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Process for refilling hot water heat

I emptied the water on my hot water baseboard heating system this past spring to fix a couple valves that were leaking and to do some remodeling. Well, its time to fill it back up and turn it on (40 degrees out last night and my wife wasn't happy about the lack of heat).

What is the process for doing this?

I assume I turn the water valve on and let water flow back into the system. Then I would imagine I have to get air out. Hopefully there is an easy way to do this? I noticed there are some bleeder valves at the end of each baseboard heating section. Do i need to bleed each one?

Can some one give me the step by step? Thanks!

Re: Process for refilling hot water heat

Yes, you have to turn the water valve back on to allow the system to refill.

Before you start, quickly check your work on the valves (and any baseboard) you removed for poor solder joints or loose fittings.

Re-solder any suspicious joints; if the system leaks after you refill it, you will have to drain again & fix the leak, which takes more time.

The system has a pressure reducing valve right after the water fill valve that allows the system to fill to ~12 psi water pressure.

As a first step, don't turn on the boiler; concentrate on filling the system with water & doing the first bleeding.

I recommend you let the system fill for about 15 minutes (you will hear water flowing inside the pipes), then start at the highest baseboard & start bleeding the little bleed valves using a small screwdriver to open & close the little valves.

Meanwhile, check for leaks on the new work you did replacing the valves in question.

Carry a small cup around with you to catch any water coming out of the bleeders, or scrunch a wad of paper toweling & place it under the bleeder before you open.

Within 1/2 hour the system should read ~12 psi on the pressure gauge on the boiler & you will no longer hear water flowing inside the pipes filling the system.

If no leaks are detected, you can then turn on the boiler by turning up the room T-stat, & flipping the emergency power switch on the boiler (or the top of the stairs) to ON.

The burner inside the boiler should come on & begin to heat the water inside the boiler; if you have zone valves in your system, it may take another 60 seconds for the burner to fire.

When the water reaches ~160 degrees on the boiler temp gauge, the circulator (pump) on (near) the boiler will start pumping the water thru all the piping & thru the baseboard.

To verify the pump is on, place the blade of a large screwdriver on the pump housing & place your ear on the handle end; you should hear a high-pitched whirring.

Allow the boiler to cycle the heat for ~10 to 15 minutes until all the baseboard are hot, then turn down the thermostat.

The burner & circulator will eventually turn off (cycle completed).

You can then go around again to do the 2nd bleeding, repeating the valve bleeding process to expel additional air that has been driven to the higher points in the system by the pump (the highest baseboards on the 2nd floor, for example).

These baseboards have to be bled to get any additional air out.

Check again for leaks on the valves & anything else you worked on.

Please post back to advise if you run into any snags, or if any leaks develop.

In the event of leaks:

If the piping near a valve or baseboard starts to leak, place a small bucket or rag under it to catch the water.

If the leak is coming from a compression (screw-on) fitting, you can try tightening the fitting with a wrench without shutting off or draining the system.

If the leak is coming from a soldered fitting, and it's very slight, a temporary fix can be to wrap the joint tightly with black friction (electrical) tape.

If that doesn't work cut a piece of rubber hose, rubber inner tube, etc. & secure it on the leak with one or two screw-on stainless steel clamps.

Since the water pressure is only 12 psi, this almost always works, & is a temporary fix to allow you to heat the house overnight & make a permanent fix the following day.

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