solar water heating
Ohioguy
in a situation where I have an electric water heater being delivered
next week. I'm thinking about putting in some sort of solar water
heater down the road, to help with heating the water, and was wondering
- is there anything I should do NOW to make adding something like that
easier down the road?
Vic Smith
No. Anything you do now that costs you an extra cent will waste that
cent if you don't put in the solar.
Might even cost you more if you let that "preparation" guide you away
from a solar heater system that is more appropriate, but doesn't fit
your "preparation."
They are basically 2 separate issues until you combine them.
And when/if you do, any changes from what can be prepared for now will
be minor.
More likely, your "preparation" won't fit, and have to be removed.
Don't waste your time/money if you don't have the solar system ready.
The one thing you might do is hold onto your old tank if it's not
leaking and is well-insulated. A holding tank is a component of most
solar heating systems. That won't cost anything except storage space.
BTW, solar water heating isn't frugal in most areas.
Hard to get your money back
If your water input is cold, an uninsulated holding tank can save you
money in the summer.
--Vic
jeff
> Has anyone out there successfully set up a solar water heater?
I'm entirely homebrew, so I won't be directly applicable to your needs.
Basically, the key is the heat exchanger. You (usually) don't want
potable water in the collectors. Gary has a good site on solar,
including this meta page on Solar Hot Water:
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm
Use the solar to preheat, it goes before your regular hot water
heater. Tankless is ideal here.
I'm in
> a situation where I have an electric water heater being delivered next
> week. I'm thinking about putting in some sort of solar water heater
> down the road, to help with heating the water, and was wondering - is
> there anything I should do NOW to make adding something like that easier
> down the road?
As long as you can redo the plumbing, which is not hard with anything
other than iron pipe, I wouldn't worry about it now. If you have iron,
you may wish to think about how your unions are set up.
Jeff
Tony Sivori
> Has anyone out there successfully set up a solar water heater?
You might like alt.energy.homepower.
--
Tony Sivori
Due to spam, I'm filtering all Google Groups posters.
Bill
> - is there anything I should do NOW to make adding something like that
> easier down the road?
>
Water freezes. So basically the "fluid" which circulates to a solar water
heater on the roof needs to be something other than water which will not
freeze. Thus there is a "closed" system and a heat exchanger to transfer the
heat to your water.
Also on cloudy days or in the evening, the water might not be as hot as you
want. So these typically have a "preheating" water tank with built in heat
exchanger. Then the water from that goes to your regular water heater.
The solar water heater tank "preheats" the water. Then your regular hot
water heater can heat the water further if needed. Or if the water is hot
enough, no additional heating is required. And you of course save money if
the solar system is doing any heating of the water because the regular water
then works less. And an electric hot water heater can be 30% of an electric
bill!
With that said, you could make room now for the preheating water tank. And
you could slowly install the plumbing. You could also install the preheating
tank at some future date, then later install the solar panels on the roof or
where you want. (Install a bit at a time...)
Bob F
It's way better than solar power.
Bob F
One of the simplest additions
http://www.google.com/search?hl=en&q=batch+solar+water+preheater&btnG=Search&aq=f&aqi=&oq=
Vic Smith
wrote:
I like the simple stuff. My old house in Chicago had a what you could
call a "leveling" or "moderating" or "economizer" tank.
Pick your term. Basically an uninsulated tank that accepted the city
water before it was pushed into the water heater.
Chicago water is very cold, even in the summer, and this tank served
to warm it up a bit before heating. Not effective in the winter
though.
When you think about the length of sunshine in northern climes, solar
makes sense only if you can store the heated water, and that takes
some doing.
With the cold water we get up here, it can probably save some money
if the system is simple.
I got to thinking about it while gardening and seeing how the garden
hose held quite a bit of hot water after some time in the sun.
My feed from the ground puts really cold water to the hot water
heater. Only a short run of 3/4" from the ground to the tank.
