ductless mini split heating and cooling

[mpeirce]

However, when the temperatures plunged into the into the single digits and below, and it was windy, they could barely keep up. Yes, they were sized appropriately according to the manufacturer. Under those conditions, they ran all out as hard as they could and when they went into the defrost cycle, the room would actually lose a few degrees. And when they run all out, they do consume a lot of electricity. Granted the insulation in these rooms left a lot to be desired but still the mini-splits were challenged at these temperatures. BTW, these were Fujitsu XLTH's rated to -15ºF. Not the typically cheaper made for DYI models.

We have the Mitsubishi MSZ-FH system for our upstairs. It’s a lake house and all the guest bedrooms are upstairs and we like that each room can be heated or cooled to the temperature the various people staying with us prefer.

This past storm we hovered around 0°F for a couple of days as this unit produced heat nicely (when there was power - see below).

That said, downstairs we have a more traditional heat pump / propane furnace setup with ducting. The HVAC folks were nervous about going 100% split mini, but in hind-sight I think it would have been fine. We’ve had temps around -10°F and still have plenty of heat coming out of the MSZ-FH system.

It does help a lot to be well insulated so whatever system you have doesn’t have to work as hard.

We lost power for 12 hours during this past storm and the temps fell inside to the low 50’s when the outside temp as around 0°F. Not terrible, though we were very glad when the power came back on.

That said, I do like the “quality” of the heat when the propane furnace is running - nice warm air. The mini splits are also nice in that the air coming out of them is pleasantly warm. I’m not a huge fan of the tradition heat pump setup - the air coming out of the vents isn’t as warm, especially at the end of longer duct runs.

 

[ncbill]

I would switch to mini-splits if I could dump my traditional split heat pump.

When I bought it over a decade ago I got a federal tax credit for picking a high-efficiency model...rated at 15 SEER.

But using mini-splits today I could have units rated over 30 SEER!

 

[skyking1]

We have electric heat and they touched the power bill down quite a bit. I turn on the central heating when the temps get down to 25. Our two 12000 BTU units are way undersized to provide heat for our ~1300 SF home, but do take care of summer cooling just fine. If i added a 9000 BTU to our master bedroom that number would be lower.
The heat pumps replaced a couple of smallish window shaker air conditioners that struggled at the hottest days.
The new house will have a 5 Ton GSHP that also produces hydronic heat for warm floors.
The first quote I have for the equipment is 19K less 5.7K tax credit, so the cost part is really apples and oranges. That's a whole lot more upfront investment than a few multizone mini splits. That is not counting ductwork parts or hydronic floor coils.
3 outdoor units and 8 indoor ones would get me 5.5 Tons for ~8K, less some tax credits.
It would be comfortable either way, but having warm floors everywhere is Da Bomba.
i only have it in one bathroom but that is enough to know I LIKE IT!
None of this addresses power outages or extreme cold, or the horrible combination of both at the same time.
I'll order the GHP with the standard supplementary heat strips.
I'd like to add direct vent propane fireplaces on each level as emergency heat, if the code allows for it in this changing environment.

 

[mpeirce]

i only have it in one bathroom but that is enough to know I LIKE IT!

Yeah, we have that too and yes, it’s very nice. Ours is electric and so we only have it turn on at night when we’re in our bare feet.

We also put them in the upstairs bathroom for guests. Again, turned off most of the time, but it makes it very pleasant for guest who visit in the winter. And they need as much encouragement as they can get.

None of this addresses power outages or extreme cold, or the horrible combination of both at the same time.

This last week sure has me thinking of getting the mini-split wired up so we can attach a “small” generator to it if the power goes out in the winter time. There are a number of reasons we don’t want a whole house generator at the Lake House, but emergency heat (and cool) seems prudent.

 

[skyking1]

This is just for me and I don't advocate doing it, but my mini splits have a required disconnect block outside near the unit. This illuminated my personal light bulb.
So far we have not had a long enough outage and we also have an RV to fall back on, but the idea was still there.

