This is true of most, I think. We put in a Fujitsu three years ago (replacing an oil furnace) and the proprietary thermostats are terrible. I don’t even try to program it, it’s just too difficult. Fujitsu doesn’t talk to consumers, only tradespeople so there’s no way to get feedback to them.
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Just installed a Mitsubishi 4 head Ductless Minisplit heatpump in out upper floor and back room. (Converted bungalow with poor HVAC airflow to the second floor and none to the back. Next is rewiring 1939 electical and finally improved insulation.
Been wanting to do this for ages.
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Why?
Because people will not do the most environmentally conscious thing – insulate and turn down the thermostat.
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I installed a mini-split heat pump in my house a few years ago in order to end our use of window ac units. Our house has hotwater radiators so there was no easy path to a central system with ducts. So I put a mini split head in our living room at the center of our small house and it cools the whole place, quiet too (compared to droning window units). I installed it all myself and hired a friend HVAC contractor to charge the coolant and commission it. He let me buy the unit thru his commercial account at great savings to me. I had Lowes come out before I decided to do it myself and got a proposal from them for 7,000usd. For me to do it, the unit, all the other parts, my friends time to charge it and get it running, was under 3,000.
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Installation cost here in UK is almost prohibitive (until recently, typical payback periods were over a decade IIRC) and for much of the much older housing stock there are other challenges such as where to put the damn thing (even more so, without it being an eyesore - e.g. the place where my utilities enter the house and where the current natural gas boiler is, feeding all the radiators, is a flower-bed outside my front door) and I think UK houses with ducting are very rare (blocks of flats perhaps less so). A 110-year-old house does not lend itself to ducting being installed (even if I could bear the expense) and I am not going to rip out all my recently renewed radiators. I need to investigate how ductless heat pumps work and how they actually replace a natural gas boiler running a traditional water-filled radiators system and also heating all my hot water.
(I also need to investigate the latest solar tech. All roof surfaces on my property are in full shade for at least half the day.)
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I had it in for the bulk of the summer last year, and although I rarely use a/c (I have a shade tree at the front, and a white, cool roof, which help to mitigate the heat), I found that it worked very well indeed; I could feel the cool air within 5 minutes of turning it on, and I generally sit around the corner from the interior unit in the kitchen. They have been used in places like Hong Kong for decades, primarily for cooling, so the a/c aspect is old tech. They are supposed to be more effective and less costly than conventional or even high efficiency air conditioners.
I will say that if you can, position the outside unit(s) on the ground to minimize vibration through the walls. They can be mounted on the exterior walls, but it can sound like a truck idling. I find that with it on the ground in the side yard, I hardly hear it at all even in the room that it’s closest to (the bedroom), and the interior units are quieter than almost any fans that I have.
Also, position the interior units on an exterior wall, if possible, because if they put them on an interior wall, say between two rooms, you will have power, refrigerant and drainage cables and pipes draped across the wall to an exterior wall, where they will exit the building. It’s unsightly and messy. I had to do it in the kitchen, because all the exterior walls are covered in cupboards or windows, so I had no choice.
You also have the option of heating and cooling areas differently if you have the heads. They will also dehumidify.
Oh, and when setting the desired temperature, many units are default set to the temp at the level of the head, which, being just under the ceiling, is warm, so it will not heat the house up to the desired temps, unless you crank the heat up a couple of degrees from where you want it, OR check the remote and there might be a button on it that says “I feel”, or something like that, and if you press that, the thermostat will be set at the height where the remote is, like a kitchen counter, or coffee table.
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Holy crap that is an unbeatable number. Definitely a winner there.
Be sure to get all the warranty stuff sent to the manufacturer. We’ve done that plenty and it has saved our hides a few times. Had a service tech come out while the unit is still under warranty, so some basic issues like a bad sensor (outside, in the compressor) and a recalled switch were all fixed for “free.”
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I did, and good advice.
I actually posted a pretty long photo blog of my install on imagur if any diyers are inspired to try.
If you can install one on an exterior wall with the outdoor unit right there it can be pretty simple. Because of the distance between my units my install was a bit more complicated.
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My FIL has the Mitsubishi split system, but he lives in Alabama, so his experience isn’t necessarily going to match ours, plus they may sell different units here due to us actually having winter. I’ve already determined where we would put the interior units. Livingroom/kitchen (it’s all open), master bedroom and Jr. Kidd’s bedroom. Mr. Kidd thinks we need a 4th unit in the spare bedroom, but it’s in direct line of sight to where I would place the downstairs unit.
