# Wintertime Minisplit use article



## peakbagger (Oct 28, 2018)

https://www.centralmaine.com/2018/10/28/hot-and-cold-on-heat-pumps-in-maine/

Interesting article I will look forward to the study conclusions. I am somewhere in between and my normal choice of fuel is electric or wood with oil as backup if all else fails. I just have one minisplit on my main floor and need to heat my office in the second floor by convection up a stairwell. I find it works well down to about 30 F but unless the sun is out the heat coming up the stairs just doesn't offset the heat loss. Its not a great setup but hard to justify switching my older office cooling only mini split until it dies. I also run the minisplit off of banked "free" solar power so I don't want to burn my surplus up to early in the season.

I do agree that the way to go in cold conditions with a mini split is set it and forget it. Its definitely takes several hours to warm up a cold house when I am out of town on business for few days. My normal approach is heat up the wood boiler storage before I head out and set back the thermostats to 60 F and then set the minisplit to 64F. That will carry the house for several days unless its really cold (below zero). When I get home I crank up the boiler to reheat the house as the minisplit may take 12 plus hours.  

The other issue is if its damp or snowing in cold conditions the coils frost up quicker and that means more defrost cycles which are noisy. Mine is situated on the downwind side of the house well off the ground with roof over it to deflect snow but it its blowing snow it can get frosted up.

I did a recent posting that a family friend that does vented kerosene heaters is getting a lot of calls from folks with minisplits to get their old Monitors repaired or new ones installed for cold weather heating. A minisplit just doesn't put out very warm air in cold conditions and along with the fan running full bore it can get drafty. A Monitor puts out a lot warmer air and can put out more of it when needed.


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## begreen (Oct 28, 2018)

Interesting article. It makes some good points. They are not the ultimate heating panacea for all situations. Maine is a pretty extreme case. Contrast this to use in mid-Atlantic or Pac NW states where temps are more moderate and the results are much more positive. I visited a neighbor on a rare 14º day. They had a Fujitsu 12000 btu heat pump in their old, small farmhouse. It was doing a remarkably good job at keeping the area in which it was installed at a comfortable temperature.


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## georgepds (Oct 29, 2018)

begreen said:


> Interesting article. It makes some good points. They are not the ultimate heating panacea for all situations. Maine is a pretty extreme case. Contrast this to use in mid-Atlantic or Pac NW states where temps are more moderate and the results are much more positive. I visited a neighbor on a rare 14º day. They had a Fujitsu 12000 btu heat pump in their old, small farmhouse. It was doing a remarkably good job at keeping the area in which it was installed at a comfortable temperature.




I have one upstairs and downstairs ( Fujitsu RLS 2- 12k ). If you are used to a wood stove.. it's cool ( Norther Ma). The only toasty place is at the kitchen table directly below the heat pump exhaust. That said.. it is never below 66F downstairs, and though cool, it is not freezing. I used to, sometimes,  wake up to frozen pipes 

With the old smoke dragon, I had propane for backup, but the unit had all the stealth of a 747 at take off, so I'd turn off the propane for sleep, the fire in the smoke dragon would die out,and the pipes would begin to freeze. The heat pump beat is as quiet as can be

Ah well.. the progress hybrid is still useful for deep warming the bones


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## peakbagger (Oct 29, 2018)

Just no substitute for good old radiant heat. I have been sitting out in front of a bonfire at -10 F and been hot from the radiant heat and cold at 65 degrees with just convective heat. Most hunting cabins have little or no insulation but crank up the wood stove and it will be warm from the radiant heat. 

Maine was pushing minisplits for older folks with not very energy efficient homes. The concept was give them one room that they could heat up with the minisplit during waking hours and keep the rest of the house cold. I expect the thermostats are cranked right up on the mini splits


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## begreen (Oct 30, 2018)

peakbagger said:


> Just no substitute for good old radiant heat. I have been sitting out in front of a bonfire at -10 F and been hot from the radiant heat and cold at 65 degrees with just convective heat. Most hunting cabins have little or no insulation but crank up the wood stove and it will be warm from the radiant heat.
> 
> Maine was pushing minisplits for older folks with not very energy efficient homes. The concept was give them one room that they could heat up with the minisplit during waking hours and keep the rest of the house cold. I expect the thermostats are cranked right up on the mini splits


I can believe it at -10. I've had the same feeling sitting in a room away from the wood stove when it's only 20F outside. With just regular R13 insulation the walls are colder and it feels like the warmth is being sucked out of your body.


