Check it out… our Fujitsu 15RLS2 ductless mini-split heat pump got installed this past Friday! Initial thoughts… I like it a whole lot, but there are definitely a few things to keep in mind with this technology. More about this later… first pictures of the install!
This is where I spend all my time during the cold winter days, is adjacent to my bedroom, and connected to the rest of the house through a set of large double sliding doors. By installing the heat pump directly above my mini beverage refrigerator, pointing towards the largest portion of the house, I’m hoping to heat the largest portion of the house/air and maximize savings.
It seemed like a pretty straightforward install, with a single heating contractor spending maybe 2 hours on the inside, and 4 hours on the outside, and the two electricians 2 hours wiring the new 240 V line to the panel, pulling a long feed across the house, and installing a disconnect next to the heat pump.
How’s it Working?
Quite awesomely! But there are still a few things we’re figuring out… particularly the best way to get it integrated in and working with our radiant heating system, and how to get the warm air to some of the, now, colder rooms.
Let me explain…
After installing the heat pump we needed to adjust the thermostats down for two of the radiant zones to take advantage of the cheaper heating price of the heat pump. So, the thermostat for the heat pump is set to 74°F (yeah I know… I get cold easily!), the radiant heat zone for my section of the house set to 70°F, and the radiant zone for the main section of the house set to 68°F. The thinking here is any time the heat pump can make enough heat to heat the majority of the house I’ll let it, and since I get cold so easily, if it ever has a hard time keeping up I’ll kick the slab on to make up the difference. Probably most people would allow for a greater temperature difference between their heat pump and primary heat source thermostats to maximize savings. I’ve also added an additional time in the programmable thermostats for the two radiant zones to kick on the heat of the zones for 30 minutes at 4 AM. This might be totally unnecessary, but I want to make absolutely sure the water in our concrete doesn’t get too cold by running the heat pump (causing those radiant zones to never heat up the concrete).
Any thoughts on this, oh so smart home building/energy efficiency people? Do I need to cycle my radiant to keep it from freezing, or is the insulated slab enough within the building envelope to keep that from happening?
Another challenge I’m trying to figure out related to this, is by using the heat pump, the radiant zone for my section of the house is being used significantly less, which means the warm water is no longer flowing underneath the floor in my bedroom/bathroom. One would hope that the warm air from the heat pump would be making it into these areas, but due to how it blows/directs the heat straight ahead my bedroom and bathroom are now cooler than I’d like.
Last night I experimented by placing a small plug-in fan inside my bedroom and blew the colder air out into my family room where the heat pump is installed. It seemed to make a dramatic difference at the temperature inside my bedroom. I’m going to test this out/try it for a few more days, and if it continues work, I’ll make a more permanent solution by installing a large CPU fan at the corner of my door and run them using a relay and temperature sensor connected to my home automation system. That way, if the temperature inside my bedroom is colder than the family room the fan will kick on and exchange the air until the temperatures are similar, at which point the fan will turn off.
A Couple More Considerations
Both the inside and outside units of the heat pump make some noise. They’re not excessively noisy, but also not as quiet as a refrigerator (like many folks suggest they are). It’s super important to take this into consideration when placing the outdoor unit. The low hum of the outdoor unit makes is completely livable mounted on the outside of my family room, but most likely would have made it hard to sleep if mounted on the outside of my bedroom. The inside unit can be anything from a low swish, to a moderate level blowing of air depending on what level the fan is set. Most often I leave the fan set on level 2 which provides a noise level I can live with and moves enough air to heat the majority of the house.
Doesn’t blow hot air like a wood/pellet stove. These heat pumps are designed to pump out an 80°F-120°F warm feeling air as opposed to the much hotter 180°F+ that comes from forced air furnaces, and wood and pellets stoves. As the heat pump gets closer to this set temperature it ramps down the temperature of the air it’s blowing out to increase efficiency. This sometimes makes it feel like the heat pump is blowing cold air, when it’s actually blowing slightly warmer air, but it feels cold because it’s lower than our body temperature and blowing.
Hot air likes to travel in straight lines. This heat pump had a very powerful fan that can push heated air easily 30+ feet into the next room, but this same heated air for the most part bypasses my open bedroom door just a few feet to the side of the unit. Additional fans or ways to move heated air around (or a tolerance for colder areas) might be necessary to get the heated air into the rooms off to the side.
