Flue Size Follow-Up

[Anonymous]

Thanks HJ and Art

HJ: You talk about having the liner fabricated. I found, on the Web, “Home Saver Co.” which has a Stainless Steel gas flex chimney reliner in 7 inch size. They don’t talk about any other product to reline the brick chimney. I believe they pour some type of filler along the liner after it’s put in the chimney. It sounds adequate to me, but I don’t know.

What do you think?

Art: I didn’t realize this was going to be so complicated, I was hoping for a simple formula.

The information you ask is as follows:

1. The chimney is brick and does not have a clay liner.
2. It’s 30 feet high from the basement floor the the top of the chimney.
3. I would prefer to use units with draft hoods for both the heaters and domestic hot water units.
4. The furthest piece of equipment would be no more than 6 feet from the chimney. If this is critical, I can lay them out closer.
5. The chimney has holes on opposite sides. I guess I can but the boilers on one side and the water heaters on the other. With a new liner, I was hoping to patch one hole and run all 4 units thru one flue pipe. No clue which is the best way.
6. The chimney is inside the house and the Gas Co. enforces the codes which are the US National Fire Code.

It’s really hard to get good information so I thank you guys.

All The Best – Lou

[SylvanLMPParticipant]

Lou, a lot of codes will allow you to use the existing chimeny under certain conditions.

One of the main conditions is getting a A licensed Chimney sweep to clean out the old soot from the chimney/ flue as oil burning equipment Oil heat is a wet heat fuel as compared to the drier Natural gas heat

The problem is the soot build up could cause a flue fire or sulfuric acid to become a problem..
Now FYI a lot of the commerical and big building boilers I installed are duel fuel nat. Gas/ # 2 oil so they do use a common chimney.

They key again is to find out if local codes will allow the licensed chimney sweep to give you a letter saying the existing chimney has been properly inspected and cleaned. Good luck

[Art_xyzParticipant]

Going by the information you have given: You can line your chimney with either 6″ B-vent pipe or 6″ Corrugated metal pipe. Under no circumstances can you vent into an unlined chimney. The down side is that you MUST install TWO 5″ connectors (but you can install the appliances in any combination of two). To be safe, take the information to your Gas Co. and get an O.K. from them before proceeding. (I’m assuming the BTU’S are input not output)

[hjParticipant]

Gas fumes have a higher percentage of water vapor and also operate at a relatively cooler temperature, so a long chimney is going to do two things. First the vapor will condense more readily, which is why you need a liner, and second the gases are going to cool off faster and if the heat is not retained, the gases will have a tendency to cool off and drop back down the chimney into the basement. Ideally the liner should be double wall to retain the maximum temperature out the top of the chimney. Once the proper size liner is installed, the connections can be made in any order, and manner, as long as the proper diameters are maintained as items are added to the branch piping.

[Author]

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