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## maple1 (Nov 10, 2018)

We just (FINALLY) got some splits installed yesterday. Two 12k Daikins. Been wanting these for a long time. I reset my energy monitor, now to see what all the hipe is about.


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## peakbagger (Nov 10, 2018)

Look forward to hearing about your experience with them in Nova Scotia. I ran mine most of this week in place of running my boiler. I cranked up the boiler this morning as the forecast is for colder week coming up plus I needed to charge up my hot water tank as my solar hot water system is at the point where it wont give me consistently warm enough water.


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## maple1 (Nov 10, 2018)

Huh yeah, I just lit a fire again this morning because storage temps were down & the splits don't cover the end of the house that only sees use now when kids are home from university. Which they are this weekend.

But that's OK. I should hopefully be looking at fires maybe every 3-4 days until winter really hits, instead of every 1-2 days. It's only been one night, but impressed so far with how far they can actually send the heat out. I was kind of leery about that part. Our house is pretty chopped up so kind of behind an 8 ball there, but it's 21°c in my office which is across the room through a hall and around a couple corners from where one of the splits is. It is 2c, windy with ice pellets & rain outside right now. And most of the night.

My father, just down the hill from us on same driveway, also got one put in at the same time but they ran out of time yesterday to get his up & running. One 15k unit. Really looking forward to what that does more than ours. He uses oil in shoulder season, last month I think it was around $10/day. From poor at times memory. The oil fill pipe is like 15' from the outside unit - imagine the oil man won't appreciate seeing that there next time he fills up lol.


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## begreen (Nov 11, 2018)

peakbagger said:


> Look forward to hearing about your experience with them in Nova Scotia. I ran mine most of this week in place of running my boiler. I cranked up the boiler this morning as the forecast is for colder week coming up plus I needed to charge up my hot water tank as my solar hot water system is at the point where it wont give me consistently warm enough water.


Daikin has been making mini-splits for a long time. I can recall wanting one in 2006, but there were no WA state dealers at the time. Many years back we had someone I think that was from Nova Scotia report on his experience with Daikins. He seemed pretty pleased with it.

Before purchase discussions
https://www.hearth.com/talk/threads/ductless-heat-pump-which-is-a-better-unit.54710/
After installation report. This was a particularly cold winter for them.
https://www.hearth.com/talk/threads/impressed-with-the-daikin-ductless-heat-pump.60963


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## maple1 (Nov 17, 2018)

It has only been a week, and I don't know how accurate this Effergy thing really is, but our two units seem to be usually using somewhere around 8kwh/day total, so far. 

The upstairs unit is a floor mount (actually on the wall a couple inches above the baseboard), and I am really impressed with it. It sends heat out the bottom and the top, if you want it to. So some of it actually hits the floor right where wifey steps out of bed in the morning. Seems to run quieter and more evenly/consistently that the downstairs wall mount. It is sending heat across our bedroom, a hallway, and down another one to the other end of the upstairs. So doing the whole upper half of the house. Now, if the kids were home, I would no doubt need to be sending some hot water heat to their bedrooms at times - but they're not, until the holiday season hits. Downstairs unit sends it farther than I was expecting also, but still need some hot water now & again in the far end of the kitchen. Where prevailing winds hit 10 windows and a door all in a row. My office is nip & tuck on colder days - I could maybe use a through wall fan in a strategic location to get the air to go in a full circle through it. So thinking about that.

I would ordinarily be burning every day now. That is down to every 2 or 3. Some of those burns are from wanting to charge everything up with heat (house & storage) in the face of an impending storm - been a darn stormy fall here. One power outage a few days ago, only lasted a couple hours though. One a couple weeks ago lasted a full 24 hours. Had a heavy snowfall warning for yesterday, but it fizzled a bit - thank you very much.


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## maple1 (Nov 23, 2018)

So - what has everyone settled on for their situation, for a 'low cut off' temp, where they will shut the splits down & use something else?

I let our two new ones go all day yesterday, in steady -14c temps, to see what would happen. Unusually cold here for November. They put out good heat all day (a full 24 hours from midnight to midnight), but my monitor is telling me they used an extra 10kwh for the day. Or thereabouts. That's only an extra $1.80 at our rates - but still I don't think I will let them go that low if I can help it, and will build a fire instead. Certainly still beats the cost of oil or our backup electric boiler though. And maybe even wood too if buying it or time is tight. 

