OT: Anyone considered a mini-split system for their garage?

demetk · Post by **demetk** » Dec 12, 2014 2:55 PM

Since the combined knowledge base around here is so damn impressive, I figured I'd put this up here in case someone has done this and figured out my particular hurdle.

Anyway, I just installed a cheap mini-split system in the garage so I can retire the wood stove that I was using for heat in the winter months. The addition above the garage is almost complete so I decided that it would be unwise to continue with wood heat in the garage and so I opted for an inverter mini-split heat pump system instead.

The 18k btu system cost $650 delivered plus another couple of hundred for the lineset, wiring, and tools that I needed for a DIY install. The thing is up and running and is spewing out the heat just nicely. Unfortunately I hit a brick wall in terms of controlling the temperature on this thing. The problem I'm having is the lowest temp set point via the remote is only 61 degrees F. It just won't go any lower than that. For a living space that wouldn't be a problem but for a garage this is a problem. I'd rather have it heated to above freezing when not being used for repairs.

I called the store I bought the system from and they indicated in no uncertain terms that mini-splits are not intended for garages and that getting a lower setpoint than 61 degrees was just not possible. So I told them in no uncertain terms that this was just a bunch of baloney and to go stuff it.

So now I have two projects that I'm working on for controlling this system with a regular 24vac electronic thermostat. One project is to simply wire up the remote so I can send a pulse to the remote's on/off button. When the thermostat activates a call for heat, my circuit will pulse the on/off button on the remote for one second and thereby turning the mini-split on. When the thermostat is satisfied, my circuit will pulse the on/off button on the remote for one second and thereby turning the mini-split off.

The other project is to decipher the on/off IR code string that the remote sends to the head unit and have the thermostat blast the appropriate IR string to the head unit. I've already bought a USB-UIRT and downloaded EventGhost and will be learning all about this mysterious home automation stuff.

Comments welcome.

cheers

ldsbeaker · Post by **ldsbeaker** » Dec 12, 2014 10:05 PM

I have been planning to do this in my garage. At least one unit.

You know how I got sold? Yup, my business trip. We had two mini splits heating/cooling a ~600 sq ft room in some of the harshest conditions, and they never hiccup'ed once. At least ours were perfect. Others failed, but when you have thousands of these units... Some are bound to fail.

I like the idea of:
Hanging inside unit like a picture
Low profile outside unit
3" circular hole in wall (security AND aesthetics)
WAAAAY more efficient than window units

They use these units just about all over the world. I was going to do a window unit, but none of the units fit the window right and there were security issues there.

I'm interested to see which one you're getting, $650 seems like a bargain.

Post by **tsmall07** » Dec 13, 2014 12:45 AM

It could be that the indoor unit requires a certain temp to operate properly and the min temp is at 61 deg to protect the unit. I can't think of what that would be since it's pretty much just a fan/coil. If I were going to do it and a GFUH wasn't possible, I'd probably do a through-wall unit instead of a split. Mini-splits are typically used when you want to have multiple zone control with one condenser unit.

Can you just get a different thermostat?

demetk · Post by **demetk** » Dec 13, 2014 10:02 AM

Some pics of the unit. It's a 18,000 BTU 15 SEER Single Zone Ductless Heat Pump System and bought it for $650 delivered to my home on a pallet. The condenser is outside,

It has a variable speed inverter compressor/condenser making it very efficient even at low temps. I should be able to drive this to 0 degrees F and still manage a 2.0 COP.

The head unit is mounted on the wall,

demetk · Post by **demetk** » Dec 13, 2014 10:43 AM

tsmall07 wrote:It could be that the indoor unit requires a certain temp to operate properly and the min temp is at 61 deg to protect the unit. I can't think of what that would be since it's pretty much just a fan/coil. If I were going to do it and a GFUH wasn't possible, I'd probably do a through-wall unit instead of a split. Mini-splits are typically used when you want to have multiple zone control with one condenser unit.

Can you just get a different thermostat?

