Questions for people running mini splits

[jcollinsks]

I have a 1700 SQ FT house with 2 stories, our goal is to completely get rid of our furnace using Mini Splits and a wood burning stove. We live in West Virginia so it can get decently cold in the winter.

My questions are has anyone here got any experience with heating and cooling your entire house with mini splits?

I've seen a ton of videos with supplemental or people claiming they do, but they never talk about the details. I'm really interested in how each room "feels" and if there are cold spots or hot spots in the house.

Is there times when you don't think the mini splits are able to keep up with the demand?

While I'm in love with how cool they are and the technology behind it, I'm concerned because we really just want things to work. Being too hot or too cold can really affect your mood

 

[50ShadesOfDirt]

You have a particular home "envelope" (shape & volumes) with a typical central furnace (and big blower motor) pushing treated air to every corner & space of that house. I'd think that this system has been sized to push air to every spot, so you don't feel cold spots.

I'd request a quote from your local HVAC folks to "replace" the central with mini-splits, and see what they say. Hopefully, the quotes won't cost you anything.

Because you already have a series of ducts (I'm assuming), as do I, I went with a wood "furnace" (many designs out there) that has a blower motor and ties into the ductwork. I can feed it anything (wood or whatnot burns in inner furnace envelope, which heats outer envelope, which the blower then pushes throughout the ductwork to every spot in the house. Thus, both a furnace, and an "incinerator", as no fumes are "inside". Wood heat, throughout the house. We're fully forested, so tons of blow-down wood & such always available in our area (plus national forest to cut from, if ever needed).

This one also has a glass front, and the ability to heat one room from the top, so it's kind of dual-purpose. We have it on the side of the living room, to get the glass front view, but the bulk of it (and the chimney piping) is outside.

Never tried to heat with mini-split in winter, and we get down to "below 0" temps where we'd have to switch to wood heat anyway, so would only use them in the couple of months of summer where it might get warm (up to 90 degrees or so outside). We do want to upgrade all window shakers to mini-splits, and perhaps drive them with their own solar panels, like the SigSolar offering.

Hope this helps ...

 

[jcollinsks]

You have a particular home "envelope" (shape & volumes) with a typical central furnace (and big blower motor) pushing treated air to every corner & space of that house. I'd think that this system has been sized to push air to every spot, so you don't feel cold spots.

I'd request a quote from your local HVAC folks to "replace" the central with mini-splits, and see what they say. Hopefully, the quotes won't cost you anything.

Because you already have a series of ducts (I'm assuming), as do I, I went with a wood "furnace" (many designs out there) that has a blower motor and ties into the ductwork. I can feed it anything (wood or whatnot burns in inner furnace envelope, which heats outer envelope, which the blower then pushes throughout the ductwork to every spot in the house. Thus, both a furnace, and an "incinerator", as no fumes are "inside". Wood heat, throughout the house. We're fully forested, so tons of blow-down wood & such always available in our area (plus national forest to cut from, if ever needed).

This one also has a glass front, and the ability to heat one room from the top, so it's kind of dual-purpose. We have it on the side of the living room, to get the glass front view, but the bulk of it (and the chimney piping) is outside.

Never tried to heat with mini-split in winter, and we get down to "below 0" temps where we'd have to switch to wood heat anyway, so would only use them in the couple of months of summer where it might get warm (up to 90 degrees or so outside). We do want to upgrade all window shakers to mini-splits, and perhaps drive them with their own solar panels, like the SigSolar offering.

Hope this helps ...

That's very helpful actually! I am hoping to try the mini splits and see if they do enough, if not I'll eventually just run them off solar panels during the day to help lower costs. We are planning a wood burning stove similar to your situation with the blowers and "sump fans" to push the heat upstairs faster and we'll have a professional install the wood burning stove!

 

[Supervstech]

I install systems in homes frequently.
Some houses have minis setup in all the rooms in the house.
Multizoned with distribution units.
The customers here love them.
I dislike the filtration in the wall heads, keeping them clean is annoying.
The setup I installed at my mother's place works well, toasty warm through the teens... cool in the upper 90s to some 100 degree high humidity days...

She has a three bedroom place with a head in each room, and a central located head in the main living area.

 

[Supervstech]

Minis are also available with ductwork air handlers so you can keep the ducts you have, and have real filtration setups.

 

[jcollinsks]

Minis are also available with ductwork air handlers so you can keep the ducts you have, and have real filtration setups.

That's great info, I was planning on keeping the furnace just to use as a filtration system, we also have 7 air purifiers at work throughout the house as we have asthma/allergy issues.

 

[740GLE]

Even if you get the mini split why would you have to get rid of the woodstove? It’d been good to have in a back up.

Always good to have a couple ways to heat.

 

[1201]

Minis are also available with ductwork air handlers so you can keep the ducts you have, and have real filtration setups.

This is what I have( Ducted mini splits) but sometimes I wish I had gone with individual units in every room

 

[Shawn Hayes]

I have a 1700 SQ FT house with 2 stories, our goal is to completely get rid of our furnace using Mini Splits and a wood burning stove. We live in West Virginia so it can get decently cold in the winter.

My questions are has anyone here got any experience with heating and cooling your entire house with mini splits?

I've seen a ton of videos with supplemental or people claiming they do, but they never talk about the details. I'm really interested in how each room "feels" and if there are cold spots or hot spots in the house.

Is there times when you don't think the mini splits are able to keep up with the demand?

