Posted by Cosmopolite on May 25, 2005, 10:57 pm
If only prpylene glycol is used, would one or two backflow
preventers, after the meter, be ok ?
Posted by DJ on May 26, 2005, 1:58 am
IFF, geometrically speaking...
There's two answers to that. One, that IFF (if and only if) propylene
glycol was the only contaminant in your water, besides water, and you
drank it, it would be extremely unlikely that you'd get sick or die
You will get no such assurances from ethylene glycol.
The second answer is: what does your local plumbing authority say?
They're the guys that can cause the problems.
And, really, guys. In a SDHW system, there's what, not even a gallon of
mixed glycol? Why the hell WOULDN'T you use potable glycol? You just
dumped several THOUSAND dollars in pumps and panels. Gonna save fifty
bucks and run poison in it instead of propylene glycol? It's alot
easier to find these days, too, than it used to be, thanks to the
popularity of "radiant floor" heating. They sell it to the heating
contractors in 50 gallon drums...
Posted by DJ on May 26, 2005, 1:11 am
For one, the suppliers I deal with (Enerworks and Thermo-Dynamics)
PROHIBIT the use of "poison" in their systems. A single drop voids the
warranties on the entire system, pumps, panels, "da werks". Don't do it
A leak in any Thermo-dynamics or Enerworks system would result, worse
case, in slightly creamy and non-toxic water... and hot water, at that.
You'd probably drop dead with the first one. It only takes something
like 50-100mls of your favorite poison to get you a dirt nap.
Posted by Bert Menkveld on May 27, 2005, 1:09 pm
I also used to think there could be no problem with a leak, since the mains
water pressure is much higher than the solar loop. However, in a closed
loop SDHW system, a leak will result in mains water leaking into the solar
loop until the solar loop is at the same pressure as the mains. At that
point, fluid can leak in either direction.
Posted by DJ on May 27, 2005, 6:49 pm
Bert Menkveld wrote:
Actually, Bert, there's usually a pressure relief on the glycol side,
that would vent lower than potable pressure.