HOT Dawg in 32*36 Pole Barn

[KM1013]

Hi,

People on this site have been very helpful. I've read up a bunch and checked some other threads. Just want some feedback I guess to be sure. So, in PA. 32*36 with 10.5' ceiling and scissor trusses. So the volume is a bit hard to calculate but figured about 12,000 cubic feet. Two R17.5 10*10 doors. One man door. 6 small hopper size windows AND a kinda loose barn door on one side. 2" rigid on the walls, insulated slab and 4" fiberglass bats in ceiling. I am obviously not super insulated. It's a hobby garage, wood work, cars etc. So, I think the HD75 (75,000 BTU) unit should do it. Now the other thing. I had a chat with one of the online companies about whether or not to draw air from the outside or not. That unit would be HDS75 and is +400. He said he didn't think it was necessary. Would love to save the money. I'm sure I'll have that ******* in a vent kit etc. Thoughts/Advice?

Thank you all,
Kurt

 

[wes73]

I'm just west of you in Lebanon county. I have the 75K HDS in a 40X30x10. Fully insulated(3.5 in walls and 6 in ceiling) with a 9x18 and 9x10 insulated OHD, 1 man door and 3 windows. I went separate combustion just to be safe. More $$$ upfront, but peace of mind knowing any fumes would not be used as combustion air. I have my tstat set at 52 for each of the time settings just to make sure it always stays at least 52 unless i turn it up when in working in there. Works great, this will be my 3rd winter. I ordered mine through https://www.h-mac.com/.

 

[finn]

40k would be plenty, until I read about the loose barn door.

You need more ceiling insulation, too.

I can heat a 32x75 part of my building w/a 75k unit, and I have 16’ ceilings. 75k should cover you, but may be marginally oversized when you fix the leaks and insulation.

 

[KM1013]

Hey Wes. Funny that is the exact company that told me I don't need the separate combustion model. But, like you, I am wondering about safety. Not enough of an expert to know what kind of risk I am at. I use a torch and weld on occasion. Now all of that would be with the garage doors open in the summer months.

Finn. I am sooooo over budget on my house build that there just isn't much left. I don't see more than 4" going in the ceilings. Once it's done, it's done as I have no access up there without unscrewing my metal ceiling. Now the loose barn door that is one of those if you want it done right you have to do it yourself deals. I guess I have to fix that too.

Thanks for all the help.

 

[wes73]

Here is the heat loss calculation I used to figure out the 75K BTU requirement for mine. It does not short cycle and keeping it at 52 minimum and running at 70 on weekends only burns through 120 gallons of propane a year.

http://www.modine.com/download/.../75-202.pdf

As for access after the ceiling is done, you could have them put in an access hole (2'x2' ish). A friend did this and he had used it a few time jut in the first year.

 

[wes73]

I also got the 2 stage valve in mine which works out well.

 

[Lonstar]

I'm in Cumberland County. My garage is 26 x 48, Half of it (26 x 24) has a 9' ceiling, other half 13'. There's a second floor above, ceiling is open floor joists. No insulation on walls or ceiling. Two 9' wide insulated doors at far end with 13" ceiling. One 16' wide insulated garage door on one side of the 9' high section, another 8' wide insulated door opposite the 16' door. Also have 2 entry doors and a few low cost windows (30x36).

I've had a 75k Modine (HD75) in the corner of the 9' ceiling area for 13 years. It gets the garage plenty warm. I mounted a 12" diameter fan at the top of the wall in the middle (13' up), that points down on the two bays in the 13' section to warm that area when needed. We park two cars in the 13' section, my 'workshop' area is the 9' section. One winter when daytime temps were in the 20's I stained a door in a 13' ceiling bay. Set the stat to 80 degrees and turned the aux fan on. It kept the entire garage at 80 degrees.

As far as cost to run it, I have no idea, never bothered to figure it out. The heater is NG and I have NG appliances and heat in the house. Use the heater as needed, sometimes days on end, sometimes not a all for weeks. It runs often when it's really cold - run for 5 -10 minutes, shut off for 5 minutes, then back on.

