Modine Hot Dawg question

[the duck]

Hello,
I'm in the middle of building a 30x40' garage, 2x6" walls, fully insulated and sheet rocked, 9' ceilings. I'm in upstate New York, with nasty winters.

I have a buried propane tank and was planning on installing a 45,000 btu, ceiling mounted Modine Hot Dawg for heating. I intend to keep the building around 40 - 45 degrees full time, and 65 - 70 degrees when I'm working in it, which will be daily.

Any thoughts on this heater, its effectiveness, and its btu's for a 1,200 sf, well insulated structure? I'd love to hear other members opinions and experiences.
Thanks for your time,
Matt

 

[zmotorsports]

Hello,
I'm in the middle of building a 30x40' garage, 2x6" walls, fully insulated and sheet rocked, 9' ceilings. I'm in upstate New York, with nasty winters.

I have a buried propane tank and was planning on installing a 45,000 btu, ceiling mounted Modine Hot Dawg for heating. I intend to keep the building around 40 - 45 degrees full time, and 65 - 70 degrees when I'm working in it, which will be daily.

Any thoughts on this heater, its effectiveness, and its btu's for a 1,200 sf, well insulated structure? I'd love to hear other members opinions and experiences.
Thanks for your time,
Matt

I can't answer on the 45k btu but I installed a 75k btu Hot Dawg in my 34'x34'x14' shop a few years ago to replace the old worn Reznor 75k btu. Works great other than the fan is just a bit louder than my old Reznor, but not enough to cause issues. I am in Northern Utah and get winters with temps in the single digits on occasion but not normally. I keep the temps @ 50* when I am not working in it, but each afternoon when I get home from work I bump it to 60-62 degrees for working temps.

Overall I am very happy with the Modine Hot Dawg and mine is a natural gas fired unit.

Mike.

 

[Streetbu]

I live in upstate NY too. I use a 75k btu furnace for my 24x34 garage. I wouldnt want any smaller. I drop it down to 40 degree's when I'm not working out there, then up to 60-62 when I am. Takes about 30 minutes when the outside temp is in the 20's and there isnt any wind. I work out there maybe two days a week so there is a lot of thermal mass to heat up. Plus if you're opening and closing a large garage door, plan on it running for a while just to recover. No personal experience but Ive heard good things about them. I would go for a higher BTU though... JMO

 

[rlitman]

Beware that these units are not rated to maintain a temperature that low. That will lead to condensation that will rot the heat exchanger out.

Best I can say is refer to the manual.

 

[zmotorsports]

Beware that these units are not rated to maintain a temperature that low. That will lead to condensation that will rot the heat exchanger out.

Best I can say is refer to the manual.

Generally about 45 is the breaking point, much less than that and yes you run the risk of condensation buildup and rusting out the combustion temperature. Plus I hate cold tools nor any condensation on my tools. In my parents shop when living at home, my dad would turn the heat off until needed. I hated it as when I needed to use his small workshop, by the time my tools dried off from the condensation, hell I was done and ready to close up shop. It was also terrible for any chemicals or automotive sealants to keep at those low temps.

Now when keeping mine @ 50 degrees it is only a matter of about 15-minutes before it is up to my 62 degree setpoint once I get home from work. Good for several hours worth of working and to be honest it really doesn't cost much more to run it and keep it at 50 than it does much less than that, its just not worth risking it in my opinion. My Reznor I ran at the same temps and the combustion chamber was still in good shape after I used it for 18 years and I think it was nearly 15 years old when I acquired it back in 1995. All I ever did was install a new fan motor and igniter in that time but I could tell it was on it's way out and the guy made me a screamin' deal when I put the new A/C and furnace in my house on the Hot Dawg for my shop. Figured I hadn't better pass it up or the deal may not come around again.

Mike.

 

[James-W]

I have a Hot Dawg 60,000 BTU natural gas heater in my 24 X 36 garage with 8 foot ceilings and it works very well. I could maybe get by OK with a little smaller unit, but on really cold days I wouldn't want anything smaller. I keep the garage at 50 degrees when I am not out there working, and I turn it up to 70 degrees when I work on a project.

 

[csp]

Having installed several of these (and other brands/models) I wouldn't go with less than 60k for that size.

