high efficiency garage heater

[stevehink]

I am going to be heating my attached garage (3 car, about 23'x28' w/

10' ceiling). I was looking at a Hot Dawg garage heater at first, then I realized the mounting location would be on a wall that is directly opposite to the living room and thought the fan noise may be a problem. I have also considered a 45,000 BTU 80% horizontal mount Goodman, but I was told that the burners are fairly loud. I have now been thinking about a 93% efficient Goodman model GCH90453BX. I believe it would be quieter, but I have been told condensate may freeze if the heater is not used in freezing weather. Doesn't all the condensate drain from the furnace, or is some left when it's shut down? I usually leave the furnace set to 45 or so in the winter, but if I did shut it down would I have a problem? I like to keep the garage warm for my diesel truck and on occasion I watch my mom's dog, and she stays in the garage, in that case or when I am working in the garage, I heat to 65 or so (BTW, I am in the midwest with cold winters). Another advantage to the high eff. furnace is that I would have to have a long run of 25' or so type b vent with an 80% furnace, the cost between the 80% and 93% isn't too much, probably about the same as the cost of the vent pipe. With the 93%, I would obviously be using PVC vent pipe that would be cheaper and easier to install. I also wanted to use a regular furnace so I have the option to add AC in the future, I have no place to put a window unit. Any thoughts on the condensate issue? I do have an easy route to run the drain to the basement through the garage wall. Thanks for any advise!

[Joe]

I have a similar situation in Central Illinois, garage 26' square, 9' ceiling. I heat it with a ceiling mounted Modine 45 K BTU Hot Dawg vented with regular double wall galvanized up through roof. There is no point at all in any other way of mounting it as the unit has a very vigorous heat flow, so distribution is no problem. IF you put it in a corner, the opposite corner will get plenty of heat. Metalbestos vent pipe is good but pricey. We used another brand from Menards that was fewer $$. A ceiling mount requires only a short run of vent and IIRC my most unusual expense was a 4+ inch hole saw to cut the vent outlet in the roof. I have used many Modine heaters in buildings over the years and the Hot Dawg is a worthy addition to their line. As far as noise is concerned, even rigid mounting on the OSB ceiling produces no more than a gentle hum when it operates. Highly recommended.

Joe

[stevehink]

Thanks for the replys. The AC would be for my mom's dog when she stays in the summer, it's very hot and humid in the summer, so not as ridiculous as you may think. Joe, thanks for the info on the Hot Dawg, that's still an option, especially if low noise. I can get the 93% Goodman for about $300 more than the Modine, so I'm going to have to think some more. The reason I have to run such a long vent pipe is that I have a very steep pitch roof and I can't run the pipe straight up from the furnace location as it would be visible from the street side of the house so there will be a bit of a horizontal run to get it to the proper exit location. It's probably going to be 25'- 30' or so. I'm not sure what Pat means about running it off the the house furnace? If you are mean running a duct out to the garage, that's against code and the furnace wouldn't handle the extra load. I'm more concerned about the freezing condensate in the furnace. Any other input would be appreciated. Thanks!

[hallerb]

If you have the bucks for AC start by insulating the entire building really well. expanding closed cell foam is about R7 or R8 per inch as it expands it seals all the tiny nooks cranies and air leaks.

goodman 90+ furnace can be directly vented thru the wall with PVC pipe.

[Don Young]

Some high-efficiency furnaces do have a condensate trap which retains water when shut down and I would imagine that freezing could damage it. It might be practical to install a heat tape or similarly protect it. You would probably have to get specific information from the manufacturer.

Don Young

[Joe]

Forgot to mention, in my garage/shop I have a big old 220 V used Frigidaire window AC unit that does a fine job in the summer. BTW, the walls are insulated and we upgraded the ceiling insulation to 6" plus. RE: heater vents, there is nothing wrong with angling a Metalbestos type vent to have it come out behind a roof peak away from the line of sight of the street. In small towns like ours, however, it didn't bother me or the neighbors to have the discreet vent visible, and in fact, it might even be a small status symbol, "Hey, he's got a heated garage!", kind of like her granite counter tops only more practical. Bottom line, the simpler HVAC solutions are far cheaper for a garage / shop where limited occupancy allows systems to operate well below domicile requirements.

Joe

[Big_Jake]

Why would you have to run that much b vent? You should be able to run it out the wall or roof pretty close to the unit.

I would be concerned about your ability to keep the condensate trap from freezing, so I would pick the 80% furnace as the cheaper (and easier) option. Depending on where you buy it, the furnace itself should be cheaper than the Hot Dawg. Plus you could run some spiral duct (or whatever) off the furnace to distribute the air better.

JK

[stevehink]

I have to run that much vent pipe because I have no wall to exit through and as I said, I have to run the pipe to a suitable exit location. I think I would save enough money on vent pipe to pay the difference in the 93% furnace. I'm not too worried about freezing as I will keep the garage heated to above freezing. If installed properly, wouldn't all the condensate drain? That's what I'm curious about, I'm not to sure how these are built and how the condensate drains. Thanks again. Steve

[Big_Jake]

It depends on the brand. For example, most Carrier (& Bryant, Payne, etc) have internal traps that could be damaged by freezing. Goodman, for example, has an external "cup" that the condensate drains into but that could freeze also, not damaging the unit but it would still need to be thawed before the furnace could drain properly. Most furnaces would need heat tape around the trap and possibly also around some internal plumbing to keep the condensate from freezing and clogging or damaging the furnace.

You would keep the garage heated above freezing all winter??

Feel free to email me off list if you want to kick this around some more.

JK