That's my thinking also. I see no reason for it to have such a high temp set point. The problem with most mini-splits on the market is they cannot be controlled via a regular 24v thermostat. They can only be controlled via the supplied remote which is a joke when compared to wi-fi programmable thermostats that can be used with your phone app. This makes them essentially dumb stand-alone systems. Some mini-splits do have wired thermostats available but they're proprietary and cost a fortune.

I've already designed my pulse circuit and built a prototype and tested it with a simple electronic thermostat. And it works!

Components I'm using,

Thermostat - $15
24vac relay - $15
12vdc delay timer - $6
24vac transformer - $10
12vdc transformer - $7

I only needed one 12vdc delay timer module to handle both on and off timing events since it has a faster reset rate than the 24vac relay's switching rate switching from NO to NC positions.

Now to connect it to my remote and see what happens. If you're interested in the circuit I can post it.

adrian in florida · Post by **adrian in florida** » Dec 13, 2014 4:19 PM

I have had a good experience with mini splits for cooling. I was gonna suggest a wood stove but then realized how stupid that was for garage use.

davintosh · Post by **davintosh** » Dec 13, 2014 8:34 PM

Hmmm... I've never heard the term "mini-split" before. Looks to be just a small heat pump, so I can't see why anyone would think it can't have a set point below 61 degrees. Like Tyler said, it's just air moving over a coil, and I can't imagine that it would the temperature of the air moving over the inside coil would make a whit of a difference to it. That's a brilliant move putting one in the garage. And for $650? That's a bargain!

We've been using a heat pump system to heat & cool our whole house for about 8 years, and it's got to be one of the best purchases we've ever made. I'm amazed that the thing can pull heat out of the air when it gets down in the 20's... Ours kicks over to regular natural gas-fired heat when the outside temp dips below 15 degrees F, but the efficiency of the heat pump when the outside temp is between 30-60 is just amazing.

demetk · Post by **demetk** » Dec 13, 2014 8:57 PM

adrian in florida wrote:I was gonna suggest a wood stove but then realized how stupid that was for garage use.

LOL. The local fire department also found it kind of odd that they were inspecting a wood stove installation in a garage.

They did pass it. But it has outlived it's usefulness. Poor thing, it think its beside itself now that I've found a new love.

demetk · Post by **demetk** » Dec 13, 2014 9:21 PM

davintosh wrote:We've been using a heat pump system to heat & cool our whole house for about 8 years, and it's got to be one of the best purchases we've ever made. I'm amazed that the thing can pull heat out of the air when it gets down in the 20's... Ours kicks over to regular natural gas-fired heat when the outside temp dips below 15 degrees F, but the efficiency of the heat pump when the outside temp is between 30-60 is just amazing.

Totally agree. When I bought the house it had an old oil furnace for primary heat and straight a/c for cooling. Needless to say the energy costs were through the roof. Installing a heat pump was the best thing I did. Energy costs were cut in half immediately. Now the new oil furnace is used strictly for emergency backup heat when temperature dips below 25F. The one thing I have always found annoying with this Goodman heat pump is its time/temp defrost system which goes into defrost irrespective if the unit actually needs a defrost or not. I'm about to retrofit a modern demand defrost control board from a Trane which will save even more money, that is If I don't blow the thing up in the process.

adrian in florida · Post by **adrian in florida** » Dec 14, 2014 12:01 AM

demetk wrote:
adrian in florida wrote:I was gonna suggest a wood stove but then realized how stupid that was for garage use.
LOL. The local fire department also found it kind of odd that they were inspecting a wood stove installation in a garage.

They did pass it. But it has outlived it's usefulness. Poor thing, it think its beside itself now that I've found a new love.

Ha, the valvoline boxes are a nice touch.

Post by **tig** » Dec 14, 2014 12:24 AM

I have a AC unit like this cooling my raised floor, drop ceiling, 3 rack equipment room.

I recently put this baby in the garage. Bought it last year, but finally got around installing it about a month ago. Works great.