As far a separate combustion, for my needs it would be a waste of money. I've done wrenching, painting, welding, you name it, and never had an occasion where I wished it had separate combustion. When doing any extensive painting in the winter I use the 13' bay (so furthest from the heater) and put a box fan in a window when spraying. The aux fan up high is the pusher, the window fan the puller.

 

[KM1013]

OK I think you guys validated my 75,000 BTU choice. Lonstar seems like it's really working for you. Two stage valve. OK. Now to find somebody to hook the thing up. My house contractor ---- too slow. Got a bid including unit from a local guy for $4500. Yeah right. Wes if you get this did you order the vent kit etc. from H-mac too? Attached is my ceiling so you guys can see there's not much room left up there.

 

[Lonstar]

My garage is a bit of a weird design, hard to describe. I'd post pics but they'd be embarrassing. I installed a ductless mini split A/C unit in the 9' high ceiling side of the garage over the summer, which spurred me to insulate and drywall the walls in that area, so I have **** stacked and strewn everywhere. I built the garage in '04 so 13 years worth of shelving, benches.....everything attached or close to a wall, had to be yanked out and stacked out of the way to do the job. The garage is in total disarray right now.

Upside - redesign of how I had things arranged. After 13 years I'm aware of every shortcoming and wrong decision I made, now is the chance to correct them. So far extremely pleased with the rebuild.

Downside - I still need to use the garage for garage things, all while finding time to put it back together in the new and improved way.....and I can't find ****. Very very frustrating. I've already had to buy things I know I have but can't find.

Anyhow, the point of this post is to add something I didn't say in my first post, seeing your trusses reminded me of it. Fans. You need fans. I'm guessing you already know this, but I'll validate it. My heater is mounted diagonally in a corner. The aux fan is about 25' away from the heater on the opposite wall, lined up roughly inline with the direction the heater blows. When I'm in the garage, 99% of the time I'm working in the 26x24, 9' ceiling area. I rarely turn the aux fan on. When I go down the 6 steps into the 13' ceiling area it's not that warm. If it's really cold outside it's cold in the lower garage area. But when I turn that little aux fan on the lower area warms up to the same temp as the upper area. Huge difference between fan off and fan on (duh, heat rises, so obviously blowing it down will throw heat down). Just my 2 cents - add a couple fans.

Attached are pics of my aux fan.....I know, it needs cleaned. I said it's a 12" diameter fan, that was a guess. Not sure what actual diameter is but 12" is pretty close. It gets the job done. It's a commercial fan I got it from a Lowes store that moved to a new location. It was in the outdoor garden area, I guess they used it to move air around for the plants? I bought 2 of them, haven't put the second one to use yet. That'll be part the the new phase garage rebuild.

As far as mounting the heater, not something you'll do on your own? It's not that difficult. Run power and black pipe, then hang it up. I can understand wanting a pro to do a vertical vent, but if horizontal, that's not difficult either.

 

[KM1013]

Thank you Lonstar. I was going to have some fans very similar to what you have from Northern tools. Mostly, though I was thinking air flow on hot days and not moving hot air around but could be both. I can fabricate and mount the unit. Vent is run out the back and you can see I have nothing but corrugated metal. I guess I'm old but gas still = explosion to me and I didn't want to mess with the actual hookup. What valve this that the other thing. But, yeah I'll get it up there. Good move on your re-design. I have **** everywhere in mine and I want to do an epoxy floor and I have nowhere to go with the junk. Thinking about renting a POD for a couple of weeks. My contractor has me so screwed on this whole project I'm constantly stressed out and I've had to resort to doing a lot more than I planed on. Maybe shoot me a pic of your installation so I can see the ducting and layout. Thanks!

 

[Lonstar]

I'll take some pics and post them. The heater isn't mounted right now, I took it down to do the drywall and am now trying to determine if I need to change the type of vent pipe I used originally. I have a post titled "Modine 75k Hot Dawg Vent Pipe", posted it a few days ago so it's not that old. If you read that you'll know why I haven't put the heater back up yet.

