Mini Split Experience

[DUMF]

Who has has had a mini split, Fujistu or Mitsubishi, in one of the colder parts of the world (like Northern U.S.) for at least a full season ? No need for AC.
1. How well they heat below 20 F, occasionally down to 0 F.
2. Problems
3. Reliability and maintenance
4. Electricity cost in winter
5. Noise
6. New cost of unit(s) installed
Thanks.

 

[peakbagger]

1, How well they heat below 20 F, occasionally down to 0 F. Noticable decrease in temperature plus frequent defrost cycles
2. Problems Need to install a roof over the top of the unit to keep snow off. Make sure the unit is on the lee side of a building and well up off the ground. if the coils have snow on them the unit will go into defrost very frequently
3. Reliability and maintenance No issues yet
4. Electricity cost in winter I don't keep track as my power is free. The COP drops as the temperature goes down so the power use will go up
5. Noise At low speed its not noticeable but its noticeable at mid speed and very noticeable at high fan. The defrost cycle is about the same as high speed fan
6. New cost of unit(s) installed I did my own install. For one ton Mitsubishi I bought it on ebay for $1,600 with about $250 for other accessories. I paid a contractor to purge the lines, and pump them down. The local contractors charge around $4,000 so they are making good bucks for 3 hours install. Note I also ran the wire and installed the disconnect which most HVAC contractors would require and electrician to do.
Thanks.

 

[DUMF]

Explain the "defrost cycle" in your unit. Your brand ?
Easier to read if you can separate your reply from the "quote"--thanks.

 

[DBoon]

1. How well they heat below 20 F, occasionally down to 0 F.
2. Problems
3. Reliability and maintenance
4. Electricity cost in winter
5. Noise
6. New cost of unit(s) installed

I have a Fujisui RLS2H that are equivalent to the Mitsubishi hyperheat models - good to well below 0 degrees F.

1. They heat very well below 20 F. I believe mine is rated for 15000 BTU output at 5 degrees F. It still generates good heat below 0 F, but the house just loses too much heat for it to supply 100% of the demand, so backup (oil furnace) heat kicks on. The heat coming from the head is very warm, even below 0 F.

2. No problems aside from a fuse replacement at initial install, ~3 years ago.

3. See 2. Haven't done anything with it aside from cleaning the filter once per year.

4. I have a solar PV system with net metering. Cost is not an issue for me.

5. Very quiet. So quiet that you can't hear the outside unit from the inside. And the inside unit is pretty quiet too. Noise is a non-issue.

6. I paid $3200 for mine, installed. Some quoted me $4500. I found someone willing to install it for a markup of ~$1400 for 2/3 of a days work - it was a simple install. The installer was very happy.

 

[peakbagger]

When the outdoor coils ice up, the unit runs backwards in air conditioning mode. This stops the heat indoors but doesn't really throw off cold air. This mode heats up the outdoor coil and melts off the ice build up. How often the coils ice up is dependent on the temperature and relatively humidity. If it a cold but clear day, it doesn't happen that often but when its foggy out or snowing, it can happen often. If there is snow blowing on the unit, the coils are going to freeze more often and the unit will defrost more often. There are baffles that can be installed to deflect snow away from the coils. When Bangor Hydro rolled out cold climate mini splits a few years ago they did a lot of training to make sure that the outdoor units where installed properly but some weren't and some folks were unhappy. Hopefully Efficiency Vermont is going to be doing similar training. I put up a removable 45 degree pitch roof up over mine the first winter and ended up leaving it in place year round. The unit is on the lee side of the house from the prevailing wind and rarely gets snow on it except in windy storms. My unit is up off the ground at least 4', many get installed lower as they look better but you really need to keep it above a typical winter snow depth.

The local installers I had do my piping and others I talked to all indicated that the units rarely failed except due to external damage. They rarely repair anything, they just swap in a new unit. There have been recalls on some units. My assumption is the high markup they charge to install pays for them to have a spare unit on the shelf. If an authorized dealer does the install there is fairly long warranty.

 

[Ashful]

I have had four Mitsubishi units installed. All work great, at least down to -8F, which is as low as I think I've tested them. I'm using them for full heating and cooling, with an MHK-1 auto-changeover thermostat.

The only issue I've had is keeping snow clear of the one unit that was mounted on a ground pad, when we get big (eg. 2 feet and more) snow storms. My advice is to get it up off the ground, whether wall-mounted or on a pedestal mount.

Loving the Mistubishi units. The outdoor units are so incredibly quiet, it's hard to tell if they're even running. Lots of options for the indoor unit, too. Toe kicks, between-joist boxes, or the standard wall mounted.

 

[valuman]

Who has has had a mini split, Fujistu or Mitsubishi, in one of the colder parts of the world (like Northern U.S.) for at least a full season ? No need for AC.
1. How well they heat below 20 F, occasionally down to 0 F.
2. Problems
3. Reliability and maintenance
4. Electricity cost in winter
5. Noise
6. New cost of unit(s) installed
Thanks.

