Posted by nicksanspam on March 7, 2006, 1:22 pm
>meow2222@care2.com wrote:
>> Lets say it saves £20 a year heating dhw only.
Would that be 20 UK pounds per year? Sounds like a very poor water heater.
It seems to me that American families pay about $20 per month for hot water.
>> Lets say we want it to break even after 10 years, interest is 5%...
>> A system that does this in 10 years is worth paying £157 for now.
Would you believe 154.43 pounds?
>>>From this emerges one clear conclusion: we need either a lot more
>> saving or a lot less cost than commercial solar dhw systems deliver.
Or both. Solar water heaters are typically undersized and overpriced.
>> If one got a bit desperate and justified a 20 year payback, system
>> value would rise to £251.
Would you believe 249.24 pounds?
>> Now, since almost all solar dhw setups fail miserably to pay their way,
>> lets see how low cost we can get. Start with a dirt cheap direct
>> drain-down system for summer use only.
There's no reason a draindown system can't work in wintertime.
>> Collector and loft piping:
>> 100' garden hosepipe: £20
>> sheet of green house polythene: £? Lets say we use a £1 poundland
>> plastic patio table cover set...
How about a solar-pond type water heater instead?
>people are looking at this the wrong way givern the above would any one
>ever buy a car,computer,tv e.t.c .
It's more rational to say
I need hot water. What's the most economical system?
Nick
Posted by Derek Broughton on March 7, 2006, 1:44 pm
nicksanspam@ece.villanova.edu wrote:
> There's no reason a draindown system can't work in wintertime.
You can risk it. I'm investing in the glycol flat-panel system.
--
derek
Posted by meow2222 on March 7, 2006, 6:25 pm
Derek Broughton wrote:
> nicksanspam@ece.villanova.edu wrote:
> > There's no reason a draindown system can't work in wintertime.
> You can risk it. I'm investing in the glycol flat-panel system.
Nick's point was that a draindown system without antifreeze can be
designed to be safe in winter.
NT
Posted by Derek Broughton on March 7, 2006, 7:22 pm
meow2222@care2.com wrote:
> Derek Broughton wrote:
>> nicksanspam@ece.villanova.edu wrote:
>>
>> > There's no reason a draindown system can't work in wintertime.
>>
>> You can risk it. I'm investing in the glycol flat-panel system.
>
> Nick's point was that a draindown system without antifreeze can be
> designed to be safe in winter.
I know what his point was. He might even be right. I, however, have no
intention of risking it. I can, and will, profitably install a glycol loop
system with heat exchanger.
--
derek
Posted by meow2222 on March 8, 2006, 9:57 am
Derek Broughton wrote:
> meow2222@care2.com wrote:
> > Derek Broughton wrote:
> >> nicksanspam@ece.villanova.edu wrote:
> >>
> >> > There's no reason a draindown system can't work in wintertime.
> >>
> >> You can risk it. I'm investing in the glycol flat-panel system.
> >
> > Nick's point was that a draindown system without antifreeze can be
> > designed to be safe in winter.
> I know what his point was. He might even be right. I, however, have no
> intention of risking it. I can, and will, profitably install a glycol loop
> system with heat exchanger.
What exactly is the risk you refer to in a system designed to be
riskless?
NT
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>> Lets say it saves £20 a year heating dhw only.