Sporadic Baseboard Heating Issue:(

[Russell Kahn]

have a multifamily property with a single boiler hot water baseboard heat. Each apartment has a pop top valve with a thermostat. In one studio apartment the heat sporadically stops working. Once 2 years ago the pipe burst. The water will stop flowing sometimes, usually on cold days here in Wisconsin like 5 degrees or below. At the boiler each apartment has its own piping, it's not a single loop system. I've changed the valve and bled it many times. Yesterday it stopped when the apartment was still 60 degrees. There was some cold air coming through the wall by the inlet and outlet (where the pipe goes into the floor) so I used foam to seal those cold areas. In areas, the pipes go through the room inside the concrete flooring. If the boiler is working and the building and other apartments are warm why would only one apartment have this issue? Is it the cold draft hitting the pipes? Any ideas why 0-3 times a winter it stops working?

[Marcus Auerbach]

We have that with water supply lines that are in the wall under a bump out kitchen. Important to keep insulation loose and warm inside air flowing around pipes. What happens is that sometimes contractor mean well and pack insulation really tight, which prevents the air flow and the clod water supply line does not have a heat source, so more insulation will slow down the temperature drop, but eventually it will freeze.

I can't see that being an issue with a boiler line, as it's constantly moving and is heated. Best thing to do is probably track the boiler line and measure surface temperature with a laser gauge until you find the spot that freezes. My guess is it's the return line that will freeze when the thermostat in the studio appartment shuts off the flow for a few minutes, because room temperature has reached the setting and does not require further heating.