Heating advice for below-grade garage

[permag]

I have a 900 sqft shop with 9 foot ceilings that is below grade. It is essentially a walkout (drive out) basement below my upper garage (floating concrete slab). All four walls are concrete along with the ceiling. Two walls of the garage are against compacted earth. The garage door is well-insulated. I live at 5600 ft in the Utah mountains and temps stay below freezing for months at a time. We would like to keep the garage at 55-60. It seems to naturally stay about 36F inside even when -10F outside.

I am setting this shop up for daily use in my fabrication business. Should I go to the expense of insulating and sheet rocking the walls if the ceiling remains concrete with unheated garage above it? I can't do anything on the ceiling as I need the full 9Ft of height.

During construction, I ran a gas line, along with 110 and 220v to the garage. I also had a vent hole bored in the concrete wall for exterior venting should we need it.

What heater would your recommend that won't break the bank to install and operate? Should we even consider 220v electric? If NG, should we spend the money on external venting?

Thanks for your advice!!

 

[theoldwizard1]

IWe would like to keep the garage at 55-60. It seems to naturally stay about 36F inside even when -10F outside.

There is your answer. The earth around the sides is an "infinite" heat sink. Without some SERIOUS insulation, all you will be doing is heating the ground. Heat rises so the garage above will be within a few degrees if you don't insulate the ceiling. Insulated garage doors leak air terribly and you will know it when the temp is below 0F !

Should we even consider 220v electric? If NG, should we spend the money on external venting?

Electric resistance heating is the cheapest to install and the most expensive to operate (unless you have a HUGE solar array and massive amounts of batteries). Any non-vented LP of NG heater will leave huge amounts of moisture inside and possibly carbon monoxide.

There is nor "cheap" solution unless you have access to FREE firewood.

 

[signcrafter]

There is your answer. The earth around the sides is an "infinite" heat sink. Without some SERIOUS insulation, all you will be doing is heating the ground. Heat rises so the garage above will be within a few degrees if you don't insulate the ceiling. Insulated garage doors leak air terribly and you will know it when the temp is below 0F !

My shop is built into a hill on two sides. Even when below zero the shop is still above freezing. Even with two garage doors. I have a natural gas heater and it takes very little time to bring the whole garage up to a good temp of 60-70 degrees. The walls built into the hill have zero insulation, just poured concrete against dirt on the outside.

 

[PWC Repair]

I think I would do the walls as you stated, and maybe glue some 1" foilback foam to the ceiling for thermal reflection and a bit of insulation. You can surely stand to lose 1". Tape the seams. Should have no problems heating to 60* with a 5k 220v shop heater. You can get one new for $100.

 

[permag]

Thanks, everyone for all for the advice. It sounds like it may be worth the investment to frame, insulate, and sheetrock the space.

Regarding solar, we actually are a net-zero, running 100% on Solar power and geothermal heatpumps (13KW of panels). We have a natural gas connection primarily as a backup and for cooking.

We get a check back each year from the power company for the power we feed them, so it's still $$ out-of-pocket to heat a garage with electricity.

I didn't think a 5kw heater would be able to heat that much space, but it sounds like its worth a try if they're that inexpensive.

Any recommendations on a 5KW? I keep getting ads for NewAir for around 250. Somebody locally is selling a new/unused Reznor 5KW for $150.

Thanks again!

 

[permag]

My shop is built into a hill on two sides. Even when below zero the shop is still above freezing. Even with two garage doors. I have a natural gas heater and it takes very little time to bring the whole garage up to a good temp of 60-70 degrees. The walls built into the hill have zero insulation, just poured concrete against dirt on the outside.

That's a good proxy for our situation. Thanks for the feedback!!

 

[permag]

I think I would do the walls as you stated, and maybe glue some 1" foilback foam to the ceiling for thermal reflection and a bit of insulation. You can surely stand to lose 1". Tape the seams. Should have no problems heating to 60* with a 5k 220v shop heater. You can get one new for $100.

Great idea with the reflective foil-back foam. We could definitely do something along those lines. Thank you.

 

[Jackfre]

Look at a Rinnai EX-22. The vent, the through the wall portion, comes with the heater. You can buy extension vent kits to run from the heater up the wall to the termination. Simple install and will be great in your space.

 

[PWC Repair]

https://www.northerntool.com/shop/tools/product_200578579_200578579

On sale $100.