DSC_1491 by t i g, on Flickr

John project car · Post by **John project car** » Dec 14, 2014 8:29 AM

Most Mini splits allow for the installation of a regular remote thermostat but you will often need an adapter kit from them. I have 21 remotes left over from an install we just did at an old age home. Guess I will ebay em.

Nice idea by the way although electric heat is a bit pricey to run and slow to warm up - still AC in the summer - I like.

Wood stove very bad in an Automotive shop thanks to the explosion hazard from fuel, all burners and burner ignition devices must be located not less than 18 in. above the floor . Surprised your inspection for the wood stove passed. I have heard of guys around here getting their insurance cancelled for wood stoves in the Garage.

John project car · Post by **John project car** » Dec 14, 2014 8:33 AM

One other thing - keep it clean , dust will kill it.

demetk · Post by **demetk** » Dec 14, 2014 9:11 AM

cek wrote:I have a AC unit like this cooling my raised floor, drop ceiling, 3 rack equipment room.

I recently put this baby in the garage. Bought it last year, but finally got around installing it about a month ago. Works great.

DSC_1491 by t i g, on Flickr

Interesting. What is it?

Kinda looks similar to the unit I saw installed in an old Lincoln once.

demetk · Post by **demetk** » Dec 14, 2014 9:29 AM

John project car wrote:Most Mini splits allow for the installation of a regular remote thermostat but you will often need an adapter kit from them. I have 21 remotes left over from an install we just did at an old age home. Guess I will ebay em.

Nice idea by the way although electric heat is a bit pricey to run and slow to warm up - still AC in the summer - I like.

How many remotes total in that house? I'd go nuts if I had more than 3 remotes to remember.

Heat pump is still the cheapest way to run around here. Even cheaper than natural gas which comes in a good second. Don't you have an abundance of cheap nuclear in Canada? Here in CT we one twin reactor nuclear plant.

waynet1 · Post by **waynet1** » Dec 14, 2014 9:40 AM

You're always re-inventing some kind of wheel, aren't you.

You're wife is special......

demetk · Post by **demetk** » Dec 14, 2014 9:53 AM

waynet1 wrote:You're always re-inventing some kind of wheel, aren't you.
You're wife is special......

LOL. I drive her nuts with all my little projects. She runs screaming for cover every time I try to discuss one with her.

My next little project is to decipher and blast IR codes for this mini-split.

Post by **tig** » Dec 14, 2014 12:44 PM

demetk wrote:
cek wrote:I have a AC unit like this cooling my raised floor, drop ceiling, 3 rack equipment room.

I recently put this baby in the garage. Bought it last year, but finally got around installing it about a month ago. Works great.

DSC_1491 by t i g, on Flickr
Interesting. What is it?

Kinda looks similar to the unit I saw installed in an old Lincoln once.

Better pic of it mounted:

Bought on Amazon:
http://www.amazon.com/gp/product/B000A6 ... =ceklog-20

demetk · Post by **demetk** » Dec 14, 2014 1:41 PM

Thanks for the pic. So that is a resistance heater which around here would be the most expensive to operate. I did this fuel comparison and based on it, I made the decision for yet another heat pump system for the garage. If we had natural gas around here then I would have ditched the oil furnace a long time ago.

http://www.builditsolar.com/References/ ... xample.htm

John project car · Post by **John project car** » Dec 14, 2014 5:42 PM

demetk wrote:
John project car wrote:Most Mini splits allow for the installation of a regular remote thermostat but you will often need an adapter kit from them. I have 21 remotes left over from an install we just did at an old age home. Guess I will ebay em.

Nice idea by the way although electric heat is a bit pricey to run and slow to warm up - still AC in the summer - I like.
How many remotes total in that house? I'd go nuts if I had more than 3 remotes to remember.

Heat pump is still the cheapest way to run around here. Even cheaper than natural gas which comes in a good second. Don't you have an abundance of cheap nuclear in Canada? Here in CT we one twin reactor nuclear plant.