Also, even with putting out that good heat all day, it wasn't reaching the far end of our kitchen good enough for the heat loss, so I needed to use storage to keep that up. So that means still burning, every other day. We would need one more unit out there to totally cover us with splits.


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## begreen (Nov 23, 2018)

It's very cold back east right now. Heating well at -14ºC is very respectable. Thanks for the update.


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## peakbagger (Nov 23, 2018)

I find that anything below 20 F overnight I am don't want to put up with the defrost cycles. Sure it will put out heat but the efficiency and output drops. I can run lower but I would rather run the wood boiler. If I leave for a few days I will leave it on down to -5F.


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## jebatty (Nov 24, 2018)

Fwiw, making a rough conversion of btus from electricity to btus from wood may aid in determining how low to go with the mini, and also comparing when to use generally. For example, that extra 10kwh for the day equates to about 6 lbs of wood in available btu content. 3412 * 10 / 6050 = 5.6 lbs, or 168 lbs for a month, which is about 5% of a cord of white birch.


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## maple1 (Nov 24, 2018)

That works out to almost $400/cord for the birch.

This is all very interesting.


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## rowan_cb (Dec 14, 2018)

First post here, but we're having two mini-splits installed in January and I'm curious about the mechanics of what's being suggested by Efficiency Maine in the article in the OP.

My understanding is that the mini-splits start to really lose efficiency in extreme cold at least in part due to their need to defrost. If its cold enough outside that the interior temperature drops to 10 degrees below what the heat pumps are set to (the delta at which Efficiency Maine is suggesting to set your furnace to kick in), why would I want to allow the mini-splits to continue to run, using energy to defrost themselves but no longer contributing to heating the house? And all to have my home 10 degrees colder than I want it?

I am honestly confused and feel like I must be missing something.


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## maple1 (Dec 14, 2018)

'For backup'. The implication I read, is if the temp dropped by 10 (or whatever you use), it is because the splits stopped running for some reason.


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## maple1 (Dec 14, 2018)

Also, they dont use much juice defrosting. They just run themselves backwards for a few minutes. With interior fans off.


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## peakbagger (Dec 15, 2018)

rowan_cb said:


> First post here, but we're having two mini-splits installed in January and I'm curious about the mechanics of what's being suggested by Efficiency Maine in the article in the OP.
> 
> My understanding is that the mini-splits start to really lose efficiency in extreme cold at least in part due to their need to defrost. If its cold enough outside that the interior temperature drops to 10 degrees below what the heat pumps are set to (the delta at which Efficiency Maine is suggesting to set your furnace to kick in), why would I want to allow the mini-splits to continue to run, using energy to defrost themselves but no longer contributing to heating the house? And all to have my home 10 degrees colder than I want it?
> 
> I am honestly confused and feel like I must be missing something.



Its not really that the defrost cycle is eating up a lot of power as much as there is less available energy in the outside air that can be moved indoors as the temps drop. As the outdoor temps drop you need more heat to keep the interior of the house warm and conversely as the temp drops there is less heat available from the heat pump. At some point the heat required to heat the house exceeds the capacity of the heat pump and the interior house temps start to drop. 

I agree with Efficiency Maine to set the heat pump and forget it with two big conditions. If the house has an automatic backup heating system and if the outdoor temps exceed 10F. I have intentionally tired to run my house on a mini split down to -10deg F and its not worth the power and the drafts caused by the fan actually makes me want to increase the temperature setting.


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## maple1 (Dec 15, 2018)

peakbagger said:


> Its not really that the defrost cycle is eating up a lot of power as much as there is less available energy in the outside air that can be moved indoors as the temps drop. As the outdoor temps drop you need more heat to keep the interior of the house warm and conversely as the temp drops there is less heat available from the heat pump. At some point the heat required to heat the house exceeds the capacity of the heat pump and the interior house temps start to drop.
> 
> I agree with Efficiency Maine to set the heat pump and forget it with two big conditions. If the house has an automatic backup heating system and if the outdoor temps exceed 10F. I have intentionally tired to run my house on a mini split down to -10deg F and its not worth the power and the drafts caused by the fan actually makes me want to increase the temperature setting.



