Zone 6/Minnesota - minisplit vs natural gas for maintaining ~50F in winter?

switchgear12470 · Jan 4, 2026

Detached garage with approximately 700 sqft. I'm working on insulating it with mineral wool in the walls (R15) and blown in cellulose in the attic (haven't decided yet, but will probably just go for the full R49). Also going to insulate the garage door and air seal everything to the best of my ability.

My goal is to keep the cars at a "reasonable" temperature during the winter so that they don't need to be started and warmed up beforehand. 50F seems to be a good balance between the ball-numbing cold of zone 6 and energy consumption. In addition, this will be my workshop. If I decide I'm going to spend a Saturday afternoon on my arts & crafts, I can crank the heat up to 60 for a little more comfort or use a small radiant propane heater connected to a 20lb tank.

I don't really care about cooling capacity; I can envision a scenario where maybe it's a little toasty or humid in the garage and it would be nice to cool off, but in that scenario I would probably just open the garage door and turn on a fan.

I'm leaning towards mini-split because of the full DIY aspect, but I wanted to see what other people in this scenario wound up doing. The garage is going to be completely drywalled so there is going to be fire rating.

	Pros	Cons
Minisplit	Can fully DIY The Blueridge air minisplit DIY version is rated for down to -22F, which should be more than sufficient for zone 6	Components are more expensive Have to upsize subfeed conductor to garage to account for additional continuous load Electricity is expensive More **** that can break/fail
Natural gas direct vent garage heater	Components are cheap Gas is cheap	Can't provide cooling if I decide I want it Combustion in detached building- may need remote fire and CO monitoring tied into my home automation/alarm system May have to consider what my insurance company says or requires Would need to hire out someone tying in and/or running gas line- may could partially DIY, but the city requires that a licensed professional perform the work in order for it to be permitted. This is the only kind of work that the city does not allow a homeowner to do

ericm · Jan 4, 2026

Here's the heating costs spread sheet: https://www.maine.gov/energy/sites/maine.gov.energy/files/inline-files/Home-Heating-Calculator.xls

sub in the gas and electric prices for your area. Also change the efficiency numbers to match the units you're looking at.

It's common for gas heaters to have more BTUs than the usual mini splits installed to match Manual S numbers. Of course that is a choice you can make at install time. If your mini split is sized normally it may take longer to raise the temp from 50 or whatever. Some have minimum set temps as high as 62 though my Daikin and Mistubishi units can go lower. There's also sometimes a freeze prevention setting.

For me the mini splits are so cheap to run- a few bucks a day to heat 2240 sq ft- that I leave them set at working temp (62) all the time. I can pop in and do something without having to mess with the setting or be cold while the space is heating up.

Bert_ · Jan 4, 2026

The minimum setpoint on minisplits has always been a major disappointment for me. I wouldn't want it 62* when working in there let alone to leave it there all the time.

Another consideration with a minisplit is cleaning. The heads are not very fun to try to keep dirt and dust out of

jack stand · Jan 4, 2026

It sounds like you have a good insulation plan.

To encourage you with the minutia and details of great insulating, (much of this is air sealing) the more you can keep the heat inside the less important your heat source decision becomes.

pcmeiners · Jan 4, 2026

As to the post link above, unless updated the utility costs are old, the following has updated data as of early 2025, download using the link provided and update the utility costs with your area's costs. Make sure any data you use has all surcharges and taxes included.

As to Blueridge air minisplits, there are mini splits with far better SEER and HSPF and output numbers. You need to research until you understand minisplit specs.

Firebrick43 · Jan 4, 2026

pcmeiners said:
As to the post link above, unless updated the utility costs are old, the following has updated data as of early 2025, download using the link provided and update the utility costs with your area's costs. Make sure any data you use has all surcharges and taxes included.

As to Blueridge air minisplits, there are mini splits with far better SEER and HSPF and output numbers. You need to research until you understand minisplit specs.

The efficiency percentage for NG and propane also need updated, Those kind of crappy numbers haven't been on even basic cheap furnaces for 30 plus years

e-tek · Jan 4, 2026

Awesome post. I'm considering the same Ina similar situation. Used to heat my old 24x40shop with a HotDawg heater, my new shop is 24x36 and considering mini split. I live in SK Canada, so same or colder as you. Sounds like the new units can handle the extreme cold. I'd go back to a HotDawg NG heater, but the gas meter for hook up is on other aide of house, so 100' away. That'll cost a couple grand to install right there, even if I tench myself. Also, summers are getting hotter, so some cooling sounds good. Great info here, can't wait to hear what you decide to go with.

