Heating a detached garage in Maine

[Ralbert]

Hi All -

Have been browsing this thread for months as I've been building a new 28x36 3-car two-story detached garage in Central Maine. Even with all I have read, I'd still like to get your opinions on what I could do to heat my garage to at least 50 degrees in the winter time, when it can be -20, -30 outside and very windy...

Here is some pertinent information:
Possible Heat Sources: Electric, Propane, Pellet (Putting in a hot water system would be difficult as I do not have running water to the garage yet and am not sure how difficult that will be...) (It's about 400ft away from a water source).

The ceiling height is 10' and I did not put tubing in the floor (I'm regretting that now)... The Garage Doors are insulated well - R19... The Ceiling, walls, etc are all blown-in closed-cell foam.(6+" most places) I worry about moisture from the vehicles in the winter and possible mold? I do have a floor drain in the center.

I've been going back and forth on a Mr. Heater or Modine Hot Dawg, Maybe 45k BTU? I don't think a heat pump would work very well with the very cold winters, operating well below the 5 degree efficiency threshold...

Please let me know your thoughts and/or other options I may have to consider. Really looking for efficiency and little maintenance. Thank you!!

 

[Ralbert]

I failed to mention that my floor is 6" concrete with 2" foam board underneath and a layer of thick poly over that.

 

[rob in nh]

i have a 60'000 btu hot dawg in a 24x 32 w/10 ceilings. it heats it up quickly and its quiet. it has a wood sliding door but plan on an insulated door so it should make it even easier to heat.

 

[rowerwet]

Gas or electric won't require one or more trips a day to refill the way pellets would. What fuels do you have in the house?
If you have oil, do another oil, gas do another gas, electric is expensive.

 

[Jackfre]

I'm pouring my floor this Thursday and do not intend to put tubing in the floor. I'm not going to mi$$ it either. I would suggest a Rinnai EX38 Direct vent wall furnace. You live in the largest market in the US for this product. I install it a few ft inside the doors so it blows across the doors. It's what I'm putting in my 30x34x10 building.

 

[DonPowers]

Ralbert I from the County.

Are you looking to maintain 50 deg all winter or only when you plan to work in your garage?

You are correct regarding heat pumps and cold weather efficiency. I checked out some specifications on units with variable speed scroll compressors. The data sheet provided electrical usage at three different temperatures, 47 deg, 17 deg and 5 deg. The efficiency at 47 deg was 271%, 17 deg 167% and 5 deg 147%. These numbers did not include electrical usage for the defrost cycle.

 

[Ralbert]

Hi Don, I would be looking to maintain at least 50 degrees all winter long... Maybe raise it a bit higher when I'm working in the garage...

 

[theoldwizard1]

Pellet stove is BY FAR, the cheapest cost of operation, but it will also be difficult to have even temperatures across the 28x36 first floor. One or more good sized fans will be required.

There are some automatic feeders that will hold enough pellets to last 5-10 days, but they are expensive. A typical stove will need to be fed 2-4 time a day, if you really want to maintain 50F. If the second floor is going to be "occupied", you are going to need another stove.

If a pellet stove (or 2) is not reasonable (do to the time/effort to haul pellets and load the stove), then the lowest cost of operation in a mini-split heat pump. 2 air handlers per floor would be required. The other problem is, even the best mini-split heat pumps start loosing efficiency at about 5F, which means you are going to need a "backup" like a portable kerosene heater.

 

[Jlbc212]

My garage is 28x35-8 with 12 ft high ceilings. I have a 75k Modine Hot Dawg natural gas fired heater. I've kept the garage at 50 degrees all winter. I don't pay close attention to the run time, but cycle times seem about right - maybe on for five minutes and off for fifteen.

 

[Strouty]

I use an older oil fired heater. Mine was a $250 craigslist purchase, it was being replaced by a natural gas system. I would not consider electric as primary and in our neck of the woods propane can be more expensive than oil. Pellets are a pain, wood can be too. I go through about 450 gallons a season to heat a 30x60x12'6" building with crappy wooden garage doors. I would think yours would be much easier to heat, you can also duct it upstairs fairly easily.

As others have asked, what is your house heated with?

I keep mine at 45 degrees when I am planning on being around, then it takes about an hour to get it to 50 or 55 depending on how cold it is outside. When I am not planning on being around for a while, I keep it at 38 degrees just so things won't freeze.

