Hybrid Car – More Fun with Less Gas

Thermal Hot Water in a Freeze Zone

register ::  Login Password  :: Lost Password?
Posted by Benign Vanilla on April 30, 2004, 2:24 pm
If living in a hard freeze zone, does it make sense to use a passive system,
and drain it for the winter? Or spend the extra cash for a more complex
system that can use anti-freeze and other measures to stay active all year
round? Are the collectors efficient in the winter?


Posted by DJ on May 2, 2004, 5:15 pm

 The term we use for that is a "drainback system". I'm sitting at 46
degrees North. Yep, we get hard freeze ;-).

 Conventional flat plate collectors work quite well for everything but
the darkest dismal days of winter, and now, the addition of the
parabolic style of collector (like the new PowerSpar), impressive
amounts of solar radiation can be trapped and converted to heat year
 The biggest factor in what you want to do is not really the price;
for most systems, the money is in the collector, either plate or
parabolic dish. Whether you have 50$ worth of propylene glycol running
through it is almost an afterthought. The heat exchanger you would
need, though, if you use glycol for the system to heat your potable
water, is a bit more pricey, but again, it's the collector that cost
you the most money.
 Nope, the biggest factor is what you want to use the system for, and
you can't really get a fair answer until you answer that one ;-).


Posted by Benign Vanilla on May 3, 2004, 1:51 pm



Fair enough...OK, what do I want to do? Hmm. I'd like to reduce my usage
non-renewal energy sources. Thermal hot water seems to be a great first step
in reducing my usage of gas an electricity. I understand the sun will be
around for a few billion more years, so I am hoping for a system that will
pay for itself in that time. LOL.

Seriously, I want my house to be more green, so I figure adding solar hot
water to the mix is a good idea. I am trying to learn about the options so I
can make a good decision. My decision is kind of time sensitive though,
because my 50 gallon hot water heater is dieing. I need to replace it soon,
so I want to consider that into the mix.


Posted by DJ on May 4, 2004, 12:56 am

The folks at NRCan (Natural Resources Canada, a gov't organization)
say a six-ish year payback for a well installed system, then
substantial savings thereafter, yep.

If you're on the grid, it's the best idea after conservation (CF
lights, insulation, etc).

Well, if it helps, you're going to need one anyway to "finish" the hot
water you need. So get a good one, and save that old one for the
recycle tank you'll need for the passive system.

 A good spot to start reading would be:


Read it all, top to bottom, and you'll know everything you need to!


Posted by Chuck Yerkes on May 9, 2004, 7:03 am
 If  NOTHING else, you can, RIGHT NOW, get a tankless
water heater.

That immediately saves you power.

What you do otherwise - say solar preheat - can be added to that.
If you're optimistic, when you plumb the tankless, talk to the
plumber about routing the pipes to make it easy to put a storage
tank ahead of it.

Benign Vanilla wrote:

This Thread
Bookmark this thread:
  • Subject
  • Author
  • Date
please rate this thread