We had a Mitsubishi FH-1800 (18,000 btu) unit installed last August and have been totally satisfied with its performance thus far.

1. I haven't run it on the few cold nights we've had this winter because I've been here to keep the wood stove cranked, so I can't speak to that end of your question. Because of all the mild weather we had October through January, when it wasn't really cold enough for the stove, we ran the HP quite a lot and it heated the house just fine.
2. No problems thus far with the possible exception of the learning curve for reading the manual to understand the symbols used for the various settings.
3. 100% reliable and the only maintenance I'm expecting is cleaning filters as needed.
4. Naturally my electricity usage went up when I was running the HP a lot, but the cost for heating the house was much lower than it would have been if I'd been running the propane fired boiler.
5. Unless the indoor unit is running on high fan, it makes less noise than a refrigerator.
6. Install costs will vary depending upon, manufacturer and size of the unit, the length and difficulty of the line-set run as well as the current state of your electrical system. I did a main panel and service upgrade with mine because of future plans for the house and it was all part of the package, so hard to say exact cost of my installation. That said, I think you're looking at $3- 5k for a ball park cost.

The a/c and dehumidification capabilities are also super efficient and a big bonus for those muggy summer days we get a couple of weeks per year too!

Where are in Vermont are you?

 

[DUMF]

I have had four Mitsubishi units installed. All work great, at least down to -8F, which is as low as I think I've tested them. I'm using them for full heating and cooling, with an MHK-1 auto-changeover thermostat.
The only issue I've had is keeping snow clear of the one unit that was mounted on a ground pad, when we get big (eg. 2 feet and more) snow storms. My advice is to get it up off the ground, whether wall-mounted or on a pedestal mount.
Loving the Mistubishi units. The outdoor units are so incredibly quiet, it's hard to tell if they're even running. Lots of options for the indoor unit, too. Toe kicks, between-joist boxes, or the standard wall mounted.

Northeast K. in VT. Too concerned with privacy to give more info.

Ashful: you really IN Phil ? That's a lot of BTU heating devices for one place. Wood stoves, furnace, mini splits, electric blankets !! Is it uninsulated ? > 3000 sq ft ? Your heating must be big $$$$. And, since when does this city get all those below zero F temps and high snow ?

All nice info folks, thanks. We're leaning towards simple hydronic baseboards with wood stoves as co-equal heating. Comments ?

 

[valuman]

Northeast K. in VT. Too concerned with privacy to give more info.

I understand. If we were closer I was going to invite you to see my HP in action, but I'm a couple hours south of you. I don't know anyone in the NEK with a HP or I'd offer an introduction.

 

[peakbagger]

If you go with low temp radiators, the you may still be able to use minisplit technology in the future. There are air to water devices that work like a minisplit, it is still developing technology and one member on the board "Tom in Maine" has had real world experience (if I remember, not great). I expect they will improve and you will be able to add the minisplit to the hydronics loop.

This weekend is definitely a time when minisplits would be pretty ineffective

 

[woodgeek]

Northeast K. in VT. Too concerned with privacy to give more info.
Ashful: you really IN Phil ? That's a lot of BTU heating devices for one place. Wood stoves, furnace, mini splits, electric blankets !! Is it uninsulated ? > 3000 sq ft ? Your heating must be big $$$$. And, since when does this city get all those below zero F temps and high snow ?

I would call Ashful's location exurbs of Phila. I'm closer, about 15 miles from the Liberty Bell.

 

[woodgeek]

All nice info folks, thanks. We're leaning towards simple hydronic baseboards with wood stoves as co-equal heating. Comments ?

Baseboards will be cheap to install, expensive to run. If you have the upfront for minis the operating costs are 1/2 to 1/3rd what the baseboards run. You could run a season with the wood+BB, and then compute an return on investment for the minis before you decide.

 

[Ashful]

Ashful: you really IN Phil ? That's a lot of BTU heating devices for one place. Wood stoves, furnace, mini splits, electric blankets !! Is it uninsulated ? > 3000 sq ft ? Your heating must be big $$$$. And, since when does this city get all those below zero F temps and high snow ?

'burbs north of the city. The 1800's and 1900's additions are all insulated, to varying degrees, but the original 1770's house has un-insulated stone walls. Yes... we are most decidedly over 3000 sq.ft., by almost 3x.

As to "all those below zero F temps," we're hitting -1F tonight. We usually get a few nights below 0F each year, but that's about it.

On a related subject, I caught one of my mini-splits not keeping up this evening. Went out to the carriage barn (work shop), and the first floor was 2F below its set point. That's a new install (last summer), so this is the first time it's seen cold weather. Will have to have that looked at, soon.

 

[peakbagger]

-18 deg F. Definitely an occasion where heating with a minisplit wouldn't work very well.

