On Tue, 08 Jan 2008 19:50:39 +0000, David Hansen wrote:

On Tue, 8 Jan 2008 19:22:59 +0000 (UTC) someone who may be Ed Sirett
wrote this:-

It might /just/ be possible to make a cost effective solar assisted HW
system if /all/ the following are true.

1) You need to replace the HW cylinder. 2) You have the time and skills
necessary to make and install solar collectors.
3) You have the time and skills needed to make the control system. 4)
You have access to the scrap raw materials needed to make system. e.g.
discarded CH pump, discarded CH radiators.

If, for the sake of argument, one takes the claims of the antis of only
a £40 saving in gas per year at face value, assume no fuel price
increases and ignore the (low) electricity cost then a simplistic simple
payback period calculation for the Navitron Budget Solar Kit
http://www.navitron.org.uk/pricelist.htm is about 22 years (£800 plus
£100 delivery, if one doesn't collect it).

That's exactly the case I was making. You've filled in the numbers.
22 years.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html