Boiler Air Lock Diagnosis Help

[Scott Gilligan, CMI]

I have to tell everyone that this is actually for my own boiler and not for a client.

I am having a problem with the boiler in my apartment that keeps air locking. The problem has been ongoing for about 4 years now and is getting worse. Recently 4 spirovents were installed on the baseboards, a expansion tank was installed, and a pressure regulator valve was installed. The system holds pressure and there isn't any signs of water damage in the building that would indicate leaks in the system. Circulator pump is working normally too.

We figure that the make-up water probably has a lot of air in it, but the spirovents should be taking care of this at the baseboards and at the air scoop a the top of the boiler. Anyone have any other ideas why the system would keep air locking? If you need more specifics, I can provide you with what I know about it.

The boiler is somewhere between 13 and 20 years old. The water that is drained to clear the air locks is always very dark rusty water. There is also stains around the vents in the spirovents that were just recently installed about a month ago from the rusty water or air bleeding out.

Thanks

[Marc D. Shunk]

You have a leak that you have not found yet. Simple as that.

If you have a fast-fill on the pressure regulator, flip it up to jack up the pressure to something approaching twice normal operating pressure (with boiler not firing), but below the 35 that the TPR will blow off at and find your leaks.

[Scott Gilligan, CMI]

That's what I keep telling the landlord Marc. Problem is that I am on the third floor and the plumbing lines are behind closed walls that come from the basement. The two tenants below me have not reported any leaks or water stains and the maintnenance staff can't seem to find anying.

[cbottger]

Tell me more, where is the boiler located what kind of seal is on the circulating pump is the make up water automatic or manual is there a sight glass on the boiler indicating water level. Where is the highest section of lines for this system and does it have a bleeder installed at that point or are they just at the baseboard heater. Does the circulating pump have gauges on the return and discharge sides of the pump and what are the pressures especially on the return side.

I Don't think air would be introduced within the make up water itself.

[Marc D. Shunk]

There normally wouldn't be a sight glass on a hot water system. They're best reserved for steam.

[cbottger]

Originally Posted by Marc D. Shunk

There normally wouldn't be a sight glass on a hot water system. They're best reserved for steam.

They are good anywhere they are installed Keeps the blind from leading the blind they would normally be installed at the expansion tank

[Marc D. Shunk]

Originally Posted by cbottger

They are good anywhere they are installed Keeps the blind from leading the blind they would normally be installed at the expansion tank

Uh-huh.

One tends to suspect a dried out circulator suction side flange gasket when air is a persistent problem.

[cbottger]

Originally Posted by Marc D. Shunk

Uh-huh.

One tends to suspect a dried out circulator suction side flange gasket when air is a persistent problem.

Uh-Huh or even the pump shaft seal a possibility

[Gary Oleski]

Originally Posted by Marc D. Shunk

Uh-huh.

One tends to suspect a dried out circulator suction side flange gasket when air is a persistent problem.

I agree with Marc.

[Scott Gilligan, CMI]

OK...We think we finally found the problem with the system I was talking about. Sometimes it is the strangest things that can contribute to a major problem. He is what we found today...

First off...the aquastat on the boiler was turned up to 230 degrees by one of the maintenance guys that apparently never turned it back down. The system was boiling the water and the disolved gases in the water were coming out of solution creating air blockages.

Secondly...the air bleed valves were closed all the way and the air could not escape when it built up.

Thirdly...the pressure regulator for the system was not set properly and did not allow the system to fill back up to a pressure that would drive it to the third floor.

And the big problem...when the maintenance staff would come out to bleed the system of air...he would practically flush the entire system and add all new water. The new makeup water has a lot more disolved gases in it and after several heating cycles would start to come out of solution and create another air blockage.

Problem should be solved now that the maintenance staff has been educated on how to bleed the air from a system.

Once the maintenance guys finally explained what they were doing, it made perfect sense to all of the experts involved in trying to diagnose this 4 year problem. Amazing!!!

[apolillo]

And the big problem...when the maintenance staff would come out to bleed the system of air...he would practically flush the entire system and add all new water. The new makeup water has a lot more disolved gases in it and after several heating cycles would start to come out of solution and create another air blockage.

not to mention the extra corrosion being created by the new water (O2)....

Anatol

[Brian A. MacNeish]

Originally Posted by sgilligan1

Problem should be solved now that the maintenance staff has been educated on how to bleed the air from a system.

Once the maintenance guys finally explained what they were doing, it made perfect sense to all of the experts involved in trying to diagnose this 4 year problem. Amazing!!!

When I was running an IAQ/TAB company, I was very surprised at the lack of training for maintenance staff on HVAC systems.

One of the worst is when we were contracted to do a TAB contract on 3 smaller military buildings. About 1/2 way through our projected timeline, we halted work and got permission to write an interim report outlining problems that would not allow us to balance these system: about 1/2 the equipment couldn't be properly balanced due to:
-Seized dampers/disconnected control arms
-disconnected pneumatic tubing/no pressures
-of course, dirty and displaced filters
-extremely poor duct design with some of the first take-offs being within 2-3 feet of the air handler fan discharge
- in one case the fan motor was turning but the fan blower wheel was stuck

If that was representative of how the military generally ran, I'm glad that we weren't at war then. Hopefully things have improved because we have Canadian forces in Afghanistan now. We wouldn't want them to be dying because of "equipment problems"!

[Gary Reecher]

Have you seen that you have a fix. Question. Is the circulator pumping towards the boiler or away from the boiler? Pumping away is the preferred method. Piping the expansion tank and the water feed between the circulator and the boiler will keep the same pressure throughout the system the same. Pumping towards the boiler will result in a pressure drop bewteen the circulator and the radiators or baseboard. Dropping the pressure will allow air bubbles to exapand in the water.