Have HVAC Questions? Ask an HVAC Expert for Answers
Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. First I’ll need some more info so I have a more complete picture of you situation.
Is the piping coming back to the boiler from the air handler(s) hot (as a pistol)?
What's the model number of the air handler.
Ok, can you locate the aquastat that's on the hot water piping to the air handler?
Is it connected to a pump relay? do you have 2 air handlers?
I have been called away. I'm going to open this up to my colleagues so one of them can help. Please don't respond (even to acknowledge this post)until you get a response from us. If you respond first it will only delay your answer.
Hello, in my 56 years fixing boilers, I have bled the air out of the radiators only to find them air locked again... bleed them again, run the pumps for30 minutes then bleed them again.
Let me know how that goes, we can go from there as needed.
Tell me in great detail what valves you open to bleed the radiators...some people use the wrong valves, I need to know which ones you are using and where they are located on the coils and what they look like.
tell me if this is what you have or not, if it is, see page 2 it shows the heating coils positioned in the air handler, there is an air bleed port at the high point in each coil.
Bleed vent is show on page 13
You mentioned checking for air in the system earlier, that would have been done at the bleed vents (AIR bleed vents)
Bleeding at the returns will not work, air is trapped at the HIGH points in the system only.
Bleed ONLY the hot water coil.... do not bleed the 'cool side' (cooling coil if that is what you meant.
THe boiler must be under pressure, 20 to 25 psig in order the force the air out of the system when hot.
I need to know in great great detail what you mean by "the cool is hot"
we can go from there
There is a pressure gauge on the boiler that tells you what the boiler water pressure is.
Hello, what is the temperature of the air that comes off of the coil?
You forgot to tell me if you found the tiny air bleed screw at the high point on the coil as shown on page 13, figure 16.
Either a squirt of air or water should come out when you turn that screw counter clockwise
The problem could be anywhere. Tell me how high above the boiler the Unico air handler is please. within 5 or 10 feet is close enough.
Is there a reason that you did not answer my previous question:
Thanks, ***** ***** bleed both coils, repeatedly, you should get a significant squirt of water out if the boiler pressure is 20 psig.
I need you to measure the air temperature that comes off of each coil. Auto supply stores carry probe type dial thermometers for about $6 each, buy several they are used a lot in this business.
the crucial thing to know about ALL hot water boiler systems is air accumulates at ALL high points in the system, even an inverted U shape, it trap at the top of the U and stop water flow
I need the air temperature as massive amounts of air flow past the coil.. not at the vent.
Earlier you said the pipes connected to the coil were hot, but now it seems only 109F water comes out the vent... its one or the other, cannot be both.
again I need the temperature of the AIR as it is blown across the coil on the down stream side.
You need a few hours of basic training on how boiler systems work in order to follow my directions.... there IS NO air vent on the floor... only drain valves.
Tell me if you want 10 hours worth of training or not, we can go from there.