3" vent outlet on Big Maxx 50k BTU unit

[Scott V]

Was wondering how some of you have hooked up the smaller 3" flu pipe outlet on the 50k BTU model-? I have a 5" vertical stack and elbow already in my garage...

-So I bought a 5" - 3" double wall increaser...

-and a 3" male snap in extension with a clamp collar end to go to the unit.

I thought I could just slip over the outlet on the heater but the inner 3" tube on the extension is the same diameter.

I'd like to see what others have done... thanks

My unit looks like the one in this thread:
http://www.garagejournal.com/forum/showpost.php?p=4284425&postcount=18

 

[Basstracker34]

I'll be watching this for an answer. I've got 4" vent through the roof from the previous installation(took heater when they lost the house) but the big maxx 50k has 3". I could have gotten the 80k which has 4" but that would be overkill for my garage.

 

[madosta]

Me too. I just bought the 80k with the 3" DuraVent kit from Northern Tool. The kit doesn't work out of the box and I need to reduce the 4" exhaust port to the 3" Dura Vent or go and buy all 4"!!!

Ergh!!!

 

[Scott V]

It turns out the outlet is meant to fit inside a 3" diameter piece. My flue pipe in the garage is a double wall all the way to the heater so I found this draft hood at Menard's that will work. Need to drill it to screw into the 3 holes they have on their outlet and then will tape everything with aluminum tape when its all mounted. I think the type of adapter you want depends on your flue pipe arrangement. I have a friend in the HVAC business who I will have inspect everything before I start running mine.

 

[Basstracker34]

Thanks for the pictures! Sure makes it easier for me to figure out installing mine.

Have you started it up yet? How is it for heating your garage?

 

[Scott V]

Glad to help but anyone doing this should really consult a professional or read up a lot on the principals of proper exhaust gas venting. And ALWAYS set up a CO monitor in your garage. I don't claim that this is the way everyone should do it, it just worked for the B vent that was already in my garage when I bought the house (which I inspected). I ended up taping all the seams with aluminum tape but left the gap open for the B vent adapter.

And now for the fun part; YES I got it running last night and was so gassed! (not literally) I got the thermostat temporarily installed near the heater and tested the fan switch. Hmmmmmm- alright it works! Then I did the whole start routine suggested in the manual. The first time I let it light on it's own it went through 2 start ups and didn't fire. That confirmed to me that the valve in the basement to the outside gas line was shut off. (this was a valve with a square head and no "ON/OFF" markings) Once I gave that a 90° turn and retried it fired right up. It was awesome. It was fairly warm in Chicago last night but it was still @ 50° in the garage. It ran for a while and got it to 60 in no time. Nice quiet operation with the TV on. Now that the weather is turning in Chicago I'm pretty excited I got this running now.

I'm going to only run it when I go out there until it goes sub-zero here and then I'll hopefully be confident enough to set it at 50 and leave it run on it's own to keep **** from freezing up and keep the slab warm.

 

[Basstracker34]

I think the drip leg on the gas line needs to be switched. Like this instead. At a directional change to force the stuff down to drip leg.

http://www.woodworkingtalk.com/attachments/f15/58554d1402619678t-installing-garage-heater-image.jpg

 

[Scott V]

Ya I wasn't sure how to approach that since the gas line comes in at floor level and doesn't drop from the ceiling like a lot I've seen.

The previous heater had a lower gas line input than the Big Maxx unit so I added a 15" riser from the on/off valve to come across at the same level as my input and thought since condensation would be affected by gravity that it would run down the drip leg like that before getting to the control valve and burner. I read the IRC code for drip leg installations but there are further comments to be found regarding "sediment trap" where it needs the 90° interuption in the flow so debris doesn't blow over the drip leg in a horizontal configuration.

Seems like an easy swap with the T fitting I already have there. The flexible line should reach.