Yes.

I also agree with set & forget, but I would use less than 10°dT between systems. I would close it up a lot, actually, maybe only a couple of degrees. So maybe more like 68°f oil stat (if you have oil), and 70°f splits. Once you get the right dT derived for your house & climate & systems, it should all be fully automatic - when the cold makes the heat loss greater than the splits can easily keep up with, the inside temp will drop those couple few small degrees, then your other system will kick in and help. Or take right over if it's really cold out & the heat loss really takes off. When the other system kicks in, it might keep the temp up above what the splits are set for & they might not kick on at all, until it warms back up again. A bit of a balancing act - individual stat differentials could also be adjusted. Or just shut the splits off or turn the oil stat up while it's real cold out if a balance can't be struck.

It's been a bit over a month for ours, and I think I am settling on somewhere between -5 and -10°c for when I get the wood fire going. But it varies, depending on who is here and the mood I'm in. Kids are home from school for the holidays, so wood fires are steadier - their end of the upstairs is the place least covered by the splits. If I didn't have wood and only had say oil, I would run them down a lot further. To -15c at least. And likely add a third unit. Still cheaper than oil at that point. Father put one in at his place at the same time, a 15k unit. It's been running steady since. His monthly oil bill dropped from $250 to $180 from 3 weeks (stormy & cold weeks) of split use in November. Electric bills haven't shown up yet.


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## Brian26 (Dec 18, 2018)

I am about to install one of these off brand Poineer units. I can buy 5 of these units for the price local companies want to charge to install name brand units in comparable size. My cousin is a hvac tech with all the proper tools such as vacuum pump, nitrogen, gauges, etc.

This $918 pioneer unit is rated to -13 and puts out its full heat down to 5 degrees. Has a HSPF of 11.2 which is pretty good. They get remarkably good reviews and the company selling them seems to honor the warranty and send out parts if needed.

Im just expecting it to last the 2 years parts and 5 year compressor warranty for the price. I could still buy 4 more units with the money I saved if it blows up. Reinstalling one of these would be simple since everything else would be in place such as pad, electrical, hole in the wall, etc. 

Researching online these are really not hard to install with a good vacuum pump, micron gauge, and valve core removal tool. 

https://www.pioneerminisplit.com/co...lit-air-conditioner-heat-pump-system-full-set


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## maple1 (Dec 18, 2018)

Installed cost here for the Daikins worked out to about $3500/unit. Canadian. That got peace of mind with a pro install and 12 year parts & labour warranty.

If I had an HVAC buddy with all the right tools who offered to do that work, I might consider a DIY. Aside from the refrigeration aspect, and a bit of electrical, it isn't all that bad a job. There is a technique to getting it to look right with all the proper shrouding components & that kind of thing. And proper stands. Miscellaneous stuff that is extra in a DIY case. But not having any or much warranty when all said & done would kind of bug me over time.


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## peakbagger (Dec 18, 2018)

I am surprised that the 12000 btu unit is 120 volt. Most of the others of that size are 240 volt. 

I agree that you are going in with eyes wide open and know someone that has the tools and the skills to swap out a unit that its a tempting proposition. I seriously doubt that the unit is serviceable if internal components fail. 

I would suggest going to supplyhouse and buy the "gutter" system used to protect the line sets between the outdoor unit and the indoors.https://www.supplyhouse.com/Line-Set-Covers-17880000, Your choice on what brand. 

 I also suggest a surge suppressor on the circuit as I expect the electronics may not be very tolerant of surges.


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## maple1 (Dec 29, 2018)

Got our power bill yesterday.

It was for a 61 day period, our splits came on line on day 18 of that. Bill was around 500kwh more than would have been typical otherwise. At 0.18/kwh, I am estimating they cost us around $2/day. There were a few days they didn't run, but also a few where I ran them at colder temps than I am doing now.

We were away over Xmas, for 4 days. Will be on the next billing period. It was kind of cold while gone, -6c days (but sunny), -12 to -14c nights. The Effergy showed about 25 kwh/day more than typical. But not sure how accurate it is. 

Sure as heck beats the electric backup boiler at like $25/day.


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## georgepds (Dec 29, 2018)

What I did was wire the heat pump in line to an electric meter...

