Garage Heater Sizing/Type/Misc questions

[MickeyG]

Hi all - I've spent days reading here and think between that and some local HVAC companies visiting I am more confused then when I started.

I have a 22x22x9.5 attached garage that is drywalled and insulated (no idea on the R value).

I live in Southern Ontario where the temperatures can get down to -18C or 0F but it's usually around -10C/14F or so.

My original plan was to get a Hot Dawk 30K as I figured that would be PLENTY for 480 sq.ft.

I have a few motorbikes which I park in there and work on with as well as now a small power rack gym in the corner due to covid. So the doors are not opened often except for snow blowing or taking the trash out.

I plan on heating it full time to 55/60F to keep the bedroom above warmer and will bring it up to 65/70F while working out which is one hour per day mon-fri and whenever out there working on bikes.

The HVAC guys have recommended the Mr Heater 50K just because it's cheap. Another one said I needed at least 60K. That sounds INSANE to me but now has me considering the HD45K.

My questions :

Should I go 45K vs 30K for a smallish double garage that I plan to heat full time.

Will the 30k be able to recover fairly quickly when the door(s) are opened?

If I am going to go through this expense I want the option to have the garage as cozy as I want, whenever I want. I would hate to spend the money and only be able to achieve 60F when it's -20/0 outside.

But, when I stand out in the garage and look around, even the idea of 30K sounds like a bunch in there...

Lastly as mentioned I work on bikes in there. Which means the odd time pulling gas tanks and carbs - so some gas fumes. This isn't very often but should I consider a separated combustion unit? Or would I be ok just opening a door while doing that or shutting heater off?

Thanks in advance.

 

[kelpaso1]

I live in southern NB with similar climate as you. Since I have no Natural gas service here I went with a 24K mini split in my similar size garage as you. It keeps the garage at a nice temp unless it gets lower than -15C outside. It basically will keep my garage 30 degrees C above outside temps. So at -10C out it will be +20 inside. When it gets to -20 out I only get about +10 inside. On those cold days I just use a small 1500W space heater pointed at me. Also mini splits are very economical in power usage. In the winter it costs and average $30 bucks a month more to keep my garage warm. I also keep it heated 24 hrs, all day/night, every day.

 

[MickeyG]

I live in southern NB with similar climate as you. Since I have no Natural gas service here I went with a 24K mini split in my similar size garage as you. It keeps the garage at a nice temp unless it gets lower than -15C outside. It basically will keep my garage 30 degrees C above outside temps. So at -10C out it will be +20 inside. When it gets to -20 out I only get about +10 inside. On those cold days I just use a small 1500W space heater pointed at me. Also mini splits are very economical in power usage. In the winter it costs and average $30 bucks a month more to keep my garage warm. I also keep it heated 24 hrs, all day/night, every day.

Thanks for the reply. I don't know much about the efficiency of mini splits but if it's 24K actual btu that's of course the same as the 80% efficient 30K unit heater.

Appreciate the usefual data point.

 

[ED26]

Im in similar boat as you; looking to add heat in my two car att garage 24x27 in Michigan. Torn between Reznor 45K UDAP or the Hot Dawg 45K HD45A model. Appears very similar, I am looking for real world experience on what is quieter as it is attached garage.

The reznor is almost $300 more for the unit

 

[MickeyG]

Im in similar boat as you; looking to add heat in my two car att garage 24x27 in Michigan. Torn between Reznor 45K UDAP or the Hot Dawg 45K HD45A model. Appears very similar, I am looking for real world experience on what is quieter as it is attached garage.

The reznor is almost $300 more for the unit

I've been reading endlessly about both as well. You make a good point about noise being below the bedroom. I'm having problems even finding a Reznor around here.

I'm open to other suggestions as well. Not dedicated to getting the Modine.

 

[ED26]

I've been reading endlessly about both as well. You make a good point about noise being below the bedroom. I'm having problems even finding a Reznor around here.

I'm open to other suggestions as well. Not dedicated to getting the Modine.

Looking at tech specs listed online

MODINE Hot Dawg HD45A 45K BTU @ 5' 57 db

Reznor UDAP 45K BTU @ 15' 40 db

Obviously 15' away will be quieter, trying to get a real world apples to apples comparison, or if someone actually has a DB meter that would be perfect for some real world noise levels

 

[sarman47]

I lived near Sarnia, Ontario and had a natural gas 45k BTU Big Maxx in my 21x20 garage for 11 years. Keep the heat at 58 deg all winter. The blower/fan noise was never an issue. Picked mine up on a Black Friday sale at Home Depot in Port Huron, Michigan.

Just moved into a new house in Eastern Ontario near Ottawa with a 45x30 attached garage. Recently installed a 80k BTU Big Maxx that I picked up last fall at Menards in Port Huron, Michigan that was on sale. Even with the exchange it was still cheaper then here in Ontario.

