Hi there, I'm new here and have a question that I haven't found an explicit answer to. A couple of years ago I built a 28x30 detached garage that I now want to heat. A couple of months ago I picked up a used natural gas Modine heater, model PAE75AC. I found and downloaded the manual for it. I was hoping to run the venting for it horizontally out the side of the wall and avoid having to cut into my roof. The manual does not give instructions for horizontal venting, only vertical through a roof. Is there any reason I can't horizontally vent this unit? It does not have a power vent, only fan on it is for blowing the air past the heater tubes. I was about to roll the dice and buy a bunch of Cat III parts to vent out the side, but figured I better check in here first since this is very expensive stuff. I'm looking for some knowledgeable advice on this. I've attached the manual I downloaded as well. Depending on which way I need to go with this, I'll have some follow up questions. I've tried calling Modine tech support but they won't talk to me unless I'm a contractor.
Heater venting advice needed
- Thread starter rgitzlaff
- Start date
if it's not listed in the manual, the answer is nope
gravity vent can only go up. you have to go through the roof
Okay, so I properly understand this, without a blower to push the gas out, the "gravity vent" relies on the hot gases rising to pull the exhaust out... and this is what is meant by "draft"? So if I horizontal vented, the gases would maybe partially back-feed into my garage?
So then do I use type B vent piping for this? Any particular type of cap that I should put on top, or does this not really matter as long as it keeps the rain out?
So then do I use type B vent piping for this? Any particular type of cap that I should put on top, or does this not really matter as long as it keeps the rain out?
The manual doesn’t cover it. It is not allowed. You may be able to power vent it with a Tjernlund Gpak, but you are ,in my opinion spending money you don’t need to spend. Get on the tube and look at how to cut a flashing into a roof. For a vertical vent on that unit you will use B-vent. Compare the cost of B-vent to Cat III and you will see how happy you are punching the hole in the roof.
For the most part, any heating unit that does not have a raft motor needs to vent straight up. Gas heaters can generally use B-vent.
Absolutely do not horizontal vent a Modine PAE75AC!!
One post mentioned a Tjernlund Gpak, but you can buy a new heater for not much more money.
You have the manual, do what it says and nothing else!
Absolutely do not horizontal vent a Modine PAE75AC!!
One post mentioned a Tjernlund Gpak, but you can buy a new heater for not much more money.
You have the manual, do what it says and nothing else!
fitter30
Well-known member
If u run vertical vent u just lost the ul and any other ratings the furnace has.
Thats not true. Its built to be Run vertical. the ul rating is rated for vertical
Steve in UT
Well-known member
I added a power vent to regular hanging heater and ran it through the wall horizontally. Worked great for years. As I remember the aftermarket power vent wasn't all that expensive. Edit: After looking around I think this one is like the one I used and apparently the price has gone up substantially since I bought one!
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I take it you added a spill switch so the unit shuts down if the aftermarket power vent fails?
Steve in UT
Well-known member
It has been quite a few years, so I don't remember everything about the wiring. I just remember the venter would start and after a delay the furnace would start. I think it is done through a vacuum switch. So if the venter isn't running, the vacuum switch will shut the furnace down.
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fitter30
Well-known member
Did u even look at his first post and the manual. Its a 80% furnace. Can't run through a side wall.
I did say "vertical" vent going up through the roof.
"Horizontal" or parallel going out the side wall.
I am saying he can not go through the side wall he has to go up through the roof...... Am i missing something that i confused you ?
I do not see from the manual that's its an 80% ul rated furnace..... i see its a gravity vented modine unit heater? are you looking at the same manual he posted?
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fitter30
Well-known member
I was wrong u wrote vertical.