Where I live there are a lot of houses with oil furnaces, so granted some of our customers don't see the necessity in putting in an electric or gas air handler when they already have a 'perfectly' fine oil furnace*cough*. So we tend to do alot of heat pump add ons to these oil furnaces and throw a coil in the return or supply obviously depending on what is more accessible with the existing ductwork. moral of the story is new electric furnaces turn on the auxillary to keep sending warm air through the ductwork while the heat pump is in defrost. but with these old oil furnaces when defrost comes on of course cold air comes out of the registers and the oil furnace does not come on to supplement the heatpump while it is doing its defrost. of course it doesnt cool there house down due to how long defrost runs but why would someone want cold air coming out of the registers when its below 32 ambient.
it tends to be a big complaint in the winter time and I hate having to say 'sorry defrost is an essential part to a heatpump being used in winter and there is not much we can do about that'
Does anybody know of any relays or controls that we could use that would turn the oil furnace on to offset the inside coil being used as an evaporator for those few minutes.
all help and criticism is appreciatedhttp://hvac-talk.com/vbb/images/smilies/2cents.gif