Questions about hot dawg heater

[rvcoaster]

hi, this is my first post here. i have read many posts on heating garage/shops here and still have a few questions.

i am in the process of installing a hot dawg HD45 propane furnace. i mounted it on the ceiling, ran power from the subpanel to a j box near the ceiling (not hooked up from j box to furnace yet) and have the vent pipe dry fitted (currently in position but not complete). i am having a professional install the propane pipe from the tank to the furnace.

the furnace came with a vent kit (b vent pipe, adjustamble elbow, adapter for furnace exit) and a pro1 t771 thermostat. the instructions/manual are contradictory about the b vent and i am more than a little confused about it. it is dry fit a this point but i need to take it apart to seal the outside wall and thimble.

b vent questions:

1. the instructions say to use b vent to exit the wall. the instructions also say to not use b vent to exit the wall. since the kit came with b vent wall exit items, i used it to exit the wall however my 36" pipe doesnt quite clear the soffit above it. can i extend the b vent pipe another foot somehow?

2. the instructions say to not use screws to fasten the b vent pipe. the instructions also say to use 1/4" #8 sheet metal screws to fasten the vent pipe together. the pipe is pretty tight fit, but i would feel better knowing it is secured together. should i use screws?

3. the adapter (b vent to furnace exit) has a gap around the furnace side between the inner and outer pipe. i am not sure if i am supposed to seal this or not, it appears i am and it appears i am not.

i am pretty impressed with the uselessness of the manual. an entire page of warnings (per page it seems) about following the instructions, and then the instructions are so precise as to say "install the wall thimble" and thats it.

thermostat questions:

the manual has an entire page filled with warnings about hooking up the thermostat correctly and then the actual instructions say "hook the thermostat up". ok. further digging at the wiring diagram suggests i use a 2 wire cable 18/2 300V and use the R and W connections of the 5 terminals in the furnace. my thermostat has 4 connections on it. it looks like (after 3 days of research) i need to use at least three wires, hook up the R, W, and C. i can also hook up G if i want but not Y. is this correct?

my shop has four walls. i'm not sure where to put the thermostat as there are no interior walls, but my minds eye tells me that the wall opposite the garage doors is my best bet. any advice about thermostat placement?

what is the best way to run the thermostat wiring from the furnace to the thermostat? i see a lot of pics of wires run out in the open into the ceiling or wrapped around the felx conduit for the power, or wrapped around the propane pipes. should i run the wires inside the walls (no wall panels at this point) or on the outside of the wall panels?

i'm a very technically oriented person who loves instructions but these instructions are pretty darn bad. they contradict themselves many times over and are so vague as to cause an experienced person to install things wrong.

thanks for your help (garage is still cold )

 

[mitymouse]

B vent should always be used when near combustibles, so yes you want to use it for your side wall exit. most b vent has a slip ring or twist lock to hold it together, however there is no harm if you want to screw it together. b vent or flue pipe does not require a super tight fit as long as you keep your crimped end of you pipe going with the flow of gases. furnaces of today use an inducer fan witch help with pushing gases out the the flue.
If your stat reqirues a common you will need to run 3 wire...I would run one for G that is the circuit that allows you to run the fan only and is sometimes nice just to circulate some air...Y is for a/c not used with unit heaters but the boards sre genaric for multiable furnaces. once you ran your t stat wire you should never have to touch it again so nothing wrong with hiding it...just dont staple it in cause you ever need to tie on to it to pull a new one.
Id reccomend placing the stat any where its not in the direct flow of heat coming from the furnace alot of people like em right below the heater to keep the area more even, if they are in the direct air stream the heated air will blow on the stat making it think its warmer in the space then it is.
Hope this helps

 

[rvcoaster]

thank you that does help.

the b vent i have has the twist lock ends.

i wondered why the furncae has a Y (air conditioning)


thanks for responding!

 

[mitymouse]

Same board is used in diffrent furnaces

 

[dave67fd]

rv,
Yes the manual is confusing. The reason is it contains alot of information for different types of installations. For example, something maybe correct for one type of installation but incorrect for another.

1. By your description i believe you to be using the horizontal vent. "Typically" most use the B vent to exit the wall. You can exit the wall with single wall pipe (if codes permit) but a thimble is required. Also typical is using B vent "with" the wall thimble for double the protection.

You should check with your local town/state on specific codes as they take priority. If there isin't any you are required to follow the manual and the requested NFPA/GAS codes.

2. If using "all" B vent pipe parts screws should not be used. When using single wall or single wall to Double wall (B) you need to use screws. In addition ALL joints are to be sealed using high temp sealer or tape.

3. Not quite sure on your wording on this one but if your refering to the outer anual area of the b-vent where the single wall and b-vent meet. Yes this should be sealed. Typically sealed/filled with the high temp silicone/sealer.

For example: directly exiting the furnace you have a reducer. This should connect/could connect to a single wall elbow or pipe which should be screwed and sealed. That pipe will then connect to the b-vent with screws and sealer with the outer portion of the b-vent filled. The b-vent will then exit the wall through a thimble to your terminator.

Of course when running horizontal vent min and max lenghths need to be adhered to by code. I believe 3' min and 5' max.

Thermostat 3 wire should only be required if you are using the fan option and/or programable. Thermostat should be located so as not to be in the heat stream. If only outside wall you can stand off from the wall to allow some heated air behind it. Don't mount near a door or window. The heater should be positioned so you are blowing warm air on the area where most cold enters (i.e garage doors). Yes do not put therm close to garage doors.

