Minisplit garage questions

[BarnBuiltBeaters]

I am looking to install a minisplit in my gatage roughly a 30x30 space with 10 or 11ft ceilings...cant remember.
Walls are R23
Ceilings R30
Relatively well sealed
I live in New York/PA border were temps regularly get into the teens and occasionally stay in single digits.
Will a "normal" mini split do the trick or do i need the "hyperheat" models that heat below 5 degrees.

I would assume most days the normal models will work just fine. On the really cold days, i would assume it would struggle. Or would it not work at all? I am fine not working in the shop for those super cold days or using an additional heater if neccassary
Would you go normal or hyper?
Would you go 18k BTU or for 100 more 24k BTU?

What has your experience been with low temps and heating performance?

 

[PoorUB]

IMO, if you want heat and your outdoor temps can get near zero you want hyperheat. The big issue is that all pretty much all heat pumps fall off in efficiency as the temps drop. A 24K BTU unit that is rated to operate down to zero might put out only half the output at 10F and not be enough to heat the garage. A hyperheat that is rated to run to -20 or -30 will have full output until zero or colder.

So when you shop for a unit make sure you get one that will run to -20F to -30F. Different brands don't use the yerm hyperheat, but call it something else. Gree for example you want an Ultra model.

 

[bdbecker]

I'll be curious as to what others with more experience have to say. I've been doing research on this as well and have a similar size space. Personally, I've been leaning towards a 24k for my 24x24x8 shop. I think 18k would do it for me, but figured a little extra capacity wouldn't hurt since its an electric heater. I also am leaning towards the 'hyperheat' option as a lot of the regular ones are only rated for temps in the teens, which we see quite often here in Iowa.

 

[Yankeefarmer]

You definitely want one that claims heating down to 0 F or lower. Several years ago I installed a non-hyper heat 18 k in my poorly insulated 30x 30 shop for air conditioning purposes. I found that it really didn’t heat worth a darn at outside temps below 30 F. Didn’t bother me at all, since that building had a propane furnace and wood stove, but I would have been disappointed if I had been counting on it for heat.

FWIW, my new shop is heated only with a cold-rated heat pump and works beautifully, right down to 0 deg outside temp. We haven’t had colder temps yet to demonstrate its lower limit.

 

[Raisedonadeere]

I am in central KY and have a Senville 18K (SENA not SENL) hyper heat with ceiling cassette in a stick frame 24x36x10. Into second year. I worried that it would turn out too small based on what others here as well as Mr Cool and Senville but I must say that would have been a mistake. The 18K just cruises year round. On the coldest days even after backing car out and closing the door the temps return to normal quickly and stay put. It is just perfect. I have r30 ceiling, r15 walls and good seal with insulated doors, 16x8 and 10x8 plus man door and 4 double pane windows.
Yes you need it to be big enough but all the oversizing just to be safe just makes it less ideal.

I went with the smaller one thinking I will just not let myself be upset if on some occasional really hot or cold days it just doesn’t hack it.

I expect that if my doors were not in good shape or if windows were not good or if a few air leaks built in, the 24k would have been needed.

hope this helps.

 

[BarnBuiltBeaters]

So sounds like the consensus is to go with the "hyper heat" type models. I was hoping I could get away without buying the more expensive unit but sounds like I cannot. I suppose id rather spend the extra and not need it then need it and not have it.

I am leaning towards the bigger unit, a 24k btu. These new mini splits can ramp down and up as needed which I would think would allow a bigger unit to not short cycle if oversized. Also, This would aid in heating it up quicker as well as if my building wasnt sealed/insulated as well as I think it is the bigger unit could compensate for it. I do know ceilings and wall insulation values as I installed myself.

I feel like i would be fine with the "normal" mini split just because it only gets below 5deg (which most are rated to) in the middle of the night. I would not be out there that late. Thoughts?

Thanks for the advice all!

 

[Musky_Hunter]

What is the operating cost of these per month? I'm look more for heating than cooling and don't want the footprint a wood furnace takes up.

 

[BarnBuiltBeaters]

Heat pumps (minisplits) are very efficient. I believe i read somewhere they can be 300 to 400% efficient. They arent producing heat only transfering it.
I believe these will be equal if not less than to wood heating unless you are getting the wood for free.
Added benefit is they heat and cool. Im looking at it for heating as well but the cooling would be a huge plus

 

[kelpaso1]

What is the operating cost of these per month? I'm look more for heating than cooling and don't want the footprint a wood furnace takes up.

