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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 22022
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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The hot water isn't going through the pipes but the boiler

Customer Question

The hot water isn't going through the pipes but the boiler does come on
Submitted: 2 years ago.
Category: HVAC
Expert:  Rick replied 2 years ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can

continue our conversation.

What is the pressure on the boiler? is the circulator/pump running? how many thermostats do you have?

Customer: replied 2 years ago.
Psi is 25 pump is running 1 thermostat
Expert:  Rick replied 2 years ago.

If you're sure the pump is running then the only reason the water wouldn't circulate (assuming all the valves are open) is air in the pipes. You'll have to purge the air out of the system. Here are instructions on how to purge the typical baseboard system.

A purge station is typically a shut off with a hose fitting above it. There can be 1 piece purge stations where both the shut off and hose fitting are combined in one piece. Or it can be a separate valve(shutoff) with a hose type "faucet" (we call it a boiler drain) above it. They are usually at the boiler on the pipe above the circulator pump. You need to determine which one goes to your problem area. I have seen purge stations in old systems some distance from the boiler on the heating line (pipe). Be sure to turn the power off to the boiler while you are purging and it’s best to let the boiler cool down to around 100 degrees (if it’s currently hot) before purging. Dumping a lot of cold water into a hot boiler is not beneficial.

You need to shut the valve, attach a hose to the hose fitting then open the hose "faucet". Some all-in-one fittings close the valve and open the hose at the same time so be sure your hose is attached first if you have one of these fittings. If you have zone valves with multiple purge stations all the zone valves should be opened manually. The common theme here is that you want to push the water through the loop and have it come out the drain. If you don’t stop the flow below the drain no air will be purged. You don’t want the water to go directly from the boiler and out the drain/hose. Closing the shut off next to the drain forces the water through the piping loop/zone. If you have zone valves and only 1 purge station then you need to open the zone valves one at a time and fully purge a zone before opening the next valve and closing the valve you just purged. You also need to jack up the pressure while you are doing this but you need to keep the pressure under 30 psi.

This is done by increasing the pressure at the feed (pressure reducing) valve.

Some types have a lever that you flip up from a "horizontal" position to straight up. This is the easiest type to use. Some require that you tighten the screw at the top of the valve. Some have a lever that moves from side to side. You should be warned that if this valve hasn't been touched in a while disturbing it in this manner can cause it to fail in which case it will need to be replaced. A feeder failure would mean that the feeder lets too much or too little water pressure into the boiler. This device is located on the water supply line to the boiler.

You need to let the water run until you hear no more bubbles coming out of the hose for several minutes. You then shut the hose off at the same time you return the feed valve back to it's original position. Then open the shutoff. Be sure the pressure on the boiler is between 10 & 15 psi when you are done and before you turn the power back on. The boiler you have has no bearing on this process. It is the same what ever type you have. Having said all that this is not something I would recommend that you try yourself unless you feel confident about doing it. You may have to call a plumber anyway if the feed valve fails.