The heat pumps  sip energy, the meter confirms it


G

https://www.hialeahmeter.com/eawame.html


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## Brian26 (Jan 3, 2019)

peakbagger said:


> https://www.centralmaine.com/2018/10/28/hot-and-cold-on-heat-pumps-in-maine/
> 
> Interesting article I will look forward to the study conclusions. I am somewhere in between and my normal choice of fuel is electric or wood with oil as backup if all else fails. I just have one minisplit on my main floor and need to heat my office in the second floor by convection up a stairwell. I find it works well down to about 30 F but unless the sun is out the heat coming up the stairs just doesn't offset the heat loss. Its not a great setup but hard to justify switching my older office cooling only mini split until it dies. I also run the minisplit off of banked "free" solar power so I don't want to burn my surplus up to early in the season.
> 
> ...



Not sure if you saw this article with the linked evaulation. Its a good read about mini splits in Mass and Rhode Island.


https://blog.greenenergyconsumers.org/blog/we-need-a-plan-for-ductless-mini-split-heat-pumps

Given that our organization works in both Massachusetts and Rhode Island, we were anxious to read a major evaluation study conducted for utilities in those states by the Cadmus Group. The study cost several hundred thousand dollars, took over two years, and analyzed data from over 150 homes. Here is a summary of some of the findings highlighted in the report

Interesting section from the study.

The figure also shows a temperature balance point about 32°F for an oil‐fired system in 2016 and 12°F
in 2015. Both winters indicate a propane balance point of ‐15°F, meaning a DMSHP would always be less
expensive than the propane option. 
Figure ES‐7 shows the same analysis, but addresses units listed as cold climate. These units operate
somewhat more efficiently, and the economic balance points shift to colder temperatures, where gas
balance points were at or above 58°F for both winters. Oil‐fired systems’ balance points were 26°F for
2016 and 8°F for 2015. These values do not account for zonal savings. For example, if a homeowner
could use a DMSHP to heat 30% less of their home, that temperature balance point would drop by 20°F
or more.


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## georgepds (Jan 3, 2019)

Good points,but do any of them address the fact that I'd freeze my but off if I relied on the mini split in the dead of winter

They work fine in the shoulder season , but will only keep my house in the 60s this time of year.( northeast ma)

Yes, I know, my installer probably did not do a proper manual j calculation. That said, two fujitsu rls 2 12 kbtu/hr units should do better in a 1500 ft^2 house

Lord help the people who believe these studies and don't have adequate (I'm talking wood stove here)backup


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## georgepds (Jan 3, 2019)

Ok... you do warn people

"Consumers need education on how to operate a mini-split. At very cold temperatures, if oil prices are low, a consumer is better off running the central heating system. But most of the time, the mini-split would be preferred."

But this is misleading

"If your house is zoned appropriately and you have 800 or so square feet that a heat pump can serve, you can shut off the central system to that area and save on fuel"

You can save during the shoulder season, when it's not so cold


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## georgepds (Jan 3, 2019)

Re"While some of the group’s members sell and install heat pumps, the association considers them to be best used as air conditioners in summer and heaters in spring and fall. In winter, it says, nothing beats a central heating system."

Can  I hear an amen?

https://www.centralmaine.com/2018/10/28/hot-and-cold-on-heat-pumps-in-maine/


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## maple1 (Jan 4, 2019)

georgepds said:


> Good points,but do any of them address the fact that I'd freeze my but off if I relied on the mini split in the dead of winter
> 
> They work fine in the shoulder season , but will only keep my house in the 60s this time of year.( northeast ma)
> 
> ...



How cold is it outside there this time of year? Likely colder than here.

We have two 12ks, in a 2700 sq.ft. two story. They don't cover the whole house, there is one end of the downstairs that will chill off without burning some wood. Far end of the kitchen. That has lots of windows. But so far this winter I'd say they could carry 3/4 of the load. It hasn't quite hit -20c yet, but we've had a bit between -15 & -20, and quite a bit between -5 & -15. I am sure if we put another unit in that problem spot, we could get through the winter totally on the splits, at less operating cost than anything else except wood. As long as the power didn't go out. 

(I would still have a wood burner though for some supplementing when I felt like it, or 'just in case').


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## rowan_cb (Jan 4, 2019)

We had 2 Mistubishi MSZ-GL's installed on Wednesday. An 18,000 btu unit downstairs, and a 12,000 btu upstairs. 

