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Posted by Geoman on July 5, 2007, 12:15 am
>
>> Just read the venting literature for the American Standard sealed
>> combustion, haven't read it lately so I thought I better see if there is
>> anything new.
>>
>> They are now saying you can come off the top of the furnace and go to the
>> bottom and vent out the crawl space, that is if you slope it correctly
>> and
>> put a trap in the lower part of the vent. Hmmmm, we already knew this,
>> but
>> thanks A.S, been doing it for years.
>>
>> You can now get the fresh air from the attic, Hmmm, Done it but don't
> like
>> to. There is a possibility of a leaking gas valve, and if the attic is
>> hotter than outside the make up air pipe in the attic could act like a
>> chimney and cause the gas to go into the attic. Realistically however,
> that
>> would have to be a BIG leak!
>
>
> The biggest issue I see here is pulling in dirty air. Especially, if
> someone
> has been up there with blown-in insulation. Or for heaven forbid, add
> addition blown-in insulation!!!!!
>
>
>> You DO NOT have to get the fresh air from the same side of the house. I
>> wonder if that only applies to the variable speed vent furnace or all of
>> them?
>
>
> ICP still requires it to be in the same atmospheric area.
>
> "This furnace
> uses outside air for combustion ONLY, it MUST be taken from the
>
> same atmospheric pressure zone as the vent pipe."
That answers my question if this was just for the Variable speed vent blower
furnace that Trane/American Standard makes.
Thanks
Rich
>
>
>> On the subject of venting, we installed a new power vented H2O tank
>> which
>> had a few nuisance calls. Of course the factory was of no help. Mark
>> found
>> that our venting was too short and the flame was lifting off the sensor
> due
>> to the air rushing into the chamber because of suck a great suction from
> the
>> ventilator. He put an orifice in the exhaust and adjusted the inch's of
>> water over fire. Works perfect now.
>
>
> Bradford White?
> If so, they discuss this in there installation manual.
>
>
>> For those who don't know it, an 80 and 90% furnace is orificed in some
>> manner to control the negative pressure over fire, not much different
>> than
>> an old 60% with a barometric really. If you installed a condensing coil
>> in
> a
>> 70% furnace and you can make it close to a 90% with consistent control of
>> pressure over the fire box. Had a lot of problems with YORK back in the
> late
>> 70's/ early 80's. Tore the things apart and under the combustion vent
> motor
>> was a plate, you would use the proper plate according to your fuel. Had
>> problems with flame roll out, since I couldn't increase the secondary air
> I
>> increase the negative pressure over fire by increasing the orifice size
>> on
>> the plate between the vent blower and exchanger. There was some
>> efficiency
>> loss but never had the problem again. Two buildings over a YORK truck was
>> working on a unit and we spoke with him, he was having the same problem.
>> Mark and I kept our mouths shut........ they make the big bucks, let
>> them
>> figure it out!
>>
>> Just thought I'd pass on this info, I'm kind of laid back tonight
> wondering
>> which customer will cut my jewels off this week because we can't get to
> them
>> immediately. :-)
>> Rich
>>
>>
>
>
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