Firebrick43 · Jan 4, 2026

switchgear12470 said:
Detached garage with approximately 700 sqft. I'm working on insulating it with mineral wool in the walls (R15) and blown in cellulose in the attic (haven't decided yet, but will probably just go for the full R49). Also going to insulate the garage door and air seal everything to the best of my ability.

I would at least go R60 in the ceiling with a mini split. Even though many can produce heat down to negative temps their capacity is reduced significantly to produce heat at those temps. I would put 2x2 on horizontally on the wall for additional insulation and lower thermal bridging as well.

switchgear12470 said:
My goal is to keep the cars at a "reasonable" temperature during the winter so that they don't need to be started and warmed up beforehand. 50F seems to be a good balance between the ball-numbing cold of zone 6 and energy consumption. In addition, this will be my workshop. If I decide I'm going to spend a Saturday afternoon on my arts & crafts, I can crank the heat up to 60 for a little more comfort or use a small radiant propane heater connected to a 20lb tank.

If your garage is tight, an unvented LP heater is a bad idea. And it should be tight for a mini split. A small oil filled electric heater next to where you are working might be a better solution. I do that in the little heated shed that my lathe and milling machine is in and it works well.

switchgear12470 said:
I don't really care about cooling capacity; I can envision a scenario where maybe it's a little toasty or humid in the garage and it would be nice to cool off, but in that scenario I would probably just open the garage door and turn on a fan.

The advantage is the mini split removes humidity, just like a dehumidifier, uses the same energy and reduces the temp at the same time. Humidity is almost as bad as the heat for discomfort.

switchgear12470 said:
I'm leaning towards mini-split because of the full DIY aspect, but I wanted to see what other people in this scenario wound up doing. The garage is going to be completely drywalled so there is going to be fire rating.

Pros Cons
Minisplit

Can fully DIY

The Blueridge air minisplit DIY version is rated for down to -22F, which should be more than sufficient for zone 6

Components are more expensive

Have to upsize subfeed conductor to garage to account for additional continuous load

Electricity is expensive

More **** that can break/fail

Natural gas direct vent garage heater

Components are cheap

Gas is cheap

Can't provide cooling if I decide I want it

Combustion in detached building- may need remote fire and CO monitoring tied into my home automation/alarm system

May have to consider what my insurance company says or requires

Would need to hire out someone tying in and/or running gas line- may could partially DIY, but would absolutely hire a professional to verify

If you make it efficient, seal the garage door, and use green hinges to prevent wind moving the door away from the seals a mini split is a very good solution unless you do high dust hobby like wood working

ericm · Jan 4, 2026

There are folks who have added filter boxes to their mini splits to keep the air handler's filter clean. But it's an extra thing to do.

PoorUB · Jan 4, 2026

IMO, natural gas is a winner most of the time, if you just want heat. Less to go wrong, cheaper to fix if it does break down and pretty much just ignore the unit and it will run for twenty years or more. The only tough part is running the gas line. Once tha gas line is in, toss a $500 Mr Heater on the cealing and ignore it. In twenty years if it dies, buy another heater and hook it up.

The new inverter mini splits are good for ten years, maybe a bit longer and when they fail trouble shooting is very difficult and parts might be impossible to get.

If you want heat and AC then a mini split is probably the answer.

In my garage I have an 80% furnace and a split AC system, same as you would install in a home. Simple to repair and reliable as a rock. A mini split might heat cheaper, but that furnace has been in the garage for over twenty years and it cost me maybe $20 for parts in that time. Oops, I guess I have replaced the venting too, maybe $50. The AC developed a leak and I fixed it myself and three pounds of refrigerant.

I could not care less about the cost to run the AC as it might run a week total in the summer, but I do enjoy having AC when it hits 90F or more.

pcmeiners · Jan 4, 2026

Firebrick43 said:
Those kind of crappy numbers haven't been on even basic cheap furnaces for 30 plus years

Trouble with those crappy numbers are most installed systems in the US are decades old and are inefficient, no less high efficiency units are not in great demand due to initial expense and costly repairs.

Firebrick43 · Jan 4, 2026

pcmeiners said:
Trouble with those crappy numbers are most installed systems in the US are decades old

we aren't talking about old existing systems are we?

pcmeiners said:
and are inefficient, no less high efficiency units are not in great demand due to initial expense and costly repairs.