Would not worry about going a little to big. I just set the thermometer for a 2 deg swing, so it cycles less. Set it for 58 deg the heater won’t kick in until it hits 56 deg and then it heats to 58 deg and the fan still runs after the heater cuts out and it usually heats up to 60 deg.

Was actually surprised how little. Natural gas it used.

Regardless of the brand Modine, Reznor, or Big Maxx it will get the job done.

 

[MickeyG]

I lived near Sarnia, Ontario and had a natural gas 45k BTU Big Maxx in my 21x20 garage for 11 years. Keep the heat at 58 deg all winter. The blower/fan noise was never an issue. Picked mine up on a Black Friday sale at Home Depot in Port Huron, Michigan.

Just moved into a new house in Eastern Ontario near Ottawa with a 45x30 attached garage. Recently installed a 80k BTU Big Maxx that I picked up last fall at Menards in Port Huron, Michigan that was on sale. Even with the exchange it was still cheaper then here in Ontario.

Would not worry about going a little to big. I just set the thermometer for a 2 deg swing, so it cycles less. Set it for 58 deg the heater won’t kick in until it hits 56 deg and then it heats to 58 deg and the fan still runs after the heater cuts out and it usually heats up to 60 deg.

Was actually surprised how little. Natural gas it used.

Regardless of the brand Modine, Reznor, or Big Maxx it will get the job done.

Thanks. Gets me swinging back towards the 45K now.

Yeah, they are a lot cheaper across the border. I'm only about 60KM from the Lewistion bridge but unfortunately I don't think heating my garage is "essential travel".

Appreciate the information.

 

[Milzo]

My shop is 36x48x15 R-19 walls R-30 ceiling. Wasn't confident in sizing recommendations by various sites & HVAC companies. Decided in the long run it was worth the $200 to pay a 3rd party company that only does HVAC design and load calculations. The heat load in my shop came out to 34,000 btu so a 45,000 unit heater. Since I don't plan to heat it all the time I went up one size to a 60,000. I was dead set on buying a Reznor but after a lot of research and feedback went with a Sterling GG. Just finished install last week. Its a lot quieter than i expected and warmed up my shop in 20 min. Got it from ACF Greenhouses, excellent price and customer service.

 

[MickeyG]

Thanks for the replies and the sizing help so far.

Any comments on getting a seperate combustion unit for the odd time there may be some gas fumes from working on bikes?

I read a comment here that mentioned by the time the fumes got high enough to reach the ceiling by the heater you would of passed out already anyway...

 

[MickeyG]

For the cost of the separate combustion unit heater I could spend a bit more and get something like a Rinnai wall unit. Would this be the safest of the bunch?

I'm likely getting paranoid as I'm sure a standard vented unit heater will be just fine and I could shut it off and open the garage doors the few times I am working with small amounts of fuel.

Basically looking at $800/1800/2400 equipment wise for unit heater/separate combustion unit/Rinnai.

I believe the venting is included with the Rinnai so that may make the two separate combustion units about even in cost?

 

[Jackfre]

In reply to your pm, yes, the vent is included with the Rinnai and will adjust from a wall thickness of 4.5-9.5" and needs only a 2.5" hole saw for the vent. Other vents up to 36" are available as options, as are vent extensions. Yes it is sealed combustion. Forgive the measurement nomenclature. I am American and not smart enough to use metric. The EX-22 will walk away with this place assuming you have decent construction. Yes, the Rinnai is much more expensive but you get the feature set to justify the added cost. Heat at the floor. I can tell you I restored an old BMW 2002 years ago in my garage in MA and it was sweet laying on a creeper and having the air come across the floor. Perhaps the best feature of the Rinnai products is that Rinnai makes everything in the unit. They make the case, HX, burners, ignition system, gas valve, make their own pcb's, programmable t'stat and they write their own software to control it all. As a result everything in the box is happy together and work together. Compare that to any other gas appliance. They assemble a bunch of components from different manuf throw them together and hope they are all happy in the same box. If you have specific questions I will walk you through them.

 

[MickeyG]

In reply to your pm, yes, the vent is included with the Rinnai and will adjust from a wall thickness of 4.5-9.5" and needs only a 2.5" hole saw for the vent. Other vents up to 36" are available as options, as are vent extensions. Yes it is sealed combustion. Forgive the measurement nomenclature. I am American and not smart enough to use metric. The EX-22 will walk away with this place assuming you have decent construction. Yes, the Rinnai is much more expensive but you get the feature set to justify the added cost. Heat at the floor. I can tell you I restored an old BMW 2002 years ago in my garage in MA and it was sweet laying on a creeper and having the air come across the floor. Perhaps the best feature of the Rinnai products is that Rinnai makes everything in the unit. They make the case, HX, burners, ignition system, gas valve, make their own pcb's, programmable t'stat and they write their own software to control it all. As a result everything in the box is happy together and work together. Compare that to any other gas appliance. They assemble a bunch of components from different manuf throw them together and hope they are all happy in the same box. If you have specific questions I will walk you through them.

