Sizing Garage/Workshop Heater

[berky2755]

Curious on how everyone would size a heater for this situation. I have a 3-car garage with a workshop in the back part of it. Walls are 10' tall. It isn't currently, but will be insulated fully when I install the heater (only the bathroom is insulated now). I have a run for gas, so I will use that instead of electric.

workshop area is open to car area as shown in diagram. I did this so I could pull a vehicle back there to work on it if needed. workshop area is about 36.5' x 15', which technically includes the bathroom. the parking area is approximately 36.5' x 21'. I don't really care about heating the car area, but it will get warmer because of the opening, which I could put a sheet or something there just to block the air flow a little bit.

Anyway, if this was your garage, would you size for the entire garage or just for the workshop area? and why?

I know the cost differences, so I want to know any other pros/cons of doing one way vs the other.

 

[PoorUB]

Keep in mind if you just hang a tarp or something similar across the opening between the two areas you will get one hell of a draft coming under the tarp.

Personally, I would put a heater in both areas, or one larger unit in the corner of shop on the left side of the drawing that blows partially out the door into the parking area and also into the shop.

60,000 BTU should do it. Assuming it is properly insulated.

 

[nadogail]

The most correct answer will of course depend on your local conditions and the intended use of the building, as well as the amount of insulation installed.

A local HVAC supply house would give you better advice than some one in Southern California.

 

[Jackfre]

Well, I’m in N CA but sold about 250,000 Rinnai direct vents in the six New England states over a 20 yr period. A Rinnai EX-38 will walk away with that job. You are looking to heat 540 sq ft of shop. In a decently insulated building the 38 will handle about twice that. Given its modulating gas valve and blower it will be firing mid-range unless you pull the curtain back and open the parking area. Buy it yourself, drill a 2 3/4” hole for the vent, whcih comes in the box, connect the gas, plug it in and you will be vary comfortable.

 

[berky2755]

Well, I’m in N CA but sold about 250,000 Rinnai direct vents in the six New England states over a 20 yr period. A Rinnai EX-38 will walk away with that job. You are looking to heat 540 sq ft of shop. In a decently insulated building the 38 will handle about twice that. Given its modulating gas valve and blower it will be firing mid-range unless you pull the curtain back and open the parking area. Buy it yourself, drill a 2 3/4” hole for the vent, whcih comes in the box, connect the gas, plug it in and you will be vary comfortable.

What advantages would this type of heater have over the 'typical' garage heater?

 

[Jackfre]

“Typical.” Well it sits on the floor and when you are under the car in winter it blows warm air across the floor. I can say from experience welding floor pans in a 72 2002 that it is pretty cool, well good maybe. The 38 will fire from 13.5-38kbtu and decides what is called for. Your typical garage heater is hung from the ceiling and when the stat calls you get 100% of its input. When the stat is satisfied it shuts off, waits a bit and does it again. It is like driving at the drag strip. Wait for it…wait for it, green light…hit it. Run run run, cross the line, shut it down and coast to a stop. Ready to go again? The Rinnai will bring the place up to temp and then sequentially, based upon it ability to see how uickly the space is cooling regulate its input. Kinda like driving a car. The drag strip is a blast, but it is not much for comfort or efficiency. The vent is included, it is quiet, cool to the touch and easy to install yourself. You may find cheaper, but not better for your space.

 

[D45]

I installed a 45k Hot Dawg in a friend's 3 car garage, fully insulated

It does a good job and heats the area well

 

[berky2755]

“Typical.” Well it sits on the floor and when you are under the car in winter it blows warm air across the floor. I can say from experience welding floor pans in a 72 2002 that it is pretty cool, well good maybe. The 38 will fire from 13.5-38kbtu and decides what is called for. Your typical garage heater is hung from the ceiling and when the stat calls you get 100% of its input. When the stat is satisfied it shuts off, waits a bit and does it again. It is like driving at the drag strip. Wait for it…wait for it, green light…hit it. Run run run, cross the line, shut it down and coast to a stop. Ready to go again? The Rinnai will bring the place up to temp and then sequentially, based upon it ability to see how uickly the space is cooling regulate its input. Kinda like driving a car. The drag strip is a blast, but it is not much for comfort or efficiency. The vent is included, it is quiet, cool to the touch and easy to install yourself. You may find cheaper, but not better for your space.

