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Q. Is it a good idea to hook up a programmable thermostat with a heat pump? Are they efficient and/or do they cause the auxiliary unit to kick in more frequently?
A. Placing a programmable thermostat on the heat pump is a very good idea but not just any such device will work for you. The thermostat has to be specifically designed to be used with a heat pump. The normal programmable thermostat is potentially progra mmable for about six different settings a day for each day of the week. They usually have an internal clock and a battery back up should the power go out temporarily you don’t have to reset everything when lights come back on.
I’ve been told that lowering the temperature between ten and fifteen degrees for eight hours of the day can save from five to fifteen percent on the overall heating bill for the year. The cost of a decent programmable thermostat starts at about $135. out of the box so it doesn’t take too much math to see that they can both pay for themselves and save you money in fairly short order.
Unlike a programmable thermostat for a gas or oil heat supply, the programmable thermostats designed for heat pumps very gradually raise the temperature at a rate that will not cause the electric resistance auxiliary heat strips to come on. Those are the back up heaters that give a quick boost to the heat pump technology should someone turn up the thermostat more than two degrees from its current setting.
Even if you are careful and diligent, manipulating a regular heat pump thermostat by yourself probably won’t save you money and you’ll end up using more electricity for your efforts. The advice generally given-- but rarely followed-- with heat pump therm ostats is to find the temperature setting you can live with and leave it alone. It’s my experience that people fiddle with thermostats and some regard the little control lever as a gas pedal and jam it up to 85º when they are chilly, expecting the house to warm faster. It won’t. The system will just keep working to get to the set temperature and will not cycle off until and if it reaches it.
I tell folks who complain that their heat pump just doesn’t do the job to set it the desired temperature setting and wait. If the room doesn’t reach the desired and set temperature in a couple of hours then something is wrong and it’s time to call in a p rofessional.
I frequently see thermostats placed by the original installers in dumb locations. If the thermostat can “see” a heat source such as an active fireplace or stove it will think it’s warmer than it is and the rest of the house will cool. I have seen split s ystems where there thermostat of the upper level system is in the hallway where the heat from the lower system can fool it. It should be in the master bedroom. Height off the floor is important too. Normally they are set about five to five and a half fee t off the floor. I’ve never known if that height was chosen as it just happens to be the eye level of the average lady of the house but I wouldn’t doubt it.
The most prevalent programmable thermostat that I see in use is the Honeywell Chronotherm III but it has been replaced by the Chronotherm IV and comes preprogrammed to what they consider an energy thrifty combination of settings that will be compatible w ith modern lifestyles. Maybe. Set points are permanently held in memory with no batteries used and retained during power outages in this newer model. But the good news is that if you take the time to read the directions you can play with the settings an d get them where you like it. Of course, when it comes to heating, the more comfortable you are-- warmer-- the more money you are sending to the power company.