House is just under 2,000 sq. ft., and the downstairs, around ~1,300 sq. ft., is fairly open (kitchen and living room (where the heat pump is) are fully opened up, and a straight shot, and the dining room opens off this space with a much wider than average opening.

So far it's been a lot of trial and error with fan speed and vent angle to see what works, but I think we're figuring it out. I've found the temperature needs to be set quite high (around 75) on the downstairs unit to keep the temperatures we're looking for, but the literature I've read from both Efficiency Maine and Efficiency Vermont (where I live) suggests this is not abnormal, and it's kept the main living area quite comfortable, even during the peak of Vermont winter. 

I was very concerned at first that, even with the heat pump at 75, the oil furnace was kicking on with the thermostat (which is on a dining room wall just inside the opening off the living room/kitchen space) set to 65. Despite the wide opening into the dining room, it seemed that the warm air from the heat pump was not getting there at all. While we spend most of our time in the kitchen/living room, the current location of the thermostat in the dining room made this problematic!

However, this was on the first night we had the units, and the temperature was right on the borderline of where (given the advice of peakbagger and maple1 in this thread) I will consider shutting the units off (got down to around 15 F). Last night, it was warmer (upper 20's) and I turned the fan up and angled the vents a little differently, and it maintained the dining room at between 64-66, meaning the oil furnace (set at 60) did not kick on at all, which I'm happy about.

The upstairs unit has kept our bedroom, which was previously pretty frigid (oil furnace is forced hot air, and the only way the heat came upstairs, was literally by coming upstairs), very comfortable, and has done a fine job heating the hallway as well when we've left our door open.

Of course, now I will have to monitor my electricity bill and make sure it is actually saving us money to run these things and keep the furnace from kicking on. In the long run, the answer should definitely be yes, as we've has a 7.98 Kwh PV system installed, but this winter may be a little rough, because the solar wasn't up and running until the beginning of December, and our PV generation has obviously been pretty dismal so far.


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## maple1 (Jan 4, 2019)

I turn the fan speed up on ours during periods where the room they are in aren't occupied. Which means nights for downstairs unit & days for upstairs unit. It really does send the heat out further.

BTW don't take my word for anything, we haven't had ours for 2 months yet, quite - so still learning.


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## Connecticut Yankee (Jan 4, 2019)

These mini-splits you are all talking about---are they geothermal heat pumps?  I'm really out of touch with this stuff, forgive my ignorance.  My impression was that in New England and points north, the climate required a geothermal installation.


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## maple1 (Jan 4, 2019)

Connecticut Yankee said:


> These mini-splits you are all talking about---are they geothermal heat pumps?  I'm really out of touch with this stuff, forgive my ignorance.  My impression was that in New England and points north, the climate required a geothermal installation.



No. They are air to air heat pumps. Google them up, all kinds of info on them.


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## Connecticut Yankee (Jan 4, 2019)

Thanks, Maple, will do.


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## Brian26 (Jan 5, 2019)

I think the best use of mini splits are for those with solar panels. Essentially free heat at 380% efficiency with the use of no fossil fuels.  Yeah they don't stand up to the quick fast heat of a wood stove or oil furnace but their efficiency blows away any other form of heating. You simply keep your main furnace/boiler in place and only use it for those very cold nights if your unit can't keep up. Not hard to figure out when to switch by just monitoring your system and temperatures. 

Here on the CT shoreline where we don't really get crazy cold temperatures they can work as a full time heating source. My neighbor who has the exact same house was using baseboard electric and reports the electrical savings is mind blowing in comparison to his old baseboards. He said its hundreds of dollars a month. CT has the most expensive electricity in the lower 48 and he will save thousands of dollars in just a few years.   He still has his electric baseboards as backup but has never needed to turn them on yet in 2 years.


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## georgepds (Jan 5, 2019)

Brian26 said:


> I think the best use of mini splits are for those with solar panels. Essentially free heat at 380% efficiency with the use of no fossil fuels.  Yeah they don't stand up to the quick fast heat of a wood stove or oil furnace but their efficiency blows away any other form of heating. You simply keep your main furnace/boiler in place and only use it for those very cold nights if your unit can't keep up. Not hard to figure out when to switch by just monitoring your system and temperatures.
> 
> Here on the CT shoreline where we don't really get crazy cold temperatures they can work as a full time heating source. My neighbor who has the exact same house was using baseboard electric and reports the electrical savings is mind blowing in comparison to his old baseboards. He said its hundreds of dollars a month. CT has the most expensive electricity in the lower 48 and he will save thousands of dollars in just a few years.   He still has his electric baseboards as backup but has never needed to turn them on yet in 2 years.



