Recommendations on heating this garage

[JDL988]

I have a pretty well Insulated 1120sqft garage built in 2016 which is all open floor, 2 windows and 2 insulated over head doors, I work out of the shop full time year round. Since it was built I have been using a 120000btu 81% afue Baird hot air oil furnace which is set up about center of the wall blowing straight to the other end of the garage. I know this furnace is oversized but I got it for free. I keep the furnace set to 67 degrees all winter long and on average I would burn under 400 gallon of off road.

To make a long story short I am faced with putting up a new chimney (selkirk stainless) and I am looking at $1800 to do so. I have been wanting to put AC in as I had to clear some land next to the shop and I don't get the shade anymore and the humidity starts to creep in, we get some long humid stretches here in NE Vermont. I have a engine machine shop and the humidity is a real enemy. I was thinking going with a propane furnace with evap coil. Or possibly a mini split but worry about electric bill sky rocketing.

From generic calculations online and being in northeast VT it looks like I would roughly need a 60000-80000btu propane furnace depending on which AFUE and 1.5 ton AC system. I have been doing as much research as possible in my spare time such as brands, AFUE percentages and the pros and cons of those percentages such as venting/intake, serviceability and what the difference will be in cost in gallons of propane VS what I have been going through in oil, and I understand oil has a higher btu per gallon than propane. Any input/recommendations would be appreciated. Thank you

 

[Mikes61]

I have a 1550 sq ft garage and I just installed a 3 ton minisplit. It’s been great and is sized right for my garage. I’m in So. Cal. so I don’t get the extreme temps like in other parts of the country.

Where are you located?

 

[JDL988]

I have a 1550 sq ft garage and I just installed a 3 ton minisplit. It’s been great and is sized right for my garage. I’m in So. Cal. so I don’t get the extreme temps like in other parts of the country.

Where are you located?

In northeast Vermont.. Temps here swing wildly especially in recent years. Could be -15 for a week and next week it could be high 30's and rain.

 

[mm08822]

Sounds like you are on the right track especially with realizing that any new furnace would be significantly smaller when purchased for your needs.

Go online and find fuel cost calculators. This spreadsheet lets you input various local fuel types, their respective local costs, btu content. With that you can further assign efficiencies to each type of furnace.

This will give you an annual estimate of the different fuel choices/furnace types independent of setpoint and degree days. Even that can be added.

It does not include things like initial venting requirements and maintenance. Initial heating/cooling equipment costs can obviously be found on the net (at least for DIY projects).

You could run this equation for each type of furnace/fuel and see where you net out in 5, 10, 15 years. Ease of use/maintenance/reliability is a big factor beyond the initial outlay:

Cost = Furnace equipment + Venting/ducting/utility provisions + annual fuel cost*(X years) + annual maintenance + misc.

 

[pcmeiners]

OP please read as many posts in this sub sub forum as you can before you get nauseous, the answer to your question has been answered multiple multiple times.

My garage is 1080squ ft, average insulation, I have a Fujitsu 12k low temperature mini-splits to heat/ cool, I have a second one which has never been turned on . So far I have hit -7° to 101° F, no problem with heat or cooling. As to electric cost, my units have a COP of 4.05 so $.25 ( average Vermont KW cost) divided by 4.05=$.06 per KW. So it costing 6 cent per KW equivalent. Runs approx. 15-$20 a month for heat/cooling running 24/7.Look at propane costs compared to an efficient mini-split cost to run, basically double the cost.

Below I edited this spreadsheet with the average Vermont electric KW cost. The only important numbers are your utility cost and the price per million BTUs.

 

[mm08822]

OP please read as many posts in this sub sub forum as you can before you get nauseous, the answer to your question has been answered multiple multiple times.

My garage is 1080squ ft, average insulation, I have a Fujitsu 12k low temperature mini-splits to heat/ cool, I have a second one which has never been turned on . So far I have hit -7° to 101° F, no problem with heat or cooling. As to electric cost, my units have a COP of 4.05 so $.25 ( average Vermont KW cost) divided by 4.05=$.06 per KW. So it costing 6 cent per KW equivalent. Runs approx. 15-$20 a month for heat/cooling running 24/7.Look at propane costs compared to an efficient mini-split cost to run, basically double the cost.

