Posted by Moe on July 4, 2007, 4:48 pm
I was wondering,... my natural gas HWT is in the basement, would
it be cost effective to install another one on the first floor and vent
the lower tank through the floor to the second tank to prewarm or heat
the water in the second tank? Would a power vent be needed to exhaust
the fumes? The second floor tank would not have a burner but only be
used to capture the wasted heat now going out the vent. Plumbing would
be changed to go to the top tank first then the prewarmed water would go
to the HWT.
Posted by firstname.lastname@example.org on July 5, 2007, 12:34 pm
could create a real safety hazard, the exhaust gasses must be hot
enough to leave the building, your idea would cool them so much and
create a carbon monoxide hazard.
sorry for the bad news but good thinking out of the box.
Posted by daestrom on July 6, 2007, 2:14 pm
If your basement heater is 'natural draft', then the gasses have to be hot
enough to create a draft up the flue. Cooling them too far may cause
problems when the wind blows wrong or the house is all 'sealed-up' for bad
If your basement heater is already a 'power vent' type, I think you'll find
the air dilution is so much that the vent outlet is pretty cool already and
you won't recover much more.
Now, if you 'natural draft' from basement to first floor, the gasses will be
hot when they reach the first floor (assuming you properly insulate the pipe
(don't forget fire-stop spacing around the flue). Then 'power vent' from
the first-floor unit to outside to maintain the draft, it might work. But
I'd be sure to have a working CO monitor, just in case.
Posted by Moe on July 7, 2007, 3:40 pm
Guys, I unhook the vent to the HWT in winter and let it heat under
the house, keeps the pipes from freezing and we have low humidity so the
extra vapor doesn't hurt, at least not in my case. I've got a couple
of CO detectors with digital read outs and alarms and they have never
ever ever registered any CO from natural gas burning. I also heat the
house with a unvented radiant wall heater and unvented central heat.
But put a cigarette under the CO detector and watch it ! 250 PPM shows
up very quickly and the alarms work. Yea I know I'll wake up dead
someday but it's worked fine for the last 20 plus years. There is
plenty of heat coming out the top of the HWT to create a draft through
another tank and in my case it would then vent into the house any way.
Interesting to watch the CO detector in the garage, start the car and
it goes up then goes down as the catalytic converter fires, about 50
ppm CO is all it will show after and hour with the door closed. Start a
lawnmower, weed trimmer, chainsaw generator etc. in the garage with the
door closed and it can easily peg it at 999 in a short time. You guys
can vent and waste 20 to 30% of the heat to the outside, I'll use it
one way or the other.
Posted by lnh on July 7, 2007, 8:20 pm
so begins natural selection...
This is so dumb. I guess all those smart engineers and firemen just must
"Waste" heat or die...let me think about that.
Seriously, if your house is leaky enough, you might just survive. And
how are the CO2 measurements? Or NOx? Not all combustion is complete all