Hot Dawg Install Question

gary the cobra · Jan 27, 2007

Guys, I am installing a 75k btu Modine Hot Dawg, I need to vent it horizontally
out the back with one 30 degree bend in the vent pipe. This is a 4 foot run, I will slant it down slightly for condensation. The back vent pipe of my heater is 3", can I run 3" all the way outside, or do I need to convert to a 4 or 5" vent pipe at the heater and continue this outside? The instructions that came with the heater are not real clear to me. I see a lot of pictures posted here convert from 3" to a larger diameter pipe to run outside. I have already purchased all 3" pipe. Before I install it I'm hoping you guys can help me answer these questions.
Thanks. Gary.

russlaferrera · Jan 27, 2007

You can not go smaller. You can go larger. However the span of 4 feet will not require any changes. Most of the instructions will tell you about the min. you can be to a combustable and were you come through the wall you have to be a min above 7 ft from the ground and to slope the vent pipe down...russ

Abodyracer · Jan 28, 2007

Gas fumes rise. Do not point it downward unless it uses a blower to force the exhaust out the pipe. If it does not use a blower make sure the pipe has rise to it. Without rise the exhaust will not vent to the outside, it will backup (for lack of a better term) into your garage.

oldgoat · Jan 28, 2007

That is what I was told when I had to replace my water heater one time anyway. I won't say for sure but I thought it was like a 1/4" per 3ft.

beetroot72 · Jan 28, 2007

This is from my install manual ...

Look at table 8.1 in your manual YOU MUST USE 5" PIPE!!

All heaters installed with category I horizontal vents
must be equipped with a vent transition (3" to 4" or 5"
depending on vent size selected) attached to the
power exhaust adapter located on the unit. All other
portions
of the vent system shall consist of 4 or 5-inch
diameter single wall vent pipe and fittings depending
on vent size selected. All joints of the venting system
must be sealed with metallic tape or silastic suitable for
temperatures up to 400°F. Wrap tape (2) full turns around
the vent pipe joint. One continuous section of double wall
vent pipe may be used with the vent system. Under no
circumstances should two sections of double wall vent
pipe be joined together within one vent system due to the
inability to verify complete seal of inner pipes.

gary the cobra · Jan 28, 2007

I plan a 1/4 inch per one foot fall of my horizontal exhaust vent.

From your replies I'm still slightly confused, but I think my best bet is to run with the larger 5" pipe. Looks like I'll be returning the 3" pipe and buying some 5".

Thanks for your input.

Gary

Dave Carney · Jan 28, 2007

beetroot72 said:
This is from my install manual ...

Look at table 8.1 in your manual YOU MUST USE 5" PIPE!!

All heaters installed with category I horizontal vents
must be equipped with a vent transition (3" to 4" or 5"
depending on vent size selected) attached to the
power exhaust adapter located on the unit. All other
portions
of the vent system shall consist of 4 or 5-inch
diameter single wall vent pipe and fittings depending
on vent size selected. All joints of the venting system
must be sealed with metallic tape or silastic suitable for
temperatures up to 400°F. Wrap tape (2) full turns around
the vent pipe joint. One continuous section of double wall
vent pipe may be used with the vent system. Under no
circumstances should two sections of double wall vent
pipe be joined together within one vent system due to the
inability to verify complete seal of inner pipes.

Why would his installation be a cat 1 ? I'm not sure what they mean by residential. Does that mean anything attached to a dwelling or what?

My installation, which is similar, uses 3", until the end (outside) when it goes from 3" to 5" to accept the cap. It's a Cat 3 in my view.

beetroot72 · Jan 29, 2007

Dave Carney said:
Why would his installation be a cat 1 ? I'm not sure what they mean by residential. Does that mean anything attached to a dwelling or what?

My installation, which is similar, uses 3", until the end (outside) when it goes from 3" to 5" to accept the cap. It's a Cat 3 in my view.

I don't know...I just cut and pasted it from the manual. I got too nervous to go horizontal when installing my hot dawg. So, because I was able, I just went straight up.

beetroot72 · Jan 29, 2007

Dave Carney said:
Why would his installation be a cat 1 ? I'm not sure what they mean by residential. Does that mean anything attached to a dwelling or what?