Mine is about $30/month in the winter. I don't use it in the summer for cooling.

 

[Musky_Hunter]

Mine is about $30/month in the winter. I don't use it in the summer for cooling.

This sounds reasonable. I just need it to stay 50 ish in the winter. My mill and lathe don't like it below freezing. I have 40 acres of woods but all the work that goes into cutting, splitting and storing is a pain. What size would be good for a 32x40x12?

 

[PoorUB]

So sounds like the consensus is to go with the "hyper heat" type models. I was hoping I could get away without buying the more expensive unit but sounds like I cannot. I suppose id rather spend the extra and not need it then need it and not have it.

I am leaning towards the bigger unit, a 24k btu. These new mini splits can ramp down and up as needed which I would think would allow a bigger unit to not short cycle if oversized. Also, This would aid in heating it up quicker as well as if my building wasnt sealed/insulated as well as I think it is the bigger unit could compensate for it. I do know ceilings and wall insulation values as I installed myself.

I feel like i would be fine with the "normal" mini split just because it only gets below 5deg (which most are rated to) in the middle of the night. I would not be out there that late. Thoughts?

Thanks for the advice all!

Like I said earlier, at 5F a standard mini split is not putting out much heat.

Look here, and go down the the heating performance.
https://www.greecomfort.com/assets/...ocuments/livo-gen3-submittal-24mbh-230v-a.pdf
This is a 24K BTU unit that will heat down to -4F. Heating performance drops as the outdoor temperature falls, but seriously falls off around 32F and drops like a rock. At 10F it produces about 60% of what is does at 50F and might not be enough to heat your shop.

Here is another one that claims heating down to -31F.
https://www.greecomfort.com/assets/...s/vireo-plus-ultra-submittal-30mbh-230v-a.pdf
If you scroll down the the heating performance you can see at 10F it produces as much heat as it does at 50F. In fact at -31F it is still performing well, about 75% of what is does in warmer temps.

 

[BarnBuiltBeaters]

I see what you are saying now and thank you for providing data. I work much better actually seeing data! Now here is my next question. What sized unit do you recommend? I think 24K is probably too big. I think 18K is probably where I want to be.

My space is 900 sqft at the biggest I believe it is closer to 28X28 so approx 800sqft. I think an 18k BTU unit is plenty fine for me seeing I am at the bottom end of their range (750-1100sqft Senville) I may be able to split the difference, get a smaller unit with Hyperheat. Spend more than what I really want but not so much more

Do you recommend Gree? Can it be used with an external thermostat?

 

[hefnerconstructionlc]

Those charts are fine. But without doing a real load calculation of the building. Taking into account your windows the wall layouts. The insulation the draftiness. All of those things are just a guess. Perform a manual j calculation and get a unit properly size to it. Then follow the charts on its efficiency and base that upon what you think your coldest days are going to be. And that will tell you whether the hyper heat is worth it.

 

[hefnerconstructionlc]

There is a website called coolcalc.com. it is a free load calculation software. Works really well and doesn't cost anything unless you want to buy reports. I would suggest that first then get your mini split.

 

[kelpaso1]

Keep in mind mini's loose efficiency below freezing temps. Ya, you can get those hyperheat ones that turn on a heating coil but then that kind of defeats the purpose of how efficient it is then.

 

[BarnBuiltBeaters]

Keep in mind mini's loose efficiency below freezing temps. Ya, you can get those hyperheat ones that turn on a heating coil but then that kind of defeats the purpose of how efficient it is then.

you are right however, at least for my case, the decision was between electric heat or a mini split due to have solar panels and also lack of an exhaust.
I believe the coil only turns on when the mini cant keep up. So i would assume the mini would be able to keep up most of the time except for the brutally cold portions of winter.

 

[Yankeefarmer]

Keep in mind mini's loose efficiency below freezing temps. Ya, you can get those hyperheat ones that turn on a heating coil but then that kind of defeats the purpose of how efficient it is then.

Hyper heat units aren’t called that because they turn on an electric resistance coil. They use an inverter (variable speed) compressor to ramp up their heat transfer capability. They have heaters, but the heater is a low wattage unit that serve only to keep condensate from freezing up at the outdoor unit.