 

[the duck]

Sounds like 60,000 or even 75,000 BTU's may be the better choice.
Thanks for the input,
Matt

 

[wes73]

I have a 75K Modine Hot Dawg in a 30x40x10. I keep it at 50 and turn it up as needed. I got the separated combustion and two stage gas valve on mine. I went through the wall using their concentric kit; only need 1 hole for both vent and intake. The two stage gas valve fires at either 50% or 100%. Last year was my first winter with it, and I went through 80 gallons of propane. That is with using it about 3 nights during the week and 8-12 hours each weekend. I usually kick it up to 74 when I'm in there. For reference I have 1 9x10 and 1 9x18 insulated OHDs, 3 windows and 1 man door. Walls are insulated with R13 and ceiling with R19.

I used Modine's heat loss calculator to figure out ho many btu's I needed.

I ordered mine from http://www.h-mac.com.

 

[Spudland_Dave]

Beware that these units are not rated to maintain a temperature that low. That will lead to condensation that will rot the heat exchanger out.

Best I can say is refer to the manual.

My understanding is the setpoint temp isn't the problem. Having a heater TOO Large will result in the condensation/rotting issue.

Key is a higher BTU heater will only cycle on once/twice to heat a small space, never really getting to full operating temp. Where a smaller/correctly sized one will cycle & run much more & longer and reach full operating temps which will burn off condensation.

Again, just my understanding of the issue.

30x50x10 high...75k Hot Dawg in Maine...Love it.

 

[the duck]

Thanks for all the input. I think I'm going to go with the 75,000 even though it may be a bit on the large size.

Wes73:
" I got the separated combustion and two stage gas valve on mine. I went through the wall using their concentric kit; only need 1 hole for both vent and intake."

Do you think these were both good additions to the unit? I've been looking at the h-mac site - is the concentric kit available there? I haven't noticed it, maybe I've missed it.

Spudland Dave - Thanks, sounds like your building and winters are comparable to mine - I'm about 45 minutes north of Albany...

Thanks again,
Matt

 

[rlitman]

My understanding is the setpoint temp isn't the problem. Having a heater TOO Large will result in the condensation/rotting issue.

Key is a higher BTU heater will only cycle on once/twice to heat a small space, never really getting to full operating temp. Where a smaller/correctly sized one will cycle & run much more & longer and reach full operating temps which will burn off condensation...

It is a little of both.

Too large a heater will result in short cycling. But too low a setpoint will keep return air temperature low, which can also result in condensation.

 

[Milton Shaw]

I have a 28x32 shop with 10 foot ceilings and a ceiling fan sure does help get the heat of the ceiling. I can run the tstat 10 to 15 lower with a ceiling fan circulating the heat that is there. Might not be as bad with a 9 foot but check temp at ceiling when you get it running and see if there is a lot of heat up there you are not being able to feel.

 

[zmotorsports]

I have a 28x32 shop with 10 foot ceilings and a ceiling fan sure does help get the heat of the ceiling. I can run the tstat 10 to 15 lower with a ceiling fan circulating the heat that is there. Might not be as bad with a 9 foot but check temp at ceiling when you get it running and see if there is a lot of heat up there you are not being able to feel.

I have found that when I turn my ceiling fans on in the winter the heater doesn't cycle on quite as many times per hour. I just turn them on enough to force the heat down, not enough to actually feel any air movement. In the summer I will turn on the ceiling fans to feel air movement which helps with cooling. My ceilings are 14' high for reference.

Mike.

 

[the duck]

Good to know - we've been thinking about installing a single ceiling fan, dead center in the middle of the 30x40' ceiling. Possibly two, one at 13' in and the second at 26' in...?
Thanks,
Matt

 

[zmotorsports]

Good to know - we've been thinking about installing a single ceiling fan, dead center in the middle of the 30x40' ceiling. Possibly two, one at 13' in and the second at 26' in...?
Thanks,
Matt

I have four in my 34x34 shop and each pair (front and rear) on different rheostats to control them.

Mike.

