Poor Man's Solar Water Heater

[Paul M. Eldridge]

First, by way of background... I consume a little over 800 litres
(210 U.S. gallons) of heating oil per year for space heating and
domestic hot water purposes. By my estimates, water heating accounts
for over half this amount and a large percentage of this can be
attributed to stack and tank related losses. My hot water consumption
is rather modest and there's probably not a whole lot more I can do to
reduce it any further (well, not without causing marital disharmony,
that is).

And therein lies the rub. I can't justify the cost of installing a
solar how water system when my DHW demand doesn't warrant it.
Furthermore, my roof faces east-west and Halifax isn't known as
Canada's sunshine capital.

That said, on those seemingly few days when the sun does shine (like
today), a regular garden hose is a simple and inexpensive way to tap
into it. As the sun shifts around the back of the house, I roll out
several lengths of hose on the patio and within an hour or so the
water is scalding hot. Using a 10-litre bucket, I then transfer this
water to my front load washer. My fuel oil savings are admittedly
small (perhaps no more than 0.25 litres per washer load), but for
roughly six months of the year I'll have the satisfaction of heating
atleast some my water with the sun and with no out-of-pocket expense.
I can probably extend the season by several weeks if I build a small
solar box and coil the hose inside, but for now simply leaving it
exposed on the ground works well enough.

Cheers,
Paul

 

[Paul M. Eldridge]

You appeared to have contradicted yourself. You imply poor solar
availability and yet brag how well your garden hose works for hot
water.

Er, how so? I do laundry on the days that sunshine is available, so
if it rains for five or six days in a row (not uncommon here on the
east coast), the dirty clothes pile up. If I expected my crude solar
hot water system (if I may call it that) to offset some portion of my
bathing and dish washing needs, then I'd obviously have a problem, as
that's not something I can put off for several days at a time.

Cheers,
Paul

 

[clare at snyder.on.ca]

Er, how so? I do laundry on the days that sunshine is available, so
if it rains for five or six days in a row (not uncommon here on the
east coast), the dirty clothes pile up. If I expected my crude solar
hot water system (if I may call it that) to offset some portion of my
bathing and dish washing needs, then I'd obviously have a problem, as
that's not something I can put off for several days at a time.

Cheers,
Paul

I'll vouch for the unpredictability and general lack of sun in
HazyFax. Of all the times I've been out there, I think I've only had 2
sunny days in a row, mabee ONCE.

Not quite as bad as the "granite planet" to the north west - - - -.

 

[Paul M. Eldridge]

I can't explain it any simpler than I did.

Then I take it you don't have much of a point, n'est pas?

Cheers,
Paul

 

[Paul M. Eldridge]

I'll vouch for the unpredictability and general lack of sun in
HazyFax. Of all the times I've been out there, I think I've only had 2
sunny days in a row, mabee ONCE.

Not quite as bad as the "granite planet" to the north west - - - -.

Not quite as bad as St. John's, but pretty damn close! (122 foggy days
versus 124)

Here's what Environment Canada has to say:

"Halifax's reputation as a foggy and misty city is well deserved. Each
year there is an average of 122 days with fog at the International
Airport and 101 days at Shearwater, on the Dartmouth side of the
harbour, although on most days fog persists for less than 12 hours.
The period from mid-spring to early summer is the foggiest time. Bands
of thick, cool fog lie off the coast, produced where the chilled air
above the Labrador Current mixes with warm, moisture-laden air moving
onshore from the Gulf Stream."

Source:
http://atlantic-web1.ns.ec.gc.ca/climatecentre/default.asp?lang=En&n=61405176-1

Cheers,
Paul

 

[[email protected]]

Then again...

http://blog.sciam.com/index.php?title=66_beer_bottles_one_cheap_rooftop_solar&more=1&c=1&tb=1&pb=1

Nick

 

[Paul M. Eldridge]

I did something similar to you folks.
I took 300' of garden hose and mounted it on a 4x8 sheet of plywood.
This wasnt elegant. It did get me 63 deg c water though. Too hot to touch.
That was still with no flow.
I hooked this up to my pool, it does heat the water up a couple of degrees.
As a former pressure vessel inspector, I keyed on the note about 105c water.
That, if released, will flash to steam with the attendant dangers. Keep your
volume small
if youre going to go that hot.
Regards.

Hi Frank,

Good advice. Although I haven't measured it, I'm guessing the water
temperature in this case reaches 50 to 60C in about an hour of full
sun (out of the tap, it's probably no more than 5C).

I connected several garden hoses together and loop them on the back
patio where they are exposed to direct sun; total collector length
might be 100 metres. That seems long enough to supply 30 to 40 litres
of hot water at a time -- more than enough for a load of laundry. My
front loader takes close to an hour to do its thing and that's plenty
of time for the hose to recharge for the next load. When done, I coil
it back up and it sits out of the way.

