Fujitsu Mini Split

[sjwaste]

OK, we're soft by northern new england standards. We just completed the install for a Fujitsu mini split system today - a 36k BTU heat pump w/ an 18k head downstairs and 2 concealed 9k units upstairs. My wife really wanted AC that performed better than our window units and I have a strong desire to reduce our oil bills in the winter. This should do both.

So far I'm pretty impressed. It wasn't warm out today so I can't really test practical performance, but these things really cool the place down fast. More importantly, they're quiet.

This model claims a COP > 2 down to 10F, and others around here have said it does a little better than that before it shuts itself off at around 5F. Is anyone else using these for cooling and heating? If you're further north, how is the heating performance in the shoulder seasons?

 

[1sikbITCH]

"Further north" of New England?

I don't think they are worried about heat pumps.

 

[bignateyk]

I just put a 36K BTU LG minisplit system in my house (did the install myself) with two 9K's, a 12K, and an 18K unit. Has no problems heating/cooling my 3500sq ft house. Was over 90 degrees the other day and it had the house nice and cool/dry at 70 degrees. Haven't had a chance to run it during extreme cold yet, but I have all my electric baseboard still installed as a backup/extra capacity if needed.

edit: I went the minisplit route because I live in a split level house where retrofitting ductwork would be nearly impossible for the lower levels of the house. The quotes I got to install a traditional ducted central heat pump were around $15000, and that would have only covered our upper two levels where they could run ductwork in the attics. I did the entire minisplit install myself (except for charging/evacuating the R410 refrigerant) for $5800 (cost of outdoor unit, 4 indoor units, and line-sets).

I couldn't be happier with the price and results. I think anyone doing a retrofit should use them.

 

[rsutoratosu]

I have the mitsubishi mr slim, installed by a friend and last winter when it was like 10 F, I had it on but occasion it was spitting out cold air. I asked my friend and he told me don't run it under 40 because you're just throwing money out the window.

The unit would NOT be able to heat the room efficiently when it was below freezing in the winter. He said that this is because the mini-splits do not have defrosters on them like the big heat pumps do and that they would basically shut off when the condenser froze.

Thats why I was getting cold air some times while the system defrost

 

[bignateyk]

I have the mitsubishi mr slim, installed by a friend and last winter when it was like 10 F, I had it on but occasion it was spitting out cold air. I asked my friend and he told me don't run it under 40 because you're just throwing money out the window.

The unit would NOT be able to heat the room efficiently when it was below freezing in the winter. He said that this is because the mini-splits do not have defrosters on them like the big heat pumps do and that they would basically shut off when the condenser froze.

Thats why I was getting cold air some times while the system defrost

Hmm.. my LG mini-split has a defrosting unit in it with inverter that will continue to put out warm air even while defrosting using a resistive heater. They lose efficiency below 35 degrees though once the defroster has to start kicking in. Even still, it's more efficient than electric baseboard which was my previous source of heat.

 

[Dari]

Wow, these are catching on in America, huh? They're standard in Japan. Whenever I decide to get a second place, I'll build it from the ground up and install one of these.

 

[Sho'Nuff]

OK, we're soft by northern new england standards. We just completed the install for a Fujitsu mini split system today - a 36k BTU heat pump w/ an 18k head downstairs and 2 concealed 9k units upstairs. My wife really wanted AC that performed better than our window units and I have a strong desire to reduce our oil bills in the winter. This should do both.

So far I'm pretty impressed. It wasn't warm out today so I can't really test practical performance, but these things really cool the place down fast. More importantly, they're quiet.

This model claims a COP > 2 down to 10F, and others around here have said it does a little better than that before it shuts itself off at around 5F. Is anyone else using these for cooling and heating? If you're further north, how is the heating performance in the
shoulder seasons?

What was the projected yearly operating cost for the mini split system? We decided to go with bio heat (pellets) a couple years ago because the cost projection was very good relative to oil. Didn't consider heat pumps because the assumption was that they would be enormously expensive to operate in the winter. Didn't consider AC options at that time, else we might have looked at one of the mini split systems.

 

[bignateyk]

What was the projected yearly operating cost for the mini split system? We decided to go with bio heat (pellets) a couple years ago because the cost projection was very good relative to oil. Didn't consider heat pumps because the assumption was that they would be enormously expensive to operate in the winter. Didn't consider AC options at that time, else we might have looked at one of the mini split systems.

I'm not sure about $$, or how it compares to a combustion fuel, but I had electric baseboard in my house prior to the heat pump.

From what I've read, the heat pump is much more cost efficient to run for anything down to about 35 degrees. Below 35 degrees it drops in efficiency, but it never get's worse than electric baseboard. I think in the worst case it's about twice as efficient as electric baseboard, so I expect to save quite a bit of money on my heating bills this coming year. Last year I paid about $2000 for the year to heat my 3500sq ft house in central PA.

