Rental Property Investor · Brattleboro, VT · Member since 2015 · 204 posts · 174 votes
Hi BP,
I'm having an issue with my boiler and thought I would ask here before calling the repair guy. I have a 5 zone boiler, system 2000. 4 zones are working perfectly, one zone has no heat at all. The thermostat is working and the boiler is calling for heat. The outgoing pipe from the boiler gets hot for about 20 feet, then it is cold by the time the pipe makes a 90 degree vertical turn and rises from the basement to the second floor. I've checked all valves which are all open and the zone valve seems to be functioning correctly. I've attempted to bleed air out of the pipe by using the spigot located on the return pipe for that zone right at the boiler. Water runs for about 10 seconds then the flow slows to a trickle. Any ideas?
@Josh Dillingham I had this happen before at 2 of our rentals. Both times they were air locked. Sounds like you tried to bless them, but maybe there is another release further down the pipe you haven’t released??
Just to confirm that this is a water system and not steam. The zone valve could be inop and would explain why its cold on both sides of the valve. Depending on the way its piped, it could be that there are other points that air may be trapped in.
A very common issue is the circulator pump (if its a hot water system which it seems to be). If the circulator pump is on the way out it may be struggling to move the water upstairs and might explain that the water moves for a few seconds but then slows to a trickle. The heat from the water in the boiler may be able to heat the pipe for a certain distance, especially if the pump is still moving the water at a low rate. But it won't be pumping at the required rate to get enough volume of water upstairs before it loses its energy (heat). I'm not a boiler tech so this is just speculation. I know it happened in my house last year that the boiler was running but the heat wasn't working upstairs.