Looses efficiency the colder it gets. By their very nature, air to air heat pumps pull heat from the outside air and by changing the pressure/phase of a refrigerant release this heat as warmer air inside the home. As the temperature outside gets colder there is less heat to pull from the cold outside air and the units become less efficient. The Fujitsu units are considered tops with their 27+ SEER and 15+ EER and the best efficiency/coefficient of performance at low temperatures, but they can only go so low. From 0°F and blow performance is significantly reduced, and I found mine to put out very low heat in the -5°F range. At that point I just turn it off and let the radiant slab do what it’s designed to do.
When the heat pump is on it never truly turns itself off. I guess this could be considered a good and a bad thing. It makes the unit far more efficient, because it ramps up and down based on the demand, but for a passive solar house with significant solar gain, this means the unit just coasts along for the entire sunny day even when you need absolutely no heat. I wish there was some circuitry, or way to have the device automatically turn itself completely off if the room temperature is significantly above the set point and increasing. For now, I just look out the window to see if it’s sunny in the morning and turn the heat pump off. I may in the future decide to interface this with my home automation system and use a predictive heat algorithm to determine the most efficient way to heat our home.
Conclusions… so am I happy?
Given everything mentioned above, am I still happy? Would I buy the heat pump again? ABSOLUTELY!
It really is an awesome device, and if it holds up to all the ultra-energy efficiency claims then we are in for saving close to $1000 per year, and paying for the device in less than 3 years with the help of the $300 tax credit and $600 rebate from Maine Public Service. Even better, while receiving all this winter savings, we now have a superefficient, very quiet cooling system in the summer and vastly increased comfort year-round. For me this is the hugest thing, as a quadriplegic who has an impossible time regulating my body temperature, having the ability to quickly heat up/cool down my room will make such an incredible difference in my life!
Before, when I used to get a chill, I’d either close myself in my bedroom and fire up the space heater (because it’s one of the smaller rooms in the house and could increase in temperature more quickly), or run the space heater for several hours in my family room. Now, I can just kick the heat pump on high with my family room door closed to the rest of the house and heat it up 5°F in less than half an hour. Then, once I’m all warmed up I can ramp the unit down, open up to the rest of the house, and keep on saving! And, in the summer, no longer will I be hightailing it to the supermarket or someplace that has air conditioning when it gets too hot. Now, I’ll be able to sit back and enjoy the comfort of my home!
good to hear you like it! i’m getting my hvac guy to size my unit for the new pad based on my calculated heating loads. as this will be my only heat source aside from the sun, i want to make sure the calculations are spot on, particularly on the coldest day of the year. regarding your radiant heat/slab question, post it on Green Building Advisor Q&A. It’ll be answered by some pros in a couple hours-excellent source of information.
Hey Matt! Definitely liking it a whole bunch! Feel free to stop by anytime you’re in Presque Isle and would like to see/hear the unit in action.
Curious what type of feedback you’ve heard from the HVAC/Green Building Advisor folks about using an air to air heat pump as your only/primary heat source. Seems that you might be getting into tricky grounds where these devices so hugely loose their efficiency the colder it gets, and particularly at the times when you’d need the heat the most. I believe the Fujitsu RLS2 units quickly run out of steam as it gets below -5°F, and I can contest that mine was just blowing lukewarm air the other night when it was -10°F. I know some people use these as their primary heat sources in more southern locales, but will it be up to the task on our -20-30F° nights. I’d hate to see you and your family shivering!
Something that might be worth checking is to read through Bob’s Passive House blog. Granted, he’s in a much warmer Pennsylvania, but he uses his heat pumps as a primary heat source for his Passive House. He also mentions about some new Fujitsu units that should be coming to market in the US that work to -15°F.
Check out his blog at: http://passivehousepa.blogspot.com/2013/01/heating-and-cooling-with-ductless-mini.html
Great info Mike. Yes, my thoughts too; I am curious to see whether or not they can keep up in sub-zero temps. I’ve actually been looking at automated wood pellet boilers, particularly Kedel whose smallest unit can modulate down to 10% its max (5400 btu). I think this paired with a radiant slab and with a mini split in the great room, I’d be golden. I’ll check out that blog, and the new Fujitsu. Thanks.
