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Clogs

Newbie

Joined: 14/12/2006
Location: Australia
Posts: 8

Posted: 03:01am 28 May 2007

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I found 3 of these solar hot water panels at the local
recycled goods shop and paid $60 for the three of them.

Has anyone out there built a solar hot water system using panels similar to these. They are "Sunbather" brand. (Sorry I forgot to measure the size)

I was thinking of setting up a closed loop system with
a solar powered circulation pump into my existing electric hot water service in the roof.

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 10:14am 28 May 2007

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G'day clogs,
Yes I built one from panels from the recycle shop too. Been going for over 10 years now no worries. Well except that it gets so hot it trips the temp release valve(a few degrees before boiling)and I can loose a lot of water if I've not turned the pump off.

With mine I have not integrated it with an existing system so do not use a cycling pump as you will have to. I used a recycled Dux HWS as storage tank up on the roof using thermo syphon.

Can't think of any pitfalls or advice for your system that common sense wouldn't tell you. Oh one thing, change your HWS systems relief valve system from the 1400kpa standard unit to a 700kpa low pressure one. All solar HWS run the low pressure ones. Don't know why.

Those 1" fittings will be hard to scrounge and expensive to buy but worth the effort.

Sorry, have a couple of pics of mine but main puter with all photos is out of action, well totally dead actually. Maybe later.

Get back to us if you have specific queries.
Good Luck.

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

Feral
Newbie

Joined: 03/12/2006
Location: Australia
Posts: 39

Posted: 03:04pm 28 May 2007

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Clogs, You will have to join all of the panels together so that you have one very long panel up on your roof.
If you have an existing tank in the ceiling you may be able to connect to it if there is sufficient room and locations on the existing tank to make the connections.

Post some photos of your roof and the tank and the existing connections into the tank located in the ceiling and I will see if it possible to be done by a non plumber.

Circulating pump not a good idea as cost is very expensive and exectrical and temp controls required.

The panals should be able to withstand town pressure and be connected to existing tank if all heights are suitable as the highest point of the panels should be lower than the bottom of the tank but this depends on the design of the roof andceiling space.

The water from the bottom of your existing tank, is colder than the top of the tank and if the bottom of the tank is connected to the bottom or the lowest point of the panel the water will run down as it is colder and the convection curents cause this to happen.

When the coldest water in the closed system gets into the panels it gets heated and rises up thorugh the small pipes in the panels then travels along the top larger pipe back up into the top of the existing tank in the ceiling.

It does depend on the type of unit in the ceiling and the difference in height you can achieve between the top of the panels on the roof and the bottom of the existing hotwater tank in the ceiling.

Post a couple of photos and get a few measurements and then we will see if its possible, I used to do this for a living but other matters are now more important.

Clogs

Newbie

Joined: 14/12/2006
Location: Australia
Posts: 8

Posted: 02:59am 29 May 2007

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Thanks for your replies guys. The hot water service is a gravity feed system so there is towns pressure water to the header tank and then the hot water is gravity fed down to the hot water taps. I wont be able to get the panels lower than the HWS so I probably wont be able to set it up as a thermosyphon.

Feral I will take some photo's of the inside of the roof and the HWS tonight. Also two of the panels I have
are as the photo shows which are made for horizontal mounting but the third is a vertical mount. Can they all still be used together?

Clogs

Newbie

Joined: 14/12/2006
Location: Australia
Posts: 8

Posted: 07:09am 30 May 2007

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This is the HWS, Its probably about 25yrs old. Does anyone know if this style of HWS has a thermostat
that switches the element on & off to hold the water at the required temperature or is the element permanently on?

brucedownunder2
Guru

Joined: 14/09/2005
Location: Australia
Posts: 1548

Posted: 09:10am 30 May 2007

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Hello Clogs,,

A fair bit of rust around the bottom of that holding tank ----- Don't know much about hot wter systems ,, but ,,the ones I've had are allways down under thehouse ,,fairly safe that way ,if they rupture-
( i'd hate to have one spill it's contents onto my lounge room or living room walls and such)

Think of it this way 25 years is a good life, get one installed under your house or adjacent to the kitchen , laundry ...
just my thoughts

Bruce

Bushboy

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 09:59am 30 May 2007

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Sure it's got a thermostat, behind that little cover plate next to the power lead in.

But really mate, if you need to ask that sort of question, do you really think it's a good idea to be playing around with electrical?

I'm all for DIY but safety first. Yeh?