Below I edited this spreadsheet with the average Vermont electric KW cost. The only important numbers are your utility cost and the price per million BTUs.

Yup, that was the spreadsheet I was hoping the OP would find.

 

[kngelv]

I have an 18K Fujitsu that is kept at 64 degrees. My garage is very well insulated and just over half the size of yours with a 12' ceiling. It's only been up for two months but costs are minimal. It looks like it cost me about $20.00 for the first month. Outside temps were in high teens to low 30's for the most part. Large garage door was opened a 1/2 dozen times which obviously lets a lot of heat out. Very happy so far. Still stunned by how quiet it is.

James

 

[Mikes61]

In northeast Vermont.. Temps here swing wildly especially in recent years. Could be -15 for a week and next week it could be high 30's and rain.

Like the others have posted, get a quality, low temp, Fujitsu minisplit, probably 18k-24k and you will be good.
My buddy and I installed mine and we didn’t get one of the flares just right. It leaked and I had to pay my HVAC friend to come over and redo that flare, evacuate the system, then refill it with new 454b. It’s been great ever since.

I put it in AUTO mode and it adjusts the fan speed and temp. output to match the temp. that you want. No messing with it, it’s really convenient.

 

[JDL988]

OP please read as many posts in this sub sub forum as you can before you get nauseous, the answer to your question has been answered multiple multiple times.

My garage is 1080squ ft, average insulation, I have a Fujitsu 12k low temperature mini-splits to heat/ cool, I have a second one which has never been turned on . So far I have hit -7° to 101° F, no problem with heat or cooling. As to electric cost, my units have a COP of 4.05 so $.25 ( average Vermont KW cost) divided by 4.05=$.06 per KW. So it costing 6 cent per KW equivalent. Runs approx. 15-$20 a month for heat/cooling running 24/7.Look at propane costs compared to an efficient mini-split cost to run, basically double the cost.

Below I edited this spreadsheet with the average Vermont electric KW cost. The only important numbers are your utility cost and the price per million BTUs.

Thanks for that spread sheet. Definitely helps.

 

[JDL988]

https://hvacdirect.com/24-000-btu-21-5-seer-aciq-extreme-series-single-zone-wall-mount-mini-split-system-wifi-enabled-r454b-id198578.html

What do you guys think of this unit?

 

[pcmeiners]

What do you guys think of this unit?

Price is good, warranty length is above average, how useful is a warranty is debatable . The ACIQ AHRI certificate has no real data to compare to other minisplits, who knows if the data is real, example below. All accessories are over priced (which is a common retail practice) , your better off buying accessories elsewhere. It appears the lower tier minisplits are catching up ( as to efficiency) with the more expensive top tier brands.

Compare ACIQ 24k certificate with sparse data below with a Fujitsu with useful data.
Formatting in the original certificates is lost in the copy/paste.

Example of ACIQ 24k minisplit certificate................

AHRI Certified Reference Number : 216032341
Model Status : Active
Old AHRI Reference Number :
Date : 03-17-2025
AHRI Type : HRCU-A-CB-O (Mini-Split Heat Pump, with Remote Outdoor Unit Air-Source, Free Delivery)
Series Name : ACIQ Series
Indoor Type : Mini-Splits (Non-Ducted)
Rated as followed in accordance with the latest edition of AHRI 211/241-0B/1B-2021 (SI), Performance Rating of Unitary Air-Conditioning & Air-Source Heat Pump Equipment and subject to rating accuracy by AHRI-sponsored, independent, third party testing: :
Indoor Model Number(s) : ACIQ-24CC-HH-MC
†"Active" Model Status are those that an AHRI Certification Program Participant is currently producing AND selling or offering for sale; OR new models that are being marketed but are not yet being produced.“Production Stopped” Model Status are those that an AHRI Certification Program Participant is no longer producing BUT is still selling or offering for sale. :
Ratings that are accompanied by WAS indicate an involuntary re-rate. The new published rating is shown along with the previous (i.e. WAS) rating. :
Rated as follows in accordance with the latest edition of AHRI 210/240 - 2017 with Addendum 1, Performance Rating of Unitary Air-Conditioning & Air-Source Heat Pump Equipment and subject to rating accuracy by AHRI-sponsored, independent, third party testing: :
Cooling Capacity (A2) - Single or High Stage (95F), btuh :
SEER :
EER (A2) - Single or High Stage (95F) :
Heating Capacity (H12) - Single or High Stage (47F) :
HSPF (Region IV) :
Rated as follows in accordance with the latest edition of AHRI 210/240 – 2024, Performance Rating of Unitary Air-Conditioning & Air-Source Heat Pump Equipment and subject to rating accuracy by AHRI-sponsored, independent, third party testing: :
Cooling Capacity (AFull) – Single or High Stage (95F), btuh : 23400
SEER2 : 20.70
EER2 (AFull) – Single or High Stage (95F) : 12.00
Heating Capacity (H1Full) – Single or High Stage (47F), btuh : 25000
HSPF2 (Region IV) : 11.60
Cooling Capacity :
EER :
Heating Capacity :
COP :
Sold in? : USA, Canada
CurrentYear : 2025