 

[Ralbert]

The house is heated primarily with Propane. I've also got a harmon pellet stove in the "great room" as well as Fujitsu Mini-Split heat pump... Which I don't use under 20 degrees... I'm more of a propane fan for the garage at this point; the pellets would be a ton of extra work I think... How efficient are the Hot Dawg / Hot Shot units? as far as AFUE %?

 

[Jlbc212]

The house is heated primarily with Propane. I've also got a harmon pellet stove in the "great room" as well as Fujitsu Mini-Split heat pump... Which I don't use under 20 degrees... I'm more of a propane fan for the garage at this point; the pellets would be a ton of extra work I think... How efficient are the Hot Dawg / Hot Shot units? as far as AFUE %?

The 75,000 unit rated input is 75,000 with a rated output of 60,000. Looks like 80%.

 

[APEowner]

Out of curiosity, why not fuel oil? It's usually more cost effective than propane.

 

[DonPowers]

Check with your propane supplier and find out where the price breaks are. For me its 500 gal. during the year. I typically don't burn that much so I pay the higher price. My brother uses propane at his business, don't know how many gallons he uses but his cost/gal is about a third of mine.

Worth checking into, especially if your house propane usage brings you close to a price break. Propane could be the way to go.

 

[tinker rick]

Welcome to the "Journal" .I have a Sterling propane in my 48x48 with 13.6 ceiling for about 3 gal. a day . Got it from ACF GREENHOUSE SUPPLY ,GG 120 .If you would like to know more PM me ,or if you would like to see it.
Rick

 

[Ralbert]

Thanks all! Was really hoping to get more opinions on the Hot Dawg and and Mr. Heater units... I'm really not interested in oil, already using Propane in the house... Plus propane burns cleaner... Any other thoughts?? Hoping not to make the wrong decision!

 

[dave67fd]

I'm running a 75k Mr. Heater in a well insulated 28 x 38 with 10.5' ceilings and it heats my space no problem.
If you plan to run it all winter in central Maine, make sure you have an adequate sized source so your not filling it as often.

Probably not too adequate if your planning to heat both floors though.

 

[Travo131]

How far of a run would it be to plump a line to your current propane tank? I'm not sure about Maine but, in Wisconsin if you have a secondary tank you get charge sales tax. So even if it costs 300 for the run you can recoupe that back in not paying sales tax. Im surprise to hear fuel oil is cheaper in that area than propane. Our current price is 1.699 compared to 2.55 for FO.

 

[jvitez]

To recap: your fuel choices are propane, electricity or pellets. You have a well insulated garage including an insulated concrete floor. You live in a cold climate. Electricity and propane are both expensive, pellets are a too much work. You want to heat all winter at a moderate steady temp.

Solution: propane fired radiant tube heater.

You've mitigated costs by excellent insulation. The radiant heater will warm your floor so great comfort and snow melt, no moving air to stir up dust, no fan noise except the burner fan, and nice even heat with the proper length of burner tube and btu input.

Here's an example: http://www.easyradiantworks.com/ezdoz.htm

I'd pick the 22 ft straight model, 40k btu would be excellent for your space, and you could run it along the back 36' wall facing the garage doors.

 

[Mr onetwo]

Hey there, If you are going to be in the Belfast area anytime soon PM me...you are welcome to come and see my tube setup. I have been in the HVAC business(now semi-retired) for over 30 years. Mark

 

[Ralbert]

I haven't researched the heat tube option vs. the Mr. Heater / Hot Dawg - Any thoughts on efficiency differences between the two?

 

[theoldwizard1]

You will be installing a pellet stove after your first year of propane bills !

 

[Spudland_Dave]

You will be installing a pellet stove after your first year of propane bills !

He may want to, but will be prohibited from doing so!

Hello Fellow Mainer!

Might want to call your insurance company...when It comes to a detached structure the rules are simple. NO SOLID FUEL. No Coal, No Wood, no Pellets, Etc. Only 3 options are Electricity, Oil & LP. Before I built my garage I had a mental plan of running a coal boiler in the garage...plumbing it into the house just like an Outdoor Wood Boiler but it would be in the garage, I'd heat my garage AND house with it, but was told Nope, cant be done if I want to insure it.

