Ok to start venting with elbow??

[Stevelaz]

Ok. I called the supply house where i purchased my 45,000 btu modine hot dawg and found i do NOT have to start with a flue adapter and can start with an elbow or any other pipe. The only issue he said i MAY have is some kind of back pressure issue shutting the unit down and setting a code. He suggested trying to start with a straight pipe first, then the elbow. That is out of the question unless i totally change furnace location. He said it is not definite i will have that problem and it may be ok. My plan is to use 3 inch type b, start with elbow to the side, then a tee, then up through the roof.

Has anyone else started the venting with an elbow? Please let me know. Thanks.

 

[Radix2]

Is there any mention of a minimum distance to the first elbow in the installation manual?
You could also try modine to see if they know of any incompatibility, if it is so common that supply house guys know about it, they and the manual should reflect that fact.

Ok, looked at the install manual - recommends min of 12" to the first bend.... You are not going to know if you can "get away with it" until you try it and it fails or not. Your other post says you want to start with two elbows, seems like a bad idea IMO, don't be the guy that doesn't follow the instructions and ends up with a flakey install, do it right the first time.

http://www.modine.com/download/1/6-583.pdf

 

[Jackfre]

Your problem will come with Elbow to tee on the horizontal. Back to back fittings are a killer. I would suggest tee to vertical riser and a 45 or whatever fitting angle you need. B-vent 45's and 90's are adjustable.

 

[zmaxmotorsports]

How about a picture of your install to get an idea what youre up against?

 

[csp]

Your problem will come with Elbow to tee on the horizontal. Back to back fittings are a killer. I would suggest tee to vertical riser and a 45 or whatever fitting angle you need. B-vent 45's and 90's are adjustable.

Where are you getting a tee in this from? I can't imagine any situation where a tee would be needed to vent one fixture.

OP you're probably going to have excess back pressure in the power vent and a limit switch will shut the unit down before it even gets going.

Three threads on the same Hot Dawg install......

 

[Stevelaz]

Ok, Here are some pics of where id like my install. Yes, i did see the recommendation of at least 12 in straight to start, however, it is a recommendation, and was hoping i could do it this way and that someone else did this with no problem. I am not going with two elbows now and planned on going with an elbow and then a tee for clean out and easier to go up through the roof.

As you can see the furnace is on a diagonal, that is why im having this issue. The flue from the furnace is not on a straight angle so i have to elbow the start if i want to keep it there. I really did not want to move it out further on the diagonal. I am kinda now thinking to just turn it sideways towards my work area and have it blow towards north wall.

 

[Jackfre]

Where are you getting a tee in this from? I can't imagine any situation where a tee would be needed to vent one fixture.

OP you're probably going to have excess back pressure in the power vent and a limit switch will shut the unit down before it even gets going.

Three threads on the same Hot Dawg install......

If you can come off the back with a 90 you can come off the back with a tee. The benefit of the tee is that it will act as a sump for any possible condensation that is returning to the unit rather than a 90 which will drain into the unit.

 

[Stevelaz]

So Jackfre, are you saying i should start with the TEE and then elbow over to where i want to come out the roof?

 

[zmaxmotorsports]

Can you move the heater out a 1' farther to start with? you can put the tee on either end ,just make sure you have fall in the pipe and Id still use 1' of pipe before the 1st offset in the flue whether its a tee or a 90.

 

[Stevelaz]

Can i even get a 1 or 2 inch straight pipe in type b double wall??

 

[Stevelaz]

Here is another idea. I talked to a friend who is a carpenter, not really a heating and air guy, but he has been around. He said he has seen all sorts of elbows and sort in these furnaces to get it exhausted out, but he cannot recall if he has ever seen an elbow from the start.

He suggested i do a temporary hookup and do the flue like i want, but not run it out yet.
Leave all doors open and see if the unit operates for a bit, if it does i should have no problem and vent out where i have it. Any thoughts??

 

[Radix2]

Tee or elbow is the same restriction in this case.
I gotta ask - why do you trust the opinion of some internet poster over the manufacturer and supplier? Recommended means 12 inches at least is proper... 9,10,11 likely OK- zero as you "hope" is just not listening (IMO). And I would use the provided vent adapter.

 

[csp]

Can i even get a 1 or 2 inch straight pipe in type b double wall??

Assuming you meant 1 or 2 foot straight, then yes you can. If your clearances from combustibles are met you could go single wall then transition to B vent as you go to a 90 and go up with it.

 

[Stevelaz]

I thought the other poster was asking if i could move it 1 inch further but i see he asked about a foot. If i move it on the diagonal another foot i think it will be out too far in the garage for my liking. My other option would be to leave it in that corner area and turn it straight pointing towards the wall in my work area. But i really like it where it is and was hoping something would work.

 

[zmaxmotorsports]

Can i even get a 1 or 2 inch straight pipe in type b double wall??

Just straighten out a 90 if you cant find a short enough piece from your supplier.

 

[zmaxmotorsports]

Some times you have to build around the equipment you can lay your hands on.

 

[Bluefox]

Cant tell from the picture how the Garage is configured from the house, can't you vent it straight out the side wall horizontal?

 

[Stevelaz]

The garage is detached from the house. Yes i could vent it horizontal but i didn't want it to look shabby for my neighbor to see. But i am starting to rethink that. However, even if i go out horizontal i still do not have a straight shot. I would have to come off the furnace with a slight 45 since the furnace is angled. I wonder if that will be ok? Or i can just turn the dam thing so it points straight to the other wall. What you think? From the picture where do you think the best spot would be to point it. Thanks.

 

[CNGsaves]

+1 for horizontal flue in your situation. Plant a tree in yard to obstruct neighbor view !

OP you know the heater can actually go HIGHER as only needs 1" top clearance?? This would give you more head room as you walk in nearby man door.

 

[Jackfre]

So Jackfre, are you saying i should start with the TEE and then elbow over to where i want to come out the roof?

No, I'm saying you use the tee to go vertically. You need to gain some draft. You will have a hell of a time going back to back horizon fittings. Doing so is the old, "hit and hope" theory. I represented venting manufacturers for 20 yrs and got to see a bazillion catastrophes in a six state area. If you can't get the rise then reconfigure your install or use some other appliance.

Using B-vent will help, because it is an insulated system. The problem with your fitting fitting install is that the flue gases tumble as they exit a fitting, they then tumble again and that creates the back pressure and these pressure switches are not even a little unforgiving.

 

[Stevelaz]

Jackfre, or anyone else, if i decide to go horizontal out the wall, is it ok to start with a slight 45 before going with a straight pipe out the wall??

Also ive been looking and the venting instructions for horizontal. Why is the pipe required different for commercial and residential? They want you to use EXPENSIVE cat 3 b vent for residential but commercial is able to use cat 1. Whats up with that? Thanks again.

 

[sammer]

This might be a bit late...
If venting horizontal you must use cat3 vent pipe according to modines web site. (Power vented non-condensing)
You will probably have to use an adapter to get the pipes turned. They have to drain any condensation either out thru the wall or to a drain. They have a specified direction of flow and without an adapter may not flow right.

I went thru this with my reznor udas45 install. Got it mounted where I wanted it and all concentric inlet and venting hooked up. Inspector poo-poo'd it and ended up having to move the unit to make the cat3 venting line up with the hole I cut in the wall.

Nova vent was fairly inexpensive, and the whole job would have been cheaper if I did it right the first time.

sam