if there's a build up in pressure in the heater, you have two options to eliminate it. Reduce the pressure in your heater, or increase the air pressure in the rest of your house. Fixing the heater could be pretty tricky, and probably voids the warranty, so option 2 is probably easier if you want to take care of the problem yourself.
first, you'll need to seal off your house including all windows, doors, vents
then you'll need one of these
which you can probably find at any aircraft testing facility.
if you ever need to actually leave or enter the house, one of these could come in handy. This brand new model can be used with either Russian or American spacesuits, but if you don't need that flexibility you may be able to get a used one cheaply.
