Heat pump revisited

We're learning some of the differences between our previous natural gas furnace and our new dual fuel heat pump. A properly sized heat pump does not provide the same amount of heat (Btu/h) as does either a natural gas or oil furnace. Our unit raises the return air by about 8 C , delivering air to the 20 C room at about 27 C. When the auxillary heat cuts in, the delivery temperature rises to about 42 - 46 C, heating the house more quickly, but at a higher cost. Our old furnace raised the temperature by about 30 C to 50 C, so you can imagine these extra Btu's would warm the house faster.

Although many suggested that we should not lower our thermostat as far with the heat pump as we did with the furnace, we tried it anyway, as we like a cool overnight temperature. This caused the unit to come on very early in the morning in a vain attempt to warm the house to a comfortable temperature for the two of us to shower, etc., each morning. I quickly realized that heating the whole house, just to make the bathroom comfortable was rather wasteful, as we're out of the house in fairly short order each morning. The solution I decided upon was to install a small, 500 watt electric baseboard heater in the bathroom, controlled by a programmable thermostat. Now, as long as we remember to close the door each night, we awake to a toasty warm bathroom, while the rest of the house remains at 14 C until mid-afternoon, when the heat pump raises it to 20 C.

The one downside we've noticed is the bathroom mirror fogs more easily in the closed room with electric heat, than it did with the circulated air from the furnace or heat pump.