Flue sizes

Bob Harper_2

According to NFPA 31, that liner should be able to handle up to 2.0 gph. '31 also does allow downsizing right at the chimney.

Before you take someone's word for it, I would ask the local AHJ what code applies. If he says '31, then ask if there are any local amendments that specifically forbid downsizing and require sizing to the appliance collar. If he produces it, then you will be limited to very high efficiency, expensive units or power venting out the side. If there are no amendments voted into law he can go pound sand.

The oil appliance mfrs. are lazy because they make a "one size fits all" boilers that can be fired over ridiculously wide ranges. Are you going to use a 7" liner on a unit firing at 0.85 GPH, 25 ft, 82% SSE??? It is simply ridiculous. BTW, when is the last time an oil mfr. looked inside a typical heater flue? You ubiquitous 8x8 has an opening of about 6.5" square but if staggered with sloppy joints and offsets, you might be lucky to get a 5" down without having to bust out flue tile. If you need more than a 6" liner, go find another chimney. Who do you think had that code put in? The mfrs. did so they wouldn't have to change. This has been argued for years by John Pilger, who sits on the NFPA 31 cmte representing the National Chimney Sweep Guild. They just won't budge. They like it because they feel safer with oversized flues. Shows just how much they know about venting.

Off my soapbox for awhile.

Noah

Chimney Liner for New Boiler

I'm reconfiguring a single pipe steam system and adding some more radiators in the process. The boiler will have to be upsized to accomodate the new radiation. The current chimney has no liner. In order to be up to code the new boiler will need a lined chimney. The current chimney will only accomodate a 6 inch liner. The Peerless boiler I need has a 7" flue size. The question is this. Can I just put a reducer on the new boiler in order to fit a 6 inch liner? The chimney is 35 feet high. The boiler specs call for a 8x8 chimney but that draft area is not possible if the chimney is lined?

Paul Fredricks_3

Try this link:

http://forums.invision.net/Thread.cfm?CFApp=2&&Message_ID=288120&_#Message288120

They were talking about liner sizes there too. I know z-flex has a liner sizing guide, but I can never find it on line and mine seems to have gone on vacation.

Bob Harper_2

liner sizing

You need to provide the input BTUs, lateral offset, efficiency range for oil, and fuel type.

Al Letellier_9

flue size

I don't know about where you live but here in Maine we can downsize the flue ONLY if the manufacturer says its OK. Otherwise we have to go full size to the chimney and the chimney flue or line must be equal in size to the area of the boiler flue

Noah

info

The boiler to be installed 1.5 gph of #2 oil, 210 MPH input, offset 3 feet, ~85% combustion eff, 35 foot liner length. I do live in Maine and it makes no sense to replace a good liner if the current liner will perform just as well. I wish I had my own liner finder slide rule for this one.

Unknown

Al's correct

That's the rule.

Noel

Unknown

Kinda jumped to conclusions, didn't you?

You CAN size to the load, when that sizing passes the testing that get's the boiler listed. It's not always the collar size.

What's your point?

Noel

Noah

Thanks Bob

Looks like I'll be all set if I neck it down right at the chimney...thanks for the input bob...it only makes since to size a appliance to its load..

Maine Ken

Just because you are in Maine doesn't require it to make sense! It is the code you must follow. Howowners and pro's alike are required to follow the code. Others who advise necking down at the chimney might get away with it in their states, not here in Maine.

Good luck. I hope you had an accurate heatloss done. Most older boilers aroud here are grossly oversized to begin with.

Maine Ken

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Bob Harper_2

So far, nobody has been able to state what code Maine is going by. Does anyone have a copy of an amendment that specifically states no downsizing unless you get a letter from a mfr?

Noel, I'm talking about the codes and so far the only code presented in this discussion is NFPA 31, which allows downsizing based on the input and you don't need a letter from Mommie to do it. Just wondering where all this is coming from because in most cases I've found, one AHJ starts a trend based on what he wants versus what is the law and nobody ever challenges him. I just like to keep them within their scope--as code enforcers and not on the fly code legislators.

[Deleted User]

Careful w/ NFPA 31

on this one. The exact wording under Annex E Relining Masonry Chimneys is, "This annex is NOT a part of this NFPA document unless specifically adopted by the jurisdiction."

Methinks a friendly conversation w/ the local code folks is in order before proceeding.

Noel

Bob, local codes certainly apply

I take offense only to you painting all boiler manufacturers as lazy, not your content.

Our oil and gas boilers each have a different flue size, in order to ATTRACT customers. We use the smallest flue connector size that will pass the independant testing to get the boiler listed. Any reductions that meet code will be approved, not by the manufacturer, but by the code enforcement body.

Code enforcement inspectors regularly call here to discuss individual situations. I hope you'll see both sides.

I certainly don't consider yourself to be "the same as ALL contractors", and I don't accept your generalization about oil boiler manufacturers. We're people.

Noel

Maine Ken

Maine has adopted NFPA 31 and 211 as well as its own Oil and Solid Fuel Board rules and regulations. If you need chapter and verse I can provide you info on where you can buy your own copies.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

TORCH_2

might not be the right thread or tell me the right one i'm new here

Hi I have a welding shop in a old shipping container for my self and I am going to be installing a very old heatarola Intency fire air duct coal stove but I'm burning wood in it and would like to use 6in flue instead of 7in since 6 is easier to get at my hardware store does any one know if it is ok in the long run? I have used the stove on 6 before but not vented in to any chimney I did it to warm a outside party I had!! or should I just use 7 if i can find and the parts and pipes? Also when I install it in my shop. I plan on venting the stove out and turn left horizontal into a raised up 35gal drum on it's side with one removable baffle and then out the top of the drum and through the steel container wall in to the next room and turning right in to the I think 14 or 16in 15 foot round concrete chimney ( Made out of old non used sewer pipes) total single wall flue before chimney aprox 10feet and 3 90's and one 45 going into the drum, but I can remove The 45 if I have to and pipe the stove into to back of the drum and out the top front . Will this thing still draft right ?? or will it take a long time to get going?? Thanks to any one or people with tips or help or ideas Thanks BEN AKA TORCH PS. If more info is needed just ask!!!!