While I'm in love with how cool they are and the technology behind it, I'm concerned because we really just want things to work. Being too hot or too cold can really affect your mood

We built new off grid, are a bit further south than you and maybe not as cold here. If you have grid power, or a huge battery bank if off grid, a mini split may be ok in the winter. Having a backup like a wood stove wouldn’t hurt. We used a 36K BTU Fujitsu mini split but installed traditional ducts to ensure even distribution of the conditioned air. (1800-1900 sqft)
We have a wood burning fireplace but using propane logs instead for the cold nights. So far I’m happy with our choice but on cold nights, I’m glad we have propane logs. In that case, we use the air handler circulation fan to move warm air around the house on cold nights.
Being off grid, I’m not going to drain my batteries on those nights, by choice, so propane as a supplement is awesome. Our water heater and stove are propane as well.
If you have grid power you will use yours more on cold nights than I will. However we have 2x6 exterior walls with spray foam insulation that helps insulate the structure.
As a side note, we recently installed a Fujitsu programmable thermostat so it can adjust temperatures on a schedule. This helps on battery usage.
So, depending on the make/model you select, look at the thermostat options before you buy. Ours only had two T-Stat options, a simple controller or a programmable one.

 

[Shimmy]

My in-laws have a air-source mini-split in their cabin in northern Sweden, along with a wood burning stove. The mini-split handles their load down to about 0F. When it is going to be a super cold night they generally put a single log on the stove which heats up everything. The cabin is well insulated and has two bedrooms, with the mini-split in the living room. They sleep with the bedroom doors open and sometimes need fans in the doors in the summer. For the winter they don't complain.

With the wall mounted mini splits, generally they cool a room well, but dog-legs to the room or adjacent spaces can lack conditioning. My master bedroom suite is kind of U-shaped with the bed and mini-split at the bottom of the U; the two legs tend to not get much cooling for the first ~3 hours it is on, but the bed area is fine within an hour.

 

[Aridom82]

I have a 1700 SQ FT house with 2 stories, our goal is to completely get rid of our furnace using Mini Splits and a wood burning stove. We live in West Virginia so it can get decently cold in the winter.

My questions are has anyone here got any experience with heating and cooling your entire house with mini splits?

Yes i have gone through the whole process myself in my 2000 sq ft appartment. Changed methane furnace heating with two mini splits (2x9000 btu mitsubishi kirigamine style) and a wood pellet stove for backup. There is a lot to cover but in a nutshell:
Information is everything. The more you know about your house situation the better your results will be.

You need to know how much heat is necessary to keep your house temperature in the coldest time of the year, so you can size the btus requirement of the mini splits. I did tests, like putting a thermometer and resistor heaters around the house in the coldest nights of the winter, turn the furnace off and see how many kw of heat do i need to keep 19-20°C until morning.

You need to know exactly how your house has been built and where insulation can be improved. The key at least for me was investing in insulation. I changed the windows, did blow in insulation in the ceiling and in space between walls, and put eps panels outside in certain areas. A flir (thermal camera) is tremendously useful in detecting weakly insulated areas. After the improvements in insulation the amount of energy i need to heat my house has been cut in HALF, and i can actually run it with solar energy most of the time.

Heat or cold spots depend on the splits situation, natural or forced air flow around the rooms, and the quality of the insulation on those areas. If you size your system correctly you practically will never need to turn on the wood stove. I just have a wood pellet stove only for when the batteries of my solar system are depleted.

Most important: do not rush into buying equipment and give yourself time to learn your house, when you know enough you will know exactly what to do.

 

[MajicDiver]

don't think the mini splits are able to keep up with the demand?

We are heating/cooling 3,700 sqft home with mini splits. 500 gallon propane tank and gas logs in two locations for “backup” heat - works well in southeast Tennessee. We have 2 mrcool mini’s and 2 mitsubishi, when it gets below 15 degrees in daytime you will want some sort of backup heat.

 

[740GLE]

We are heating/cooling 3,700 sqft home with mini splits. 500 gallon propane tank and gas logs in two locations for “backup” heat - works well in southeast Tennessee. We have 2 mrcool mini’s and 2 mitsubishi, when it gets below 15 degrees in daytime you will want some sort of backup heat.

Unless you have mini splits for cold weather, our hyper heat are good to -10f. Granted they suck the energy down at that temp and supplemental heat hydronic baseboard keeps the house feeling warmer.

 

[Madcodger]

My questions are has anyone here got any experience with heating and cooling your entire house with mini splits?

I grew up in WV and now live in Maine, where we have mini-splits in both our home and our guest house. As others have noted, each is easily heated and cooled by mini-splits. One of our units is rated down to 5F but has performed well at just below zero in a pretty well insulated building. The other is rated down to -14F and has of course performed even better, despite being in a house with only mediocre insulation. They do suck up a lot more electricity at those very low temps compared to even 25F, but when I ran the calculations they were still more economical than propane even in single digits or below. None of our units have "backup" resistive heat strips. We have been able to run them off our 12Kw generator without a problem when the electricity has gone out.

We do have backup propane heat in each building because where we live, you really need a backup source of heat, just in case you experience a mechanical failure of the primary heat. But we rarely use it, and fire it up only on the very coldest days mostly to exercise it just a bit. We also have wood stoves but almost never use those. They really dry the house out too much, while the mini-splits allow us to retain humidity and keep it at a comfortable level in winter.

 

[Sundog33]

That's great info, I was planning on keeping the furnace just to use as a filtration system, we also have 7 air purifiers at work throughout the house as we have asthma/allergy issues.

Yes, If you have existing ductwork it just makes sense to take advantage of it for evening out the house and added filtration.
Setting the thermostat on "Circulate" will randomly turn on the Blower fan.

I don't think you can go wrong, this is true also:
"if not I'll eventually just run them off solar panels during the day to help lower costs."