Bleeding a Hydronic Baseboard
Hi all, found this blog through google search. I have a rental house built around 1964, Just converted to a 120k gas boiler from old oil boiler. Three zone system. All two zones seem to heat fine, 3rd zone newer Honeywell thermostat in the master bedroom. When that thermostat is set to 68 degrees, the second bedroom sometimes gets down to 62-64 degrees at night the tenants father says. I just had New Jersey Gas do an energy audit and they say to insulate the attic, etc. That floor has older hydronic baseboards, the second bedroom bleeder valve is stuck and so can’t bleed that baseboard. All of the other baseboards can be bled. The company that installed the new gas boiler said that that baseboard was heating and so there was no air in that baseboard. I think all baseboards should be able to be bled, that’s why they are there. I could get a plumber to cut the copper bend pipe and put on a new bleeder valve. Any thoughts? The house is in North New Jersey where it can get down to 0 degrees in the winter.
I am also thinking of insulating the attic and also insulating the 1 inch pipes in the basement.
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How did it heat before the boiler change? Are the supply pipes getting hot and is the return less so? Zoned with pumps or zone valves?
I asked the tenant that same question and he doesn't remember. One side note I tried moving the thermostat from the master bedroom to the 2nd bedroom and set it at 70 degrees. The tenant complained that now his room (master bedroom) was now 75 degrees and he had to open his window so I moved the thermostat back to the master bedroom where it is now. I am going over there tomorrow to check if the bottom and the top of the baseboard is the same temperature.
If the radiator is getting hot it doesn't need to be bled. If these are the Slant-Fin type baseboards where a 3/4" copper pipe runs through the middle they don't hold much water and it's pretty easy to get the air out.
As to why your heating system isn't maintaining temperature, there's two general directions to look in. The first is that heat isn't being delivered by that radiator when the thermostat calls for it. That's a problem with the control mechanism -- thermostat, zone valve, circulator. The second possibility is that the radiator is delivering heat, it's just not enough to get to the set point. If this is only happening at night, I'd ask what else is going on. Like are they turning off the heat to the rest of the house? Because, yeah, on a cold night one zone isn't going to be able to keep a temperature a lot warmer than the other zones. If that's the case the solution is simple, don't turn the other zones down so much. They're not saving any energy -- it takes a certain amount of energy to heat the bedroom to 68F, the one zone can't supply that much energy, the other zones need to kick in. But it's the same amount of energy as if the first zone could do it all.
Bleeding baseboards isn’t what you want to do - that just introduces makeup water into the system (full of bubbles, so even more air). It’s a closed system. There should be no leaks and no air.
I'm not sure if the installers who put in the new gas boiler drained the system in the bedroom zones. These hydronic baseboards are probably original to the house (1964)? The downstairs has the old cast iron radiators. It is nice and warm down there. I am going over there tomorrow and use pipe wrap insulation on the downstairs pipes from the boiler to hopefully stop heat loss.