Thanks. By "walk away" do you mean it's oversized? I've read enough to know these should be sized right to run more often than not.

How close can they be positioned beside man a door?

 

[Adk Mike]

My shop is 20 by 25, nine and 1/2 ceiling. I have similar climate as you. I’ve had the Modine HD 45 for 16 years. It’s about perfect . I’d get the 45 it heats the building fast and is not over sized.

 

[Jackfre]

Apologize for my nonchalant language. The 22 is the unit you want for your space.

 

[MickeyG]

Decided to go with a Reznor Separate Combustion 30K. I rarely open my garage doors in the winter, and just really like the idea of outside air for combustion.

Thanks for all the help.

 

[ED26]

Decided to go with a Reznor Separate Combustion 30K. I rarely open my garage doors in the winter, and just really like the idea of outside air for combustion.

Thanks for all the help.

How is the noise level?

 

[MickeyG]

How is the noise level?

I don't have it yet, but I will let you know.

 

[MickeyG]

Back with another basic question that I can't readily find the answer to. The unit has external tstat connections with R W1 G W2 with W2 being unused on the strip. I want to use a wifi tstat and see that the control board has a c connection on the molex plug. Can I just drop another pin in the C of the molex plug and run it up to the terminal strip and connect it to W2? I would then re-label W2 as C on the strip of course.

 

[jlv03]

This manual gives some ideas on finding the common: https://literature.nortekhvac.com/p...ey=Reznor&lgt=6915115061c3d1caf59163907568511

Manual for thermostat wiring: https://literature.nortekhvac.com/p...=Reznor&lgt=6915115061c3d1caf5137948240382401

 

[Mogana]

I am a bit confuse sizing a heater for my 250 square feet garage. Any option to recommend?

 

[toyotadriver]

I am a bit confuse sizing a heater for my 250 square feet garage. Any option to recommend?

Friendly suggestion....start your own thread with more details and we’ll be happy to help you!

You’ll get more views specific to your install and recommendations tailored to what you need. Fair warning.....you’ll get a few conflicting opinions as well!

 

[banjopete]

You'll really enjoy the reznor, I'm in a 26' x 24' x 8' in Edmonton and went with a 45k reznor, it's been awesome. I wish I did it sooner, it makes tons of heat.

Sent from my SM-G960W using The Garage Journal mobile app

 

[MickeyG]

You'll really enjoy the reznor, I'm in a 26' x 24' x 8' in Edmonton and went with a 45k reznor, it's been awesome. I wish I did it sooner, it makes tons of heat.

Sent from my SM-G960W using The Garage Journal mobile app

Thanks. I'm pretty excited about it. Been working in the cold far too long!

 

[yeldogt]

In reply to your pm, yes, the vent is included with the Rinnai and will adjust from a wall thickness of 4.5-9.5" and needs only a 2.5" hole saw for the vent. Other vents up to 36" are available as options, as are vent extensions. Yes it is sealed combustion. Forgive the measurement nomenclature. I am American and not smart enough to use metric. The EX-22 will walk away with this place assuming you have decent construction. Yes, the Rinnai is much more expensive but you get the feature set to justify the added cost. Heat at the floor. I can tell you I restored an old BMW 2002 years ago in my garage in MA and it was sweet laying on a creeper and having the air come across the floor. Perhaps the best feature of the Rinnai products is that Rinnai makes everything in the unit. They make the case, HX, burners, ignition system, gas valve, make their own pcb's, programmable t'stat and they write their own software to control it all. As a result everything in the box is happy together and work together. Compare that to any other gas appliance. They assemble a bunch of components from different manuf throw them together and hope they are all happy in the same box. If you have specific questions I will walk you through them.

Up front cost is always a deterrent -- ?

I always use a cabinet style if at all possible --- the install ease alone gives them the edge.

 

[ED26]

You'll really enjoy the reznor, I'm in a 26' x 24' x 8' in Edmonton and went with a 45k reznor, it's been awesome. I wish I did it sooner, it makes tons of heat.

Sent from my SM-G960W using The Garage Journal mobile app

How is the noise level?

 

[banjopete]

Good I'd say. No problems with the noise level for me working in there, and outside the garage it's hardly audible over ambient environment noises.

Quick measure goes from mid 50db to mid 60db from in the garage to running heating fan on. Measure from about 12ft away, very quiet. So far one year in I'm a big fan like I said.


Sent from my SM-G960W using The Garage Journal mobile app

 

[ED26]

Did u get the Reznor installed

 

[MickeyG]

Yes. It's very quiet. Can't hear it at all in the bedroom above the garage.

 

[ED26]

Yes. It's very quiet. Can't hear it at all in the bedroom above the garage.

I’m thinking of the same unit for 24x28x9...or should I get the udap45

Any way you can send me a video or post to YouTube I’d love to hear this thing before I get it.