An insulated "economizer" tank would make a difference.
If I did the solar here, I'd put an insulated holding tank in the
basement to prefeed the water heater. Run the cold water to the yard
to flow though some kind of ray absorbing piping laid out in the sun,
then back to the holding tank.
Piping could be some sort of black PVC, or copper loops painted black.
Don't think I'd put anything on the roof, or even use a glass
enclosure.
Up here for about 5 months of the year I'd restore the normal feed to
avoid freezing.
It would pay off, but not much. And it'd be a hassle and an eyesore
with that collection method. But it's a cheap way to go.
Have to time your heaviest hot water use to make the best of it.
--Vic
Vic Smith
That would be "uninsulated."
jeff
> "Ohioguy" wrote in message
>> - is there anything I should do NOW to make adding something like that
>> easier down the road?
>>
>
> Water freezes. So basically the "fluid" which circulates to a solar water
> heater on the roof needs to be something other than water which will not
> freeze. Thus there is a "closed" system and a heat exchanger to transfer the
> heat to your water.
The popular alternative is a drain back. This simply drains the water in
the collectors back into the reservoir, no antifreeze needed. That may
have some issues if you have a large drop in height from the collector
as the fall in pressure can cause a decrease in the boiling point. Good
for one story, perhaps not two stories. This is all calculatable.
>
> Also on cloudy days or in the evening, the water might not be as hot as you
> want. So these typically have a "preheating" water tank with built in heat
> exchanger. Then the water from that goes to your regular water heater.
Yes.
Note that the temperature of the "tempering tank" will fall as you
remove heat. Generally just storing a days worth of heat is good enough
to shoot for. You can figure out the size by knowing the amount of BTUs
in and the temp range this will operate over. Solar heaters are less
efficient at higher temps as they have more losses. So, there are trade
offs to finding a sweet spot.
To design a solar heater that doesn't require supplemental is a lot
more expensive.
Jeff
Gary Heston
Vic Smith <thismaila...@comcast.net> wrote:
[ ... ]
>If I did the solar here, I'd put an insulated holding tank in the
>basement to prefeed the water heater. Run the cold water to the yard
>to flow though some kind of ray absorbing piping laid out in the sun,
>then back to the holding tank.
Put the holding tank in your attic, over a tray to catch
condensation. It'll absorb heat in the summer from solar
gain, and in the winter any heat escaping into the attic
will help warm it--although not much, it'd be better than
nothing.
Gary
--
Gary Heston ghe...@hiwaay.net http://www.thebreastcancersite.com/
"It's kind of hard to rally 'round a math class."
Paul "Bear" Bryant
Lou
"Gary Heston" <ghe...@hiwaay.net> wrote in message
news:Z6WdnajJuImMkvLW...@posted.hiwaay2...
> In article <83ksm5ld11vvf3rg9...@4ax.com>,
> Vic Smith <thismaila...@comcast.net> wrote:
> [ ... ]
> >If I did the solar here, I'd put an insulated holding tank in the
> >basement to prefeed the water heater. Run the cold water to the yard
> >to flow though some kind of ray absorbing piping laid out in the sun,
> >then back to the holding tank.
> [ ... ]
>
> Put the holding tank in your attic, over a tray to catch
> condensation. It'll absorb heat in the summer from solar
> gain, and in the winter any heat escaping into the attic
> will help warm it--although not much, it'd be better than
> nothing.
>
Around here, people insulate the floor of the attic, not the ceiling - the
attic volume is open to the winter air via vents. I wouldn't put a tank of
water that might freeze above my living space. Or anywhere else, if I
wanted the water to stay in the tank.
vjp...@at.biostrategist.dot.dot.com
in the summer.