 

[maple1]

Baseboards will be cheap to install, expensive to run. If you have the upfront for minis the operating costs are 1/2 to 1/3rd what the baseboards run. You could run a season with the wood+BB, and then compute an return on investment for the minis before you decide.

Might need some clarification from the OP on this one. Hydronic baseboards aren't exactly a cheap easy install - they need a boiler, to start with. And they aren't usually expensive to run. OP- what exactly do you mean by 'hydronic baseboards', and what are you starting with? Is this a new build, or is there a heating system already there?

 

[DUMF]

Might need some clarification from the OP on this one. Hydronic baseboards aren't exactly a cheap easy install - they need a boiler, to start with. And they aren't usually expensive to run. OP- what exactly do you mean by 'hydronic baseboards', and what are you starting with? Is this a new build, or is there a heating system already there?

I was referring to oil filled electric baseboards a.k.a. hydronic baseboards; hard wired or plug ins. Should have been clearer.
Heating is wood stoves with simple propane space heater rarely used.

 

[jebatty]

Any resistance electric heat is going to be comparatively expensive to use. The heat value of resistance electric is only 3412 btus/kWh, and nothing will increase that. An electric space heater and so-called hydronic baseboards both are resistance electric and provide the same amount of heat per kWh. 1-1/2 pounds of seasoned wood burned for heat at 80% efficiency will produce about the same amount of btus as 1 kWh of resistance electric.

 

[semipro]

In other words, claims of "high efficiency" electric baseboard heat are bogus.
Adding oil to them is like adding soapstone to a wood stove - longer to warm up, longer to cool down, more even output of heat over time.

 

[maple1]

Electric resistance heating is very efficient.

But also usually expensive due to the higher fuel ($/kW) cost compared to other fuel choices.

 

[Ashful]

Electric resistance heating is very efficient.

Not when compared to heat pumps. Your electric resistance may be 100% efficient, but a mini split is more like 300%, dependent on exact HSPF ratings.

 

[velvetfoot]

Does noise get transmitted to the interior when exterior unit is mounted on a wall? I'm thinking wood frame house.

 

[valuman]

Does noise get transmitted to the interior when exterior unit is mounted on a wall? I'm thinking wood frame house.

While I wouldn't advocate installing the condenser unit directly under your bedroom window, they are very quiet and smooth running. That said, because the walls of our old house are 2 x 4" construction, I decided to go with a ground mount. If our walls were 2 x 6" I would have wall mounted it instead.

 

[peakbagger]

I don't detect noise during normal operation from the exterior unit hung on my wooden framed wall which is 2x6 construction with flash and bat insulation. I have a fixed double panel pane window right next to it. I built my own mount out of unistrut and bolted to the studs and expect it beefier than a factory mount. On startup or defrost cycle I occasionally get some sort or resonance that causes a rumble of the wall. Its not all the time but I expect its temperature related and I cant pin down exactly what is resonating. I did buy vibration isolation pads that the outdoor unit sit on top of the strut.

When I had a contractor purge and fill my system they commented that the best thing to do is to minimize exterior exposure of the tubing and make sure its protected from physical external damage and to minimize the length as that is big majority of their calls . I would be worried that a ground mount introduces a bit more potential of movement between the outdoor unit and the house compared to a wall mount. I bought the special snap lock gutter from Pex Supply to run the tubing in outdoors. It pretty well covers the tubing right from where it comes through the wall to the unit. It would have been nice to put in gutter in the wall but so it was invisible but that would have required a lot of extra work.

Most of the pros in Maine really push proper outdoor installation, if the unit is too low and fills up with snow or is oriented so blowing snow goes in the coils its almost a guarantee that the unit wont work well in winter. Given the potential for snow in my area, mine is at least 4 feet off the ground and I have had to shovel out from under it a couple of times after heavy snow. I don't see much of a choice except for a wall mount. have seen and heard of ground mounted units that get physical damage from ice buildup in the components which is another reason to get it up off the ground and consider a roof over it.

You can help things a bit by locating the outdoor unit near a corner of the house versus the center of wall and consider fabbing up a mounting bracket that spans a longer distance up the wall then an out of the box bracket. Mine ties into the wall below the outdoor unit by about 10 inches and runs up the full height of the unit to the upper mounting points. It is decidedly "industrial" but given the solar panels on the house I generally don't worry about form versus function.

 

[maple1]

Not when compared to heat pumps. Your electric resistance may be 100% efficient, but a mini split is more like 300%, dependent on exact HSPF ratings.

Yes, true. But that 100% efficiency is better than most anything else, aside from HP tech.

 

[iamlucky13]

Yes, true. But that 100% efficiency is better than most anything else, aside from HP tech.

It's really best to look at heating options from an overall cost standpoint.

For example, an 85% efficient natural gas heat source is significantly less expensive to run than a 100% efficient electric baseboard in most parts of the country, because the fuel is significantly cheaper per BTU. The baseboards will be cheaper to install, but over the life of the system, will likely cost more in total unless you're in a low heating demand region.