Refilling a drained baseboard system

Brad White

You may be fortunate to have high point key vents, in which case you open them with the appropriate key and let the air out. I usually fill to a higher pressure first, say if I need 12 PSI for proper fill, take it to 18 or 20. This makes the bubbles smaller and gives more motive pressure to get the air out. Doing so also saves running up and down the stairs to top things off.

Absent high point air vents, you will have to purge. If you can isolate each circuit, great. The idea is to force water in at a high pressure and constant stream and literally carry the air out with the water at the other end.

Picture the other end as a closed ball valve with a tee and drain valve in front of it. This is your purge valve. Run water in at a good clip and watch the outflow. A few gushes of air-bound water will spew forth. Let it run at least a minute after all of the bubbles seem to be gone. Then close the outflowing drain valve while you close, just behind it, the incoming fresh water valve.

(Close off the outflow and you will rapidly fill to relief pressure, so watch that gauge.)

Isolate what you have purged and repeat for the others.

Once you heat the water to above 140 or better to 180 F. for any length of time, you will have freed up more dissolved bubbles, driven out of solution.

A repeat may be in order but I have it on good authority that Dawn dishwashing detergent, just an ounce or so, will break those bubbles up like Officer Krupke breaking up a riot on West Side Story, only without music nor Natalie Wood.

Dr. Z

Refilling a drained baseboard system

I'm hoping you pros can offer some help for a DIY'er who is stuck in what should be a very minor job.

I drained my boiler/baseboard system to replace a baseboard. That job is done and I'm trying to get things put back together before the Buffalo winter hits (although they are calling for near 80 tomorrow).

I've refilled my system with water, and bled all baseboard valves free of bubbles. But, only a few of my baseboards now heat, and I can hear bubbles in my circulator pump when it is on. The supply pipe 'sounds' full when I tap with my screwdriver; return pipe rings hollow.

What have I missed?

This is a 2 story home, no zone valves, running on a simple 105K BTU Dunkirk boiler. Can't be that hard. . .can it?

coalcracker

If you have a drain valve at the end of your loop(s), I like to hook up a garden hose to that and put the end of the hose outside, higher than the highest radiator and then open the fill valve until all the air is purged. Do each loop separately or all at once. Very easy method.