Boiler heat help

[ddsans]

I live in an upstairs apartment in a house with radiator/boiler heat. The landlord that owns the house lives downstairs and pays for the heat. His radiators work fine on his level but two in the living room on the upstairs level are cold. The one in the bathroom upstairs works fine. The repair technician said it's a problem with the circulating pump and he came out today and put a brand new one in ($350 for the part). Should the two radiators get warm right away after the circulating pump is replaced or how long would it take? Any other ideas why the two radiators would be cold? Thanks.

 

[Leon82]

they should start to warm up within a few min, the time it takes to pump the hot water thru the cold pipe there could be air trapped of a blocked valve somewhere

 

[Sponsor]

 

[Dana]

Unless the zones are on separate pumps it's rare that a cold radiator on the second floor would be due to a pump issue when the first floor radiators are working fine.

Low system pressure insufficient for raising water to the upper floor rads, or large amounts of air in the system limiting flow to the upper floor loop are far more likely. Air bubbles will naturally collect in the upper floor radiators, and that air needs to be purged or bled any time large amounts of air are introduced into the system, such as when it's opened up for a pump swap.