and removed the air bleeders above them and then checked the pressure in them. One had no pressure in the bladder. I added air and waited and it held hmmm. So I closed things back up and applied water to the system and it went to 15psi seamed ok. But then I went and looked at the pressure gauge on my wood boiler and it was at zero!. Very odd... So then I decided to force the system to pump some water around, I activated the circ and I opened each zone valve one at a time and circulated water around and to get the air out of the system. Then the pressure started to creap up to 20. Mind you when I got the pressure up to 15 initially I shut the feed valve off. After circulating water around the pressure at the WB went up to 15 or so, but the oil boiler pressure was reading 20.

So this caused me to think the trb was with the boiler mate as no place else for the water to come from. I turned the valves off on the system syde that feed the boilermate for both supply and return and left it after draining the system to 15psi. After over an hour the pressure stayed steady. So then I opened the valves and left it again and it still held for over 30 min wierd. It got late and my wife wanted heat so I fired the wood boiler up, after about 15 min the pressure went back up to 15 PSI.

So still could be the boilermate. Tomorrow morning I will close off the valves to the boilermate and get pressure to 15 and leave it for the day and come home and if still at 15 Ill open the valves and wait again without making fire for several hours and see if it creaps up..

~ Phil

 

[mpilihp]

OK I left the system yesterday with the FEED off and the valves to and from the boilermate (Heat side) ball valves off as well. I drained off some water to get the pressure to 15psi and left. Upon coming home I found the system pressure was about 0-5psi. This indicates to me that the drop in water temp of the system lowered the pressure right?

So then I opened the ball valves to the boilermate and went out for several hours, about 4 hours later (9pm) checking showed the pressure still arould 0. So I think the boilermate is fine and its an expansion issue, not enough room to expand. Firing the system up and again it went up to 20psi once warmed up. It held at 20psi till this morning. Tapping on the two 3gal exp tanks they sound the same doesnt appear one is waterlogged, though one had no pressure in it when I tested them. I filled it back up and it appeared to hold, maybe I should check it again. Unfortunatly that one I tried to remove and its not budging so I may have to abandon it and get a larger one for the other 3gal unit.

I think its just an expansion issue. I left the system off for today and will see if the pressure drops as the temp cools.

~ Phil

 

[altheating]

Sounds like a faulty expansion tank or a tank that is undersized.

 

[mpilihp]

Yup I agree, looking the part number up, I have two 2 gallon units, one of which is not agreeing with being removed. Im going to replace the one other 2 gallon unit with a 7 gallon Extrol #60 unit. Doubling my expansion room, hopefully that stops the problem.

~ Phil