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

Feral
Newbie

Joined: 03/12/2006
Location: Australia
Posts: 39

Posted: 02:30pm 30 May 2007

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Gill those sort of comments are not appropriate as he was simply requesting assistence on setting up the solar panels and if that can be done he can turn the power off. Its obvious you cant assist in this field.
Clogs, the tank you have can be used as it would be a copper tank open to the atmosphere as it has a float controlled filler valve keeping the 250 Lt tank filled with water. Is it possible to raise the height of the tank and by how much ?
If you raise the height of the tank will it then allow you to have it a little higher so that the low point of the two panels (horizontal mounted along the bottom of the roof) are then lower than the bottom of the tank ?
The heigh point of the panels,two only, when mounted along the roof should not be any higher than the red pipe on your tank. Better to be lower but level will require pump.
It does look as if it is possible but if the heights for the primary flow and return are insuficient then you will have to use a hot water circulating pump connected to simple electrical timer for 8 Hour day use only. If you use a hot water circulating pump, the pipes connecting panels to tank can be standard 1/2" lagged copper tube and I do believe that there is also poly pipe that will do for these tempretures.
If you can get the heights right and have the convection currents flowing the plug in the bottom of the tank gets connected to the bottom of one end of the panels and the top of the panels gets connected to a new additional Tee connection at the same place where the red pipe connects to the tank. A pump that is suitable would be Grundfos Comfort series 1/2 - 240 Volts Details at http://www.grundfos.com/web/HOMEau.NSF/Webopsl*g/F399452AC86 77450C1256C050039BAAA

Clogs

Newbie

Joined: 14/12/2006
Location: Australia
Posts: 8

Posted: 12:00am 31 May 2007

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First to Gill, thanks for your reply as it appears you
may have a genuine concern for my safety, your knowledge and experience are always welcome although your lack of tact is not.
I had assumed that the HWS was thermostat controlled
& was simply looking for the opinion of someone with more experience with hot water services than me.
I always treat 240v electricity with the respect that it deserves.

Second to Feral, your reply was the kind that informs &
educates and is what this site is all about.

Lifting the tank may be an option so I will see if it is possible. Thanks for your reply and the info on the pump.

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 01:19pm 31 May 2007

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G'day all,
Yes I did have a real concern for your safety hence my deliberate manner of response. I do not apologies for that.

I did however misread your query. I understood that you were asking where it was, and like if my grandkids ask "Where is the axe?" it's a safe bet they intend to mess about with it. This raised a concern that I rushed in to respond to. I should have reread the post as you were merely after the units features.

As I say this was my error for which I sincerely apologies.

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

RonS
Newbie

Joined: 19/06/2007
Location: Australia
Posts: 18

Posted: 02:27am 08 Jul 2007

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For solar hot water systems thhat don't have mains pressure hot water, a useful and failure-free pressure release mechanism is a "Shephard's Crook' where you use a vertical length of copper pipe, the top of which is bent over in a loop like a shephard's crook such that the 'mouth' of the open end touches the vertical riser. It will still work if it doesn't touch, but the water dripping on the roof from some 2 - 3 metres up in the middle of the night will drive you nuts!
With a Shephard's Crook, the water can boil happily without blowing anything up. Doesn't do a lot for the longevity of some parts of the system, however. My Dad and I built a solar hot water system in 1953 for the farm house. We didn't know how to calculate what area of glass was needed, so we used ten salvaged windows that totalled about 15 sq. metres. In summer, the thing boiled before ten o'clock each morning so we got some 'Holland' blinds, took out most of the return spring and the latch and rivetted a sheet-metal trough to the bottom edge, The water spurting out of the Shephard's Crook was directed into these troughs to drag the blinds across to cut off the sunlight. It worked .... sort of. That is, if you liked permanently boiling hot water. We later covered up all but one window for summer time and all but two in winter. It was still working fifty years later when the house got destroyed in a storm. We used blacked copper sheet and tack-brazed copper pipe, also blackened, with a back insulation of 'dag-wool'. (we ran sheep).

Avoid strong drink. It makes you shoot at tax collectors ...and miss.

Gill

Senior Member

Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 03:51am 08 Jul 2007

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My father built one too in the late 50's. Though ours was at mains pressure and could be reconnected to 240v if the need arose(it never did).

here's an old pic of the installation.

The Shepard's crook can be seen extending well above the roof, and I too recall the annoyance of boiling water released onto the roof at the hottest times of the day.
I'm not sure how my father incorporated the Shepard's crook with the mains pressure though. I have always wondered.

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

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