What type of gas are you using?
What size gas pipe are you running to the heater?
How long does your gas line need to be?

Might be able to hook you up with some parts you need (at a good price). Reading is about an hour from me.

 

[dkmc]

I can't help but point out that the Separated Combustion feature isn't just about safety. I will also save gas because with non-separated combustion,
the burner pulls in combustion air from the room. It also pulls make up air in thru all the cracks and loose fitting doors and windows, cooling the room off faster. Separated combustion takes in outside air right at the heater, uses it for combustion and then out the exhaust. No negative pressure in the room.
It can save some bux over several heating seasons.
Sterling offers a SC vent kit for their regular non SC heaters. Seems like it's $250-ish. Lower cost than some SC units from other mfgrs.

 

[Lonstar]

I can't help but point out that the Separated Combustion feature isn't just about safety. I will also save gas because with non-separated combustion,
the burner pulls in combustion air from the room. It also pulls make up air in thru all the cracks and loose fitting doors and windows, cooling the room off faster. Separated combustion takes in outside air right at the heater, uses it for combustion and then out the exhaust. No negative pressure in the room.
It can save some bux over several heating seasons.
Sterling offers a SC vent kit for their regular non SC heaters. Seems like it's $250-ish. Lower cost than some SC units from other mfgrs.

That's a good point, didn't think about that.

 

[bobbyjean]

modine offers a two stage valve for their garage heater's.................
i learned something new today and i didn't even have coffee yet
great info

 

[KM1013]

Hi Everyone,

Well this is starting to get confusing again. To answer some questions. Garage is separate from the house and gas will enter through a conduit buried in the ground. I doubt any black pipe will be used at all. The run has to be 60ish feet. This is a natural gas hookup.

So we have separate combustion chamber and an upcharge of $199 if I want two stage valving. I'll assume about $250 for vent but didn't see it on their website (will Google for the Sterling vent kit).
https://www.h-mac.com/modine-hds75-ss.html
or
https://www.h-mac.com/modine-hd75.html
with something like this for venting:
https://www.h-mac.com/Z-Vent-3In-5Ft-Horizontal.html

I'm still stuck on my must haves vs. my this would be great to have if I had nothing but money.

 

[dkmc]

If your install is long term, 15-20 years, it's probably for sure worth the extra investment up front. The stainless comb chamber is a plus as well, as steel and aluma-steel units do have a shorter life. Double the price makes it a tough pill to swallow tho.

 

[James-W]

If you do painting or if you use chemicals that have fumes that could potentially burn, then I would certainly go with bringing in outside air for combustion. Also, if you do woodworking and have a lot of dust in the air, it would be best to bring in outside air for the heater.

If you just use the building for parking vehicles and maybe do a little woodworking and/or a little wrenching, it would still be a good idea to bring in outside air for the heater, but I don't think it would be anywhere near as important.

 

[KM1013]

Hi,

So I've been pounding through more threads. Here's what I see. Most everyone who asks sealed or not sealed gets encouraged to go sealed. Now sealed does not mean explosion proof and I question my odds here since there is no lit pilot in the first place. That said there are other advantages to sealed and I get that.

Now let's throw this in the mix. Sterling SG75. Sealed with vent kit and piping comes in at $1177 on my doorstep. There is no option to go two stage but that comes in close to my budget for parts of 1G. Puts it's 500-600 cheaper than Modine. See below.

http://www.littlegreenhouse.com/accessory/heaters4-sterling-gg.shtml

 

[Pruittx2]

I'm doing Big Maxx 80,000 in 28x48x10, pole barn. Two 9ft insulated doors. 60% of walls are sprayed already, no windows. got heater for 425 delivered. going with an all B-vent, thru roof vent, and doing all work by myself. Propane co will test and hookup gas lines, and do first burn. Probably $600 total all in.