As you may recall, I wrote a post about my personal heat pump experience nearly two years ago. Remember, I'm a home inspector and not an installer and not associated with any installation company or heat pump. I installed it myself and all of my experiences are my own and not shared with me by anyone else. I'm drawn to the heat pump efficiency, low cost of operation, cooling in summer, and ability to install myself with a DIY system (not for everyone).
My experience since the original post has been similar. My electric bill has been relatively constant (other than normal seasonality) and I continue to run my heat pump constantly with very little fluctuation in temperature. My oil usage has also been similar, still a 40% reduciton from where it was pre-heat pump.
I have an 18,000 btu unti with a single interior head located in a large room (living room/kitchen combination). The living room portion has cathedral ceilings and my home's insulation is average, at best (thanks a lot 1978...). This heat pump is supplemental. When my boiler decides to quit on me, I can almost guarantee I'm going full heat pumps to replace it.
A few things that I have learned since my last post:
Auto Settings are the Devil! Ok, maybe a bit too far but I found my heat pump attempting to change from heating to cooling modes automatically when interior temperatures rose above the set temperature. In my world, this is the equivalent of me turning up the thermostat without permission when I was 9 years old. This was in late fall when we get a lot of morning sun after my oak leaves were (finally) down. That passive solar energy brought the inside temp up and the heat pump tried to change to cooling mode. As you all know, too much heat will take care of itself pretty quickly in cooler months and I'd rather not waste it. Now I know to keep the unit in cooling mode during summer and heat mode during winter. No more auto for me...
Fan Settings Are Just As Important: Sorry if I get a little nerdy, but I found a way to increase the temperature inside without using much more electricity. A heat pump is called a "split" for a reason. One exterior condenser is "split" from the interior fan/head. Basically, the outside unit works its magic to draw heat from outside air and condense it into refrigerant (hot and cold). The heated or cooled refrigerant travels inside where a fan blows recycled, interior air over the hot or cold lines. This makes hot or cold air. Most of the power is used to make the refrigerant hot or cold. The interior fan is just that: A simple, basic fan.
My unit has four fan settings: three levels and the dreaded "Auto." Have I mentioned I hate auto? (If the Terminator was in "Auto", I'm convinced there would have never been a sequel and Arnold would have continued bodybuilding). Simply moving the fan to level 2 increased my overall first floor temperature without me increasing the thermostat. The stronger fan setting sent warm air deeper into my house, increasing the overall comfort level of the main floor. Going to level 3 would be too much as it would reach temperature too quickly and cause the heat pump to start/stop too much, reducing some of the energy efficiency. Remember, slow and steady for a heat pump. Think of it as cruise control for your heating and cooling.
Clean that Filter: Filter? What filter? Each interior head has its own filter. As mentioned earlier, the head uses recycled interior air. A filter is there to help keep dust out of the air before it gets blown over the hot/cold lines. When the filter becomes clogged, the fan is underperforming, reducing heating/cooling potential and using the same amount of energy.
Simply open the front panel on the interior head unit (pull at the bottom as the hinge is at the top), remove the filter and clean in the kitchen sink using warm water. Dry the filter COMPLETELY (otherwise dust will stick even more) and then re-place. Nothing to purchase, just a little elbow grease to keep it running optimally. Some people need to clean it annually and some monthly. It all depends on your lifestyle. Check it often.
Lastly, my confidence continues to grow with the heat pump's ability to act as a primary heat source for a home. Without question, they will use more energy during the coldest periods, but I have nothing that shows me they cannot reach set temperatures. Older, drafty homes are on their own as any heating system will struggle in that environment. If you have one of those homes, focus on air sealing and insulation prior to making any heating system decisions.
I still hear discussions that heat pumps are not ideal as they require electricity and won't function during power outages. Well, so does every other oil/propane/gas heater. They all require power to ignite, manage temperature, or control a fan. Even pellet stoves stop functioning as the auger used to deliver pellets runs on electricity. Your only option without electricity is a wood stove or a propane/gas stove without a fan (not effective.
But what about this new heat pump technology? Nope. Not new. It's the same technology as a refrigerator where it removes the heat energy from the fridge interior and dumps it outside the fridge (the back is always warm, yes?). It's just in reverse during the winter. "Dump" the heat accumulated outside into the home. Same thing.
I manage another property in Western Maine where the winter temperatures are 10 degrees colder during the coldest months, December-March. There is no other heat source other than a wood stove that is only operating when people are there. The unit is larger at 24,000 btu and the home is very well insulated and air sealed. This is not a primary residence. On a fan setting of 1 (low), the home has no issues maintaining a set 55 degree temperature while vacant and can reach upper 65+ within an hour when needed. Simply moving to fan level 2 and jacking up the temperature to 70 is all it takes. The electric bill is well below what any oil/propane bill would be. I'll keep you posted with performance after the dead of winter.
Please remember this is my only experience but is 100% unbiased. I know I can get a little anal about performance management as I measure and track electricity usage, oil usage, interior and exterior temperatures, etc. While I hope you would see the same results, each home is different and will perform differently with similar systems.
As my wife often says: "It must be exhausting being you."
Happy Holidays!
Matt
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