HVAC help

[John Miliunas]

Maybe a bit OT, but it's a pwered "tool" used to heat up my shop! :D Anyhow, I got that Hot Dawg unit by Modine and am contemplating its intall. Two things: 1) Nowhere in the manual does it state the actual pipe size/thread needed for the final hookup to the unit. Is there a "standard" size used for this? (It's an LP type unit.) 2) I plan on using the B-Vent type of pipe to exhaust fumes, horizontally out of the shop. For this configuration, the installation manual refers to keep a *minimum* downward pitch (for drainage) of 1/4"/foot. My problem is, for me to install the unit in its intended spot, I will not only be able to sustain this pitch, but far exceed it. I can't go with just the 1/4"/ft., because it would end up above the soffit. Does anyone know if it's OK to drop it more than their minimum per foot pitch? BTW, the unit does have a powered vent. :cool:

[Dale Thompson]

John,
I've got a Modine-type heater installed in my rec. room up at the cabin. That's where I run my 20' by 8' slot car track (1:32 scale). The heater is hooked up with 1/2" npt black pipe. There is absolutely NO problem with keeping the heater fed, even at twenty below. The room is 24' by 24'.

As far as the horizontal vent is concerned, I have the same setup. The downward pitch is to keep rain water from running back into your heater. With a powered vent, I don't see that you could have a problem with increasing the negative pitch. Also, LP is heavier than air so it should not back up on you. Natural gas, on the other hand, is lighter than air and could have a back up problem if not completely burned.

If the manufacturer of your unit has a website, you may wish to give them a visit and get their reaction. LP is great but (I won't bore you with the story) it can REALLY be mean if misused. It doesn't disperse like natural gas does.

Stay Warm in our first scheduled blizzard. I've got a new Pantera with six miles on it. I hope to live long enough to at least double that. :)

Dale T.