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KE's solar heater
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Author:  King Erik the 14th [ Feb 17th, '08, 19:22 ]
Post subject:  KE's solar heater
I'm having trouble sourcing a pump to go with my solar hot water panel. Creative pumps gave me 2 sugestions but neither of them fit into my (wifes) budget. Does anyone else have any ideas?
Thank you for your Pump enquiry.

From your information the following is details on pumps for your application

Little Giant 2 MD-HC Part no. 580614 $ 612.00
http://www.lgpc.com/Product/ItemDetail. ... ductID=608

OR

Flojet 2130-232 although max temp is 71"C $ 382.00
http://www.creativepumps.com.au/work/a_ ... 30_232.htm

I'm planning to run it as a closed loop using some type of poly pipe, an inline pump, perhaps a stainless steel heat exchanger, and with the panel mounted on the roof of my house. The pump will be connected to a timer to run in daylight hours and a thermostat in the fish tank. I imagine that the water in the loop will be pretty hot as it leaves the panel, but will cool down somewhat after it leaves the fish tank and runs back through the pump, but I really dont know what temp it would be.

Attachments:
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Author:  Outbackozzie [ Feb 17th, '08, 19:28 ]
Post subject: 
71 should be heaps - I assume the pump will be in the fish water curcuit, and the hot water is syphon through the heat exchanger?
Author:  Sleepe [ Feb 17th, '08, 19:39 ]
Post subject: 
If its not being abled to handled by a cheap pump you will either be running too much flow or your heat exchanger is not worth a cracker.
Alternately you have just broiled your fish.
Author:  veggie boy [ Feb 17th, '08, 20:28 ]
Post subject: 
There are some pumps at that joint in Melbourne that F&F is always talking about that should do the job. Sorry I can't give the detail right now - but I looked at them when I was researching for my solar heating system - yet to be set up.
Author:  Hex [ Feb 17th, '08, 21:26 ]
Post subject: 
A central heating pump would probably do it if the HE is parked in the tank with a closed circuit through the panel.
Most have 3 speeds, last for years and can handle at least 110C.
Author:  Sleepe [ Feb 18th, '08, 06:45 ]
Post subject: 
Had a look at that again, problem is likely to be head not heat.
You can either pump fast so that the water does not have time to get really hot or slow and allow the heat exchanger to dump the heat before return to the pump. Spa pumps can handle reasonable heat.
The critical thing KE is going to be the cut off from the thermostat. Even in winter those panels can generate large amounts of heating.

Hex Central heating pumps are great but sourcing a second hand one in Adelaide may be difficult. Stacks in the UK but not so common over here.
Author:  Clogs [ Feb 18th, '08, 06:55 ]
Post subject:  Re: KE's solar heater
Check out the Davies Craig 12v Circulation pump on the 12 Volt Shop website.
The part no. PUDC12. Price is $195. Thats the pump im going to use for my solar hot water panel setup.The 12 Volt Shop
Author:  Sleepe [ Feb 18th, '08, 07:11 ]
Post subject: 
KE One more thing, it shouldn't be fully closed loop so arrange a sheperds crook above the Panel. This allows for gassing and excess pressure and is simple and cheap.
Had second thoughts on the head problem because of the return line pressure. Might not be a problem.
Author:  King Erik the 14th [ Feb 18th, '08, 09:13 ]
Post subject: 
I guess it will take a bit of experimenting with the thermostat and temps. The thermostat will be set in the fish tank not the loop. I would set it at a few degrees lower than what I want so that when the pump switches off it will allow for any heat that still comes out of the coil.
Would it be a problem if I dont run it at all during the really hot days? I imagine the water in the panel will get to much greater than 100C, so is there going to be a build up of heat and pressure that will possibly burst something? Sleepe, is that what the "sheperds crook" is going to prevent? (What is a sheperds crook?) Is it possible to make one or would I buy it at a plumbing store?
Author:  creative1 [ Feb 18th, '08, 09:59 ]
Post subject: 
Bleeds off heat KE, in the form of steam or drips, as the water heats up it expands and needs to let off excess pressure.
We have one attached to the chipheater!
There is a ratio that needs to be followed (diameter x height etc)!
When the kids were young and got excited (put too much wood on the fire)
we had a cappo machine on the roof or the tap if you were silly enought to
turn one on! :shock:
Excess water returns to the watertank via guttering.
I would love to tell you more about heat convection as I think this would be a better pump, but I am sure I read a lot of conversation about this before!
Author:  Sleepe [ Feb 18th, '08, 11:00 ]
Post subject: 
KE

A shepherds crook is just a piece of copper pipe with a slight hook in the end. All it is for is providing a low pressure saftey valve ie if pressure builds up in the system it vents out of that pipe.
C1 is right about the hight of the pipe, the taller it is the more pressure it puts on the bottom components before venting. Yours would not need to be very high at all. Don't think the diameter matters probably just go with 1/2 inch.
If you are using poly pipe from the collector I would worry about the heat from the collector to the heat exchanger blowing the pipe or the fittings on that side of the loop.
Author:  creative1 [ Feb 18th, '08, 11:06 ]
Post subject: 
Oh yeh, thanks sleepe I forgot to mention it looks like a shepherds crook. :oops: :roll:
Author:  Sleepe [ Feb 18th, '08, 11:17 ]
Post subject: 
And I forgot to tell him about the height :oops:
Author:  creative1 [ Feb 18th, '08, 11:28 ]
Post subject: 
Our HWS islow pressure @ 7lb and the crook is about 8 feet tall (above the tank).
It starts off with 3/4" and goes to 1/2" at the top.
Author:  Sleepe [ Feb 18th, '08, 11:37 ]
Post subject: 
KE's would be running at basically no pressure, and I don't think he would want any so its really just a vent pipe.
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