Chimney tape

[doc623]

I have a add on wood and coal furnace.
I took the pipe off yesterday to clean and it was difficult getting a good draw until the fire was going last winter and got a lot of back or down flow from the masonary chimney.
The stove/furnace had very little soot in the pipes or the stove - less than 1/4 built up on the inside of the pipes/stove/chimney.
When I put the pipe back together am still having trouble lining up one section - yes it is the correct order as I took pictures and marked the sections before taking apart.
I have basically three questions.
1. DoI need to tape the joints - they were not originally taped?
2. There are a couple of extra screw holes in the middle section; I"m assuming from the original installation. Do I need to cover these holes?
3. Amy thoughts on the drawing/back flow from a cold chimney? Or how to get the stove/furnace to draw better from the start?
Thanks.

 

[Corey]

To answer some of your questions:

1. Do I need to tape the joints - they were not originally taped?

- I don't think there is any tape recommended - or that will even stand up to the temp of a wood/coal flue temperature. No tape should be needed or required.

2. There are a couple of extra screw holes in the middle section; I"m assuming from the original installation. Do I need to cover these holes?

- Assuming we're talking about the little sheet metal screws used to hold sections of pipe together - As far as creating more draft, it won't do anything, thought you might wish to put a screw back in the screw hole to seal it up and prevent any chance of smoke or a spark getting out. If it is all original, the holes should line up with corresponding holes on the next section of pipe and you can put the screws back in to secure the pipe.

3. Amy thoughts on the drawing/back flow from a cold chimney? Or how to get the stove/furnace to draw better from the start?
Thanks.

- That is mostly just the nature of a cold chimney. Various methods have been discussed on here including lighting a single sheet of newspaper at the base of the flue, using a hair dryer to blow warm air up the flue, lighting a firestarter log at the base of the flue, and others. I find that for my situation, using an extra amount of small kindling, then lighting the fire and immediately closing the door usually works. I keep the door closed until the warm air in the stove gets the air flowing in the proper direction, the re-open to add more wood as needed. Though I have not tried it, the hairdryer would seem to be a good choice as it doesn't produce any fumes at all, so if the flue doesn't start flowing immediately, the only thing spilling into the room would be warm air.

PS - you may also want to look around and make sure you're not venting any house air outside...kitchen stove fans, bathroom fans, clothes dryers, etc all move some inside air to the outside - so if you have one of those running, it may be extra hard to get the flue flowing properly.

 

[begreen]

No, don't use tape on the flue pipe. The extra holes if small screw holes shouldn't be an issue if there are only a couple holes, though you could put a screw in them as plugs.

Is this in the basement? What is the flue setup and chimney height? You might look for competing appliances running in the basement. Are there a clothes dryer, gas HW heater, furnace or bathroom fan in the basement? Or is the basement sealed very tightly? If yes, the wood furnace may need an outside air supply.

Another thing to check is any horiz run in the flue connection. Ideally they should be very short and pitched uphill at least 1/4"/ ft.

 

[BrownianHeatingTech]

3M has a tape rated to 600F, which you can use to seal flue pipes.

You can also use high-temp RTV silicone.

Flue pipes should generally be sealed - leaks reduce the draft available to the appliance, giving you the "cold chimney" effect (low draft at the appliance) for longer. A cold chimney will take time to warm up, no matter what. The only solution (short of re-working the chimney) is to install a draft inducer, which will mechanically create draft for the appliance, even before the chimney is able to.

Joe