TheBackShed.com

Forum Index : Windmills : solar hot water

Author

Message

AllanS
Regular Member

Joined: 05/06/2006
Location:
Posts: 67

Posted: 09:40pm 12 Jun 2006

Copy link to clipboard

Print this post

Here's a nice solar HW system. Would be a lot cheaper if you made your own collectors.

http://www.suburbia.com.au/~mickgg/K4/kernkraft.htm

dwyer
Guru

Joined: 19/09/2005
Location: Australia
Posts: 574

Posted: 02:47am 13 Jun 2006

Copy link to clipboard

Print this post

Hi Allan
Thank for showing us about solar hot water as lhave seen before but this one exellence

Dwyer the bushman

Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5111

Posted: 03:39am 13 Jun 2006

Copy link to clipboard

Print this post

I've been tempted to make a solar hot water system, but was worried about air locks. I have a lot of "bubbles" in my water when I'm using the bore, and when I switch from tank to bore and back, I end up with one great big bubble!. With the solar collectors up on the roof, any air pockets would end up there. Is there a easy fix for this, or would I need to bleed the air off every few days?

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

AllanS
Regular Member

Joined: 05/06/2006
Location:
Posts: 67

Posted: 06:10am 13 Jun 2006

Copy link to clipboard

Print this post

Make a closed loop. If you used distilled water in the collector and a small heat exchanger, it'd work ok. A polypipe sleeve around the cold inlet pipe of your HW cylinder would work as a heat exchanger, maybe? The solar heated water passes thru the sleeve, and convection should move the heated water into the tank.

It also means the collector wouldn't have to be under mains pressure. You could then make a really cheap collector: a corrigated iron sandwich held a mm or two apart using dobs of silicon, all sitting in an insulated box with polycarbonate glazing.

I've read that some people use antifreeze in the collector to slow corrosion, but it goes gooy after a few years and needs replacing.Edited by AllanS 2006-06-14

RossW
Guru

Joined: 25/02/2006
Location: Australia
Posts: 495

Posted: 08:58am 13 Jun 2006

Copy link to clipboard

Print this post

Gizmo said I've been tempted to make a solar hot water system, but was worried about air locks. I have a lot of "bubbles" in my water when I'm using the bore, and when I switch from tank to bore and back, I end up with one great big bubble!. With the solar collectors up on the roof, any air pockets would end up there. Is there a easy fix for this, or would I need to bleed the air off every few days?

Glenn

Glenn, I had a similar issue using my genset to heat my hot water storage tanks.

The local pump shop (specialist) offered me a cute little device - it is an "air release device".

Mine has a 1/2" BSP thread, needs to sit vertically, and is made of brass. Internally, I believe it has a small float arrangement.

It works on POSITIVE PRESSURE SYSTEMS ONLY - it can't be used on the suction side.

He described its internal workings as being like a float that covers the bleed hole. While the float is immersed in water, the hole is sealed. If there is a bubble, the float sinks, letting the air bubble out until there is again water sufficient to re-float and seal.

In practice, it hisses and "spits" as bubbles pass and are excluded.

It was moderately expensive - about $90 I think, but good to about 20 bar from memory.

I'll go take a photo if you like?

Print this page

To reply to this topic, you need to log in.