Help with modine hotdawg instructions

[ripsnortMN]

In my modine hotdawg manual is says and I quote "When the vent passes through a combustible INTERIOR wall or floor, a metal thimble 4" greater than the vent diameter is necessary".

What does this mean? Do I need a 7" wall thimble now? I will be using a 3" double wall "b" pipe. Can anyone shed some light on this? Thanks fellas.

 

[busted knuckle]

If your using a 3" diameter pipe the a 4" thimble is good. This will give a 1/2" gap which will reduce radiant heat from building up. The 2 walled pipe also reduces the radiant heat. I've had mine in since November and the pipe has never been to hot that I couldn't have my hand on it.

 

[ripsnortMN]

If your using a 3" diameter pipe the a 4" thimble is good. This will give a 1/2" gap which will reduce radiant heat from building up. The 2 walled pipe also reduces the radiant heat. I've had mine in since November and the pipe has never been to hot that I couldn't have my hand on it.

If a 4" thimble is sufficient why would they list that it needs to be 4" greater than the vent diameter? I just want to do this safely and correctly.

 

[ripsnortMN]

Do they even make a thimble that big?

 

[rickairmedic]

Rip what they are refering to is the overall diamater of the thimble not the hole in the center the hole in the center of the thimble will match the size of pipe you are using the outer diameter of the thimble is what should be 4" larger which gives you 2" all the way around the pipe of non combustible wall.This is what you need only in a 7" version.


http://www.idealtruevalue.com/servlet/the-40219/Detail

Rick

 

[ripsnortMN]

Hey great rick thank you. Do you know where I can get a 7"?

 

[rickairmedic]

Rip I would check with your local Johnstone supply they are a wholesale outlet that will sell you what you need.


http://www.johnstonesupply.com/corp...ocationResults/tabid/564/Default.aspx?find=MN


Rick

 

[rickairmedic]

I am pretty sure this is the one you want here Johnstones part number is on the page .

http://www.johnstonesupply.com/corp.../tabid/1780/Default.aspx?Product_Code=L89-782


Rick

 

[ripsnortMN]

I wonder if home depot or menards would have one on these. The closest johnstonesupply is quite far away from me.

 

[rickairmedic]

Rip you could try them they may have it if not ACE hardware is another good place to try. Home depot online has a 3" stainless steel vent kit its a little pricey but they may have just the thimble alone.

Rick

 

[ripsnortMN]

Awesome thanks. I'll go look around tomorrow and chime back in if I find anything else.

 

[rickairmedic]

Rip you want the thimble to fit the doublewall tight that way you shouldnt have issues with water entering the garage .

Rick

 

[ripsnortMN]

Yeah I was planning on sealing all the joints with high temp rtv instead of the tape. I read in the modine manual that I could do this. It just might be hard to disassemble it later on.

 

[rickairmedic]

ip I'll be honest thats really not needed all of your joints should have a tight factory fit so sealing them isnt needed . I have never used tape or any other sealant on metal flue pipe and I have been doin this 20 years plastic flue pipe is a differant story but metal pipe doesnt need a sealant just make sure theres 3 screws per joint on single wall and where the singlewall hits the doublewall.

Rick

 

[ripsnortMN]

You definitely know more about this than I do so i will listen to whatever you recommend.

 

[ripsnortMN]

I just got back from home depot and they did not have the 7" thimble. The biggest they have was a 5".

 

[rickairmedic]

Rip did you happen to measure the inside diameter of the Thimbles . I dont use a great deal of thimbles but I am pretty sure the size relates to the inner opening not the actual diameter of the thimble . I am pretty sure what you want is a 3" thimble which will have a center hole of 3" and have the proper outside diameter you need. Here is a 3" from Lowes site it states in the description it provides the proper wall clearance .


http://www.lowes.com/lowes/lkn?action=productDetail&productId=26300-41698-187703R




Rick

 

[ripsnortMN]

Im not really sure rick. This is right from the modine manual that I am looking at right now..

"When the vent passes through a combustible INTERIOR wall or floor, a metal thimble 4" greater than the vent diameter is necessary".

I guess I don't really understand what this means. I know I need a 3" hole in the middle. But do I need a thimble with a 7" outer diameter?

 

[rickairmedic]

Rip I would say yes but I would take a tape measure with me or snag one from the tool department and measure a 3" wall thimble . They are most likely 3" inside and 7" or so outside diameter . Wall thimbles are pretty much universal and from what I can tell the size on the thimble is the inside diameter which will give you the proper outside diameter . I could check with one of my suppliers for you as I havent put one in in a couple years but I would bet that is the case since all pipes need a 2" clearance from combustables.