 

[toyotadriver]

I have a 30x40x10. Open rafters but the roof is insulated. Well insulated. I live in a warmer climate than you. I put a 45k btu Mr Heater. It would heat the shop but took a long time to warm it up. I replaced it with a 80k btu Mr Heater and am much happier.

 

[the duck]

Leaning toward the 75,000 BTU Hot Dawg - We have some weeks in January/February where the highs may be in the single digits and the lows are in the negatives. It sounds like a little extra fire power may be useful, especially during those extreme weeks.
Thanks for all the input - it's nice to hear from some experienced users. This whole process makes me wish there were about half as many choices - lights, heaters, doors, etc. So many options, they're making my head spin...
Thanks again,
Matt

 

[351cmach]

I have a 28' x 38' 12' ceilings 2x6 walls insulated and sheet rocked. I have a 75k BTU Hot Dawg. I only use it when I'm in the garage. Quick warm up and doesn't have short cycles.

 

[csp]

I have four in my 34x34 shop and each pair (front and rear) on different rheostats to control them.

Mike.

[hijack] You have two fans on a single rheostat? Mind if I ask what rheostat you're using? I have a pair of fans on one circuit and didn't think about each one needing its own circuit if I were to use standard fan controllers. Haven't bothered to look for a controller/rheostat that will work on two fan motors. [/hijack]

 

[zmotorsports]

[hijack] You have two fans on a single rheostat? Mind if I ask what rheostat you're using? I have a pair of fans on one circuit and didn't think about each one needing its own circuit if I were to use standard fan controllers. Haven't bothered to look for a controller/rheostat that will work on two fan motors. [/hijack]

Nothing special, just a 20-amp potentiometer for each pair. I did put a nice white knob on them so they match my wall switches and label them for aesthetics though.

Mike.

 

[wes73]

Wes73:
" I got the separated combustion and two stage gas valve on mine. I went through the wall using their concentric kit; only need 1 hole for both vent and intake."

Do you think these were both good additions to the unit? I've been looking at the h-mac site - is the concentric kit available there? I haven't noticed it, maybe I've missed it.

Yes, both were good additions. With the separated combustion chamber there is no need to worry about fumes and the flame. Yes, the concentric kit is available from them as well. I also have 2 52" ceiling fans. Helps during all seasons.

 

[LX-Markham]

Question about the use of a fan to circulate the air: is it not possible to turn on the fan without igniting the burners? Can the fan be used to circulate air all the time?

 

[mc1984ss]

Beware that these units are not rated to maintain a temperature that low. That will lead to condensation that will rot the heat exchanger out.

Best I can say is refer to the manual.

I learned this the hard way. Mine rotted out due to me keeping it at 40 degrees the first couple of years

 

[jpeterson1976]

I just had a 45,000 put in. This is for a garage 24x24. 9 ft ceilings. Oversized because I have an addition 1 stall I may open up and insulate in the future.

Looking forward to seeing how it works. It sure is quiet when they did the test start up.







Sent from my SM-G935V using Tapatalk

 

[2CRUZ]

I have a 30x40 garage and I have a 125 thousand btu Hot dog heater. My garage is insulated top and all sides with plastic vapor barrier top and sides. It doesn't take it long to warm up the garage. I don't know if it will damage the heat exchanger or not? If it does can it be repaired?

 

[Orionrising]

Direct vent propane heaters in a well sealed garage will put a lot of moisture in the air

Sent from my Moto G (4) using Tapatalk

 

[csp]

I have a 30x40 garage and I have a 125 thousand btu Hot dog heater. My garage is insulated top and all sides with plastic vapor barrier top and sides. It doesn't take it long to warm up the garage. I don't know if it will damage the heat exchanger or not? If it does can it be repaired?

You will get many, many years of service out of it. Don't let the chicken littles make you think it's going to go kaput right away.

A bad heat exchanger is an item that means the heater needs to be replaced. It isn't cost efficient to replace and isn't repairable.

Hot Dawgs are NOT direct vent, so that comment isn't applicable. They vent externally.

 

[toyotadriver]

Direct vent propane heaters in a well sealed garage will put a lot of moisture in the air

Sent from my Moto G (4) using Tapatalk

I think you mean UNVENTED heaters will put a lot of moisture into the air.

 

[csp]

Neither term is applicable in this case.