The 98 and 99 percent furnaces are for sure, but 95% single stage are the minimum standard. I haven't seen a an 80 percent or less installed in decades on a new build/installation. In 2028 you won't even be able to buy a furnace under 95% efficiency.

kngelv · Jan 4, 2026

I just went through this. Check my thread here: https://www.garagejournal.com/forum...rage-detroit-area.539796/page-3#post-11350109. I would just get a mini-split and leave it around 62 degrees. Going fom 50 to 60 takes longer with a mini-split than gas because of how they heat. I have mine at 64 and it cost me about $45.00 to operate for the past month and it's been quite cold here for December. I want it heated whenever I go out there and I don't like having to pre-plan. I have a Fujitsu but Mitsubishi and Daikin are also top units. Blue Ridge, Mr. Cool and most others are all made by Midea. They are generally less efficient than the big three brands and the savings is not that great on units that work in extremely low temperatures. Also be careful on their ratings. I know Mr. Cools efficiency drops off a cliff when it gets below 20 degrees while mine is stable down to -15. No offense but using propane and dumping all that moisture in there when you would already have a mini-split is a bad idea. I don't think people realize how low the cost is with a good mini-split. Go R-60 in the ceiling for sure. Your stuck at R-15 in the walls if they are 2" x 4" unless you go with spray foam. I have R-23 rockwool in my walls and love it. Good luck.

James

pcmeiners · Jan 4, 2026

Was referring to the present installed base boiler efficiency.....

"The average efficiency of installed residential gas boilers typically ranges from
60% to 85% Annual Fuel Utilization Efficiency (AFUE), depending heavily on the age and type of the unit"

Gas furnaces can not burn gas at 99% or even near it.....the only fuel that is >99% within a residential heater is electric

"Each type of fuel has specific measurable heat content. The maximum amount of heat that can be derived from a fuel is based on using pure oxygen as the oxidizer in the chemical reaction and maximizing the fuel gas mixture. In field practice, the oxygen is derived from the air which is 20.9% oxygen, 78% nitrogen and 1% other gasses. Because the oxygen is not separated from the air prior to combustion, there is a negative effect on the chemical reaction. Air is primarily nitrogen. While nitrogen is inert, and plays no role in the combustion process, it cools the chemical reaction (burning temperature) and lowers the maximum heat content deliverable by the fuel. Therefore, it is impossible to achieve combustion efficiencies above 95% for most fuels, including natural gas, when air is used as the oxidizer in the combustion process"

Good point as to higher efficiency gas boiler/furnaces @95%, so I added a row in the spreadsheet above. Not updating propane.

switchgear12470 · Jan 4, 2026

pcmeiners said:
As to the post link above, unless updated the utility costs are old, the following has updated data as of early 2025, download using the link provided and update the utility costs with your area's costs. Make sure any data you use has all surcharges and taxes included.

As to Blueridge air minisplits, there are mini splits with far better SEER and HSPF and output numbers. You need to research until yo

Eh, I'd like to challenge that; any that are substantially better are going to be significantly more expensive, and gated by HVAC technicians and/or specialty equipment. $5-8k to have a 'premium' model professionally installed whereas I can do it with a Blue Ridge for $2k. I don't care about SEER rating.

The 18k BTU Blueridge Air model I'm looking at is rated for 18k BTU @ 5degF; 12k BTU for -13F. Its HSPF2 Region V rating (8.5) is competitive to a Fujitsu Hyper-Heat (8.7), which is a top of the line model.

ASHP

ashp.neep.org

For Minneapolis, the mini split should be able to output 18k BTU for 95%+ of the winter:

Minneapolis Climate, Weather By Month, Average Temperature (Minnesota, United States) - Weather Spark

In Minneapolis, the summers are warm and wet; the winters are freezing, snowy, and windy; and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 9°F to 83°F and is rarely below -11°F or above 92°F.

weatherspark.com

I'm still researching DIY models but so far this is the best cold weather rating I have found.

Firebrick43 said:
If you make it efficient, seal the garage door, and use green hinges to prevent wind moving the door away from the seals a mini split is a very good solution unless you do high dust hobby like wood working

Woodworking is going to be the primary use of the garage (outside of storing cars). If I go this route I may need to look up a DIY air filter box. I plan to install a dust collection system, but it's still going to be way dustier than a traditional building.

kngelv said:
I just went through this. Check my thread here: https://www.garagejournal.com/forum...rage-detroit-area.539796/page-3#post-11350109. I would just get a mini-split and leave it around 62 degrees. Going fom 50 to 60 takes longer with a mini-split than gas because of how they heat. I have mine at 64 and it cost me about $45.00 to operate for the past month and it's been quite cold here for December. I want it heated whenever I go out there and I don't like having to pre-plan. I have a Fujitsu but Mitsubishi and Daikin are also top units. Blue Ridge, Mr. Cool and most others are all made by Midea. They are generally less efficient than the big three brands and the savings is not that great on units that work in extremely low temperatures. Also be careful on their ratings. I know Mr. Cools efficiency drops off a cliff when it gets below 20 degrees while mine is stable down to -15. No offense but using propane and dumping all that moisture in there when you would already have a mini-split is a bad idea. I don't think people realize how low the cost is with a good mini-split. Go R-60 in the ceiling for sure. Your stuck at R-15 in the walls if they are 2" x 4" unless you go with spray foam. I have R-23 rockwool in my walls and love it. Good luck.