Due to the natural gas boom here in PA, electricity is cheap as hell at the moment. Hopefully that trend continues.

edit: Here's a good chart for comparison of fuel types:
http://www.ctheatpump.com/

According to that, my cost should be cut in half, so we'll see.


edit2:

Here's a good graph showing how a heat pump becomes more inefficient below 35 degrees:

https://www.e-education.psu.edu/egee102/files/egee102/images/Lesson_08/BalancePoint.jpg

Basically, as it gets colder your house needs more heat, and the colder it gets, the less heat the heat pump can put out due to having to defrost. Where the two lines intersect is where you start to lose efficiency.

 

[rsutoratosu]

Yeah, i have radiant heat with gas boiler.. so this is my backup in case the boiler breaks.. for the winter. Hopefully both will live forever

These do save massive money, I really only got it for the AC. I used to have a 22000 btu window unit that I only run from 11PM to 7AM and my monthly bill was around 300-450 during the hotter months. When I got the split unit, I ran it from 6pm till 7am and it was only around 220-250 during the hotter month one year later. That also included the 10% rate increase by coned. So I was so happy it's so much cheaper to run the ac

 

[snoturtle]

I have looked at these before and it still seems to be the same
They are fine for cooling and spring and fall heating needs but can't do winter heating needs in New England

Maybe can't isn't the correct term perhaps very inefficient would be correct
At that point is it still a cost savings or do you shut the heat pump off and just run oil/gas/pellets/etc...

Seems like a great add on for older homes that don't have duct work to add AC

 

[Midwayman]

Wow, these are catching on in America, huh? They're standard in Japan. Whenever I decide to get a second place, I'll build it from the ground up and install one of these.

Depends on where you are. In areas of the country with older houses they are reasonably common. They're far cheaper to retrofit than those high velocity central AC systems. However so much of the US is new enough that they have central system already that its not super common.

 

[bignateyk]

I have looked at these before and it still seems to be the same
They are fine for cooling and spring and fall heating needs but can't do winter heating needs in New England

Maybe can't isn't the correct term perhaps very inefficient would be correct
At that point is it still a cost savings or do you shut the heat pump off and just run oil/gas/pellets/etc...

Seems like a great add on for older homes that don't have duct work to add AC

Yeah once you get below freezing it's probably more cost effective to run a combustion source of heat if you have it. The advantage that the heat pump has is that it's no work and no mess. You can't leave a coal/wood/pellet stove go while you're on vacation for 2 weeks. Natural gas is the way to go if you have it, but we didn't have the option to have natural gas run to our house.

 

[snoturtle]

I wish we could get natural gas

Looking at adding in a propane fired hot water heater this year so we can get it off of the oil fired steam boiler

Only use the boiler for hot water and when it gets really cold in the winter and the pellet stove can't handle it

But these look like a great way to get in AC without ducts
Wife has been asking for it since we bought the house
She is from Florida were everyone has central air

Will have to revisit these units for next summers project

Yeah once you get below freezing it's probably more cost effective to run a combustion source of heat if you have it. The advantage that the heat pump has is that it's no work and no mess. You can't leave a coal/wood/pellet stove go while you're on vacation for 2 weeks. Natural gas is the way to go if you have it, but we didn't have the option to have natural gas run to our house.

 

[bignateyk]

I wish we could get natural gas

Looking at adding in a propane fired hot water heater this year so we can get it off of the oil fired steam boiler

Only use the boiler for hot water and when it gets really cold in the winter and the pellet stove can't handle it

But these look like a great way to get in AC without ducts
Wife has been asking for it since we bought the house
She is from Florida were everyone has central air

Will have to revisit these units for next summers project

They're pretty easy to install yourself if youre handy. I just paid someone else to do the refrigerant work. ($200). I ordered the equipment online, poured a concrete pad for the compressor, mounted the outdoor and indoor units, ran the drains and linesets and made the electrical and plumbing connections myself.

I went with LG because they still honor the warranty if you do the work yourself. Most of the brands only warranty their products if you pay a contractor to install it.

 

[rsutoratosu]

I saw a lot of the online vendors are in florida, you can probably pick it up locally

mitsubishi actually warns against some internet dealer not being authorized and probably offers no warranty

http://www.mitsubishicomfort.com/en/consumer/consumer-resources/internet-sales

My local dealer was around 200 more than the internet dealer and i did not have to worry about missing or damage shipment.. so I just bought it locally

 

[Jeff7]

Wow, these are catching on in America, huh? They're standard in Japan. Whenever I decide to get a second place, I'll build it from the ground up and install one of these.

They certainly sound appealing.

Though I ran the numbers through this calculator, and found that I'd need around 10 years of operation for its energy consumption to break even with what I've got now. The calculator adjusts its values for the expected usage requirements in the location you enter.
Installation is also reportedly expensive, possibly more than the cost of the unit itself.

But it would also let me get rid of the window unit here, reducing the amount of noise that gets inside from the goddamn-loud motorcycles in the summer.