Well I can see the steam from Niagara Fall from my house , and yep we also have lots of Nuclear - about 52% if I recall correctly. But Natural gas is cheapest - tons of it around here. Lots of people even have their own well. Still neither are as cheap as they should be - government messed it up pretty well .

davintosh · Post by **davintosh** » Dec 14, 2014 5:58 PM

demetk wrote:
John project car wrote:Most Mini splits allow for the installation of a regular remote thermostat but you will often need an adapter kit from them. I have 21 remotes left over from an install we just did at an old age home. Guess I will ebay em.

Nice idea by the way although electric heat is a bit pricey to run and slow to warm up - still AC in the summer - I like.
How many remotes total in that house? I'd go nuts if I had more than 3 remotes to remember.

Heat pump is still the cheapest way to run around here. Even cheaper than natural gas which comes in a good second. Don't you have an abundance of cheap nuclear in Canada? Here in CT we one twin reactor nuclear plant.

Heat pump efficiency drops as the outside temp drops, which is why ours kicks over to natural gas heat at 15 degrees. I guess that can be adjusted, but the outfit that installed ours had done the math on cost/efficiency curves and that was the number that was suggested. But that was 8 years ago. Maybe it's time to look at that again.

unt0uchable · Post by **unt0uchable** » Dec 15, 2014 2:33 PM

I've got one these bad boys leaning against the wall just begging to keep the temps in my garage half way decent in the winter.

But I'm too cheap to buy the wire set to install it considering my panel is at least 50-75 feet from where it would end up....240v wiring isn't cheap, and I can't imagine the cost to run the heater is much different. So for now, I deal with the ~40* temps most of the winter. I might like it better if it were closer to 55* in there in the winter but until I pony up...

That's not half bad for the mini split tho! I also need to insulate my garage doors and the garage ceiling before I think about conditioning the air in there...

stuartinmn · Post by **stuartinmn** » Dec 15, 2014 2:51 PM

Electric unit heaters like the one in the picture above do have some advantages. Although electricity on a per unit basis is usually more expensive than natural gas, they are generally less expensive to purchase and install when compared to a gas unit heater. You don't have to run gas lines, install air intake or exhaust pipes, etc. They are typically safer for use in a garage as well, since an electric heater has no open flame. Also, depending on the size (and insulation) in your garage, a gas unit heater may be too large for the room - it will short cycle, which reduces its lifespan as it doesn't run long enough to burn off condensation (much like only driving your car on short trips.)

Remember that garage heaters are often only used occasionally. If you were running an electric heater all the time, the bill at the end of the month may be pretty high, but if you're only turning it on for a few hours on Saturday it's not that big a deal. If you do want to leave it on, use a low temp thermostat so you can turn it down to 50 degrees F or whatever you want when you're not out there, and then only turn it up when you are working in the garage. As long as the garage is well insulated and weatherstripped, an electric heater can be a reasonable alternative.

Post by **tsmall07** » Dec 15, 2014 5:09 PM

I don't have an issue with a wood stove in the garage if you're smart about it. I wouldn't store any gasoline in there and I wouldn't leave it unattended. The obvious drawback is you can provide freeze protection with a wood stove which, it seems, is what the OP was after. A wood stove isn't more dangerous than a Kerosene or natural gas/propane heater and I see those all the time.

davintosh wrote:Hmmm... I've never heard the term "mini-split" before. Looks to be just a small heat pump, so I can't see why anyone would think it can't have a set point below 61 degrees.

Mini-splits are very useful for putting A/C into an old house without having to provide duct work. You just mount the convector to the wall and run the line set to it. You can also attach multiple convectors to one condenser so you can have multi-zone control with only one condenser. Saves cost and real estate.

demetk · Post by **demetk** » Dec 15, 2014 5:42 PM

tsmall07 wrote:I don't have an issue with a wood stove in the garage if you're smart about it. I wouldn't store any gasoline in there and I wouldn't leave it unattended. The obvious drawback is you can't provide freeze protection with a wood stove which, it seems, is what the OP was after. A wood stove isn't more dangerous than a Kerosene or natural gas/propane heater and I see those all the time.