I'll be installing a HotDawg 75k this summer into my 30x50.

I haven't had any heat in mine since I built it....its fully finished, insulated, sheetrocked, etc... and it RARELY gets under 35 degrees in there. Coldest its been all year was towards Mid-End of Feb...got as cold as 28. So for me, as you mentioned, once the heat is installed, I'll set it to 35-40 degrees, just to keep stuff from freezing. I cant imagine that maintaining that temp is gonna be a deal breaker even on a relatively expensive fuel for us (LP). Where we win is the cost for a HotDawg is so cheap to install.

 

[Mr onetwo]

You are correct sir! This isn't just about insurance...The national fire code (NFPA 211) states........

12.2.3 Solid fuel-burning appliances shall not be installed in
any location where gasoline or any other flammable vapors or
gases are present.
12.2.4 Solid fuel-burning appliances shall not be installed in
any garage.

 

[Kevin54]

My garage is 28'x36' with 2x4 walls, R13 insulation in the walls, and R30 in the ceiling, plus I have only 8' ceilings. I have a 45,000 btu Hamilton heater, similar to a Hott Dawg.

I have a 120 gallon propane tank and I have to fill it maybe every 1- 1 1/2 months when it is around zero out. I'm usually out in the garage every day and when I am out there, I'm in short sleeves and keep it at 65-70 degrees, but turn it down to 50 at night. Most of the time, it will retain the heat and not get down to 50 but will hover around 53-55 degrees. There have been times when I have came out though when it was maybe 10-20 below, and the furnace was running, so I know the temps dropped down that low.

But that is in Midwest Ohio, and very rarely do we have howling winds for an extended period, but may have 10-20mph winds in the winter.

 

[Spudland_Dave]

You are correct sir! This isn't just about insurance...The national fire code (NFPA 211) states........

12.2.3 Solid fuel-burning appliances shall not be installed in
any location where gasoline or any other flammable vapors or
gases are present.
12.2.4 Solid fuel-burning appliances shall not be installed in
any garage.

Thanks for that! Nice to know its actually grounded in some sort of regulation and not just some arbitrary insurance determination...

From a purely academic standpoint though, I fail to see the big difference between a wood stove and a LP stove in a shop...I know it may be "old school" but if I have a Pilot light on a LP Fired heater, in my garage, how is that any better then a pellet stove?

Or a wood stove...90% of which are only used when the shop is being used, again...I can think of 100 things more dangerous in terms of fumes + fire in an actively used shop.

**Edit...see you got a couple Case's...I picked up a 110 last fall to restore for/with my son.

 

[Mr onetwo]

Thanks for that! Nice to know its actually grounded in some sort of regulation and not just some arbitrary insurance determination...

From a purely academic standpoint though, I fail to see the big difference between a wood stove and a LP stove in a shop...I know it may be "old school" but if I have a Pilot light on a LP Fired heater, in my garage, how is that any better then a pellet stove?

Or a wood stove...90% of which are only used when the shop is being used, again...I can think of 100 things more dangerous in terms of fumes + fire in an actively used shop.

"ELEVATION OF IGNITION SOURCE"
{Equipment that has a flame generates a spark or uses a glowing ignition source open to a garage in which it is
installed must be elevated at least 18 inches above the floor. Equipment enclosed in a separate compartment
having access only from outside of the garage may be installed at floor level, providing the required combustion
air is not taken from the garage. Water heaters listed as flammable vapor ignition resistant can be installed
at floor level.} This is one reason you see so much suspended overhead heating equipment in garages. Codes vary state to state...check with your local code compliance office to verify what applies in your area.

 

[Mr onetwo]

**Edit...see you got a couple Case's...I picked up a 110 last fall to restore for/with my son.

Yes I really like them! Are you on CCI? I don't know much about the 110 series, but all Case's are cool!

 

[DonPowers]

You are correct sir! This isn't just about insurance...The national fire code (NFPA 211) states........

12.2.3 Solid fuel-burning appliances shall not be installed in
any location where gasoline or any other flammable vapors or
gases are present.
12.2.4 Solid fuel-burning appliances shall not be installed in
any garage.

Thanks Mr onetwo

I just bought a used wood fired boiler for one of my garage heat sources and planned to put it inside a room in my wood shed, which is a separate building from the garage. This makes me feel better about my decision to place the boiler in the shed and provides a lot of good guidance on installation.