Something else that’ll be to your advantage is any time we have a sustained supercold weather it’s always sunny, so I would think if your thermal slab is sized appropriately it should gain/store enough heat during those very cold days to hopefully hold itself throughout most of the night. I know that’s what my home does with only double pane windows and too much glazing on the South. During those sunny -20°F days it’ll heat up enough to hold 70°F until at least 1 AM. And, during those prolonged periods of overcast weather/no solar gain you’ll be able to run the heat pump(s) because there’s never moisture in the air when it’s supercold.
If it were me, I wouldn’t consider a pellet stove for a Passive House (or any house for that matter). Why pay approximately 3 times as much for wood as you do with chopped wood when you’ll need it so seldom. Just put a nice cast-iron stove in the middle of your place and call it good. Then you’ll always have the cozy woodstove to fire up anytime you feel like you want to make it extra comfy.
just checked out the new Fujitsu. http://www.greendroplet.com is selling the 9000 btu for $1649 (free s+h). pretty short payoff time versus any other active heating sources on the market. I didn’t know that they all performed at a max of 22000 heating btu/hour (it’s the cooling power that is directly related to its sizing). So far the numbers show that’s what my house will demand for heat when its -25F outside. I’m optimistic. I will also have a small cove radiant heater mounted in each bedroom (x3) (~750W) that don’t receive the direct solar heat gains (just in case). I’ll be in touch.
One thing to consider is Fujitsu offers NO warranty for heat pumps purchased online, and the only way to get the $600 Maine Public Service Rebate and $300 Government Tax Credit is to purchase and have the unit installed by an authorized person. Going through traditional routes might end up costing a few hundred dollars more, but the 7 year warranty and all incentives is easily worth it.
thanks for the pointers. i’ll be sure to let you know the next time I’m in PI. i’d like to see your new baby.
The Fujitsu heat pump is a great product and i have been installing them for quite a few years now. The RLS2 systems will make a little expansion type noise at very low outdoor temps because it is going into defrost mode more often. Fujitsu just came out with the RLS2H models in 9-12-&15,000 Btu’s that will heat down to -15 degrees. The Fujitsu system is the best mini split system out there and i have installed all of them in my 29 years in this trade. Please have a qualified contractor install them as there is a lot of thing that need to be done properly to assure the units runs efficiently.
Thanks for the extra information! Would this little expansion type noise be the slight rumbling/rattling noise I hear sometimes at night when the unit goes into defrost? Also, do you know if the RLS2h models have made it to market yet?
I’ve been extremely happy with mine so far! It’s amazing how much of our large, very spread out 2400 ft.² home this little unit can heat. The thermostats in the 3 main zones of the house were on for less than 5 hours last week!
MIke-Yes they are on the market. My dad just purchased one today.
Isn’t that just the way life happens sometimes… Literally 2 days after having mine installed I find out about a newer model that works down to lower temperatures better!
Just my thoughts, I have been installing the 15rlq,rls,rls2’s ffor quite a few years,
If I am not mistaken the 15rls2 does not meet the requirements for the federal
Tax credit for tax years 2012 and 2013 , I really don’t understand why because the AHRI reports are not in line with the actual performance of the unit. If anyone out there can clarify this issue I would really appreciate it. The 15rls2 works at lower temps. But the eer rating does not make it as far as AHRI is concerned.
Hey John, are you sure the 15RLS2 doesn’t qualify for the federal tax credit? I was quite sure that it does. Now I do understand the 15RLS2h to be quite a different animal, because in order to get the -15°F operating temperature they had to increase the compressor size and add an electrical element outside which together significantly decrease efficiency.
Do you mind telling me the total cost by email? Thanks!
Email on the way, but am happy to write the cost right here. Around $4000 for the Fujitsu 15RLS2 unit and installation.
Hello Quadomated! We had two 12,000 Fujitsu units professionally installed in the lower floor of our 1903 Houlton home in mid-October, and are very pleased with them. I am far from being quadrapleagic (sp) but at 81 I do need to move around carefully, and be comfortable. The house has hot water baseboard heat in all rooms, and the mini-splits are serving nicely to keep our four most frequently used rooms really comfortable; it is like being in a nursing home, which is what we are trying to approximate for ourselves. Eventually, we will be old, and will need it for sure. Our units cost $3200 each, installed, and the $500 check came today.
