Airlocked oil fired boiler

[labtek]

Hello to the group and good day. I have an oil fired boiler with 2 zones, each one controlled by an electric zone valve. Probably a fairly standard installation.

Recently during a renovation, a 3/4 inch copper pipe for one of the zones was punctured by a screw. I shut down the zone, drained and repaired the pipe. I had thought at the time that I had re-pressurized the zone OK since I had hot water circulating back at the boiler.

Now a few days later, I have no circulation in either zone and the circulation pump is turning but seems to be not pumping water. There is no water at any of the air bleed screws at the baseboard radiators upstairs. The system will not thermosiphon with the zone valves opened manually.

Is it possible that the boiler has become airlocked somehow and the circulation pump does not have any water to pump? If so, how can I get the system working again?

Thanks for any suggestions.

 

[Matt30]

Is your boiler functioning correctly? Fed at 20 psi?

Does the return side have a drain? Open the drain and dry forcing air out that way (zones open, one at a time. Any auto-air vents not working?

Some circulators have check valves, have you checked to see if those were stuck closed? Another thing is too, the motor of your circulator would going, but the impeller could be no good.

Lots of bases to cover here, unfortunately fighting an air lock can be very simple, or a nightmare

 

[johnjh2o]

What is the water pressure on the boiler? It sounds like the auto feed isn't working. If your not getting any air or water when venting the system the pressure is to low. Normal pressure should be 12 psi.

John

 

[LiQuId]

Does sound like a boiler feed valve issue, you shoudl be able to purge the air from the high points in the system by use of pet cocks or auto air vents.

does the pump sound like popcorn ?? this indiacates cavitation ( air in the pump exploding ) it kills the impellar of the pump fast..

is the pump red hot ?? this also is a bad sign.... busted pump - replace pump.

Regardless you Should be able to achieve pressure in the system by means of the boiler feed.

Not too familiar with oil burners but A boiler is a boiler regardless...

I toss in my 2c here about the pressure.

the pressure has no "normal" setting although its typically not more that 20 psi at max, and usually closer to 10-14 psi. it is decided by the system design and various factors, but its basic principal is that it takes .433 psi to lift water 1 foot, so the pressure required varies depending on the hight of the system allong with various aspects.

.... sorry guys, I'm feeling mathematical today and have been putting together a quote for a heating project ..lol

 

[labtek]

Thanks for the helpful posts. I had planned to remark in my original post that I suspected the autofeed system which perhaps had not replaced the water that I had removed from the system when I drained the line to repair it. Now, maybe there is not enough water to fill both of the zone lines as well as the boiler.

My well pressure varies from 30-50 PSI and the pressure regulator on the boiler cold intake is set to 12-15 PSI and the boiler pressure is presently running at 8 PSI, so the regulator should have allowed extra cold water to be drawn into the closed system to replace what was drained out. Perhaps the regulator has become seized over the years and is now not wirking properly.

Is it possible that these pressure regulators can cease to function properly? It's been in operation for many years now. If so, can they be repaired or should I replace it?

Thanks again for the posts

 

[johnjh2o]

Replace it. They do go bad and quite often. But there is also a chance when You turned off the valve to drain the zone the valve may not be opening. If you have no heat you could temporarily refill the system with a hose. All you need is a section of hose with two female ends. (a clothes washer hose will do) Connect one end to the drain on the boiler and the other to a hose bib. Turn them on but keep an eye on the boiler pressure gauge. When it reaches 12 psi turn it off. Then vent your system. After venting you may have to top off the pressure again. But don't let the pressure exceed 12 psi. This will give you some time until you replace the auto feed.

John

 

[labtek]

Thank you John for the post. I don't have heat from the boiler but I do have a secondary heat source while I replace the regulator valve on the autofeed system.

I'll try your refill suggestion in the meantime.

Thanks again.

 

[labtek]

Hello again to the group.

As a postscript to this thread, today I used John's suggestion and attached a garden hose to the boiler drain from my well and put higher pressure water into the boiler to a maximum of 12 PSI therby by-passing the defective autofeed system.

I then bled the air from one zone and then the other while replacing the water that I drained out while doing so.

I'm pleased to report that both zones are now running hot and the boiler is maintaining 12 PSI.

Thanks to all who posted responses to this thread. Perhaps this will help someone else with a similar problem in future.

Since the boiler is scheduled to be replaced in the Spring and assuming no further breaches in either zone I will delay installing a new pressure regulator valve and will replace it with the new installation.