boiler pressure too high

[jklingel]

Weil-Mc boiler installed in '00 by a pro. Pressure is now 20-40 psi in the boiler. Pop-off valve was leaking; I replaced it. I replaced pressure reducing valve, leaking expansion tank, and press/temp gauge; old gauge was faulty. Problem: Pressure still goes to 40 when boiler is at 185 F, 20 psi when boiler is at 150 F. Diagnosis step: I shut off the boiler, and drained some water off w/ pop-off valve. Pressure goes to 0, but as soon as pop-off valve in closed, pressure goes to 20. Suggested problems/solutions: (1) Pressure reducing valve is set too high, from factory. Adjust it. (2) Expansion tank, which reads 15 psi when the boiler gauge says 40, is above boiler and upside down, ie, Shrader valve is on top. Exp tank may have an air lock, should be below boiler, and Shrader valve should be on the bottom, so the water is above the air in it. Turn expansion tank over. QUESTIONS: (1) Does it matter if the expansion tank is "upside down"? (2) The expansion tank has been where it is for 30 yrs, and always "upside down". Any need to move it lower? (3) The exp tank is above all air vents, and, via water, way far away from them. Install a vent above and near the exp tank? Lots of questions; sorry. Any ideas? Thanks. john

 

[Gary S]

First make sure your expansion tank isn't full of water. My furnace repairman drained my expansion tank of water, then put a small amount of air pressure in it before reconnecting it to the boiler. That air in the tank is what keeps your water pressure under control.

 

[jklingel]

Gary: Thanks. Tank is new, and had the appropriate 12 psi in it when installed. It now reads 15, and I tapped on the side to check for being full of water. It is OK. j

 

[6t7gto]

maybe this will help...
http://www.terrylove.com/forums/showthread.php?34069-Boiler-over-pressurizing

 

[jklingel]

6t7: Thanks for the link. That particular one didn't do it, but that looks like a site that caters more to boilers. I'll poke around over there. j

 

[mikefromme]

There is a guage at the expansion tank that reads 15 psi? If so the boiler pressure gauge may be the issue - can you swap the two and see if you get the same readings?

 

[Ron Lombardo]

I would remove the old style expansion tank and install a pre pressurized Extrol #30 depending on the size of the system ..in my home I have 2 ... the watts 1156 feed valve should be preset to 12 - 15 psi ... also a bad pump could make the pressure elevate because you have no circulation .. whats the temp going up to ?

Ron

 

[jklingel]

Mike/Ron: Thanks for the suggestions. The Extrol #30 expansion tank is new, pre-pressurized to 12 psi, and, according to my tapping, still has air on one side and water on the other. The exp tank gauge is not on the exp tank; just a tire pressure gauge I used. I still can not figure how the exp tank reads 15 to 17 when the boiler reads 40; new gauge on boiler, reading similar to old one. I will triple check that. The house is still plenty warm (was down to 20 below for a few days, now 0) and pipes get hot, etc, as heat is called. One suggestion was made by a guy here, and that is to move the exp tank below an air bleed, or leave it above the boiler and install an air bleed, which it has not had for 35 yrs. Also, it is apparently upside down; the air is above the water. Extrol said that it will work that way, but it is not the best for the tank. Monday I’ll move the tank and flip it. The pop-off valve, set to 30 psi, does not pop when the boiler pressure goes to 40, which is also interesting. Soon, I am going to buy a new boiler gauge and see if that $65 experiment doesn’t solve this mystery. Thanks again for the suggestions. I’ll keep feeding trial info, and sooner or later this will get solved.

 

[mikefromme]

What was the size of the old expansion tank? Could be that the new one is big enough -- might need a second one.

 

[jklingel]

That is a question mark yet (may need 2nd one). I put the system in 35 yrs ago, and bought all the parts from the same place, and they looked at my rough schematics, suggesting this size.... fwiw. In 2000, some pros put in a new boiler and did some small pipe changing, because I wanted to go fishing instead. They either left my Extrol in, or put this one in; don't recall. Thus, I assume it is the right size.... ha ha. Pros are not perfect. Too, when I spoke w/ Extrol the other day, I gave the guy my rough house specs, and he said a #30 sounded big enough. I can't hold him to much, though, as he had no complete data in front of him. I will therefore dig around and see if this #30 is big enough. I have a 2800 sq ft house and a 4-section Weil boiler; the #30 seems to be pretty standard on all the houses I've been in that are about my size. That is just a rough estimate, I realize, so I'll check this out. Thanks for the suggestion. I don't know exactly where to go for data, but I suspect the plumbing places here know; if not, Google.

 

[jklingel]

Progress, maybe solved "good nuff". I reinstalled the exp tank right-side-up, and below an air vent instead of above the vent and upside down. When the boiler was down, the pressure gauge on the boiler went to zero; pressure in the exp tank remained at 12 psi. As soon as I shot the water to the boiler after the re-install, the gauge on the boiler went to 22; exp tank still at 12. When the boiler temp went to 185 degrees, the gauge on the boiler read 32; exp tank reads 15. 32 psi is better than 40 to 42, but I still don't see why the exp tank and the boiler read such different figures. For now, I am going to assume the gauge on the boiler is weird, but I may tinker w/ the pressure reducing valve and slowly drop the pressure it allows through, seeing how it affects the gauge on the boiler and the exp tank's pressure. Either way, the pop-off valve is not popping, and everything appears to be OK. Thanks again for the input. j

 

[jklingel]

Ok, lyao!!!!

This is a huge embarrassment. I would not believe I did what I did, had I not done something like this before in my life.... a few times. Get your laughing hat on; this one's on me. THE PROBLEM has been, the whole time, that, despite my thinking about this and "making sure" I was reading correctly, I was READING THE FEET OF WATER DIAL, NOT THE PSI DIAL! Screw thunder! The two dials are nestled w/ in each other on the boiler gauge, and somehow my eyes drifted as I read the numbers on one side and then read around the dial to the other side where the units were marked. Good God, John! I've had about 15 psi the whole freaking time, which explains why the boiler gauge was "reading something different than the expansion tank's pressure"; it wasn't! OK, get off the floor now, and settle down to a mild giggle.... Oh, sigh.....