Thanks for the reply. I will definitely consider this unit as well. Thankfully I'm not in a hurry to get anything before this winter.

Definitely appreciate everyone's thoughts on the matter as well.

 

[4x4Pete]

I would heat the whole thing, if it is built well insulated and sealed up it isn't going to be a big deal as far as ongoing costs go. You will regret not heating the whole thing, similar to not building it bigger! I also wouldn't want a heater mounted on the floor. It is valuable space and there is a much higher risk of damage, which could be incredibly dangerous. In my shop I installed a gas fired radiant tube heater (Superior Radiant Systems) mounted up at the ceiling along the long dimension of the shop (30x32x12). The shop is kept warm so it doesn't cycle too much, has no circulation fan to blow around the dust, and heats the objects, not the air. The floor, tools and bench are warm too. My dad was an auto mechanic, he complained later in life about his hands and thought that cold tools caused arthritis in them. I don't need A/C so a mini split wasn't a candidate. In floor radiant would probably be nice, but I'd rather not have a boiler, feed water, and pump to deal with. The typical unit heaters are usually noisy and again blow the dust around. No offense to anyone who has one of those systems, but my experiences servicing hvac systems of all sorts is the radiant tube is the best option. I have also heard the argument that the paint on your car could get damaged with radiant tube heaters, I haven't had any issue there, I have had a vehicle parked under it regularly for the past 4 years. The only problem with it is that it is so comfortable in the shop, I stay out there way too much, according to the wife!

 

[berky2755]

I would heat the whole thing, if it is built well insulated and sealed up it isn't going to be a big deal as far as ongoing costs go. You will regret not heating the whole thing, similar to not building it bigger! I also wouldn't want a heater mounted on the floor. It is valuable space and there is a much higher risk of damage, which could be incredibly dangerous. In my shop I installed a gas fired radiant tube heater (Superior Radiant Systems) mounted up at the ceiling along the long dimension of the shop (30x32x12). The shop is kept warm so it doesn't cycle too much, has no circulation fan to blow around the dust, and heats the objects, not the air. The floor, tools and bench are warm too. My dad was an auto mechanic, he complained later in life about his hands and thought that cold tools caused arthritis in them. I don't need A/C so a mini split wasn't a candidate. In floor radiant would probably be nice, but I'd rather not have a boiler, feed water, and pump to deal with. The typical unit heaters are usually noisy and again blow the dust around. No offense to anyone who has one of those systems, but my experiences servicing hvac systems of all sorts is the radiant tube is the best option. I have also heard the argument that the paint on your car could get damaged with radiant tube heaters, I haven't had any issue there, I have had a vehicle parked under it regularly for the past 4 years. The only problem with it is that it is so comfortable in the shop, I stay out there way too much, according to the wife!

Thank you for another perspective! *IF* I would go this route, do you think I would need 2 of these? 1 for the workshop and 1 for the front (since there's a wall mostly between the 2 areas)?

 

[4x4Pete]

You could use two. Some manufacturers make them in a 10' long 25k btu configuration. It might make the inital cost higher than what you are thinking of spending, but it would give a lot of flexibility. Like I said though I keep my shop warm. This prevents most of the "issues" that some have with radiant tubes.

 

[berky2755]

Thanks.

I guess I should point out that I would mainly use the heater to keep the garage above freezing temps and then warm it up only when I'd be working out there. I don't do that every day, and maybe only a few times per month or 'as needed'.

Given that, would it change anyone's perspective on what might be a better option for this use case?