Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 10-14-2011, 12:05 PM   #1
Newbie
 
Join Date: Oct 2011
Location: Fargo, ND
Posts: 20
Share |
Default

Install Help on 75K BTU Garage NG Furnace


I have a 32x26x12' high garage that I'd like to heat full time for winter. I have purchased a Mr. Heater 75000 BTU Garage/Shop Natural Gas furnace for this task.

I have a question regarding the flue install. Several homes in my area have this type of unit, all were professionally installed with a roof chimney. Since I'm doing it myself, I don't want to put more holes through the roof and would like it to exhaust out an exterior wall.

But I'm not sure how the thimble goes through the wall with respect to the vinyl siding. Does the metal thimble have to go thru a square box vinyl siding peice or get covered by the square box with a hole for the pipe. Also what type of sealant should I use for the thimble against the house wrap / or vinyl siding square? Fire stop caulk?

How far does the exhaust pipe have to be from the soffitt and how far does it have to extend from the exterior wall?

Thanks for the help, trying to do a good job up to code, just not sure of the codes to follow.

Beware that the gas line hook up will be done by a pro, and tested. Not interested in doing connections there.

live4spd is offline   Reply With Quote
Old 10-14-2011, 01:57 PM   #2
Retired from the grind
 
gregzoll's Avatar
 
Join Date: Dec 2006
Location: Midwest - Central Illinois
Posts: 13,992
Default

Install Help on 75K BTU Garage NG Furnace


Call a roofer to do it. As long as you have materials, the job should not be more than maybe $150 to $250 at the most for labor.

__________________
Ren: Now listen, Cadet. I've got a job for you. See this button? Ren: Don't touch it! It's the History Eraser button, you fool! Stimpy: So what'll happen? Ren: That's just it. We don't know. Maybe something bad, maybe something good. I guess we'll never know, 'cause you're going to guard it. You won't touch it, will you?
gregzoll is offline   Reply With Quote
Old 10-14-2011, 02:05 PM   #3
HVAC Tech/Owner
 
Join Date: Nov 2010
Location: VA
Posts: 436
Default

Install Help on 75K BTU Garage NG Furnace


Quote:
Originally Posted by live4spd View Post
Beware that the gas line hook up will be done by a pro, and tested. Not interested in doing connections there.
But that's a connection that can pass the "sniff test"......CO from the flue just puts you to sleep forever.....
Technow is online now   Reply With Quote
Old 10-14-2011, 02:22 PM   #4
Newbie
 
Join Date: Oct 2011
Location: Fargo, ND
Posts: 20
Default

Install Help on 75K BTU Garage NG Furnace


Hire a roofer for that really? What's the advantage of the roof vent versus horizontal vent. Just doesn't seem that hard to do, I'm trying to justify why it should go vertical, etc.
live4spd is offline   Reply With Quote
Old 10-14-2011, 02:42 PM   #5
Member
 
Join Date: May 2008
Location: Near Philly
Posts: 1,990
Default

Install Help on 75K BTU Garage NG Furnace


THe install instructions show 12" space minimum from wall overhang to termination cap.
Have you read the instructions? If so, and it they are still not clear, I'd pay someone who knows how to do it and sleep better at night. Might want to check into a chimney repair, fireplace installer for installation.
Instructions for the thimble may provide guidance for your other questions re: sealing etc...
bob22 is offline   Reply With Quote
Old 10-14-2011, 06:24 PM   #6
Member
 
raylo32's Avatar
 
Join Date: Nov 2006
Location: Maryland (DC 'burbs)
Posts: 1,044
Default

Install Help on 75K BTU Garage NG Furnace


The other thing I would look at is sizing. 75KBTUH for one room, albeit a big one?? Seems waaayyy oversized. It might be semi-reasonable if you only heat the garage part time and want a rapid warmup when you head out there. But for full time heating of such a small space a much smaller unit should suffice.

Last edited by raylo32; 10-14-2011 at 06:27 PM.
raylo32 is online now   Reply With Quote
Old 10-14-2011, 06:28 PM   #7
Newbie
 
Join Date: Oct 2011
Location: Fargo, ND
Posts: 20
Default

Install Help on 75K BTU Garage NG Furnace


Well far as sizing I need 60k according to the pros. But only the 45k and 75k are readily available.
live4spd is offline   Reply With Quote
Old 10-14-2011, 06:42 PM   #8
Member
 
raylo32's Avatar
 
Join Date: Nov 2006
Location: Maryland (DC 'burbs)
Posts: 1,044
Default

Install Help on 75K BTU Garage NG Furnace


Maybe so, but seems way off base to me, unless uninsulated in the Yukon... or perhaps the pros are sizing it for a part time fast heat up scenario as I mentioned. If you don't want to pay for a proper heat loss calc try the link below. It will give you a fairly accurate estimate and a reality check for what they are telling you.. I really don't believe 60K just for a garage... but that's just me.