The wood stove was very useful over the 8 years I had it but when not in use, the garage was basically a cold space even though it is insulated. Before the wood stove I heated with kerosene and IMO that is the worst heat source you can have in a sealed space. Having freeze protection means I can store stuff like my paint and my beer that would otherwise spoil if frozen.

A little update on my little thermostat project. I inadvertently touched a hot lead to one of the diodes on the delay timer board and it shorted out the transistor. There was a spark and then there were words. Waiting on some new delay timers to arrive.

demetk · Post by **demetk** » Dec 27, 2014 11:15 PM

Yeah baby. This crude prototype is working nicely at overcoming the 61 degree F set-point limit inherent in mini-spilt systems. I can now keep the garage a toasty 45 degrees F. Notice the hardwired remote control. I got this idea from the garage door opener remotes that some here have hardwired.

Mike W. · Post by **Mike W.** » Dec 27, 2014 11:52 PM

demetk wrote:Yeah baby. This crude prototype is working nicely at overcoming the 61 degree F set-point limit inherent in mini-spilt systems. I can now keep the garage a toasty 45 degrees F. Notice the hardwired remote control. I got this idea from the garage door opener remotes that some here have hardwired.

45F garage??? I wouldn't have thought that little split system would get it that cold!

Actually I remember rebuilding an engine one time, long ago, in a friends semi heated garage in snow country. I'm not sure what the temp was, but it was above freezing and out of the wind. And I was appreciative.

It wasn't really an elective rebuild although I did drive it in and out, it was going thru so much oil it was a necessity, not a luxury.

demetk · Post by **demetk** » Dec 28, 2014 12:04 AM

Mike W. wrote:
demetk wrote:Yeah baby. This crude prototype is working nicely at overcoming the 61 degree F set-point limit inherent in mini-spilt systems. I can now keep the garage a toasty 45 degrees F. Notice the hardwired remote control. I got this idea from the garage door opener remotes that some here have hardwired.
45F garage??? I wouldn't have thought that little split system would get it that cold!

Actually I remember rebuilding an engine one time, long ago, in a friends semi heated garage in snow country. I'm not sure what the temp was, but it was above freezing and out of the wind. And I was appreciative. It wasn't really an elective rebuild although I did drive it in and out, it was going thru so much oil it was a necessity, not a luxury.

Haha, good one. I guess I should have clarified that in HEAT MODE these silly things don't allow set-point temps lower than 61 degrees F. I guess in FL you may still need to cool your garage in the winter but up here in chilly CT, heat is what you're ideally aiming for, because working in the cold on your bimmer is no fun.

davintosh · Post by **davintosh** » Dec 28, 2014 1:51 AM

Working in a cold garage in SD isn't much fun either. So far all I've used for supplemental heat is one of these;

No need for thermostats; if it gets it warm enough in there to keep water-based stuff from freezing, that's as good as I need it. Too bad most of its heat just goes up into the rafters of the garage. Using it does make me a bit nervous though. It's never left unattended.

Mark in Toronto · Post by **Mark in Toronto** » Dec 28, 2014 11:51 AM

^^^^Personally, I would not feel comfortable using that heating element and a 30 lb tank in an enclosed space.

It lacks basic safety features such as low O2 auto shut off.

This winter I'm using the Mr. Heater Big Buddy. It's portable, 18,000 btu's so it can easily heat the garage to 60 + degrees and uses dual 1 lb cylinders or you can attach a hose and hook it up to a 30 lb tank.

wkohler · Post by **wkohler** » Dec 28, 2014 11:55 AM

I had one of those heaters on a propane tank. It was in the explosion and didn't catch on fire. There was still propane in it even. No, I did not save it.

davintosh · Post by **davintosh** » Dec 28, 2014 2:41 PM

Mark in Toronto wrote:^^^^Personally, I would not feel comfortable using that heating element and a 30 lb tank in an enclosed space.

It lacks basic safety features such as low O2 auto shut off.

I wouldn't exactly call my garage "an enclosed space". Drafty as a corn crib.