 

[old medic]

Extra benefit, you can probably ditch propane also - in some mountainous places it can be a bear to convince the propane company to deliver the goods.

No we will still have propane anyway for the stove and WH. Its nice to have when the power goes out. Delivery is not issue. Currently run off a 100 Lb tank and its a 3/4 mile drive to get it filled.

 

[old medic]

Case in point: my mini split in the NC mountain cabin had no issue at all keeping up with the recent cold snap.

We hit 6 here... Friends in the Tryon area said their mini-splits barely made any heat for a few days.

In power failures .......Most people choose a 20KW whole house generator. I could probably get by with a 4KW if I zone cool.

We have had several long-term power outages here over the years. Worst was the Blizzard of 93... 13 days.. But mostly shorter than 48 hours. Unfortunately they are generally winter weather related. In rebuilding this house, we are trying to keep it were we can get by with small inverter generator to run essentials.

 

[JoeWras]

Mini splits are cool and innovative. I like the quiet stealth operation.

There is one thing that I don't like: their filtering.

They have filters. They are typically a fine plastic mesh that you can wash. On the good side, that's eco friendly. On the bad side, they just don't remove as much dust and stuff as a conventional forced air system. The filters sometimes are not very effective and you can get buildup inside on the coils. Removing such is difficult. Make sure to wash those filters regularly.

This may not matter. After all, for generations homes had radiators or baseboard heat which didn't do any filtering.

It is just part of the calculation of decisions you need to make when looking at them.

 

[skyking1]

I run a couple of rabbit air filters in the house all the time. I suspect that will not change in the new home, because there is a whole lot of shoulder season that the air handler will sit idle and the dust does not stop.

 

[explanade]

What are the pros and cons of 230 vs. 115 volt units?

Obviously would have to pay an electrician to run a 230 volt line but do one type perform better or last longer?

Also, Home Depot only seems to have brands you’ve never heard of.

 

[gooddog]

What are the pros and cons of 230 vs. 115 volt units?

230V is more efficient than 115V, which cuts your power bill. There are other advantages, but that is the most important to most home owners.

 

[Happyras]

What are the pros and cons of 230 vs. 115 volt units?

Obviously would have to pay an electrician to run a 230 volt line but do one type perform better or last longer?

Also, Home Depot only seems to have brands you’ve never heard of.

Not so certain on efficiency versus voltage. I have installed both and the HSPF and SEER ratings seems to be the same. Home Depot models seem to be made in the same china plant as Mr Cool, but they do not advertise the DYI line sets. I would stick with Mr Cool through Costco or IWAE.com that are second generation and DYI unless you own a vacuum pump for HVAC. Or you want to pay someone to plug them in for you......

 

[ncbill]

The only downside I see is higher current draw on the 120VAC ones versus ones that run on 240VAC assuming they're rated for the same efficiency.

 

[explanade]

How do the HSPF and SEER ratings work? The higher the better?

I'm interested only in one room, which is at most 10 x 10 or maybe 12 x 10.

So I was looking for the lowest BTU unit but Home Depot only has 9000 or higher.

I would need it installed because I assume you have to drill through the wall and run the hose down to the outside unit?

 

[Chuckanut]

My new mini-split Mitsubishi system is now helping to warm me as it goes through its first Winter. So far so good. The lows have only been in the high 20’s as of today. I held a thermometer in front of the inverter during 32 degree mornings and the air coming out was 126 degrees. That seems pretty good to me. The compressor certainly is working harder when the temp falls near or below freezing. I do wonder how long it will last. It has a ten year warranty on the compressor itself, but not on the labor to replace it.

As Winter progresses, I am sure we will have a few morning with lows in the teens unless this is an unusual Winter. I’ll see how it handles that.

 

[wmc1000]

How do the HSPF and SEER ratings work? The higher the better?

I'm interested only in one room, which is at most 10 x 10 or maybe 12 x 10.

So I was looking for the lowest BTU unit but Home Depot only has 9000 or higher.

I would need it installed because I assume you have to drill through the wall and run the hose down to the outside unit?

