What size UPS do you use, and how long does it run for? I've thought of doing that, but never sorted out which UPS to get. I've heard that some have problems driving pumps - something to do with the sine-wave modulation?
dan.
Build a solar chimney and stick the radiator at the bottom of it?
Was there any Science (tm) involved? i.e. calculations for size of tank, coil, size of surrounding greenhouse etc. or was it a bit hit-and-hope? (no disrespect intended if it was the latter)
I'm always intrigued as to how much planning goes into many of these projects - and how much is either guesswork or simply using whatever materials happens to be lying around :-) I'm sure a physicist would produce pages of calculations first based on all sorts of variables - but does the typical builder of projects like this bother?
Yes and no. I modelled the hell out of all of it, but then the design was fundamentally limited by "found materials" anyway. Modelling did suggest it was worth bothering though. Basically solar gain of the greenhouse, minimal contribution from sun on the tank itself. The only real cost or work involved was trenching and piping from the greenhouse across the garden and into the house. The pump was an old beer pump, the heat exchange coil was pulled from a scrap HWC and much of the old oil boiler found itself being pressed into service.
I have a 1500 VA UPS. (It's an MGE model - double conversion true sine wave which is nice, but a bit innefficient) More by accident than design as it was about to be thrown out - a new set of batterys later and ...
In my experience over many years of using USPs, the typical run time is
15 miuntes on half load and 5 miunte on full load, and they're more or less linear at half load and less, so 30 miuntes on quarter load.The CH pump is 40 watts, so lasts for long enough. (The max. it's normally supplying is 70 wats for servers, switches, adsl modem/router, phone)
Gordon
Good stuff!
I'm happy to build stuff, but I went the eletronics & computing route rather than physics, so the thermodynamics and whatnot is something of an unknown to me (and lots of sites describing projects like this just explain what the builder did, rather than what led them to their final design; I can follow exactly *why* it works, just not why it works as well - or not - as it does)
Maybe I need to do some more studying :-)
cheers
Jules
The xcel seems to offer a power free method, a thermostatic valve that at 95C allows cold mains water to run through the coil and dumps it via a tundish to a drain.
Out of interest, how not-cheap?
like:
Average UK summer sunshine 5.3Hours per day. That implies 5.3kW hours of panel power per day, which apparently is only 1/6th the makers rating. Taken over a UK summer/winter year that averages out at 3.5kW hours per day and at say 3p per unit for gas, implies a 25 year payback just for buying the panel, disregarding all the ancilliary kit and installation costs. I've obviously missed some technical aspect.
Yebbut it's Green, innit?
And it goes up to 11.
And WD-40, which it would seem is the solution to all problems,
Perhaps it should have been called WD-42.
Groan, but I smiled. :)
:)
(I'm getting to think that Green stats are about 99.9% made up.)
£2-3k depending on size and options.
and maintenance - 25 years is a long time for everything to keep working. Will the technology have moved on by then anyway?
Chris
Wasting mains water, eh? Not very green, is it?
Mind you, I think anyone who thinks there is going to be such a vast amount of waste heat from this system is suffering from delusions.
I think your assumptions are a little pessimistic. Let's do a plausibility check:
Solar radiation at the earths surface is circa 1.3kW/sq metre "normal" to angle of incidence
Claim of 30kWh/day for (say) 6 sq. m implies 5kWh/sq. metre/day (round numbers). Remember that is PEAK.
As an example this manufacturer claims 17MJ/sq metre/day:
++++++++++
Least year I "bought" ~25000 kWh of gas which cost about 800 quid (all heating no cooking). Remember that's the input energy. Probably an absolute maximum of 2/3 ended up in my radiators or water tank. Say 17000 kWh
It's reckoned that well implemented solar can deliver 1.3kWh/sq metre/day year round average. Something like 2750 kWh/year with a my proposed setup.
I'm under no illusions. the gas usage might only go down 15% but I believe it will be at least 25% for a variety of reasons. It's going to be interesting.
David Mackays book is a good read on this subject. Look at figures 6.3 and
6.4 here:
Lots of makers get their numbers from SPF tests
dan.
On Wed, 25 Nov 2009 15:22:27 -0800 (PST) someone who may be snipped-for-privacy@jjdesigns.fsnet.co.uk wrote this:-
Source?
Remember also that direct sunlight is not needed for the panel to work.
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