Bleed air from gas boiler hydronic heat system
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Hello all,
I have a gas boiler with 2 zones. 1 zone for first floor, 1 zone for second floor. My second floor heats up great. My first floor gets nothing. I can set the thermostat, hear water pumping through the pipes, boiler fires up, but no heat in zone 1. I feel the pipes, they get hot until they hit one of my hydronic heaters and it goes cold from there. I believe there is air in the system and I'm not sure how to bleed it from the boiler. I only have one bleeder on one of my hydronic heaters and it doesn't do me much good. Here's a few pics of my pipes. Which valves do I open/ shut to bleed?
Please and thank you
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Thank you for the replies, I know to some people this is stupid simple but I have no experience tinkering with boilers. There's 2 zones, 2 shut offs, multiple places to drain from so I wanted to reach out and ask one of you before I do something backwards. There's drain valves above and below the circ so I think it's understandable how someone with no experience could have questions.
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It looks to me like the pipe with the red valve handle is the hot water out of the boiler and the blue handle is the cooler water coming back.
What you want to do is run water through the loop faster than it normally does to try and push out the air that is trapped there. You want to open the zone valve on only the zone you are trying to purge. You want to close the ball valve that is right above the circulator, and open the drain that is right above that. if you provide a source of water on the boiler side of the loop the will flow out of that drain after flowing through the loop. I like to put a short piece of hose on the drain and put the end in a bucket of water so you can see as the air bubbles come out.
There's three ways to get a source of water. The boiler is hooked up to the cold water supply of the house, I can see it in the background. There is a pressure reducing valve with a lever on the top that lets you bypass it. You can also just hook up a hose with house water to a drain on the bottom of the boiler, that's the red-handled valve in the picture. Or you can hook up a pump to a bucket of water.
I like doing the pump method because if you pump out of the same bucket that the purge water goes into, you don't have to worry about overflowing the bucket, and you can see how much water the system takes.
Does your system have antifreeze? If so, you have to use the pump method.
Turn everything off before starting.
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An even simpler way to do this is just turn the thermostats all the up in both zones for a few hours and the air will migrate back to the basement and be vented out. As Mr. Holohan is fond of saying if you are getting nothing but water it is not an air problem. If nothing changes you may have to shut the system down, drain it and clean the spirovent of debris.
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Turn the thermostats up, open the globe valve, manually open the zone valves and just wait. Whoever designed that mess does no deserve a medal.
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OP, show us your zone valves, you might be able to purge from there, or as written above at the circulator,
turn off the circ and boiler power, manually open the 1st floor zone with the air, close the valve at the circ, and drain from the hose bib there, you need to keep the system pressure up about 20psi while doing this, and set it back down to 12 when done, show us the makeup feed valve for the system also,
known to beat dead horses0
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