My Home Depot purchased 24000 BTU mini split, (Ductless Aire), heats my entire 1800 sq. ft. barn with 12ft ceilings even when temps have dropped to -5 or less overnight. Of course I did super insulate the walls and ceiling after it was built.

 

[Chuckanut]

I had a mini-split heat pump installed last year mainly because my home needs more help staying warm in the winter. The AC in the Summer is a nice extra, but enough of a reason to pay for a mini-split vs a window AC unit.

Now that I have several months of cool and cold weather under my belt, I have a feel for the savings. My electrical power usage is down about 36% compare to the average usage in the three years before the installation. There are some fixed costs associated with our rates so I won’t see a 36% decrease in the total cost. I am estimating more of a 25%decrease in the monthly cost.

I am on a fixed monthly payment plan where they adjust the payment once or twice a year so that each month is 1/12 of the expected yearly charge. So far those adjustments have not been made. Normally, it is done in August, but if things change a lot they will do another one earlier.

 

[Chuckanut]

Mini splits are cool and innovative. I like the quiet stealth operation.

There is one thing that I don't like: their filtering.

They have filters. They are typically a fine plastic mesh that you can wash. On the good side, that's eco friendly. On the bad side, they just don't remove as much dust and stuff as a conventional forced air system. The filters sometimes are not very effective and you can get buildup inside on the coils. Removing such is difficult. Make sure to wash those filters regularly.

This may not matter. After all, for generations homes had radiators or baseboard heat which didn't do any filtering.

It is just part of the calculation of decisions you need to make when looking at them.

I have a 20 inch box fan with a 20x20 filter attached. I keep in running most of the time unless it’s a nice day and I open the windows to let in the fresh air - about 5 to 6 months a year. After a day or two the amount of dust accumulation in my living area is noticeably reduced.

 

[JoeWras]

I have a 20 inch box fan with a 20x20 filter attached. I keep in running most of the time unless it’s a nice day and I open the windows to let in the fresh air - about 5 to 6 months a year. After a day or two the amount of dust accumulation in my living area is noticeably reduced.

That's a good affordable work around.

You should post it on the What We're Making thread, although if you are like me, I slowed down posting there because my hack projects can't hold a light to the incredible craftsmanship posted there lately.

 

[Badger]

I have a 20 inch box fan with a 20x20 filter attached. I keep in running most of the time unless it’s a nice day and I open the windows to let in the fresh air - about 5 to 6 months a year. After a day or two the amount of dust accumulation in my living area is noticeably reduced.

I saw this on "This Old House" some months back. It looks like a good and inexpensive idea.
Four 20x20x2 filters is $40 and a box fan is $25 at HD. So you can make this for $65 and some duct tape.

 

[JoeWras]

I saw this on "This Old House" some months back. It looks like a good and inexpensive idea.

And super easy, anyone could do that. Could come in handy for a temporary solution when wildfires pop up nearby.

I think if I had a house with minisplits, I would instead build a nice good looking cabinet with light weight finish grade plywood with decorative grilles and run just one of these 2" filters.

Or use a commercial filtration device, however, this kind of DYI thing is so much more cost effective.

 

[ERD50]

That's a good affordable work around.

You should post it on the What We're Making thread, although if you are like me, I slowed down posting there because my hack projects can't hold a light to the incredible craftsmanship posted there lately.

Please do post the 'hacks'! My inferiority complex takes a hit with all the fantastic work there! We need to see some of what us mere mortals can accomplish!

And I hope no one takes that the wrong way either, I love seeing the excellent, creative work that some are doing at a very high level. I love those posts. It's inspiring!

-ERD50

 

[JoeWras]

Please do post the 'hacks'! My inferiority complex takes a hit with all the fantastic work there! We need to see some of what us mere mortals can accomplish!

And I hope no one takes that the wrong way either, I love seeing the excellent, creative work that some are doing at a very high level. I love those posts. It's inspiring!

-ERD50

Based on your encouragement, I just posted my latest "reuse" hack. Don't throw that door away!

The cabinet makers on the thread probably are spitting out their coffee at my post.