Although crude, it will supply all of my laundry related needs for six
or seven months of the year, *and* at no cost (these are the same
hoses I use for watering my garden); the little bit of exercise
running the bucket back and forth is an added bonus. I need to
schedule my laundry whenever the weather permits, but that's not a
hardship, and while the monetary rewards are small, the personal
satisfaction is quite large.

Cheers,
Paul

 

[Paul M. Eldridge]

Hi Frank,

It's a valid question and I gave it some thought as well. The only
downside is that dragging a long hose through the house will
inevitably bring dirt and debris along with it and I might end up
scuffing the walls.. The bucket seemed like a safer way to go.

Cheers,
Paul

 

[Paul M. Eldridge]

Water expands when it gets hot. And expanding hot water inside the
water hose may create so much pressure that the water hose can be
damaged if the hot water has no where else to go. The expensive kind
of water hose may or may not have this problem. But the low/moderate
cost version of water hose may not be able to handle that kind of
pressure. I used to have a water hose rolled up on a black top
driveway, and I didn't drain the water from the water hose. One week
of doing this later, several areas in the water hose were expanded out
and the surface of the water hose became thin and one of the weakened
area ruptured.

Whatever saving that you have using the hot water may be offset by the
cost of replacing the water hose.

Jay Chan

Hi Jay,

These are, in fact, good quality hoses and I haven't noticed any sign
of damage thus far, but I will keep a close eye on it, thanks. I haul
it out an hour or so before I do laundry and, when done, shut off the
outside tap and roll it back up; it's not exposed to direct sunlight
any longer than required -- typically no more than two to three hours
at a time.

Cheers,
Paul

 

[no spam]

Water expands when it gets hot. And expanding hot water inside the

water hose may create so much pressure that the water hose can be
damaged if the hot water has no where else to go. The expensive kind
of water hose may or may not have this problem. But the low/moderate
cost version of water hose may not be able to handle that kind of
pressure. I used to have a water hose rolled up on a black top
driveway, and I didn't drain the water from the water hose. One week
of doing this later, several areas in the water hose were expanded out
and the surface of the water hose became thin and one of the weakened
area ruptured.

Whatever saving that you have using the hot water may be offset by the
cost of replacing the water hose.

The problem isn't from the water expanding from the heat. Its from the hose
material being weakened by the heat and failing under the standard water
pressure from supply.

 

[[email protected]]

The problem isn't from the water expanding from the heat. Its from the hose
material being weakened by the heat and failing under the standard water
pressure from supply.

Swan makes black hot water garden hoses, "up to 160 F," with a lifetime
guarantee, eg Grainger's stock number 2P098 at $37.85 for 75'.

Nick

 

[clare at snyder.on.ca]

Hi Jay,

These are, in fact, good quality hoses and I haven't noticed any sign
of damage thus far, but I will keep a close eye on it, thanks. I haul
it out an hour or so before I do laundry and, when done, shut off the
outside tap and roll it back up; it's not exposed to direct sunlight
any longer than required -- typically no more than two to three hours
at a time.

Cheers,
Paul

The hose is made to withstand normal domestic water pressure - and as
long as it is connected to the domestic supply the pressure will NOT
exceed the domestic supply pressure UNLESS you close both ends of the
hose.Expanding water just inches back the supply line a bit, just
like with your normal domestic water heater.

 

[clare at snyder.on.ca]

-

I think you are exactly right. In my case, the water hose was closed
in both ends, and the hot water has no where to go but expanding
against the water hose. This may suggest that we may want to leave
one end open. Having said this, I have a feeling that opening one end
to let hot water to expand into the water supply (to relieve water
pressure) may not be a good idea. Won't that violate some code
requirement (like the code requires us to install a back flow
preventer)?

Jay Chan

Code Schmode - you'll get at most a couple cups of hot water back
into the "system" = about 3 or 4 feet's worth at best.

What do you think happens with your water heater????

 

[stu]

-
Code Schmode - you'll get at most a couple cups of hot water back
into the "system" = about 3 or 4 feet's worth at best.

What do you think happens with your water heater????

Well that would depend. Here they have a pressure/temp relief valve and a
back flow preventer. Of course you don't need either as long as you are sure
the thermostat wont fail "on". Then things get interesting.

 

[clare at snyder.on.ca]

Well that would depend. Here they have a pressure/temp relief valve and a
back flow preventer. Of course you don't need either as long as you are sure
the thermostat wont fail "on". Then things get interesting.

No backflow preventers in Canada.

Then again, in Zambia the "geyser" was gravity fed from a "float tank"
in the attic. No pressure releif valve - and basically no pressure on
the hot water side. Solar hot water assist in the summer - the attic
must have been 160F onder that tin roof. Never turned the geyser on
for 6 months of the year.