That's what I do.. solar + heat pump

Basic problem is I sized the units using the rule 12kbtu/hr for every 600 ft^2. Should have used bigger for the dead of winter. A proper manual J calc would show that

They work, but set at 72, they deliver 66, less if I'm away

At the time I was concerned about oversized AC, the bang bang compressor problem. Turns out modern high efficiency heat pumps do not have that problem, they use variable speed compressors, and do not on/off cycle


BTW, I grew up on the Connecticut shore ( cove pond). Like you say, it's a lot warmer than northeast Massachusetts shore, but not so cold as Vermont


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## maple1 (Jan 5, 2019)

Mine hold heat right at setpoint. Lower level set at 21c, upper level at 20c. Or 19c. Depending what someone finds comfy for sleeping on a particular night.

As with any heating system, a heat loss calc should be done if the system is desired to cover all the heat loss. Square footage vs square footage can vary wildly depending on all kinds of things.


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## ryanwc (Jan 5, 2019)

I'm pretty sure this is a lame question.  I'm at the forum because of my new fireplace insert, but also interested in energy efficiency.  In reading this thread it suddenly occurred to me that the air conditioner we inherited from the previous owners is a mini-split - a Mitsubishi electric MSY-GE24NA.  

In doing some reading, I've realized there is or was a twin system, the MSZ-GE24NA, that would have provided air conditioning and heating.  Could the system I have be upgraded in some way to be 2-way?  Or would I have to replace both ends of the system?

Currently, on the newer GL systems, the difference between the air conditioner and the all-season heat pump is $300 on $2,000 of equipment, that they probably paid to install as well.  Wish they'd sprung for the extra $300.  

But if it's just a matter of different controls, rather than different machinery, I wonder if it could be upgraded.


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## georgepds (Jan 6, 2019)

ryanwc said:


> I'm pretty sure this is a lame question.  I'm at the forum because of my new fireplace insert, but also interested in energy efficiency.  In reading this thread it suddenly occurred to me that the air conditioner we inherited from the previous owners is a mini-split - a Mitsubishi electric MSY-GE24NA.
> 
> In doing some reading, I've realized there is or was a twin system, the MSZ-GE24NA, that would have provided air conditioning and heating.  Could the system I have be upgraded in some way to be 2-way?  Or would I have to replace both ends of the system?
> 
> ...



I don't know your equipment, but from what little I know of air conditioning and heating, the equipment is different in the outside unit

You'd have a simpler time with a window air conditioner.. turning it around in the winter to get the hot side on the inside


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## peakbagger (Jan 6, 2019)

Not a lame question, I am in the same situation. I had asked the question of a tech several years ago and was told they might be able to salvage the tubing and the condensate drain run as long as the refrigerant is compatible. The installed cost for a new one should be less although the tech may differ as the refrigerant is supposed to be recycled from the older unit. The guts of the outdoor unit are far more complicated with a cold source unit.


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## ryanwc (Jan 6, 2019)

peakbagger said:


> Not a lame question, I am in the same situation. I had asked the question of a tech several years ago and was told they might be able to salvage the tubing and the condensate drain run as long as the refrigerant is compatible. The installed cost for a new one should be less although the tech may differ as the refrigerant is supposed to be recycled from the older unit. The guts of the outdoor unit are far more complicated with a cold source unit.


Thanks for the replies.


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## georgepds (Jan 9, 2019)

For another point of view, the folks at GBA think air source heat pumps can work well in New England if the house is properly air sealed and insulated

https://www.greenbuildingadvisor.com/article/ground-source-heat-pump-right-choice


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## begreen (Jan 9, 2019)

I suspect they are correct. My BIL's house in southern New England is tight and very well insulated. It uses remarkably little fuel to heat in comparison to a conventional stick built house of the same size.


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## peakbagger (Jan 9, 2019)

It really comes down to that 90th percentile day where the outdoor temp is down below zero, the wind is blowing and its snowing. Even though a cold source heat pump is putting out some heat at that temp, the COP is dropping close to one and its output is going down. No matter if there are snow baffles around the outdoor unit, fine wind driven snow will get up inside the coil causing frequent defrost cycles. I know this from practical experience when I intentionally tried to run down subzero in during a snowstorm. I expect it would have kept the pipes from freezing but sure wasn't maintaining setpoint. 