http://www.builditsolar.com/Referenc...s/HeatLoss.htm
raylo32 is online now   Reply With Quote
Old 10-14-2011, 06:55 PM   #9
Member
 
raylo32's Avatar
 
Join Date: Nov 2006
Location: Maryland (DC 'burbs)
Posts: 1,044
Default

Install Help on 75K BTU Garage NG Furnace


I just ran your scenario on that calculator assuming no windows and a 10 degree F design outside temp (it has a built in 70 degree inside design temp) and got 35K BTUH heat loss. Also assuming R20 ceiling and R10 walls. This would make the 45K unit about right for you and sounds a lot more reasonable to me. Not definitive... just another data point for you.
raylo32 is online now   Reply With Quote
Old 10-14-2011, 07:02 PM   #10
Newbie
 
Join Date: Oct 2011
Location: Fargo, ND
Posts: 20
Default

Install Help on 75K BTU Garage NG Furnace


Well appreciate the work. FYI this is in Fargo ND so outside temps can be -30. Might figure differently in the calculation.
live4spd is offline   Reply With Quote
The Following User Says Thank You to live4spd For This Useful Post:
gregzoll (10-14-2011)
Old 10-14-2011, 07:03 PM   #11
Newbie
 
Join Date: Oct 2011
Location: Fargo, ND
Posts: 20
Default

Install Help on 75K BTU Garage NG Furnace


Raylo32- what's your opinion on horizontal versus vertical exhaust?
live4spd is offline   Reply With Quote
Old 10-14-2011, 07:11 PM   #12
Member
 
raylo32's Avatar
 
Join Date: Nov 2006
Location: Maryland (DC 'burbs)
Posts: 1,044
Default

Install Help on 75K BTU Garage NG Furnace


Well, -30 F calc gives 48K heat loss. Not sure how often you get that... or why you would be in the garage then. But I am sure glad I don't live there!

I will defer to the pros on the venting question. I assume you are talking about an 80% efficient type B vent. I have never seen one of those that didn't go out the roof. If horizontal is allowed I would be very careful as to the code and all specificed clearances and overhangs. They exist for a reason.

What I would do is get a high efficiency condensing furnace that can be more readily vented horizontally (still lots of clearance and overhang requirements) and also save a lot of $ over those long cold winters.

Quote:
Originally Posted by live4spd View Post
Raylo32- what's your opinion on horizontal versus vertical exhaust?
raylo32 is online now   Reply With Quote
Old 10-14-2011, 07:17 PM   #13
Member
 
raylo32's Avatar
 
Join Date: Nov 2006
Location: Maryland (DC 'burbs)
Posts: 1,044
Default

Install Help on 75K BTU Garage NG Furnace


Oh, I have to revise the first 10 degree loss calc. It had a default value for a floor loss (I assume this is a garage on slab) that I neglected to zero out.

So the calcs show:


10 degree F design temp: 29K
-30 degree F design temp: 48k
raylo32 is online now   Reply With Quote
Old 10-14-2011, 07:24 PM   #14
Newbie
 
Join Date: Oct 2011
Location: Fargo, ND
Posts: 20
Default

Install Help on 75K BTU Garage NG Furnace


Well either way that's alot closer to 45k than 75k.

Alright thanks for the advice.
live4spd is offline   Reply With Quote
Old 10-14-2011, 08:06 PM   #15
I=E/R
 
a7ecorsair's Avatar
 
Join Date: May 2010
Location: Minnesota
Posts: 2,052
Default

Install Help on 75K BTU Garage NG Furnace


Quote:
Originally Posted by raylo32 View Post
Well, -30 F calc gives 48K heat loss. Not sure how often you get that... or why you would be in the garage then. But I am sure glad I don't live there!
Ya got to keep the snowmobiles running
Sometimes you have to fix the snowblower
Sometimes it gets to -40 in Fargo

a7ecorsair is offline   Reply With Quote
The Following User Says Thank You to a7ecorsair For This Useful Post:
gregzoll (10-14-2011)
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Furnace in garage - clearance to garage door? vacatari HVAC 5 11-05-2010 10:20 PM
enclosing a furnace in a garage Big Daddy1 HVAC 4 01-02-2010 06:47 AM
Quote on attic install new furnace (sorry-newbie) drowell HVAC 1 10-29-2009 04:05 AM
Need to install a sub-panel in the garage serrano Electrical 3 02-11-2009 10:48 PM
Trane xv80 install draft exhaust wires on furnace biggiant HVAC 5 02-10-2009 06:50 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.