James

Great info! Thank you!

pcmeiners · Jan 5, 2026

AHRI certificate data is supplied to AHRI by the manufacturer by the honor system (it is the fox guards the hen house). AHRI does NOT verify the data; the last I checked AHRI rejected only ONE manufacturers submission out of thousands since it's start . Also there is no specific data required from the manufacturer so they can fudge the data such as in the following Blueridge post... good numbers but not at the rated output....you can not trust manufactures or AHRI certificates.

Compare the 18kBlueridge to the Fujitsu 15k 15LZBH, note the maximum column especially a the low temperatures. The Fujitsu will put out 109% of the maximum heat output of the 15LZBH which is 15,805 BtU at -15° F. The Blueridge maximum is 12200 at-13°F. At 5° the Blue 18k unit outputs 18000 BTUs, Fuzitsu 15k unit puts out 18400BTU

In the link below look at the headings "Max Htg % of Nominal Capacity at..."

https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/pdf-fcus-support-ctlg-626fg2028-2023-10.pdf

AHRI Certification Directory

switchgear12470 said:
"and gated by HVAC technicians and/or specialty equipment. $5-8k to have a 'premium' model professionally installed"

As far as Fujitsu, I have a 608 universal and have (5) of my mini-splits registered, I read another post where Mitsubishi also registered a warranty from a DIY with a 608 cert. My 30x36', standard insulation, 2 door garage is heat/cooled by a 12k low temp Fujitsu split, so far from -7 to 101°, with plenty of heat/cooling at extremely low utility cost. Paid $2000 for my 12k unit, needed to run a dedicated electric line.

"I may need to look up a DIY air filter box"
Correction...... I will need a DIY air filter box

Check your utility company for rebates .

switchgear12470 · Jan 5, 2026

pcmeiners said:
AHRI certificate data is supplied to AHRI by the manufacturer by the honor system (it is the fox guards the hen house). AHRI does NOT verify the data; the last I checked AHRI rejected only ONE manufacturers submission out of thousands since it's start . Also there is no specific data required from the manufacturer so they can fug the data such as in the following Blueridge post... good numbers but not at the rated output....you can not trust manufactures or AHRI certificates.

Compare the 18kBlueridge to the Fujitsu 15k 15LZBH, note the maximum column especially a the low temperatures. The Fujitsu will put out 109% of the maximum heat output of the 15LZBH which is 15,805 BtU at -15° F. The Blueridge maximum is 12200 at-13°F. At 5° the Blue 18k unit outputs 18000 BTUs, Fuzitsu 15k unit puts out 18400BTU

In the link below look at the headings "Max Htg % of Nominal Capacity at..."

https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/pdf-fcus-support-ctlg-626fg2028-2023-10.pdf

AHRI Certification Directory

As far as Fujitsu, I have a 608 universal and have (5) of my mini-splits registered, I read another post where Mitsubishi also registered a warranty from a DIY with a 608 cert. My 30x36', standard insulation, 2 door garage is heat/cooled by a 12k low temp Fujitsu split, so far from -7 to 101°, with plenty of heat/cooling at extremely low utility cost. Paid $2000 for my 12k unit, needed to run a dedicated electric line.

"I may need to look up a DIY air filter box"
Correction...... I will need a DIY air filter box

Check your utility company for rebates .

Huh I was looking at the wrong Fujitsu model somehow.

How did you get a Fujitsu mini split for only $2k? I can only find them for ~$3-4k.

Do you have a guide you used on what tools to purchase and how to evac the line set?

finn · Jan 5, 2026

e-tek said:
Awesome post. I'm considering the same Ina similar situation. Used to heat my old 24x40shop with a HotDawg heater, my new shop is 24x36 and considering mini split. I live in SK Canada, so same or colder as you. Sounds like the new units can handle the extreme cold. I'd go back to a HotDawg NG heater, but the gas meter for hook up is on other aide of house, so 100' away. That'll cost a couple grand to install right there, even if I tench myself. Also, summers are getting hotter, so some cooling sounds good. Great info here, can't wait to hear what you decide to go with.