 

[jetnow1]

My mini split heats a 24 by 30 fairly well insulated garage, not an ultra model but good till lower teens. Below about 15 I give it some help with a propane heater for an hour or so, then it maintains at least as long as I do. One thing to factor in
when sizing, if too large the a/c will not run long enough to dehumidify, to me that was an important consideration. I also
use the space as a work area, so heat to me means mid 6o's is perfect. Central Connecticut.

I built an in-law space for my mother that is 22 by 22 with a 15 foot high vaulted ceiling. The space has a lot of windows,
patio doors, and Mom came up from Florida so she wants it warm. Dual hyper heat units to handle that space, and the
entire envelope is foam insulation. This was on my sisters house, and she is a block from the ocean, lot of wind off the ocean. Connecticut/ Rhode Island border.

 

[Yankeefarmer]

My mini split heats a 24 by 30 fairly well insulated garage, not an ultra model but good till lower teens. Below about 15 I give it some help with a propane heater for an hour or so, then it maintains at least as long as I do. One thing to factor in
when sizing, if too large the a/c will not run long enough to dehumidify, to me that was an important consideration. I also
use the space as a work area, so heat to me means mid 6o's is perfect. Central Connecticut.

I built an in-law space for my mother that is 22 by 22 with a 15 foot high vaulted ceiling. The space has a lot of windows,
patio doors, and Mom came up from Florida so she wants it warm. Dual hyper heat units to handle that space, and the
entire envelope is foam insulation. This was on my sisters house, and she is a block from the ocean, lot of wind off the ocean. Connecticut/ Rhode Island border.

Doesn’t your mini-split have a ”Dry” mode? Ours do, and we use that quite a bit to dehumidify without over-cooling the space.

 

[PoorUB]

Keep in mind mini's loose efficiency below freezing temps. Ya, you can get those hyperheat ones that turn on a heating coil but then that kind of defeats the purpose of how efficient it is then.

What heating coils?
The "hyperheat" units I sold would heat to -31F just using the heat pump cycle.

I don't know of any mini splits with heating coils

 

[kelpaso1]

What heating coils?
The "hyperheat" units I sold would heat to -31F just using the heat pump cycle.

I don't know of any mini splits with heating coils

I thought some had coils maybe I'm wrong. But in any case you can only get so much heat out of -30 degree air outside.

 

[cstmg8]

May have been mentioned, but what is the price difference? I'd be tempted to get the regular model, then get a supplemental heat source to back it up in very cold temps. Example would be an electric heater that kicks on at 50* or something. If you have the electrical capacity.
Seems easiest, and you have a backup if something is down.

 

[PoorUB]

I thought some had coils maybe I'm wrong. But in any case you can only get so much heat out of -30 degree air outside.

You would be wrong. It sure doesn't help the conversation when someone helps with incorrect information!

I see what you are saying now and thank you for providing data. I work much better actually seeing data! Now here is my next question. What sized unit do you recommend? I think 24K is probably too big. I think 18K is probably where I want to be.

My space is 900 sqft at the biggest I believe it is closer to 28X28 so approx 800sqft. I think an 18k BTU unit is plenty fine for me seeing I am at the bottom end of their range (750-1100sqft Senville) I may be able to split the difference, get a smaller unit with Hyperheat. Spend more than what I really want but not so much more

Do you recommend Gree? Can it be used with an external thermostat?

I sold Gree for a couple years. We had very good luck with them and the support was great.
As for which unit, I would lean towards the 24K as I doubt the 18K would keep up in severe cold. My seat of the pants BTU calculator says about 21K for heating.

If you go online many of the online calculators are nuts and claim twice as much as you need. I did HVAC for a living so have experience sizing heating loads.

I heat my house on 24K BTU until it gets to -30F. Guys told me I needed 60K to heat it!

 

[kelpaso1]

You would be wrong. It sure doesn't help the conversation when someone helps with incorrect information!


I sold Gree for a couple years. We had very good luck with them and the support was great.
As for which unit, I would lean towards the 24K as I doubt the 18K would keep up in severe cold. My seat of the pants BTU calculator says about 21K for heating.

If you go online many of the online calculators are nuts and claim twice as much as you need. I did HVAC for a living so have experience sizing heating loads.

I heat my house on 24K BTU until it gets to -30F. Guys told me I needed 60K to heat it!

That's what I said and you told me I was wrong

 

[PoorUB]

That's what I said and you told me I was wrong

???