Rick

 

[ripsnortMN]

That would be great if you could check. I will just be hanging it this week but won't be doing the exhaust for a couple weeks.

 

[rickairmedic]

Rip I just called and verified what you want is a 3" thimbe . I havent used one in at least a year as that was the last time I put in a garage heater with Metal Flue pipe . I pretty much only install 90% plus furnaces nowdays and they dont need a thimble .

Rick

 

[ripsnortMN]

Hey thanks Rick. You have been a great help. So whatever the outer diameter of the 3" is, is what I need?

 

[rickairmedic]

Rip no problem at all I figure HVAC is my area of expertise I can offer here and I try to help everyone I can . Yes the 3" will have the proper outer diameter you need .

Rick

 

[ripsnortMN]

Thanks again. Anything you need just let me know. I would say that my area of expertise is stuffing big engines into small cars/trucks.

 

[rickairmedic]

Rip I stuffed a 454 into a Vega yeaaaaaaaaaaars ago but I am by no means an expert there . I am still debating a 514 Stroker in my 63 F100 but I will see what gas prices do when I get that far.

Rick

 

[ripsnortMN]

Wow a vega huh? Nice. I like those cars. Like a mini camaro. I am doing a carbed 6.0 ls1 into and s10. Not sure if your familiar with an ls1? Will be 550hp on 87 octane and maybe a little nitrous too.

 

[rickairmedic]

Rip LS1 high powered Chebby motor .I am a ford guy at heart but I pay attention to the others as well plus I watch the powerblock on Spike and thats one of their favorite motors . I would say an LS1 should make an S10 fun to drive .


Rick

 

[ripsnortMN]

Should be easy 10 second truck...I hope. I have a 355 sbc in it right now. And am ditching it for the ls1. The truck goes mid 12's right now.

 

[mulepackin]

Just to give you another possible source for your part:www.ventingpipe.com/productView.cfm?uniqueID=6766
I got all of my venting supplies from this company when I installed mine. I could get some of what I needed here and there locally, but not all of it. I ordered it all from them with no hassles.

 

[ripsnortMN]

I just went and got a thimble. The modine manual says I can use single wall vent pipe from the heater to the thimble then double wall through the thimble. I was wondering if i could use double wall for the whole thing? Also I have vinyl siding on the garage and was wondering if the thimble goes over the siding or under it?

 

[ripsnortMN]

It would seem that the thimble should go over the siding just so the siding doesn't come in contact with the pipe. Even though the double wall pipe wouldn't get that hot. I just don't know how to make the thimble look "decent" or fit up to the vinyl siding good if I do put it over the siding.

 

[rickairmedic]

Rip sorry dont know how I missed this yesterday yes the thimble goes over the siding and yes can use doublewall all the way although I recomend at least 12" of singlewall at the heater so you dont have condensation and eventually rust problems with your flue pipe.


Rick

 

[rickairmedic]

Rip about the only thing you can do is trim the siding sso the thimble will slip through it not much can be done to make it pretty .

Rick

 

[ripsnortMN]

Thanks Rick you're a big help. I'll probably do the vent piping first and then move on to the gas line. It looks like the manual wants black pipe. I was going to look into a 100lb propane tank and keep that in the garage or put it outside. Would you recommend a different setup with the propane tank? Thanks again Rick.

 

[rickairmedic]

Rip with Propane you can actually run copper gas lines if you like not with NG but LPG is fine with copper pipe . I would look into a couple 100 LB tanks that way if one goes empty you have a backup while you run for a refill . I would also keep them outside the shop . You can run black iron as well if you wish but if you are any good at flaring tubing then copper is alot easier .

Rick

 

[ripsnortMN]

Yeah I just don't really know what way to go with the tank. It gets nasty cold here in MN. The garage is 20'x22' well insulated and will only be heated while im out there a day or two a week. I guess I don't want one of those huge tanks they deliver to your home. I heard of some guy doing the 100 gallon as opposed to the 100lb. I wonder what a 100 gallon would cost to fill.

 

[rickairmedic]

Rip just call a local propane supplier and ask them what they are getting a gallon . They may even come out and deliver a filled 100 gallon tank and hook it up for you .

Rick

 

[ripsnortMN]

Thanks Rick i'll have to look into what they are going for.

 

[rickairmedic]

Rip alot of suppliers at least here will pretty much give you the tank and hook it up as long as they are the ones filling it when you need a refill .

Rick

 

[ripsnortMN]

Yeah that would be nice if i could get the tank for free. My buddy has a 100lb empty tank he said he would sell me for $60. Its just hard to say what size to get you know?