Boiler Pressure Keeps Climbing to 20

Good morning
Up until this weekend the boiler pressure had been staying at just about 15 psi. I noticed Sunday that it was up to 20 psi, quite a bit higher then I'd like it to be, so I drained off a bit of water, checked the pressure and it was 13 or 14. Went back and checked an hour or so later and it was back up to 20, drained a little more water, pressure was good. Now I'm back at 20 again...obviously something isn't right or I'm doing something wrong, I don't know which. I've been using the drain just above the circ on the return. I've attached pictures of all the piping, I'm using the DHW coil in the oil boiler. another thing I should mention is there is a quiet ticking type noise coming from (I believe) the expansion tank on the EFM supply. Aquastat: 180LL 15ldf. 4 teeth, 4.5 air.

Your automatic pressure regulator valve that lets water in the boiler to maintain pressure is probably going bad. It's either that or your DHW coil is leaking. Cheapest way to test this is shut off the makeup water valve, return the boiler to normal pressure. If it goes up again it's your DHW coil. To verify that shut the DHW coil valves, return the boiler to regular pressure and if it doesn't go up, it's the coil.

Rev. Larry
New Beginning Church
Ashland Pa.

The valve to let water in to maintain pressure was replaced 2 or 3 years ago, do they go bad often?

northernmainecoal wrote:The valve to let water in to maintain pressure was replaced 2 or 3 years ago, do they go bad often?

I've had em bad out of the box. Easy way to check it. Close the water inlet to the regulator, drop your boiler pressure, see if it stays there. If it does it's the regulator.

Rev. Larry
New Beginning Church
Ashland Pa.

Ok I shut a valve on the boiler side of the regulator there wasn't any good valve to close to stop supply to the regulator itself....Dropped the pressure and now we'll wait and see what happens.
While I was home I took a recording of the ticking/knocking noise that the expansion tank is making...any ideas on the cause?
Thanks

Has the boiler water temperature fluctuated significantly lately?

Don't forget that the pressure will rise as the boiler temp does. If 20 psi is all you see, relax. The PRV blows at 30, so you have a looooong way to get to that point. It could be lots of things, so shutting down the boiler feed is a good 'first look'. Hard water can corrode the inside of the valve. However if that is not the issue, look toward the domestic coil...could have a pinhole starting.

Don't overlook the expansion tank either. Tap if with your knuckles and evaluate the sound. If you are short on valves to isolate, I'd give some serious thought to resolving that issue.

The biggest drop in temp was about a month ago (I think) I had a shear pin break and the water got down to 135-140. Other than that the water temp stays within the 15 degree diff.

I was under the impression the expansion tanks would absorb any rise in pressure when the water heats? I do need to work on adding more valves, the newly installed section is in good shape, but the rest could stand to be cleaned up and have more valves added...it's on the never ending to do list

long read - but the link I posted in this thread appeared to have helped the OP and his pressure drama

maybe you too??

Which thread is the link in?

The expansion tank sounds hollow when you rap it with your knuckles. If you have an increase in pressure along with an increase in temperature, check the circulator. If the temperature doesn't increase, check the coil, as stated.

Its possible the expansion tank is water logged and can't take any expansion...

But likely the other possibilities already mentioned...

northernmainecoal wrote:The biggest drop in temp was about a month ago (I think) I had a shear pin break and the water got down to 135-140. Other than that the water temp stays within the 15 degree diff.

I was under the impression the expansion tanks would absorb any rise in pressure when the water heats? I do need to work on adding more valves, the newly installed section is in good shape, but the rest could stand to be cleaned up and have more valves added...it's on the never ending to do list

You say Tanks...are there more than one?

Do they read the same pressure?

Does one sound more so hollow when you rap your knuckles on it?

stoker-man wrote:The expansion tank sounds hollow when you rap it with your knuckles. If you have an increase in pressure along with an increase in temperature, check the circulator. If the temperature doesn't increase, check the coil, as stated.

It should sound solid above the seam and hollow below it. If it sound solid top to bottom, then it for sure needs to be replaced.

Another test is to QUICKLY depress the Schrader valve. You don't want to bleed off the factory charge. If ANY water comes out, the tank is dead.