 

[jetnow1]

Doesn’t your mini-split have a ”Dry” mode? Ours do, and we use that quite a bit to dehumidify without over-cooling the space.

it does but if you are cooling and don't want it cycling it should be sized right.

 

[BarnBuiltBeaters]

My mini split heats a 24 by 30 fairly well insulated garage, not an ultra model but good till lower teens. Below about 15 I give it some help with a propane heater for an hour or so, then it maintains at least as long as I do. One thing to factor in
when sizing, if too large the a/c will not run long enough to dehumidify, to me that was an important consideration. I also
use the space as a work area, so heat to me means mid 6o's is perfect. Central Connecticut.

I built an in-law space for my mother that is 22 by 22 with a 15 foot high vaulted ceiling. The space has a lot of windows,
patio doors, and Mom came up from Florida so she wants it warm. Dual hyper heat units to handle that space, and the
entire envelope is foam insulation. This was on my sisters house, and she is a block from the ocean, lot of wind off the ocean. Connecticut/ Rhode Island border.

Thanks for including your location. I used to live in Cheshire, CT for about 20 years so i am super familiar with that weather. I would say where i am now located the weather is a but more extreme but not by too too much.

Definitely sounding like i need the hyperheat if I am to do it totally right. I suppose it is only some 400 or 500 more and I know it would be worth it.

Ill have to play with some calculators to see.

Thank you everyone on the advice so far i appreciate it! Although im getting mixed opinions on 18 vs 24k

 

[SLAYER6669]

I went with a Senville Aura 24k (rated down to -22) for my 3 car detached garage which is approximately 925 sq ft. I did the entire install myself, however they are not technically a "DIY" unit and require pro install for the refrigerant portion for warranty. I feel like these are a pretty good value for the money. I got mine at Amazon. We've been having temps in the single digits in the mornings here in NJ and it hasn't skipped a beat.

My only minor gripe is the lowest temperature setting is 62* (some brands are high 50s). I would prefer a lower temp to keep costs down, especially for when I am not out there. I am going to see how my electric bill looks for Jan and if I feel it's a bit too high, I might just run it in the FP (Freeze Protection) mode which heats to 48* in the future and then I can just raise it up ahead of time if I am planning to be out there.

I am certainly no expert on sizing them, I would likely say just go with the 24k since they are variable speed anyway. I assume a bigger unit will help recover quicker as well (such as when you open a door and heat escapes). I noticed Senville, in particular tends to have their mini split sizes rated for larger spaces than most. When I chatted with them, they basically said I was at the top of what an 18k can handle and 24k would be the safer bet. The difference right now, between 18k and 24k on Amazon is literally a whopping $70.

Good Luck!

 

[BarnBuiltBeaters]

I went with a Senville Aura 24k (rated down to -22) for my 3 car detached garage which is approximately 925 sq ft. I did the entire install myself, however they are not technically a "DIY" unit and require pro install for the refrigerant portion for warranty. I feel like these are a pretty good value for the money. I got mine at Amazon. We've been having temps in the single digits in the mornings here in NJ and it hasn't skipped a beat.

My only minor gripe is the lowest temperature setting is 62* (some brands are high 50s). I would prefer a lower temp to keep costs down, especially for when I am not out there. I am going to see how my electric bill looks for Jan and if I feel it's a bit too high, I might just run it in the FP (Freeze Protection) mode which heats to 48* in the future and then I can just raise it up ahead of time if I am planning to be out there.

I am certainly no expert on sizing them, I would likely say just go with the 24k since they are variable speed anyway. I assume a bigger unit will help recover quicker as well (such as when you open a door and heat escapes). I noticed Senville, in particular tends to have their mini split sizes rated for larger spaces than most. When I chatted with them, they basically said I was at the top of what an 18k can handle and 24k would be the safer bet. The difference right now, between 18k and 24k on Amazon is literally a whopping $70.

Good Luck!

Yes i noticed that the price difference was very minimal which urged me to go with the bigger unit as well. Glad yours is working out for you. How does the app work? Can it work with Alexa/Google? My entire shop is smart so I would like that functionality too if possible. Senville seems to be the best bang for your buck from what I have seen too with good reviews to back it

 

[SLAYER6669]

Yes i noticed that the price difference was very minimal which urged me to go with the bigger unit as well. Glad yours is working out for you. How does the app work? Can it work with Alexa/Google? My entire shop is smart so I would like that functionality too if possible. Senville seems to be the best bang for your buck from what I have seen too with good reviews to back it

Unfortunately the app is pretty basic. It has since been updated since I installed mine so maybe it was fixed, but getting it connected to the internet was a bit quirky but once connected I've had no issues. It does what I need it to do. No Google or Alexa compatibility that I'm aware of. I wouldn't mind this too.