The blowers do a surprisingly nice job of distributing the pleasantly warmed air all over the rooms. The units are nearly silent. Our electric bill jumped up, of course, but we have not used the oil burner at all so far this fall; I figure that tankful of No.2 down there will keep forever. I am glad to know that these things will give good heat with outside air as low as 0; I had planned on not using them below 10 or so. The outside units are mounted on the south and west sides of the house, with rain covers.
Glad to hear there are others out there enjoying the heat pumps! Why mess with splitting wood, carrying bags of pellets when there is such an effective and inexpensive way to heat your home! I need to sit down and really figure out the numbers as far as the exact increase in electric consumption and how much less oil we’re using, but judging from the historical data of my thermostats I can tell you the change/savings is significant, and that my heat pump is doing an incredible job heating a very large/spread out home. Add into that the comfort factor, being able to quickly raise/lower the temperature of my room, and the air-conditioning in the summer and this is absolutely the best home-improvement modification I’ve made yet.
Really glad to know they’re working out so greatly for you!
Great writeup, I’ve got one slated to go in my new house next month. May look at putting in a small pellet stove too to use in combination with the heat pump. I’m confident that this will save me loads on oil. Any idea how much your oil consumption was actually reduced?
I had a Fujitsu put in this spring (2014)like the air conditioning but the heat not so well. Have it turned up to 76 and I am freezing, only feel cold drafts. The outside temperature was 26. Forget about heat to the other rooms. Not happy after putting paying that much to keep warm and to get away from oil and wood.
May put in one for AC but not for heat. Anyone got some dry hardwood?
I have been installing fujitsu systems for a few years now, as Eric says it is very important to find a qualified HVAC installer registered with fujitsu. you warranty could be void other wise. also the fact they know when your system is working at its fullest. there are many things to consider and things that can be done wrong witch will effect the efficiency of the system.
on the rls2 heads there are manual right and left louvers just inside the air outlet. from your picture it looks like adjusting the right side as far as you can toward the door you could move some air there. a ceiling fan is a great way to move air around your home. if you have a forced air system you can run your fan all the time to help move the air. or running your HRV on circulate. the reason the system is left on and the fan keeps running on low speed is so the system keeps a more even temp in the space. excessive noise can be caused by a few things. if your system is excessively noisy get a fujitsu dealer to look at it. your system should be at 100% capacity at 0F watch for excessive defrost, long defrost (over 10 min) or going into defrost at warmer temperatures.
for your in floor heat, not a bad idea to time it. also running the circ pump without the boiler on will help the water from freezing.
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I have a partially finished cabin in NW Iowa. It is essentially a great room, one bedroom, a loft and a full basement. There is a continuous screen porch on all 4 sides with 4-track “windows.” Electricity and plumbing is in. I plan to insulate and use car siding to finish the interior walls (not wall board). Natural gas isn’t available. All electric (or could be propane).There is no duct work, no furnace, no AC.
With no heat, I only use the cabin June-Sept. I would like to extend that time by 4-6 weeks on either side…which means temps in the 30’s. AC is only necessary about 10 days each summer.
Would a mini split like you have work? If I read your posts correctly, you can turn the heat pump off but must do it manually – yes?
I am concerned about the noise of the inside units. How does it compare to a wall unit like those found in motel rooms which are so noisy they can wake you up?
Hi, Read the article,
1. Move heat from room to other spaces: They now have Transfer Grill kits in market that you can use to move air from the room, thru the wall with a mini fan and thermostat. Google Tjurnland.
2. Noise Level of your units?
I am not sure why your outdoor unit is loud as you describe,
I have seen many units, that we had to put paper in front of the fan to prove it was actually running outside.
things I would review,
1. is unit level?
2. does the unit have the minimum line set length, and secure,
3. is the frame bracket vibrating to make some of the noise?
Not sure why the unit is so loud for you to hear inside with the windows closed in heating especially. I would look for a reason if it was my unit.
At $1500, as a web purchase, if you’re going to install it yourself, does it matter if there’s no warranty? Saving $1500 to $2000 installation would more than pay for repairs or a whole new one.
bought one new model run it several times and was 66 degrees in the morning inside house and 45 outside run all night only warm to cool air coming out
sticking to my wood stove its not the installers fault purchase date was 8/30/2015 good money wasted and no way to get it back
Kind of a off-topic question, but do you happen to know what type of control signal is being sent back to the outdoor unit from the blower head. I mean the “low voltage signal” wire. I am trying to do something a little different with the compressor unit.