Big Maxx horizontal vent slope questions

[Pflumph]

Long time lurker, first post.
I'm adding a Big Maxx heater to my garage. I have 2 questions I haven't found an answer to:
1) The manual calls for the CatIII vent to slope inside with a drain tee. Why? Can it slope outside and just drip condensate on the ground?
- Minimum vent length is 3'. I'm planning to use a 4' section of 4" CatIII, which would put the heater just under 3' away from the inside wall.
2) Nevermind the sizing question

 

[PoorUB]

Wow, no offense, but this gets rehashed every week or two!

I worked in HVAC for 20 years. a 30,000 BTU will heat you garage just fine as long as it has reasonable insulation. I have installed 30,000 BTU heaters in 1,000 square foot garages here in North Dakota.

I heat my 930 square foot rambler, plus the same size basement on 24,000 BTU until 30 below then I have to turn on second stage. Then people respond, but a house is different from a garage. You mean to tell me my 1950's rambler with the original wood windows and hardly any insulation in the walls will heat better than a newly constructed garage? I don't think so! The walls in my house are are roughly R4.

At the very most go with the 50,000 BTU.

A 50,000 BTU heater will be overkill, and 80,000 BTU heater will be 3 to 4 times over kill. Keep in mind when it is 20 F outside you probably can heat the garage on 15,000 BTU. Over sizing a heater will cut it's life span as the heat exchanger will be wet from condensate on the inside all the time and rust out.

 

[Pflumph]

Wow, no offense, but this gets rehashed every week or two!

I worked in HVAC for 20 years. a 30,000 BTU will heat you garage just fine as long as it has reasonable insulation. I have installed 30,000 BTU heaters in 1,000 square foot garages here in North Dakota.

I heat my 930 square foot rambler, plus the same size basement on 24,000 BTU until 30 below then I have to turn on second stage. Then people respond, but a house is different from a garage. You mean to tell me my 1950's rambler with the original wood windows and hardly any insulation in the walls will heat better than a newly constructed garage? I don't think so! The walls in my house are are roughly R4.

At the very most go with the 50,000 BTU.

A 50,000 BTU heater will be overkill, and 80,000 BTU heater will be 3 to 4 times over kill. Keep in mind when it is 20 F outside you probably can heat the garage on 15,000 BTU. Over sizing a heater will cut it's life span as the heat exchanger will be wet from condensate on the inside all the time and rust out.

I figured as much! Just looking for confirmation I guess...
Still curious why they call for condensate to run into the building, though

 

[The Cobbler]

maybe so the condensate doesn't drip & freeze up outside, eventually causing an ice dam ?

 

[Pflumph]

maybe so the condensate doesn't drip & freeze up outside, eventually causing an ice dam ?

Wouldn't the 10000 BTU running out the vent prevent that?

 

[Showkey]

Horizontal vent is not subject to ice dams. Ice dams on vertical vent on roof with warm exhaust melting snow and ice and refreezing lower on the roof.

My horizontal vent is tipped ever so slightly down and drips in the ground in very cold temps.

As a side note ……..my radon vent is also now a horizontal wall vent and also drips. When the radon vent was vertical on the roof created a HUGE ice dam complete with leaks. That radon vent was there when I moved in and prior leaking was noted during the inspection.

Water or condensation is function of combustion ( by product) so a larger heater consumes more fuel which creates more water.

 

[PoorUB]

I figured as much! Just looking for confirmation I guess...
Still curious why they call for condensate to run into the building, though

If it was mine it would have a slight slope to the outside. Keep in mind there will be an iceberg under it. You shouldn't vent out over a sidewalk, any place ice will be an issue.