My installation, which is similar, uses 3", until the end (outside) when it goes from 3" to 5" to accept the cap. It's a Cat 3 in my view.

Oh yeah, I'm in a big "subdivision" in McHenry, Illinois and the village/inspectors are Ball Busters. If some jackass neighbor saw a pipe sticking out the side of my garage and didn't like it I'd be in trouble for sure.
Also, they're are still building in my neighborhood and inspectors are all over the place.

:dunno:

gary the cobra · Jan 29, 2007

So more questions:What catagory is my 75k modine? I am in a residential area,but my heater is going into my free standing shop.Does this heater have a powered vent that pushes out the exhaust? If it is powered can i use my 3" exhaust pipe?
Thanks,
Gary

beetroot72 · Jan 30, 2007

gary the cobra said:
So more questions:What catagory is my 75k modine? I am in a residential area,but my heater is going into my free standing shop.Does this heater have a powered vent that pushes out the exhaust? If it is powered can i use my 3" exhaust pipe?
Thanks,
Gary

Gary the sites I looked at wehen Buying my Heater sold vent kits. The Horizontal kits were 5" Here is what one of the site sold....

Side Wall Venting (with B-Vent):
Must Have:
(1) 3GVRRA-5 3" to 5" Adapter
(1) 5GVWT 5" Wall Thimble
(1) 5GVT 5" Tee

Option Piping:
5GV60 5" x 5' Pipe
5GV48 5" x 4' Pipe
5GV36 5" x 3' Pipe
5GV24 5" x 2' Pipe
5GV18 5" x 18" Pipe
5GV12 5" x 12" Pipe
5GVL45 5" 45 Degree Elbow

Roof Venting (with B-Vent):
Must Have:
(1) 3GVF 3" Roof Flashing up to 7/12 Pitch
(1) 3GVSC 3" Storm Collar
(1) 3GVVTH 3" High Wind Top Cap
(1) 3GVT 3" Tee
(1) 3GVTC 3" Tee Cap
(1) 3GVC 3" Draft Hood Connector
(1) 3GVVFS 3" Fire Stop

H :FIREdevil

ope this helps

Dave Carney · Jan 31, 2007

gary the cobra said:
Does this heater have a powered vent that pushes out the exhaust?

Yes, it has a powered vent.

russlaferrera · Jan 31, 2007

Abodyracer said:
Gas fumes rise. Do not point it downward unless it uses a blower to force the exhaust out the pipe. If it does not use a blower make sure the pipe has rise to it. Without rise the exhaust will not vent to the outside, it will backup (for lack of a better term) into your garage.

My manual states down 1/4 " per 1 ft. This is to allow condensation to exhaust. Should the condensation make it back to the furnace it will corrode the heat exchanger over time. There is more than enough room in the pipe for exhaust fumes to vent....russ

krowbar · Feb 11, 2007

gary the cobra said:
Guys, I am installing a 75k btu Modine Hot Dawg, I need to vent it horizontally
out the back with one 30 degree bend in the vent pipe. This is a 4 foot run, I will slant it down slightly for condensation. The back vent pipe of my heater is 3", can I run 3" all the way outside, or do I need to convert to a 4 or 5" vent pipe at the heater and continue this outside? The instructions that came with the heater are not real clear to me. I see a lot of pictures posted here convert from 3" to a larger diameter pipe to run outside. I have already purchased all 3" pipe. Before I install it I'm hoping you guys can help me answer these questions.
Thanks. Gary.

The Modine Hot Dawg,per instructions, state that you need a 3 to 5 increaser at the unit and contine on with 5in. B-vent is prefered.

Captain Sparky · Feb 14, 2007

Basically what it comes down to is that if this unit is vented in 3" in a residental application you will have to vent with Category III venting material such as the SS vent pipe that has it's own seal for each joint or you can increase up to 5" Galv. single wall vent pipe which would make it a Category I vent system, all joints would have to be taped or sealed and you are allowed 1 B-Vent joint inside of the building which is used when you make your penetration thru the wall. Confusing ain't it!

Hot Dawg Install Question

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