The farm supply stores like Orscheln and Rural King also usually have one for $100.

 

[theoldwizard1]

https://www.northerntool.com/shop/tools/product_200578579_200578579

On sale $100.

The farm supply stores like Orscheln and Rural King also usually have one for $100.

What part of the following do you not understand

Electric resistance heating is the cheapest to install and the most expensive to operate

The isn't an occasional usage. This is for "daily usage".

 

[yeldogt]

Actually -- you may find that adding a lot of insulation will not provide huge returns.

Your building is maintaining above freezing temps .. because leakage and the delta to the earth is lower vs the outside.

Block or poured foundations don't leak air -- seal up any leaks around the doors.

What's your electric rate ? Do you have any electric heaters available to test the load -- I can heat 1700 sf w/ 4000W .. well insulated in PA. My NYC garage is block .. framing would cost me too much space.

Placing a few heaters in the space and seeing how they do will give you an idea of need -- with NG .. that's going to be cheaper to run.

A cabinet heater with with outside combustion would be ideal .... where is the hole for the vent? More $$ vs a hanging -- but they can be bought that modulate .. and the heat is down low where you want it.

You can always buy an electric 4-5k unit and use it With the properly sized NG.

Most people buy too big a heater ... a NG sized for maintaining the load would be great w/ a supplemental electric. I did this in my old place with propane when I woudl leave for an extended time .... the heater was sized for maintaining a temp. It would get my studio from mid 50's to 70 in a few hours ... but if I arrived at the house and wanted to do something that night ... I would turn up the propane and flip on the electric. The electric was down low and would send nice hot air my way.


The ability of any heater to warm a cold space has much to do with the amount of things in the shop -- lots of metal .. tools ... takes a while to heat regardless of heater size.


You don't want to use a ventless gas heater -- they will throw a lot of water vapor into he room as well as combustion gasses. Most hanging heaters use air in the shop for combustion ... the bigger the heater the more you are sucking that heated air out of the building. Everything going up the flue had to come from the building ... creates negative pressure.

A sealed combustion is the way to go .... pay for the correct product once. Better comfort .. lower operating costs.

I would get an electric and test it out -- for $100 and some wire and plug.

 

[u3b3rg33k]

Thanks, everyone for all for the advice. It sounds like it may be worth the investment to frame, insulate, and sheetrock the space.

Regarding solar, we actually are a net-zero, running 100% on Solar power and geothermal heatpumps (13KW of panels). We have a natural gas connection primarily as a backup and for cooking.

We get a check back each year from the power company for the power we feed them, so it's still $$ out-of-pocket to heat a garage with electricity.

I didn't think a 5kw heater would be able to heat that much space, but it sounds like its worth a try if they're that inexpensive.

Any recommendations on a 5KW? I keep getting ads for NewAir for around 250. Somebody locally is selling a new/unused Reznor 5KW for $150.

Thanks again!

Since you have solar, and assuming you want to keep the garage a little warmer, it might be worth considering a low temp heat pump/mini-split. it'll cost more than a resistive heater install, but long run it'll be far more economical with respect to total cost of ownership.

Actually, if you have Water-to-Water heat pumps, have you considered a fancoil or baseboard for the garage?

 

[Falcon67]

I use this 5 kW Dayton unit

It pulls right at 21A on 240VAC and does pretty well in heating the larger 684 sq/ft area of my shop, and excellent in the 288 sq/ft work room. However, I'm not at 8500' in the mountains, I'm at 1800' in open west Texas where it may freeze for a few nights then it'll be 85 F in January and I'll mow the yard. The R-13 in the walls and ceiling are plenty for around here.

 

[Showkey]

There is your answer. The earth around the sides is an "infinite" heat sink. Without some SERIOUS insulation, all you will be doing is heating the ground. Heat rises so the garage above will be within a few degrees if you don't insulate the ceiling. Insulated garage doors leak air terribly and you will know it when the temp is below 0F !
.

No difference than any basement in the Midwest or the east coast........yes insulation reduces cost, but far less important than a building above ground which will lose heat more quickly.

Earth berm building use to be very popular.

 

[TractorJeff]

As he is NET ZERO!
Then first I would think about the Hot Water system. Next I would look at how much the Utility is paying back each year to consider going Electric.