After reading Thom’s article, I went down a bit of a rabbit hole looking into options. There’s a company in Sweden that’s going to make a direct air-to-water boiler replacement for hydronic systems. I’m going to keep my eye on whether or not this heat pump is ever produced and reviews if it is.
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That is my big concern, that it won’t be able to handle the coldest days of the year and we’re still going to need to keep around our gas furnace just for those 5 days a year. Am I wrong about this?
Though, I’m on the west coast of BC, which gets decidedly less brutal winters than New England, so maybe that’s not a worry.
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I’ve started doing the research on replacing my gas boiler with one of these, and it looks like the more modern systems can run with a wet radiator system, and generate hot water. The drawbacks are that the system runs cooler than the standard gas boiler, so you might have to replace your radiators (You may have to swap out single panel ones for double panels, or get taller radiators that take up more of your walls to get the same heat flux out) And if you’re looking for it to provide hot water, you’ll need to have a hot water tank (or space for one). it can’t do instant hot water.
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Or, they have already done those things and are still trying to heat with an oil furnace, which was our problem. Heat pumps are the most efficient method of heating. Replacing the oil furnace saved us a ton of money, reduced our carbon footprint (we’re on mostly hydro-power).
Mine is a Trane 23 Series Split System (R-410A) Multizone, Inverter System 24,000 BTU/Hr (this is important; it is calculated from the “Manual J”, and determines the appropriate size of unit you need, My house is about 1,300 sq. ft.) 4TXM2324A. For what all of that is worth,
Insurance companies will require a supplemental heat source, because they don’t quite trust these yet, but my heating contractor said, and I’ve read this too, that thermostatically controlled baseboard heaters are fine, and he said that the portable ones are okay; they don’t need to be wired in, but check with your insurance company. So for you, I don’t know that I’d worry about the spare room, unless it really is occupied frequently, and just put in a baseboard heater in case it doesn’t get warmed enough from the stack effect from the downstairs unit when it actually is occupied.
You can have one big exterior unit, which is what I have, with multiple indoor heads, or a one to one ratio of smaller exterior unit to interior unit, which is supposed to be more efficient. But as I’ve said, my house was perfectly comfortable all winter, down to -4 F, and this unit is supposed to work fine even below that, but we never got lower than that.
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I’ve never been worried about it personally, I’m on the coast so it’s a little warmer here than inland… but every winter we’re bound to get a cold snap that keeps us under 0ºF for a full week. I’ve had the heat pump keep the house reliably warm ~68ºF at -10º… but it couldn’t warm the house to >70º at temps that low.
Even at a full week of sub-zero temps I wouldn’t keep a gas furnace around. If I really wanted to warm things up in extreme cold, a single small electric space heater would likely be plenty to supplement (but in the 7 years of living here with a heat pump, I’ve never felt the need).
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From the Wirecutter article:
“You could put in a watt of electricity and get four watts of heat out of it. ”
This melts my brain in a good way. It’s sort of like realizing how much space there is between the atoms in a seemingly solid wall.
In this case, it’s realizing that even cold outdoor air is hundreds of degrees above absolute zero. Heating it 46 degrees Fahrenheit is only increasing it about 10% in absolute units. We are surrounded by heat even when it’s freezing. Gives hope that someone might discover an even more efficient way to burnturn that power into heat.
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Well, I replaced all my radiators a year ago, as the 30+ years old ones were clogging up, rusting away and no longer highly efficient. The house is now much snugger and I can turn the thermostat dial down more often. It cost a small fortune and I am not expecting to do it again while I live in this house (and I have no intention of ever moving). But my system does drive a hot water tank rather than instantly heating water on demand.
If the system runs cooler on a heat pump, does putting in bigger/more heat pump capacity fix that, I wonder. More research to do…
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The system runs cooler because the heat pump doesn’t heat the hot side as hot as burning fuel does. So to get the same heat output from radiators, you need more surface area on the radiators and/or faster flow of the water through the system.
You’d have to check with your installer if your new radiators are big enough for the job, but they might be ok- The level of insulation that your house has is also a key factor.
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Yeah, I get that - but logic suggests that adding more heat pump capacity to the same system ought to increase the amount of heat pumped into it. I guess there are constraints…
(But in due course it is something I’ll be looking into.)
