Hot water boiler pressure always too high

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  #1  
Old 10-16-10, 11:30 AM
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Hot water boiler pressure always too high

A couple of years ago, the relief valve on my boiler kept blowing off and/or dripping constantly. I replaced it, but should have saved my money because the new one did the same thing. Turned out the pressure kept climbing up way too high (I should have checked the gage first). So I replaced the automatic fill valve (a Watts 1156F) with a new identical model. Problem solved....for only one season! Last year, same problem again. So, this time I used a Taco 329 T3, and, once again, problem solved. You know where this is going! This year, now that it is getting chilly and the heat is on again, I have a leaking relief valve and pressure going sky high once again.

Could this just be bad luck, getting two short lived valves in a row, or is something else going on? I hate to make this a yearly ritual!

Rob
 
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  #2  
Old 10-16-10, 12:11 PM
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How high is the pressure and temp? What was the system pressure this fall, before you started up the boiler?

You probably have a shutoff valve ahead of the pressure reducing valve? Shut it and drain down the boiler to the correct pressure. Then see if the system pressure remains steady. That would pretty well prove that it's the pressure red valve leaking through.

Those valves should last more than a year. Maybe there is sediment in your make-up water that somehow erodes the seat? Does your valve have a built-in strainer?

Another long-shot possibility: if you have a slow leak somewhere, maybe the pressure reducing valve's seat becomes wire drawn, leading eventually to leakage?

Many people choose to run with the shutoff valve isolated. If you do that, you should keep an eye on the pressure gauge regularly. I would certainly shut the valve when the boiler off for the summer. Did the pressure rise during the summer or after you started the boiler this fall? If the latter, I would suspect the expansion tank has lost its air cushion.

If the valve is leaking, I think it should have leaked all summer, not just when you heated up the boiler for the first time this fall.
 

Last edited by Mike Speed 30; 10-16-10 at 12:27 PM.
  #3  
Old 10-16-10, 02:48 PM
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The temp is set at 190, and the pressure creeps up to near 30 psi. Actually, I had the fill valve (which is ahead of the pressure reducing valve) closed all summer, and the boiler was off since I have a separate hot water heater. When I started it, the pressure was about 5 psi. I opened the shut off valve and it gradually climbed to high enough to blow the relief valve. It keeps blowing, so I had to close the shutoff.

By the way, the first time I replaced the pressure reducing valve, I also replaced the expansion tank for good measure. The whole system is 30+ years old and it is really on it's last legs. I just want it to last one more season, when hopefully enough $$ will be available for a new boiler and all the peripherals But for now, I'm stuck with this..
 
  #4  
Old 10-16-10, 03:40 PM
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Originally Posted by robnovotny View Post
The temp is set at 190.... When I started it, the pressure was about 5 psi. I opened the shut off valve and it gradually climbed to high enough to blow the relief valve. It keeps blowing, so I had to close the shutoff.
OK, I'm pretty well satisfied that the problem is, as you think, leakage through the pressure reducing valve. But, starting the boiler and opening the shut-off valve at the same time leaves a slight gap in the "scientific method" for pinpointing the cause.

It seems that you lost quite a bit of pressure over the summer - with the isolation valve shut. For comparison, my system loses zero pressure over the summer. Your 5 psi, if correct, is little more than the static pressure from a single-storey house with the boiler in the basement. (A 2-storey house would be even more.) I'm suspicious that you may have a leak somewhere.

Why are you running the system at 190 deg? Is your gauge accurate?

When you say the system is on its "last legs," what else is wrong with it?
 
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Old 10-16-10, 05:51 PM
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My system holds pressure indefinitely also...

Before installing a new reducing valve always FLUSH THE LINE full blast. Since little water flows through that line normally, it's pretty common for 'crud' to collect in it. You might consider installing a wye strainer on that line if you think crud is what's causing the problem.

0379081 - Watts 0379081 - 1/2" 777SI Bronze Wye Strainer (Threaded)

Bladder type expansion tanks should, IMHO, be checked EVERY YEAR for the correct air charge... at the very most, every two years.