 

[BarnBuiltBeaters]

Does anyone know of a brand (sub $1500) that can be paired with Google Nest or at least use the Google assistant?

 

[Phuckin' Jim]

Senville Smart WiFi USB Kit for Mini Split, Works with Alexa

Find a selection of ductless mini split air conditioners with heat pumps. We offer the best split air conditioner models and ductless air conditioners in Canada.

senville.ca

 

[SLAYER6669]

Senville Smart WiFi USB Kit for Mini Split, Works with Alexa

Find a selection of ductless mini split air conditioners with heat pumps. We offer the best split air conditioner models and ductless air conditioners in Canada.

senville.ca

Good to know. Apparently the wifi stick that comes with the Aura models can already connect to Google. I just linked Senville in the Google Home app.

 

[glennm]

I have this and it works fine with my sennville 12k

Mini-Split Thermostat | Mysa

Shop smart mini-split thermostats online at Mysa. Get 10% off your first order.

shop.getmysa.com

 

[BarnBuiltBeaters]

I Just purchased my Senville SENA 24k BTU minisplit. Should be here in the upcoming weeks. Hoping I can do the majority of the installation and just have a tech out here to charge the lines/ verify the electrical to get my pro-installation warranty on the product.... I mean I sometimes like to think of myself as a Pro...

 

[glennm]

I installed mine and got a guy to test with nitrogen and vac it. Worked out great. I’m down in Florida right now and I can log into the Mysa and change/check the temp any time

 

[brianh]

Last fall I installed 2 Pioneer 12k units in the house, they claim heat to -13f it hit -11 for two days here and they were putting out 104 degree air, I was quite impressed they were pulling 900 watts each. In the teens and 20's they average 500 watts each.
Bought them at Home Depot for under 800 a unit. Got them thinking they would fill in during the milder times to not overheat the house with the wood stove and AC in the summer. The performance exceeded my expectations

Going to install another this year. So far since November they have consumed 910 Kw hours we do run the wood stove but not burning like crazy as past years.

 

[BarnBuiltBeaters]

How much did the guy charge you to charge the system?

 

[bobkat]

So sounds like the consensus is to go with the "hyper heat" type models. I was hoping I could get away without buying the more expensive unit but sounds like I cannot. I suppose id rather spend the extra and not need it then need it and not have it.

I am leaning towards the bigger unit, a 24k btu. These new mini splits can ramp down and up as needed which I would think would allow a bigger unit to not short cycle if oversized. Also, This would aid in heating it up quicker as well as if my building wasnt sealed/insulated as well as I think it is the bigger unit could compensate for it. I do know ceilings and wall insulation values as I installed myself.

I feel like i would be fine with the "normal" mini split just because it only gets below 5deg (which most are rated to) in the middle of the night. I would not be out there that late. Thoughts?

Thanks for the advice all!

I have the senville 24k unit it is not hyper heat, I live inTexas so bought more for cooling than heat. my shop is 24x40 with 1/2 12 foot ceiling and other half 16 foot. Cooling wise it is great can drive down to 72 degrees on 100 deg day fairly easy, heat wise it struggles at temps below 35 or so. It will put out 79 degree air at the colder temp, not enough to warm the shop in any decent time. At 45 degrees and higher it will put out 114 degree air and heat pretty good. Cost wise best I can figure using smart meter on heat mode is about 1.5 kw per hour. A/c mode about 1 kw. My cost for elec is .088 delivered. so i am figuring about 75 cents for 8 hours in A/C mode and somewhere 98 cents in heat mode.using 72 degrees for both cool and heat.

 

[BarnBuiltBeaters]

Thanks for the response! Wow you have some really cheap electric! mine is around 13 cents/kwh. I am glad I went with the hyper heat model. Sounds like most are not happy with the performance of the standard model when expecting heat.
It seems a if my mini split is being delivered by bicycle as it is taking forever and only traveling GA to NY. I received parts from the UK recently that came quicker! Hoping this weekend I can rough it in.
I will let you all know my results. Fortunately, but unfortunately the coldest weather seems to be over so I wont know how well it performs with frigid weather.