Mail bag

This week we will deal with some questions in our mail bag.

Q. We have an air source heat pump and an electric furnace. Ever since it was installed over 8 years ago the furnace fan runs continuously and the heat pump never seems to shut off in cold weather. The house feels drafty much of the time. Can anything he done? -- Dan W., Bowmanville.

A. Dan, you have a two stage system! That is, the 1st stage operates on the heat pump and the 2nd stage operates on your backup electric furnace. The heat pump supplies the base heating load for the house. For example: suppose you have a 2 1/2 ton heat pump. At 32°F an average heat pump output is around 20,000 BTU's/hr. As the temperature outside falls the heat loss from the house increases. At some point when the heat loss of the house exceeds the heat output of the heat pump, then your electric heat will kick in to provide the extra additional heat your house needs. At this point your heat pump will run continuously as well as your furnace fan. As far as your complaint that the house is drafty feeling during cold weather, this is due to the fact that the heat pump can only supply about 90°F heating output through the registers. At this low temperature the placement of registers becomes very important. If located near people this tepid air soon becomes unbearable. Duct design and register location is very important to avoid complaints with heat pump systems. If the pump does not cycle on and off in milder weather, above 32°F, I would suggest you call a qualified heat pump technician to discuss your problem!

Q. We have a gas furnace that is 12 years
old. The furnace fan seems to run all the time when we use the furnace over the winter. Is this normal? -- Cathy, Bowmanville.

A. Cathy, this is definitely not normal! Your furnace fan should cycle on and off in response to heating demands from your thermostat. During the no heat cycle your fan should shut off. Running the furnace fan unnecessarily causes higher power consumption (hydro) and drafts due to cool air being blown out the hot air vents. If you have a heat/cool system make sure fan is set to auto on thermostat. Also make sure your summer/winter setting is correct. If problem continues, a qualified and licensed gas and electrician should be called. My bet is a problem with the combination fan/limit control on your furnace.

Q. I wish to install a used gas furnace in my garage/workshop. Can I do this? -- Dave, Newcastle.

A. In most cases you probably can. The installation must comply with the latest installation codes.
A qualified gas technician should be able to give you a definite answer. Some things that must he addressed are: ventilation, gas piping, venting of appliance and protection from getting damaged from cars, or other objects. An inspection of the heating appliance heat exchanger is important, especially if it is a second hand appliance, before it is hooked up for carbon monoxide reasons.

Some newer appliances are direct vent which draw air from outside and hence are less prone to venting problems. These can also he installed through the wall in most cases, avoiding a chimney being installed.