Still a lot to be said for having a backup heating source for very cold weather be it woodstove, electric baseboard or vented kerosene heater. I like the wood as all the other options are not very useful without power.


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## begreen (Jan 9, 2019)

peakbagger said:


> Still a lot to be said for having a backup heating source for very cold weather be it woodstove, electric baseboard or vented kerosene heater. I like the wood as all the other options are not very useful without power.


Definitely right for a northern cold climate. Out here the coldest I have seen is 8ºF and that was in the 70's. I stopped by at a house with a Fujitsu Halcyon unit several years ago when it was 14º out. They were snug and warm and the unit was humming along quietly. Our current heat pump system however will only heat down to about 25º so we have resistance electric and the wood stove to fall back on.


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## SpaceBus (Jan 12, 2019)

@begreen Thanks for letting me know this had updates. I was keeping an eye on this thread back in Nov when we first moved into our house. When I was in Afghanistan most of the "housing" for soldiers was just shipping containers made into little shacks. We kept warm with these ductless pumps, but not the nice ones being used in this thread. Ours were usually Chinese knockoffs of the Fujitso and Mitsubishi pumps. They did work, but tiny metal cans are tough to keep above 65 when it's around 0f outside and windy. My particular pump didn't like to defrost, so in the middle of the night when the compressor was covered in ice I had to go out out with a knife and carve the ice out! 

I am thinking about putting in two 12-15k btu mini splits in my 1200 sqft well insulated two story salt box, one on each floor to make winter a little easier. Our electric baseboard heaters are working this winter, but they are expensive. The first floor is almost entirely open and has the wood stove. Upstairs has two bedrooms and a bathroom and is a little more cut up. There are however two registers in the walls allowing heat to pass between the bedrooms, which is a huge help. It's just myself and my wife with no kids, so heating the other bedroom isn't crucial anyway. What's the recommendation on make and model for living on the most Northeastern part of the US right on the coast?


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## maple1 (Jan 12, 2019)

I am partial to my Daikins.

Also Mitsubishi or Fujitsu, those 3 IMO are the top 3. Might come down  local installers/dealers. That are good.


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## maple1 (Jan 12, 2019)

I will add my models when in front of my computer again...


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## DBoon (Jan 13, 2019)

For Maine climates, look for Fujitsu RLS models or Mitsubishi HyperHeat - these are good down to -18 degrees F (or so) and still generate rated output at these temperatures. My Fujitsu RLS pushed lots of warm heat out at below zero temperatures - it's not the cold register heat you might know/remember from an old-style ducted heat pump. 

If you are running electric resistance heat right now, these types of units will cut your heating bill to a third of what it was, maybe a fourth.


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## SpaceBus (Jan 13, 2019)

DBoon said:


> For Maine climates, look for Fujitsu RLS models or Mitsubishi HyperHeat - these are good down to -18 degrees F (or so) and still generate rated output at these temperatures. My Fujitsu RLS pushed lots of warm heat out at below zero temperatures - it's not the cold register heat you might know/remember from an old-style ducted heat pump.
> 
> If you are running electric resistance heat right now, these types of units will cut your heating bill to a third of what it was, maybe a fourth.



Thanks for the heads up! We are supplementing with the resistance heat currently as our firewood situation is less than ideal. The grand plan is to have the minisplits for backup heat and the resistance heaters for emergencies or to help the mini splits if we can't burn for some reason.


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## georgepds (Jan 13, 2019)

Good advice,but, My fujitsus are  one rls2 and the other the more recent rls3

It's 15f today and last night , and they struggle to keep the house in the 60s

That said they are great backup for the wood stove, the house won't freeze with these sentinels on guard


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## DBoon (Jan 19, 2019)

georgepds said:


> they struggle to keep the house in the 60s


They will produce less heat when it is really cold, but they still produce heat. I did find some technical manuals on-line when I purchased my Fujitsu RLS2 some years ago, and I recall that the rated output (15k BTUs for mine) was at 5 degrees F and still 10k BTUs at -17 F, or something like that. And the air that blows from them is warm. 

But to your point, you have to match the units to the heating load of the house at the temperature you want to use them at.


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