Re: [GBlist] Gas-fired tankless water heaters?

["malcolm.scott" <malcolm.scott@ntlworld.com>]

----- Original Message -----
From: "RET John" <retjohnd@home.com>
To: "Mike Rogers" <rogers.mike@verizon.net>; "Green Builders Server list"
<greenbuilding@crest.org>
Sent: Thursday, February 22, 2001 4:54 AM
Subject: Re: [GBlist] Gas-fired tankless water heaters?


> on 2/21/01 21:16, Mike Rogers at rogers.mike@verizon.net wrote:
>
> Wednesday, February 21, 2001 21:48
>
> > Do you know if the direct vent model is sealed combustion?
> >
> > -Mike
>
> No it is not. No such thing as a "sealed combustion" direct vent hot water
> heater that I am aware of. ANY product that uses a gas fuel all have to
have
> oxygen to burn the fuel so therefore you really cannot have a "sealed"
> combustion area so to speak.
>
> If you do not want combustion then you can buy an electric direct vent
> hot water heater, but of course your cost per BTU will be around $26.00 or
> so depending on the cost of electric in your area. Now that natural gas
and
> propane have gone up so much an electric instantanious electric hot water
> heater may not be such a bad idea. One has to compare fuel costs on a cost
> per BTU basis!

The direct vent model IS sealed combustion.  It requires one wall
penetration for both inlet and exhaust.  There is an alternative using room
air exhausting up a flue.  Electrical water heating is a bad idea because of
the poor power station efficiency.
Malcolm