High AFUE gas furnace recommendation + questions

[PierreG]

I am about to move from oil to natural gas (central heating with hot water).
I am looking for a 85000 BTU furnace able to run without electricity.
My neighbor had one recently installed but is not happy with the way the
exterior air intake was fixed.
When speaking with the utility gas tech he told me that not all the
furnaces need an fresh air intake from the outside and that the very
high efficient furnaces also don't need a liner in the chimney, pvc pipe
is enough.

Does anybody have any suggestion on brand and/or model? (no intake from
the outside, pvc pipe for exhaust)

Other question about hot water: I also was told that some furnaces are
able to produce domestic hot water through a separate circuit inside the
body of the boiler. What are the advantages/drawbacks of such a system.
Plumbers seem to prefer install a gas furnace AND a gas water heater
instead of the combo stuff. I guess they get more money by installing 2
systems but is it the only reason?
Thanks for any tip.

Pierre

[Robert Hancock]

If you want to vent with a PVC pipe then it will have to be a 90% or higher
efficiency model, and I believe all of those use an air intake from outside.
An 80% class midefficiency model will vent through the regular chimney, but
a liner will probably be required if it's a real masonry chimney (not a
metal B-vent). Typically 80% models don't use outside combustion air.

I can't think of any modern heating system, other than a wood stove or
something, that is capable of operating with no electricity however.

--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hanc...@nospamhome.com
Home Page: http://members.home.net/hancockr

"PierreG" <car...@cam.org> wrote in message
news:3916DBDC...@cam.org...

[John McGaw]

External air -- not necessarily. I have a 92% furnace from Goodman that
doesn't require an external air intake although they sell a model that
looks virtually identical that does use one. PVC does work nicely for the
venting on this one and it gets barely warm to the touch in operation. It
does condense out a LOT of water during operation though. One thing for
sure, all of these super-efficient furnaces need something to force the
draft and since they aren't using a big temperature differential they can't
be using waste heat to manage it -- that means that some sort of a blower
is required.
--
John McGaw
Knoxville, Tennessee, USA
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Robert Hancock <hanc...@nospamhome.com> wrote in article
<cdHR4.131456$l41.5...@news1.sshe1.sk.home.com>...

[Tim Lapin]

Actually, this is close to how our furnace works. We have a Wiessmann
millivolt gas furnace, with a 83% AFUE rating. It uses a pilot light
system combined with a very sensitive connection to a millivolt digital
thermostat. As such, there is no connection to Hydro-Quebec except for
our pumps which push the hot water throughout the house.

In case of power failures, we simply bypass the pumps using a shunt,
while our thermostat flips over to batteries. Naturally such a system
is less efficient during a loss of power, but at least we have heat when
all else has failed.

We were planning to do this anyway, but the ice storm of 1998 forced our
hand.

In article <cdHR4.131456$l41.5...@news1.sshe1.sk.home.com>, "Robert
Hancock" <hanc...@nospamhome.com> wrote:

>
> I can't think of any modern heating system, other than a wood stove or
> something, that is capable of operating with no electricity however.
>
> --
> Robert Hancock Saskatoon, SK, Canada
> To email, remove "nospam" from hanc...@nospamhome.com
> Home Page: http://members.home.net/hancockr
>
>

--
Tim Lapin Desktop Consultant Concordia University
TEL: (514) 848-7639 FAX: (514) 848-7622
e-mail: mailto:ti...@alcor.concordia.ca
web: http://alcor.concordia.ca/~timl