$2.00/foot for my propane company to run a line from my house to the new sauna, plus the second regulator, which was $50 Or $60.

I don’t know where your $2000 came from. It would be $250 for me, and I don’t understand why NG would be significantly higher.

finn · Jan 5, 2026

kngelv said:
I just went through this. Check my thread here: https://www.garagejournal.com/forum...rage-detroit-area.539796/page-3#post-11350109. I would just get a mini-split and leave it around 62 degrees. Going fom 50 to 60 takes longer with a mini-split than gas because of how they heat. I have mine at 64 and it cost me about $45.00 to operate for the past month and it's been quite cold here for December. I want it heated whenever I go out there and I don't like having to pre-plan. I have a Fujitsu but Mitsubishi and Daikin are also top units. Blue Ridge, Mr. Cool and most others are all made by Midea. They are generally less efficient than the big three brands and the savings is not that great on units that work in extremely low temperatures. Also be careful on their ratings. I know Mr. Cools efficiency drops off a cliff when it gets below 20 degrees while mine is stable down to -15. No offense but using propane and dumping all that moisture in there when you would already have a mini-split is a bad idea. I don't think people realize how low the cost is with a good mini-split. Go R-60 in the ceiling for sure. Your stuck at R-15 in the walls if they are 2" x 4" unless you go with spray foam. I have R-23 rockwool in my walls and love it. Good luck.

James

You jumped the shark with the comment about propane and moisture in your dissertation. A vented hanging propane heater dumps no more moisture to the interior of your garage than a mini split does. The moisture is in the exhaust, which goes out the flue.

The arguements supporting mini splits always gloss over the wide range of local electric rates, and seem to assume everyone lives in an area that has subsidized rates via massive federally funded hydroelectric projects. That’s simply not a valid assumption for some of us.

Notgrownup · Jan 5, 2026

My blueridge 18000 Btu has been running 24/7 for the last 10 years.I leave it on 62 on heat and on 81 on cool in the summer. Different region . I use it as a dedicated woodworking shop. I clean my screen on the unit regularly and I run a simple fan filter box.

loganb · Jan 5, 2026

I've got the DIY Mr. Cool in an attached 3 car garage in Omaha NE and it's not a blip on the monthly bill and it stays in upper 60's during the winter. If it gets below around 15 degrees it will start to go into Defrost mode and below about 5 degrees it doesn't work at all but this isn't a "hyperheat" type unit with the lower cold weather operation rating. If I was putting it in a detached structure farther north I might plan out a backup plan for heat(likely 240v electric) so I had it ready to go in a long cold snap but otherwise it's been great. Cleaning of the filter/head unit I do maybe 2x a year....rinse out the coils on the exterior a couple times a year....that's it.

I'd have no problems installing it and setting it at a comfortable for me 65 and seeing how it does for the first month then adjusting from there.

pcmeiners · Jan 5, 2026

switchgear12470 said:
How did you get a Fujitsu mini split for only $2k? I can only find them for ~$3-4k.

Do you have a guide you used on what tools to purchase and how to evac the line set?

All my split were purchased from Got Ductless, all are single zone low temp models (1) is a 9k model, have(2) 12k wall mounts, (2) are 12k floor model (like indented radiator), all purchased between late 2023 and early 2024. Good company, was sent (3) units missing an WIFI based module due to Fujitsu's mistake, Got Ductless sent out the modules within days, no questions asked. The 9k is a bit loud , the floor units are quieter but a little less efficient . Have not heard any new Mitsubishi splits lately, they may be quieter than Fujitsu.

As to needed tools and procedures read past posts, this has been cover many times. IF you follow the procedures as recommended it is not difficult but critical you do not cut corners.

pembol · Jan 5, 2026

pcmeiners said:
AHRI certificate data is supplied to AHRI by the manufacturer by the honor system (it is the fox guards the hen house). AHRI does NOT verify the data; the last I checked AHRI rejected only ONE manufacturers submission out of thousands since it's start . Also there is no specific data required from the manufacturer so they can fudge the data such as in the following Blueridge post... good numbers but not at the rated output....you can not trust manufactures or AHRI certificates.