It was a cheap solution that has come in handy, but I don't really use it often enough for it to be a huge concern. So far maybe twice this season is all.

Mark in Toronto wrote:This winter I'm using the Mr. Heater Big Buddy. It's portable, 18,000 btu's so it can easily heat the garage to 60 + degrees and uses dual 1 lb cylinders or you can attach a hose and hook it up to a 30 lb tank.

That looks like a decent option, but if I were going to do something different I'd probably opt for something that doesn't require a tank and doesn't sit on the floor. Maybe an electric heater like this one:

Mounts up high, doesn't clutter the floor, has a fan to move the warm air around, and no danger of CO2. There are also some wall-mounted non-vented propane/natural gas heaters that would work well for about the same money. Neither are likely to happen this season anyway; we'll see what next year brings.

WilNJ · Post by **WilNJ** » Dec 28, 2014 2:54 PM

The big difference in the OPs solution and the others offered is that he can maintain the garage at a desired temp even in an unoccupied setting.

demetk · Post by **demetk** » Dec 28, 2014 3:11 PM

davintosh wrote:Working in a cold garage in SD isn't much fun either. So far all I've used for supplemental heat is one of these;

No need for thermostats; if it gets it warm enough in there to keep water-based stuff from freezing, that's as good as I need it. Too bad most of its heat just goes up into the rafters of the garage. Using it does make me a bit nervous though. It's never left unattended.

I also used one of these temporarily when I needed some heat in the garage or in my unfinished addition but I always kept an eye on it. So, what are the products of combustion with them? I'm assuming since they're not vented, CO would be a concern.

The electric resistance heaters would be a solution when used with a thermostat but straight resistance heat is the most expensive heating option around here. A heat pump beats natural gas, propane and oil heating in terms of cost to operate. Natural gas heating would be my choice if I had that option but I have no natural gas lines around me. I do have propane though and even though it's an expensive option, I would consider using a small direct vented propane heater as an aux backup to the mini-split when it got bitterly cold.

Interested to see what others are using, so please post up.

waynet1 · Post by **waynet1** » Dec 28, 2014 3:30 PM

demetk wrote: Interested to see what others are using, so please post up.

Mark in Toronto · Post by **Mark in Toronto** » Dec 28, 2014 4:00 PM

davintosh wrote:Maybe an electric heater like this one:

Mounts up high, doesn't clutter the floor, has a fan to move the warm air around, and no danger of CO2. There are also some wall-mounted non-vented propane/natural gas heaters that would work well for about the same money. Neither are likely to happen this season anyway; we'll see what next year brings.

Yes, electric heat is a good option. Once the Big Buddy has warmed up the garage, I have two ceiling mounted electric quartz heaters to maintain a comfortable temperature.

The quartz panels are much more energy efficient when compared to conventional electric heaters.

demetk · Post by **demetk** » Dec 28, 2014 6:24 PM

waynet1 wrote:
demetk wrote: Interested to see what others are using, so please post up.

bastard. I think I need to move there.

davintosh · Post by **davintosh** » Dec 28, 2014 7:20 PM

waynet1 wrote:
demetk wrote: Interested to see what others are using, so please post up.

Kaleighphourkneuns.

Post by **Justin_FL** » Dec 28, 2014 7:55 PM

demetk wrote:bastard. I think I need to move there.

Err, unless you like sweating your ass off even at X-mas, it really is highly overrated!

I do need an A/C system in the garage.

waynet1 · Post by **waynet1** » Dec 28, 2014 8:14 PM

Justin_FL wrote:
demetk wrote:bastard. I think I need to move there.
Err, unless you like sweating your ass off even at X-mas, it really is highly overrated!

I do need an A/C system in the garage.

That is very true.
demetk, I would much rather be in your beautiful neighborhood and house tinkering with the heat in your garage then being here any day. I really dislike it here, but I dislike being cold even more. I wouldn't recommend living here to just about anyone, unless you're in the yacht industry, even then it is difficult.

Justin, you might want to try one of those free standing A/C units. I've seen them pretty inexpensive at Big Lots.