Your thermostat wiring should be inside the walls as your electrical especially if the walls are not finished. Try and keep at least 6" distance from other electrical/lighting circuit wiring if possible to minimize noise coupling. leave 3' or more at thermostat mounting incase you decide or have to move it abit.

 

[rvcoaster]

thank you.

i am running all horizontal. its all b vent interlocking duravent (twist) with what i believe is a c to b connector on the draft hood of the furnace.

i could not find and 3 wire thermostat cable but i was able to find 5 wire. its very inexpensive.

i also bought the smallest run of FMC i could get today which is around 8 times as long as i need lol

i'm wondering if i should be using a trim collar on either side of the thimble; the thimble has large triangle holes in the outer ring (looks like this one)

i appreciate all the help

 

[Coyote37]

Just joined the forum and found this thread which caught my interest. Type B Vent is actually pretty straight forward. Though there are a few things not stated in previous post.
-Clearance to any combustible is 1", however if switching to single(which is not desirable) is 6" to any combustible. I have never seen it acceptable to penetrate a wall with single wall even when using a "thimble"/ sleeve.
-When running horizontal b vent, the pipe needs to slope back towards the unit at a 1/4" per foot.(seems strange sloping back towards the unit, but it is the code).
-We seal the connection to the equipment with a fire rated cauking, but the rest of the connections just require a metal(non-cumbustible) tape. It is acceptable to use 1/4" screws, they are not required for anything under 8", and CANNOT penetrate the interior liner.
-The vent termination needs to be a minimum of 12" away from the exterior of the building (the acids in the gas will eat paint, cause stains, etc.)
-As for the exterior penetration, you should install a storm collar around the pipe that you seal to your building, and to the pipe.
Another thing to take into consideration is combustion air/fresh air intake. Depending on the BTU's of the heater it will use up the air in a garage rather quickly.
Hope this helps. Sheet metal worker by trade, so I take interest in this stuff.

 

[mrobins297aaa]

"B" vent should not have any screws in it except where it attaches to the appliance.
I'll tell you why, just exactly like the simpson dura vent engineer told me when I had him on the phone trying to get him on my side to get me out of a jam with the Detroit heating inspector. Plain and simple when you put screws in "B" vent you lose the UL rating because it wasn't tested that way. He told me there was no way he could give me his blessing with screws in that pipe, and I said but its ok to screw it to the appliance and he said "yes because thats the way it was tested to get the UL rating".

we had a **** load of gas fired unit heaters that we had "B" vented thru the roof at the Chrysler Jefferson plant and we had put a few screws in that pipe because it was just to dam sloppy, anyway the inspector being and old tradesmen end up letting me go on that one.

 

[dave67fd]

mrobins297aaa,
Screws are only allowed when connecting single wall to B pipe. No screws if all b pipe is used. One companies example below. I have read many more ok'ing that type of installation. Notice there only real concern is noise?

Can you use sheet metal screws in B-vent?
Generally, NO, Hart & Cooley does not want sheet metal screws used in the assembly or installation of our Type B gas vent. Screws can generate serious noise problems that adversely affect the perceived performance and value of our product. They are not needed to secure a connection because the connection is already UL listed as it is designed. However, there are exceptions that we allow screws and that is for connections of single-wall pipe to the B-vent. Fold back the outer wall locking tabs that can act like an access "door" to secure the aluminum inner wall and single wall pipe together using 1/4" stainless screws.

 

[mrobins297aaa]

Dave i think that is what I said basically, you can use screws when you connect to the appliance which is always a single wall connector/pipe.

I should also say that the larger sizes do have some provisions for screws and probably were tested that way for the UL label......I really wonder if hart and cooley makes there own "B" vent or do they buy it from someone else. I remember they use to sell grilles and registers that was there main business.

Noise?, what kind of noise could you possibly get from screws in the sheetmetal?
I would be more concerned that if the screws pierced that inside liner, which is alum. on "B" vent and a cad plated screw that you would have some problem with dissimliar metals and corroding away that inside liner. Especially since it is a pretty moist enviroment in there.
Anyway when we did screw that "B" vent we always used those 1/4" scews so we didn't pierce that inner liner and after that episode with the Detriot heating inspector I don't think i ever screwed any "B" vent again. He told me if he caught me doing it again he'd make me tear it all out no matter what.

 

[hardhat]

I believe the max run on horizontal B vent is 4.5ft. If you step up to cat III venting then you can run over 18ft. The cat III venting is air tight.
Ive heard that when exiting under an eave or soffit you have to be 3' below it? I know with fireplace or intant water heaters are surface mount terminations but these heaters have to be min 12" from the wall. Cant I have my termination a few inches below the soffit as long as its out past it not letting exhaust gather under the soffit?

 

[Coyote37]

This is from dura-vents (the type the OP is using) website, as with anything every manufacture is differant as is the local codes.

Sheet metal screws are not needed for 3”
through 8” diameter pipe. However, if desired,
use 1/4-inch long sheet metal screws for 3”
through 8” diameter pipe. Never penetrate
the inner liner with screws. For 10” through
16” diameter pipe, DuraVent recommends
using a minimum of (4) 3/8” sheet metal screws
per joint, and a minimum of (6) 3/8” sheet metal
screws are required per joint for 18” and larger
diameters.