Here is a copy of the 2003 edition of NFPA 211 for those who might like a little light reading.
http://woodheatstoves.com/free/NFPA211_old.pdf

 

[Spudland_Dave]

Yes I really like them! Are you on CCI? I don't know much about the 110 series, but all Case's are cool!

Yes I did join last fall when I got the 110...I found it on CL...in talking to the guy we ended settling on free as a sale price...I picked it up and to my dismay its got a belt driven gear transmission like every other mower after disassembly I discovered the input shaft on the Peerless ****** is junk...SOOOo dunno what I'm gonna do with it. I got it merely as a "Go Cart" for my 5 year old son. Was hoping for hydro drive so I can control speed a bit better, etc.

All sanded down, ready to prime & paint sitting on a pallet in my shop. I would have gotten more done but my shop isn't heated yet...this is my last year for no heat

 

[Mr onetwo]

I'll bet you can get that transaxle for next to nothing from one of the guys on CCI. http://casecoltingersoll.com/forum.php

 

[Mr onetwo]

Thanks Mr onetwo

I just bought a used wood fired boiler for one of my garage heat sources and planned to put it inside a room in my wood shed, which is a separate building from the garage. This makes me feel better about my decision to place the boiler in the shed and provides a lot of good guidance on installation.

That is perfectly fine. Make sure you maintain clearances to combustibles per mfg instructions. Those wood boilers can be very persnickety. What brand is it?

 

[DonPowers]

That is perfectly fine. Make sure you maintain clearances to combustibles per mfg instructions. Those wood boilers can be very persnickety. What brand is it?

Its a 2008 New Yorker WC 90 with stand.

I'm closing off a bay that's 10 x 10. Will have a concrete floor and plan to use backer board on the interior walls. That still leaves two 10 x 10 bays for firewood, a two year supply.

The instruction manual calls for 18" minimum clearance, will most likely use 2 ft. so I can easily get around the unit.

Will also duct heat from the room to a greenhouse and also plan to run some pex under the soil.

 

[Adk Mike]

I've had a Modine Hot Dawg for 12 Years. This year I did a little service on it. Very good unit You need the HD60 Model. Your climate is the same as mine the 45,000 Is too small. I work in tbe propane industry and know from experience.
I found after the first year I didn't Heat the shop every day. It seldom freezes in there. I turn mine on on Fridays for the weekend.
With propane on your house run a line to the shop and never look back.
One source of fuel trucked in to a property is enough. With propane get the biggest tank you can. Fill it a couple times a year. Best way to go.

 

[walrus]

...check with your local code compliance office to verify what applies in your area.

Its Maine, whats a code enforcement officer

 

[Spudland_Dave]

Its Maine, whats a code enforcement officer

Amen!

But seriously it varies from area to area....I know some towns have a CEO and its impossible to get anything done...in other areas you're free to do as you see fit on your own property.

I could heat mine with a Unicorn Burning Furnace if I wanted to...if insurance weren't an issue... I'm guessing Unicorns are considered to be a solid fuel.

 

[Strouty]

Unicorns have a lot less BTUs than burning vegetarian tears. Those tears can only be collected while the vegetarian is watching people enjoying veal, otherwise they won't burn.

 

[DonPowers]

Unicorns have a lot less BTUs than burning vegetarian tears. Those tears can only be collected while the vegetarian is watching people enjoying veal, otherwise they won't burn.

 

[Ralbert]

Thanks Mike. The garage is across the street so running off one take likely won't happen. Any reason why I would want to do this?

I was under the impression 60k would be too much and oversizing a propane heating unit makes it less efficient. Any thoughts?

 

[jvitez]

Do a proper heat loss calc and be sure of what you need.

FWIW, I had a 22x24 attached garage with 10 ft ceilings in my old house in our cold Canuck prairie climate. It had one common wall with the house, 3 exterior walls at R12, ceiling R40, with an insulated steel 7x16 garage door. It heated well to 10-12°C with a 4800W electric heater, or 9.1 watts/sq. ft. That would be 31,200 btu/hr for your garage. If you used an 80% efficient propane heater, either forced air unit heater or infrared tube heater, the gross input would calculate to 39,000 btu/hr.