They lose their air charge just like a child's baloon... the air molecules migrate right through the rubber bladder.

Watts and Legend both make valves that make changing a tank or checking the air charge real easy. The Watts valve is fancy, and about $40 ... the Legend valve is a bit more basic, but has the same function as far as the expansion tank port goes. It's about $15.

0386466 - Watts 0386466 - RBFF, 1/2" Residential Boiler Fill Fitting

41672 - Webstone 41672 - 1/2" Pro-Pal Full Port Brass Ball Valve w/ Hi-Flow Hose Drain (600 WOG)

You can also 'roll your own' with a ball valve, a tee fitting, and a boiler drain.

So, bottom line is while you are working on the system, and have the pressure drained, check and adjust the expansion tank, and if you are so inclined, add the valving that makes it easy to do so.
 
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Old 10-16-10, 06:16 PM
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Speakin' of Leakin'

One thing you could do even before you change the reducing valve out... with the boiler stone cold, open the shutoff valve and feed water until you are at 12-15 PSI. CLOSE the shutoff valve. Run the boiler let it get up to high limit (crank the thermostat). Check pressure, it should be around say 20 PSI... then shut it off, let it get stone cold again. Check pressure. It should return to 12-15 PSI.

One thing that should be mentioned also... about expansion tanks... is that you can NOT check or adjust the air charge if there is ANY pressure on the boiler side of the bladder. You will NOT get an accurate setting. The boiler side must be at atmospheric pressure.
 
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Old 10-17-10, 07:39 AM
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Originally Posted by NJ Trooper View Post
You might consider installing a wye strainer on that line if you think crud is what's causing the problem.
My Bell & Gossett pressure reducing valve has an inlet strainer built it. The strainer nut is on the bottom of the valve. Don't know about other brands.

I've cleaned the strainer every couple of years. Can't remember for sure, but I don't think it had much sediment.
 
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Old 10-17-10, 08:20 AM
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The Watts 1156 doesn't have an easily serviced strainer such as the B&G does. Not sure about the Taco model...

Nice thing about the wye strainer ahead of everything though is that you can remove the 1/4" plug and install a small ball valve... open valve, blow down strainer... done.

Thing about those strainers is that the mesh ain't real fine... some particles can still sneak through and get under the valve seat.
 
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Old 10-17-10, 03:30 PM
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A city-water system with a Watts #9 backflow preventer, followed by a pressure reducing valve: Would you put the wye strainer ahead of or after the #9? And why?

P.S. Many years ago, the Navy much preferred Mueller duplex strainers - turn the handle, and the other strainer is on line while the first one is off-line, ready for cleaning. (You don't want to be attacked while a wye strainer happens to be isolated! And, of course, for the Navy price was no object.) I just checked - Mueller duplex strainers are still made - but, just guessing, maybe several thousand dollars each?
 

Last edited by Mike Speed 30; 10-17-10 at 03:49 PM.
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Old 10-17-10, 04:23 PM
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Would you put the wye strainer ahead of or after the #9? And why?
Ahead of... why not protect that also? ... judging from all the leaking and plugged up reducing valves (and to a lesser extent 9D's leaking out the atmospheric vent) we hear about here.. I'd call it cheap insurance (about $15).

If you've ever put a water filter on city water and looked at it after a few weeks in service, I think you would be very surprised at what you see!

I don't like 'dead ends' on a plumbing system either. The water that sits out there in that pipe... barely moving... gettin' all stanky... who wants their drinking water flowing right past a pipe with stanky old water in it?

I'm on private well here, not chlorinated (but ultra-violeted) and I don't have a strainer... but I do have a boiler drain just ahead that I flush the line periodically. Most ppl probably aren't as AR as I am about this stuff, so let's call my suggestion of a wye strainer ahead of the 9D a luxury.
 
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Old 10-17-10, 06:48 PM
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Barely moving gettin' old and stanky? Isn't that all you drink when you are on well water?