Compare the 18kBlueridge to the Fujitsu 15k 15LZBH, note the maximum column especially a the low temperatures. The Fujitsu will put out 109% of the maximum heat output of the 15LZBH which is 15,805 BtU at -15° F. The Blueridge maximum is 12200 at-13°F. At 5° the Blue 18k unit outputs 18000 BTUs, Fuzitsu 15k unit puts out 18400BTU

In the link below look at the headings "Max Htg % of Nominal Capacity at..."

https://www.fujitsugeneral.com/us/resources/pdf/support/downloads/pdf-fcus-support-ctlg-626fg2028-2023-10.pdf

AHRI Certification Directory

As far as Fujitsu, I have a 608 universal and have (5) of my mini-splits registered, I read another post where Mitsubishi also registered a warranty from a DIY with a 608 cert. My 30x36', standard insulation, 2 door garage is heat/cooled by a 12k low temp Fujitsu split, so far from -7 to 101°, with plenty of heat/cooling at extremely low utility cost. Paid $2000 for my 12k unit, needed to run a dedicated electric line.

"I may need to look up a DIY air filter box"
Correction...... I will need a DIY air filter box

Check your utility company for rebates .

The current Midea and previous Gree units sold as 'Blueridge' efficiency is comparable to the Fujitsu/Daiken/Mitsu. I have the Gree Saphire version from 2024, and at the time, it was about as good as you could get for a 24k unit, and significantly cheaper than the main stream options. The current Midea 18k unit, the XS6 series, has some amazing specs - HSPF2 (IV) of 16.

I have only had it installed for a few months, but it has been working well and been great on energy usage. If I were a pro, would I go with Blueridge? Probably not as Mistsu etc are better supported and likely higher quality. As a DIYer they are a reasonable option and are cheaper and easier for the DIYer.

You have brought up your concerns about AHRI/NEEP specs many times - do you have a better option for comparing specs? According to AHRI, the equipment specs need to be provided by an independent certified lab, not he equipment manufacturer.

theoldwizard1 · Jan 5, 2026

OP - Excellent summary ! Glad to see you have done your homework !!!

switchgear12470 said:
Have to upsize subfeed conductor to garage to account for additional continuous load

Electricity is expensive

What size are the conductor going to the garage now ? Distance ?

Nat Gas isn't cheap either. You have to understand the thermodynamics of heat pumps. In the long run, YOU WILL SAVE MONEY !

theoldwizard1 · Jan 5, 2026

switchgear12470 said:
Huh I was looking at the wrong Fujitsu model somehow.

How did you get a Fujitsu mini split for only $2k? I can only find them for ~$3-4k.

True. Selecting the correct model for your application is not easy !

switchgear12470 said:
... how to evac the line set?

YouTube ! Dozens of examples. Biggest issue is flaring the line set and checking for leaks.

You might be better to find an HVAC tech who will evacuate, check to leaks and fill.

fitter30 · Jan 5, 2026

Lp 91,500 btu per gallon X efficiency of furnace. 80% = 73,200 btu
Air is easy to heat compared to mass. Cars and tools and structure.
Walk into a cold garage a hp will take hours to take the chill off. Furnace a lot faster. Hp will have less btu's for heating a building fast verses all the time and loses btu's the colder it is outside.

pcmeiners · Jan 5, 2026

pembol said:
According to AHRI, the equipment specs need to be provided by an independent certified lab, not he equipment manufacturer.

Like II said, it is the honor system. The manufacturers get to pick the lab (they get to pick the Fox who guards the hens). Have read many certs, and many provide data which can not be possible, ******** .
Then you have to wonder why a manufacturer would not cite who the independent lab they used is in the certificate; all scientific studies have to cite sources or there is no credibility. Technically there is no mandate to use a lab certified to perform certificate validation, so ANYONE can state they are an independent lab, your mother, brother or your next door neighbor can run an "independent lab".

As to Fujitsu and Mitsubishi, when I researched for my purchase I found an extensive government paper testing of both which verified the data they published at the time I purchased.

There is no better option other than spending a lot of time researching, it is a shame there is no government agency which maintains the integrity of the HVAC industry thank in part to the lobbyists.

WildBill · Jan 5, 2026

Bert_ said:
The minimum setpoint on minisplits has always been a major disappointment for me. I wouldn't want it 62* when working in there let alone to leave it there all the time.

Another consideration with a minisplit is cleaning. The heads are not very fun to try to keep dirt and dust out of

Do you have one? Its kinda a non issue, they are so cheap to run it makes sense just to leave them at 62F or whatever their normal low setting is. If you really want to make it lower most have a freeze prevention or some other name deal where you can set it lower. I can set my Mr.Cool to turn on at 40F and off at 45F if I want, but its only a couple dollars more a month to leave it at 62F, and I'm not warming it up 4 times a week when I go out there to work.