- = -
Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist
http://www.panix.com/~vjp2/vasos.htm http://www.facebook.com/vasjpan2
---{Nothing herein constitutes advice. Everything fully disclaimed.}---
[Homeland Security means private firearms not lazy obstructive guards]
[Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]
Ohioguy
incoming water from something like 52 degrees F (the ground water temp
here year round) to a higher temp when it enters the electric water
heater would be a way to go. Too bad there is not some simple way to
get the waste heat out of the drain water from our 3 showers/bathtubs,
and use some of that to help preheat this water. Sounds like that would
be too complicated, though.
And then, if I were to use some sort of solar heating system, sounds
like it would be best to be on from about April 1 to November 1.
Otherwise, I'd have to rig up some sort of antifreeze based exchanger
system.
The simplest solution would probably just be to rig up an insulated
bathtub in the basement, fill it up 2/3 of the way and put a floating
heat blanket on top of it. Then I could use a solar powered pump and
some small black plastic tubing with water, & see how hot it gets. If
it worked, I could just use the sun to heat all of my bath water.
jeff
> So from what I'm hearing, having a holding tank to increase the
> incoming water from something like 52 degrees F (the ground water temp
> here year round) to a higher temp when it enters the electric water
> heater would be a way to go. Too bad there is not some simple way to
> get the waste heat out of the drain water from our 3 showers/bathtubs,
> and use some of that to help preheat this water. Sounds like that would
> be too complicated, though.
Google that. It's fairly common. There are even some home brew
devices. Typically it is used to warm the cold water line feeding the
shower.
>
> And then, if I were to use some sort of solar heating system, sounds
> like it would be best to be on from about April 1 to November 1.
No, year round. The efficiency, particularly depending on the type
falls in colder weather. Also, the sun is lower in winter, so there are
tradeoffs. Solar is big in a lot of cold climates. Here, I take
advantage of the deciduous trees losing their leaves and have one
vertically mounted collector. So it is tuned for winter. My solar is
primarily for home heating, the leftover goes for DHW. In the summer,
I'll have plenty of hot water.
> Otherwise, I'd have to rig up some sort of antifreeze based exchanger
> system.
No. Drain back. If you need to go up in height to mount the collector
you will need a closed loop (for reasons in my other post), probably
with antifreeze. There are options even there.
>
> The simplest solution would probably just be to rig up an insulated
> bathtub in the basement, fill it up 2/3 of the way and put a floating
> heat blanket on top of it. Then I could use a solar powered pump and
> some small black plastic tubing with water, & see how hot it gets. If
> it worked, I could just use the sun to heat all of my bath water.
I don't think that is worth your while.
The simplest/cheapest these days is a modified Thomason Trickle Down,
high efficiency to boot. No antifreeze in that. Or a batch heater.
Jeff
Rod Speed
> So from what I'm hearing, having a holding tank to increase the
> incoming water from something like 52 degrees F (the ground water temp
> here year round) to a higher temp when it enters the electric water
> heater would be a way to go. Too bad there is not some simple way to
> get the waste heat out of the drain water from our 3 showers/bathtubs,
> and use some of that to help preheat this water. Sounds like that
> would be too complicated, though.
>
> And then, if I were to use some sort of solar heating system, sounds
> like it would be best to be on from about April 1 to November 1.
> Otherwise, I'd have to rig up some sort of antifreeze based exchanger
> system.
Nope, just automate a drain back system for the winter.
> The simplest solution would probably just be to rig up an insulated
> bathtub in the basement, fill it up 2/3 of the way and put a floating
> heat blanket on top of it. Then I could use a solar powered pump and
> some small black plastic tubing with water, & see how hot it gets.
It wont get that hot in winter without some transparent cover over
the black plastic tubing if you get much snow and ice in winter.
> If it worked, I could just use the sun to heat all of my bath water.
That doesnt work too well if you mostly bath first thing in the morning early.
Its dark here when I get up in summer.
RickMerrill
Just a reminder: do not run an antifreeze loop inside the potable hot
water tank. (Otherwise a single leak could poison you.) I think there
are non-poisonous anti freezes these days however.