Below is a Fujitsu certificate with useful data, formatting from the original certificate did not copy over................................

FUJITSU H-Series
Central Air Conditioning Heat Pump (HP)
Singlezone Non-Ducted, Wall Placement
AHRI Cert #: 204740066
Outdoor Unit Model #: AOUG09LZAS1
Indoor Model #: ASUG09LZAS
Maximum Heating Capacity (Btu/h) @5℉: 15,400
Rated Heating Capacity (Btu/h) @47℉: 12,000
Rated Cooling Capacity (Btu/h) @95℉: 9,000
Advanced Data -
Sizing for Heating
Information Tables
Brand FUJITSU
Series H-Series
Ducting Configuration Singlezone Non-
Ducted, Wall Placement
AHRI Certificate # 204740066
Outdoor Unit Model # AOUG09LZAS1
Indoor Model # ASUG09LZAS
Indoor Unit Type Mini-Splits
Furnace Model #
EER 18
SEER 33.1
HSPF (Region IV) 14.2
EER2 18
SEER2 33.1
HSPF2 (Region IV) 13.4
HSPF2 (Region V) 11
ENERGY STAR V6.1
ENERGY STAR V6.1 Cold
Climate
ENERGY STAR V5.0
Capacity Maintenance
(Rated 17°F/Rated 47°F)
61%
Capacity Maintenance
(Rated 5°F/Rated 47°F)
128%
Capacity Maintenance
(Max 5°F/Rated 47°F)
128%
Variable Capacity
Integration
Connectivity
Operational Diagnostics
Refrigerant R410A
Sold In USA, Canada
Performance Specs
Heating /
Cooling
Outdoor
Dry Bulb
Indoor
Dry Bulb Unit Min Rated Max
Cooling 95℉ 80℉ Btu/h 3,100 9,000 12,000
kW 0.11 0.5 0.85
COP 8.26 5.28 4.14
Cooling 82℉ 80℉ Btu/h 3,150 - 13,500
kW 0.09 - 0.73
COP 10.26 - 5.42
Heating 47℉ 70℉ Btu/h 3,100 12,000 22,000
kW 0.17 0.66 1.93
COP 5.34 5.33 3.34
Heating 17℉ 70℉ Btu/h 5,200 7,400 16,000
kW 0.42 0.6 2.06
COP 3.63 3.61 2.28
Heating 5℉ 70℉ Btu/h 4,000 15,400 15,400
kW 0.4 2.1 2.1
COP 2.93 2.15 2.15
Heating -6℉ 70℉ Btu/h 3,100 - 14,000
kW 0.38 - 2.09
COP 2.39 - 1.96
Btu/h)
Heating/Cooling Capacity Graph
20k
25k
ASHP https://ashp.neep.org/#!/product/30807/7/25000///0
1 of 2 6/8/2023, 10:40 AM
Outdoor Temperature (°F)
Heating Max. Cap. Cooling Max. Cap. Heating Rated Cap.
Cooling Rated Cap. Heating Min. Cap. Cooling Min. Cap.
-6 5 17 47 82 95
0
5k
10k
15k
Highcharts.com
Pan Heater
Type N/A
Input Power (W)
Operation
Additional Heat Pump Images
Related Products
ASHP https:/

"Thanks for that spread sheet. Definitely helps."

I wish Maine would update the spreadsheet ocassionaly. This spreadsheet is one of the most useful and understandable fuel cost comparisons.