You are right about city water. The water in my town has lots of sediment in it. I put a whole house filter on a year ago. If I cut one of my water lines open, there is a bit of sediment sitting in the bottom. I think it's largely rust for the old water mains.
 
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Old 10-17-10, 11:26 PM
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Mike, duplex strainers are made by several companies besides Mueller. They are used on systems that require 100% of the fluid to be strained and cannot be shut down for servicing. Fuel oil, lubricating oil, hydraulic oil, cooling water and such in power plants are the primary systems where the flow simply cannot be stopped for a strainer cleaning. And yes, they ARE expensive.

As for using a "blow out" valve on a simple Y strainer my experience has shown that blowing the strainer usually has minimal cleaning effect, it is necessary to isolate and remove the screen to properly clean it.
 
  #13  
Old 02-11-13, 06:09 PM
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Creeping Water Pressure Problem

The creeping water pressure problem in my case was fixed as explained in the image below
Mine is 1 in Watts water pressure regulator
The main problem was a leak through the Thermal Expansion Valve due to dirt accumelation between the plastic ball & the Brass seatting
http://www.hirmiz.com/images/WattsPr..._Regulator.jpg
 
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Old 11-08-14, 09:05 AM
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Reviving an old thread to ask if I'm on the right track based on the above advice.

(note - about 6 years ago, folks here helped me replace nearly all the moving parts on my system - I'm eternally grateful!)

I'm having the same problem as above - replaced the pressure relief valve due to leaking. Pressure gauge was showing pressure creeping up to just under 30psi, which I know is too high - but I threw my blinders on and hoped for the best.

Went to the basement today after a week or so of heat usage to find a wet floor. Ran the system, watched the pressure climb to 30psi, valve opened as it's supposed to.

Age of existing parts:
Backflow preventer - at least 10 years.
Pressure reducing valve - 6 years
Pressure relief valve - 1 month
Expansion tank - 6 years
Small relief valves on the pipes and tanks - 1-6 years, all caps easily unscrew - there is evidence of leakage from the one on the expansion tank.

Right now, I'm letting the system cool to ambient with the fill shut off valve turned off. As it's cooling, pressure keeps dropping to 0-5psi. I open the valve, raises to 10-11 and stops.

My plan based on above - let it cool completely, fill back to 10-12 psi, turn off the fill and let 'er rip. If pressure remains in the safe zone, it's the reducing valve. Anything else to check before turning the system back on?

Thanks in advance,

Ken
 
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Old 11-08-14, 09:32 AM
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Nevermind! Expansion tank has failed - just checked the pressure and water came out. Guess I know what I'm doing today!
 
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Old 11-08-14, 09:54 AM
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Sounds like it... more fun than finding the source of the dead animal smell in my garage... I'll trade ya!

Read this, at the bottom some tips when you replace tank... add those optional valves and make future life easier.
 
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Old 11-08-14, 10:00 AM
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Thanks, Trooper! You were the one who helped me years ago. Glad to see you're still helping here!

Off to the basement...

Edit - that did the trick. Thanks again to everyone here.

PS - I do think the dead animal would be the worse option here!
 

Last edited by alken; 11-08-14 at 11:17 AM.
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Old 11-08-14, 02:50 PM
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Glad to see you're still helping here!
Yeah, I keep thinking I'm gonna hang up my spurs, but I just keep going! Maybe when I get to 30,000 ...

Glad you got 'er fixed up.

PS - I do think the dead animal would be the worse option here!
Still haven't found it... smell comes and goes... there's so much crap out there it could be anywhere! I did actually find a skeleton, but that must be the one I smelled a few years ago and couldn't find then.
 
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Old 11-08-14, 06:15 PM
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Critters die in wall cavities all the time!

On topic - my pressure reducing valve is also done for. Pressure climbed to 35psi and dumped again. I turned off the fill, it's stable. Problem contained for now! I'll get to the valve next week.
 
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Old 05-03-15, 02:07 PM
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Closed thread... Post was hodge podge of postings...OP never came back after 2 posts...
 
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