I guess if you like working in 40F you could use the freeze prevention mode all the time.

Cleaning it is not terrible, takes 20 mins twice a year. Worth it for the inexpensive dead silent cooling and heating.

Bert_ · Jan 5, 2026

WildBill said:
Do you have one? Its kinda a non issue, they are so cheap to run it makes sense just to leave them at 62F or whatever their normal low setting is. If you really want to make it lower most have a freeze prevention or some other name deal where you can set it lower. I can set my Mr.Cool to turn on at 40F and off at 45F if I want, but its only a couple dollars more a month to leave it at 62F, and I'm not warming it up 4 times a week when I go out there to work.

I guess if you like working in 40F you could use the freeze prevention mode all the time.

Cleaning it is not terrible, takes 20 mins twice a year. Worth it for the inexpensive dead silent cooling and heating.

I like about 55* to work in. 62-64 is what I set the house at. These are just comfortable temperatures.

I've installed several mini splits and been around many more. When they are working they are awesome. But you better just plan to replace it in 12 years.

I have one I put in the kitchen/living area where some workers from south of the border stay. That thing is absolutely disgusting. It has a washable filter but you can only get it clean about once or twice then I just order a new one. Most garages aren't exactly a clean environment.

pembol · Jan 5, 2026

pcmeiners said:
Like II said, it is the honor system. The manufacturers get to pick the lab (they get to pick the Fox who guards the hens). Have read many certs, and many provide data which can not be possible, ******** .

As to Fujitsu and Mitsubishi, when I researched for my purchase I found an extensive government paper testing of both which verified the data they published at the time I purchased.

There is no better option other than spending a lot of time researching, it is a shame there is no government agency which maintains the integrity of the HVAC industry thank in part to the lobbyists.

I would be very interested to see 'government paper testing' of heat pumps. As far as I know, the testing for government programs like Energy Star is also conducted by third party labs, hired by the manufacturers, or is based on the AHRI testing.

Again, I am not saying all the data from AHRI, NEEP or EnergyStar is always 100% accurate, but it is the best resource we have to compare these. I am also not seeing any evidence of widespread fraud in these tests. AHRI claims they independently test a random sample of listed products to make sure there is not widespread fraud.

switchgear12470 · Jan 5, 2026

OK after y'alls discussion and some thoughts I'm leaning towards gas now:

I'm going to be doing lots of wood working, so I will have to stay on top of a mini split filter
I'm concerned about the recovery time of a mini split in the dead of winter. If I open the garage door for a few minutes to unload supplies, it's going **** the heat out and it will take time for the minisplit to get the room back up
I'll be able to maintain a more reasonable temp in the winter (50-55) with a gas heater, anything above that is wasteful to me
I called the city code department and they said there was no minimum spacing between electrical and gas in a trench, so I wouldn't need to dig a separate trench for gas
Gas allows me to use a smaller feeder cable since it reduces ~15A of continuous load I need to account for

HOWEVER, in my city there is no homeowner exemption for DIYing gas lines or gas heating appliances. In order for it to be permitted and inspected, it HAS to be done by a licensed individual. I'm thinking I will just dig a trench and pay a plumber to run a line out to the garage. I'll install the heater later at my own convenience.

I'm eyeing the 30k BTU heat dawg at the moment.

Jagmandave · Jan 5, 2026

For a unit that needs to run all the time, I think a Mini-Split is the answer for your use, other than having to upsize the electrical feed to the shop it should be pretty much a DIY install. Electricity would be the preferred way, no combustion to worry about if you're using chemicals and so on. Keeping the cars warm in winter is a real benefit too!

Just get the best one that fits your budget.

Edit: Just read your update about wood working in the shop - is that a consideration when using an open flame heater? Dust in the air I mean?

pembol · Jan 5, 2026

switchgear12470 said:
OK after y'alls discussion and some thoughts I'm leaning towards gas now:

I'm going to be doing lots of wood working, so I will have to stay on top of a mini split filter

I'm concerned about the recovery time of a mini split in the dead of winter. If I open the garage door for a few minutes to unload supplies, it's going **** the heat out and it will take time for the minisplit to get the room back up

I'll be able to maintain a more reasonable temp in the winter (50-55) with a gas heater, anything above that is wasteful to me

I called the city code department and they said there was no minimum spacing between electrical and gas in a trench, so I wouldn't need to dig a separate trench for gas

Gas allows me to use a smaller feeder cable since it reduces ~15A of continuous load I need to account for

HOWEVER, in my city there is no homeowner exemption for DIYing gas lines or gas heating appliances. In order for it to be permitted and inspected, it HAS to be done by a licensed individual. I'm thinking I will just dig a trench and pay a plumber to run a line out to the garage. I'll install the heater later at my own convenience.

