Concentric heater box in attic or garage?

[RABRods]

The wife just gave me an early Christmas present! A Beacon Morris separated combustion heater!

I want to get it mounted and vented to my HVAC guy can come connect gas.

After reading through the instructions for the separated combustion venting it leaves me confused. It states that you must use "one piece" of B-Vent through the concentric box up to the vent cap. The longest B-Vent I have ever seen is 5 ft. Does two pieces properly connect and caulked count as one?

If not how are you guys making this work, how do you meet the "one piece" requirement, the 2ft above anything withing 10ft requirement, and the snowfall requirement (which from what I can find is 3ft for MI)? I have a 4/12 roof and I planned to put the concentric box in the garage not attic. In order to do this I would need a b vent at least 7ft long.

Any thoughts?

 

[RABRods]

After reading more closely I realized another complication the, "one piece" vent must be UL 1378 vent pipe, NOT B-Vent. Therefore I need to use "Special Gas type/BH type/Cat III type" venting, which comes in even shorter lengths than B vent. Those of you who have used the concentric vent kits, what do your installs look like what pipes did you use? I have looked and searched and have seen little details on here about the actual venting for the concentric vent setups. Thanks for the help ahead of time. I hope to have this mounted and vented in the next few weeks so can have the hvac company come out and run gas/inspect full install.

 

[RABRods]

Ok so maybe I should have done more research before I posted...anyways I contacted the manufacturer, who were very helpful by the way!

So to answer my own questions in case anyone runs across the same questions in the future....

1) For the separated combustion setup, the flue(exhaust) pipe must be UL 1378 single wall rated (special gas type stainless) NOT B vent no matter if it is vertical or horizontal venting. This is something I didn't realize initially and it seems some ignore in their setups.

2) The intake pipe that is concentric to the flue pipe does NOT need to be UL 1378

3) The "single piece" requirement is from the concentric box inside the garage up to the point where it exits to the outside at the roof, at that point you can connect as many extensions as needed to meet the clearance requirments.

4) A 90 degree right off of the unit then vertically is not recomended like I see many people do on here, you need some sort or condensate drain/condensate trap T even in vertical operations.

So far that is the info I have, maybe most of you already know it. I will post more pics as I install the unit/venting/etc and get it approved.

 

[samert111]

I installed the same heater last fall with the concentric vent kit but went thru the wall instead of going up thru the roof and everything I read kept referring to "B" Vent and I really didn't read up on the UL 1738 rating. If you read up on all the other manufactures of these heaters they just reference "B" vent so that's what I used.

I did call the local inspection contractor for our township and I'm pretty sure he said to just use the "B" Vent so that's what I used with a wall thimble which gave me the 1" clearance around the "B" vent.

The heater ran fine all last winter but now you have me wondering about the UL-1738 rating which from what I read now has a Stainless Steel inner pipe (vs. Aluminum) and the joints actually have a silicone gasket seal. I think it's got something to do with the combustion by products being a little corrosive when they condense. I guess I could see it on a really long run. Mine is only 6 ft. total and the exhaust doesn't cool down much at all to form any condensation.

My 23 yr. old 85% efficient, power vented furnace in the house has been hooked up to a "B" vent for it's entire life without any problems. But then again I'm sure the codes may have changed since then.

 

[RABRods]

Samert111,

Yea looking at the manual that came with the unit it does state B Vent, yet if you look online it seems the latest manuals on their website all state UL 1738. And their tech confirmed this with me. It's actually single wall stainless not even double wall. The pipes all have a gasketed air tight fit seal. So I assume as you it is mostly due to the corrosive by products, but I think it is also due to the air tight seal gasket.

It seems that using the UL 1738 (special Gas type) vent pipe with the concentric 6" air intake pipe, acts as a double wall still which is why UL 1738 single wall is OK.

I wish I could just go with B vent as it is far cheaper, yet I feel that as the latest manual now states UL 1738, if there ever was an issue in the future I could be liable.

What material did you use for the 6" air intake pipe? I like your setup by the way it looks good.

 

[samert111]

What material did you use for the 6" air intake pipe? I like your setup by the way it looks good.

Thanks,
I used a pc of 6" wood stove pipe I found at Menards. It's made from heavier gauge material.

I just remembered that I didn't use a wall thimble after all. I just used the 6" stove pipe thru the wall with a collar to trim it out on the outside because it gave me the 1" clearance to combustibles for the "B" vent that I needed.

I went out to the barn and fired up the furnace and took some temp reading with my IR gun. The single wall pipe coming directly off the heater was running appox. 110° and the OD of the "B" vent pipe was running approx. 90° and the 6" pipe running thru the wall was approx. 70°.

I also pulled my installation instructions for the concentric vent kit and it only references "Double Wall Vent" that goes thru the wall inside the 6" pipe but in the text it does actually reference UL-1738 so they must have changed their instructions recently also putting the UL-1738 reference on the diagram. Probably was confusing to some.

I did some internet searching today on this subject and found several forums where HVAC guys were saying they use "B" Vents on these heaters, but most of the posts were a few years old and codes may have changed. I would check with your HVAC guy or call your local inspector and see what he has to say about using regular "B" Vent. If they are OK with it then your covered if something happens.

Where in Mi. are you located? I'm just North of Grand Rapids.

 

[RABRods]

Good call, I will check with my HVAC guy and inspector. Once I get it up and running if I end up having to use the UL-1738 pipe I will take some temp measurements as you did, might be intersting to see how the temps compare. I am hoping within the next few weeks....

Im over in Harrisont Twp, MI, so about 2.5 hours SE of you.

 

[RABRods]

I meant to ask, where did you get your concentric kit from? I saw www.globalindustrail.com has the kit for $175, best price I have seen yet. On that note, is the concentric box itself made of galvanized or stainless?

 

[samert111]

I got mine from Global. It's all galvanized steel.

Looked on Menards website last night and they were $254 for the 30-75K BTU kits.

Even with the shipping costs from Global it's still the best deal I've found.