Modine Hot Dwag gas heater HD vs. HDS model

[James Zhu]

I am in the process to convert 2-car garage to workshop, need to add the heater. I am looking at the Modine Hot dwag 45000 BTU unit, the HDS model uses external fresh air for combustion instead of indoor space air used by HD model.

I know the HDS model is a better choice, but the cost is more than doubled here in Canada (750 vs. 1650 before tax). I have dust collection in the shop, also have Festool system for handheld tools.

Is it necessary to buy the more expensive HDS model? Have you had any issue using the standard HD model in the workshop?

Thanks,
James

[Ray Newman]

I have the Hot Dawg and find it to be very efficient.

Problem with not drawing combustion air from the outside is not only a problem with dust control, but also with the fumes from non-water based/volatile finish, degreasers, cleaners, etc.

[lawrence dosson]

I have the HDS model myself bought last year for my shop in propane version
my heating guy said that the dust would be a real problem with the non sealed combustion unit
bought it from greenhouse supply for $800 or so here in the USA and easily installed it myself and had the heating contractor [my friend] inspect it before I called the county inspector
I love it I am heating a well insulated 32 x 24 ten foot ceilings

[James Zhu]

I have the HDS model myself bought last year for my shop in propane version
my heating guy said that the dust would be a real problem with the non sealed combustion unit
bought it from greenhouse supply for $800 or so here in the USA and easily installed it myself and had the heating contractor [my friend] inspect it before I called the county inspector
I love it I am heating a well insulated 32 x 24 ten foot ceilings

Do you have the 45000 BTU unit? My 2-car garage is 19 x 18 ten foot ceiling, kind of small. If 45000 BTU unit works for your 32 x 24 garage, I may just buy the 30000 BTU unit.

[Ray Newman]

"Do you have the 45000 BTU unit? My 2-car garage is 19 x 18 ten foot ceiling, kind of small. If 45000 BTU unit works for your 32 x 24 garage, I may just buy the 30000 BTU unit. "
--James Zhu

It could work, but seems to me a great deal depends upon how well your shop/garage is insulated and how tight the weathers tripping is around the doors, windows, etc.

[Marty Tippin]

I would just buy the cheaper one and be done with it.

I see very little risk of any issue with fumes - by they time they get to a high enough concentration at ceiling level (where the heater is) that they could combust, you'll have left the building or passed out. Dust from sanding is even less likely to be a problem - never enough concentration to combust and small amounts that get sucked in will just go out with the exhaust.

And since you're in a garage, you're going to have more than enough air leaks to easily make up the air used in combustion.

[lawrence dosson]

Do you have the 45000 BTU unit? My 2-car garage is 19 x 18 ten foot ceiling, kind of small. If 45000 BTU unit works for your 32 x 24 garage, I may just buy the 30000 BTU unit.

yes I have the 45000 my shop is R50 ceilings R25 walls and the floor is insulated also no overhead door
protected entry way the building is 32X48 I have 24 feet walled off hence 24X32so one wall is not to the outside
that little heater does not run very much Michigan winter last years propane bill for me was less than 200 dollars I never shut the heat off just down at night to 55 and 65/70 when im out there

[Bill Adamsen]

I have the HDS75 and one advantage is with a simplified install. The external air intake is around the pipe ... simplifying the shielding requirements for the exhaust. The unit works better than expected. No condensation issues at all, which was a concern going in to the project. I suspect the HDS reduces the amount of condensation by not pulling in outdoor air.

[roger wiegand]

Very happy with the HDS here (an 80k natural gas unit). Perhaps not a concern in a garage, but I did spray foam insulation and am working to get the shop building tight (an interesting task in a 1901 barn), didn't want to then have to worry about makeup air for the heater. Bought it online for a lot less money than you're talking and had my plumber install it, he charged about $300 for installation as I recall, homeowners can't do gasfitting here. Also happy to not have to worry about sucking list and solvent fumes into the combustion chamber, whether or not it's a huge problem. My basement shop conventional furnace in the last house was a mess with all the dust.

[Patrick Walsh]

Roger,

I am just down the street from you in Natick.

I am also about to add heat to my basement shop. Someone here suggested a direct vent Rinnah unit. I also hope to purchase the unit online them pay a plumber to instal.

Would you mind sharing your plumbers info with me. Beleive it or not i am a carpenter a d work for a builder out of Dover. The plumbers we use do not do side work so im kinda dead in the water on this.

Very happy with the HDS here (an 80k natural gas unit). Perhaps not a concern in a garage, but I did spray foam insulation and am working to get the shop building tight (an interesting task in a 1901 barn), didn't want to then have to worry about makeup air for the heater. Bought it online for a lot less money than you're talking and had my plumber install it, he charged about $300 for installation as I recall, homeowners can't do gasfitting here. Also happy to not have to worry about sucking list and solvent fumes into the combustion chamber, whether or not it's a huge problem. My basement shop conventional furnace in the last house was a mess with all the dust.

[Bill Adamsen]

Just as an fyi ... I installed (hung) Hot Dawg Unit myself including the venting. I had my electrician validate the electrical and my HVAC guy ran the propane. Planning for the heat, I'd had a branch line with regulator installed just outside the shop at foundation level, below where I planned to put the heater. So hookup was pretty straightforward. I mention only because my building department approved of this approach and I was happy to get the details right in terms of direction and exhaust. It was not very difficult.

Photo below illustrates the install after hanging the unit, connecting the electrical and placing the exhaust, but before connecting propane and fresh air intake. The small box next to the wall is the box that allows the fresh air to come in around the exhaust and then separate out to a fresh air intake. The second photo just shows the outside with the exhaust above and propane regulator at foundation level.

[Ray Newman]

Bill Adamsen: nick looking shop. Like the design and what I see of the interior. Posted any more pictures of it?