Loving the passive solar effect on those sunny days, but often finding myself with a shiver on the cloudy/overcast days. That’s one of the annoying things about being a quadriplegic, I’m always cold unless it’s 76+ degrees, but I hate to keep my room that warm all the time because I know the sun will kick it up a notch any time it’s clear outside. So, I’ve been using an electric heater quite a bit this winter to avoid the 4 hour wait of heating the radiant slab up a few degrees. Everyone loves the toasty warm feet, and I love the energy storage/efficiency of the huge thermal slab, but it sure does take a long time to get it to temperature. Not a good thing when I’m cold!
Heat Pumps and Humongous Rebate/Incentives
So in the midst of all this electric heating I started to think about a better solution to my keeping warm needs. Seems that it was just in the nick of time, because our local utility recently did a media blitz plugging the incredible efficiency/cost savings of these new ductless heat pumps. And even better, they are providing a $600 rebate as an incentive for homeowners to purchase one, and the federal government is providing a $300 credit.
Decided I’d calculate out a few numbers to see if these heat pumps are really cracked up to all that they said.
Comparing a Heat Pump to a Radiant Electric Heater
By definition 1 Watt = 3.412142 BTU/hr
Output of my 1500 W Radiant Electric Heater
1500 Whr * 3.412142 = 5,100 BTU/hr
Contrast this to the new Fujitsu Halycon 15RLS2 inverter driven ultraefficient heat pump that puts out 14.01 BTU/Whr according to the Energy Star ratings and you would get 21,000 BTUs out of this same 1500Whrs of electricity
1500 Whr * 14.01 BTU/hr = 21,000 BTU
An increase of efficiency of over 400%.
The increase in savings ends up being even more than this because my utility company reduces the electricity rate for heat pump users from $0.15/KWhr to 0.11/KWhr for anything over 600 kWh. Figuring in this reduced electricity rate means I can run the electric heat pump and get the same amount of heat (BTUs) for approximately 1/5th the price of that radiant electric heater. Granted, this is rather overly simplistic, and doesn’t take into account the reduced efficiency of a heat pump at extreme low temperatures, but you get the point, they’re far more efficient/cheaper to run.
Comparing a Heat Pump To a High-Efficiency Oil Broiler
Let’s take this a bit further, and compare the price of the heat pump to my high-efficiency Pensotti Quatech Series Oil Boiler.
1 gallon of #2 fuel oil has 139,000 BTUs. At my boiler’s 88.6% efficiency thismeans my boiler is putting out 123,000 BTUs of heat from a gallon of #2 heating oil.
139,000 BTU * 88.6% = 123,000
At current fuel prices this is $3.47 for 123,000 BTUs of energy.
Contrast this to the Fujitsu 15RLS2 for 123,000 BTUs
123,000 BTUs / 14.01 BTU/Whr = 8.8 KWhr
8.8 KWhr at $0.11 KWhr = $0.97 for that same 123,000 BTUs
Please someone check my math here, because this seems absolutely incredible. The heat pump creates the same amount of heat as my high-efficiency oil boiler for only 28% of the price. WOW, and this only gets better as the price of oil goes up.
Still astounded by these calculations, and obviously very skeptical as to whether they’ll hold up in the real world, but if they do the savings will be considerable. Like payback in 3-5 years.
Couple additional things that sweeten the pot even further. Since I have all this overabundance of electronic gear, overzealous audio amplifiers, big TVs, incandescent lights at the moment (yes I know, shame on me) my power consumption is already over the 600 KWhr minimum for the heat pump discount. That means as soon as I hook the heat pump up, I’ll get the 26% discount from my electric utility for everything over 600 KWhr, even the excessive energy I use on all my electronics. Probably not the greenest/environmentally friendly of incentives, but still very real money.
And then there is the comfort. As a quadriplegic, when I get cold I feel absolutely miserable, like nerve pain, crazy intense contractures in my shoulders/neck, overall just not fun. The only way I can get this to go away is to get warm again. Now I’ll have a way to get warm again, and real quickly. I’ll be able to let my room/slab cooldown more at night because it won’t take so long to heat up when I want it to, and in the summer when it’s crazy hot and I’m overheating I’ll have a very quiet/highly efficient air-conditioner to cool me down. Really seems like I can’t lose with this upgrade!
Please, somebody, burst my bubble here, tell me my calculations are screwed up, anything! These new high-efficiency heat pumps just seemed so incredible, like FREAKING AMAZING, I can’t wait to get mine installed like yesterday!
February 1, 2013 – Our Fujitsu 15RLS2 unit got installed! Come read my my initial thoughts:
Fujitsu 15RLS2 Heat Pump Installed – My Initial Thoughts
Mike,
Sweet machines, I know. I think, however, to get the 4-5 cent per KWh rate decrease, you need to be heating your home with >50% electricity source. I think that’s what MPS said to me when I talked to the them. It’ll work for me as all I’ll be heating with will be electric and solar, 50/50. Check out the efficiency of the Fujitsu vs. the new Mitsubishi.
Matt
Very impressed with them, the more I read, the more seems this technology is close to the efficiency of geothermal (except at extreme low temperatures) for a fraction of the price. Hoping to get close to 50% of my heat from this electric source, but when I talked to the folks at Maine Public Service yesterday, they mentioned the discount just by purchasing a qualified unit and using over 600 kWh of electricity.
Curious to see the data showing the efficiency of the Fujitsu versus Mitsubishi, from what I’ve seen the Fujitsu comes out on top in terms of SEER and HSPF, but some people online feel like the Mitsubishi is a little better build quality. When it comes right down to it I think it’s comparing very minute details and it’s more important to go with what my contractor has installed the most and is comfortable with.
What are you using for a secondary heat source? These mini duct heat pumps can’t be used as your primary source due to their low efficiencies at very cold temperatures.
You must keep in mind that EERs of 14 may only be assumed at relatively moderate outside temperatures (>45F). When temps drop to fewer than 20 or 10 degrees, COPs drop as well to as little as 1.85 with their corresponding EERs of < 7.0
So depending upon the region, these assumptions may not always pan out. But, certainly, given more moderate temps, these minis essentially can outperform geothermal systems because they are ductless and don't lose efficiency to ducting nor have energy losses due to fluid circulation systems.
In our 6000TFA (60,000CF) passive house, we only need two 9RLS2s to heat since the heating performance between the 9,12,15 are nearly identical.
Our mini experiences can be found below:
passive house heating
New updated minis are on the horizon. We have included a section in the above article.
Bob
Thanks for the additional information… and, you’re most certainly right! By using the EER of 14 I most likely overstated my savings, but at the same point the amount of energy saved quickly heating up the air of my room versus bringing up the temperature of my gigantic concrete slab cannot be understated. Where before I used to have to run the boiler for 3-4 hours to increase the temperature of my room 5°, I can now do it in way under an hour!
Just real quickly cruised through your website/blog; looks like all kinds of really great information! Man, you sure did put a whole lot of thought into building your home… EXCELLENT! I can’t wait for some more time to really sit back and read through all your articles!
Do you find your Heat Recovery Ventilator does a good enough job of dispersing the heat pumps’ heat throughout the house? I’m having a little challenge getting heat into some of the rooms perpendicular to the heat pump and wondering the best way to solve the problem. Maybe I’ll just throw up a few CPU fans in the corner of the room and see if that helps.