I'm eyeing the 30k BTU heat dawg at the moment.

Many minisplits have a 'do not freeze' setting, which on mine holds the temp at 46F, which is about perfect. It takes < 1 hour to get back up to 62F for actually working out there. What size service do you have at the moment? As long as it is 240V, you may not need to upsize for the minisplit - my 24k unit needed a 25A 240v circuit, some of the 18k units may only need a 20a 240v circuit.

switchgear12470 · Jan 5, 2026

Jagmandave said:
Edit: Just read your update about wood working in the shop - is that a consideration when using an open flame heater? Dust in the air I mean?

It is a consideration- it will incinerate the airborne dust

In all seriousness, I would go with a sealed combustion unit, so it's not a concern.

pembol said:
Many minisplits have a 'do not freeze' setting, which on mine holds the temp at 46F, which is about perfect. It takes < 1 hour to get back up to 62F for actually working out there. What size service do you have at the moment? As long as it is 240V, you may not need to upsize for the minisplit - my 24k unit needed a 25A 240v circuit, some of the 18k units may only need a 20a 240v circuit.

It seems like the freeze protection mode's temp varies by model, but that is an option.

It is currently fed by a single 120V 15A circuit, which is not enough for... well, anything, except a few outlets, a light and the garage door opener. Regardless of the option I go with, I'm putting in a subpanel.

ericm · Jan 5, 2026

I left a 12x12 door open for a couple hours when I was moving tractor implements into the shop last month. The mini splits had it back up to temp in half an hour and they weren't even blowing hard. Two 24k btu Mitsubushi units for 2240 sq ft. They did much better than I expected.

theoldwizard1 · Jan 5, 2026

fitter30 said:
Lp 91,500 btu per gallon X efficiency of furnace. 80% = 73,200 btu
Air is easy to heat compared to mass. Cars and tools and structure.
Walk into a cold garage a hp will take hours to take the chill off. Furnace a lot faster. Hp will have less btu's for heating a building fast verses all the time and loses btu's the colder it is outside.

theoldwizard1 said:
You have to understand the thermodynamics of heat pumps. In the long run, YOU WILL SAVE MONEY !

A heat pump just moves "heat" (energy) from one place to another. I know, it is hard to comprehend that there is "heat" in outside air when the thermometer says -10F, but there is !

theoldwizard1 · Jan 5, 2026

switchgear12470 said:
Eh, I'd like to challenge that; any that are substantially better are going to be significantly more expensive, and gated by HVAC technicians and/or specialty equipment. $5-8k to have a 'premium' model professionally installed whereas I can do it with a Blue Ridge for $2k. I don't care about SEER rating.

You should care about SEER ! It directly affects your electric bill !

The issue is, how many additional years will a higher SEER/more expensive model take to "pay back". Difficult to calculate !

theoldwizard1 · Jan 5, 2026

switchgear12470 said:
I'm eyeing the 30k BTU heat dawg at the moment.

Any "open flame" (not vented) LP/Nat Gas releases both CO and H2O ! Run a "not dog" for a long time and you will be dripping !

If you decide to go gas, at least get a vented wall mount furnace.

theoldwizard1 · Jan 5, 2026

switchgear12470 said:
If I decide I'm going to spend a Saturday afternoon on my arts & crafts,
.
.
.
I don't really care about cooling capacity

Easy to say now ! Even in northern MI, 80+F and high humidity will make you wish you had bought the mini-split.

IT WILL SAVE YOU MONEY IN THE LONG RUN !

switchgear12470 · Jan 6, 2026

theoldwizard1 said:
Easy to say now ! Even in northern MI, 80+F and high humidity will make you wish you had bought the mini-split.

IT WILL SAVE YOU MONEY IN THE LONG RUN !

I'm originally from Michigan,
but have lived in Kentucky for the last 13 years. I can confidently say I don't need the mini split for cooling!

Zone 6/Minnesota - minisplit vs natural gas for maintaining ~50F in winter?

Member

Well-known member

Well-known member

Well-known member

Well-known member

Attachments

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Member

Well-known member

Member

Well-known member

Well-known member

Well-known member

ALLIANCE MEMBER

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

ALLIANCE MEMBER

Well-known member

Well-known member

Member

Well-known member

Well-known member

Member

Well-known member

Well-known member

Well-known member

Well-known member

Well-known member

Member