"Bob F" wrote:
philo wrote:
We just got done with a very cold winter.

On some of the coldest days there was a lot of condensation in the
house right near the ceiling adjacent to the chimney.

I have a standard gas furnace that's about 22 years old and there is
NO liner in the chimney. Various chimney repair companies have told
me I should get a liner installed to avoid condensation.


I was about to do so then realized that I'll probably need a new
furnace within the next few years anyway and now might be the time to
not only get a high efficiency furnace but to get central air instead.


The 100 amp service in my 116 year old house is maxed out so I have
hired a contractor to upgrade the service to 200 amps.


Now, my question: I still have a gas hot water heater using that
chimney which will be otherwise unused. Is it likely I'll still get
condensation on cold winter days?

I can't say for dure about the condensation, but the chimney will likely not
operate correctly with just the gas water heater. When I converted to a
condensing gas furnace with PVC pipe out the wall, I, by code, had to install 4"
"B" vent in the chimney for the water heater. The chimney is designed for the
larger heat of the gas furnace. I would imagine, condensation might be one of
the problems with only the water heater especially if it is already a problem in
cold weather.

They tapped into the chimey on my gas water heater. It has a 6 inch ceramic
liner. Seems ok, but I still need to install top hat. On the other house, I
got same condensation problems. No liner, and the hole is over 10 inches.
It also feeds to the older gas furnace. I don't intend to fix that
situation, but I still need a top cover.
On my old house, I installed a galvanized pipe down through the asbestos
chiney. I figured it is best to narrow the system. It was easy as the roof
was not steep, and had easy access, so I did it myself.


Greg