Solar water heating

60% of washing machines sold in the UK are Hotpoints. I don't know why as they are complete crap. They also hold the market for fridges, which they are better at.
Reply to
Doctor Drivel
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Mine takes water up to 60ºC, so I'd expect some can.

Depends largely on the run length of the hot pipe to the dishwasher, but as the short prewash and first rinse don't have to be so hot, the initial cooler water from the pipes may not be such a problem.

cheers, Pete.

Reply to
Pete C

Okay, and if there is no check-valve in the pump or its suction, I can see that working. Maybe even a baffle just to be sure of little splash. Shut-off head of the pump will still have to be high enough to initially fill the collector, but once the return has flooded, less pressure should be needed to maintain flow.

Now, just need a large enough tank to accomodate the drain-water, and you're all set.

daestrom

Reply to
daestrom

You're right if the pipework is sealed, in effect once all the air is pumped through it's running a syphon, I was thinking the water would trickle through the panels which were open to atmosphere. This syphon makes it look a good system to me, header tank can be below the panels which can then run from ridge to eave. Now I guess this means the pump needs to sit a bit below the header tank, have sufficient pressure to initially refill the system but no foot valve so that the pipe work above it can drain when the pump stops, it still needs a small air bleed from header to pipe above pump or a valve.

This falls apart if the height difference of the solar circuit top to bottom exceeds about 9m.

I seem to have missed the distinction between drain back and drain down systems. From another post it appears that one of these can be sealed. From David Hansen's post it looks like there are very good reasons for not going sealed, as with a wood stove.

You asked why put the panels on the roof and my answer is that this is the only un shaded space I have.

So looking at 16mm twinwall clear polycarbonate one 700mm by 4m sheet costs 60 quid and covers 2.8m^2. It has ~6mm by 700mm = 0.0056m^2 of built in water or air passage. From the SAP data Tony B pointed me to this device may be capable of intercepting 75% of the 1000*2.8=

2100kWhr(t) per annum, potentially 63 quid a year if it is used for DHW in summer and heating in winter ( I was considering DHW in summer and forced air in winter in the same panel). It looks like the cost of the associated fittings and plumbing is was spoils the picture.

AJH

Reply to
AJH

If by 'hosepipes' you mean the 'outside faucet' used to water the garden/etc..., around here we use 'frost-free' faucets. The valve stem is quite long (about 12 inches) and the actual valve/seat located inside the house. As long as the hose is disconnected so the foot long section from actual valve to the faucet can drain, these don't have a problem even in 0F winter nights like we have here in NY. Because none of the flooded portion upstream of the actual valve seat is exposed to freezing conditions.

daestrom

Reply to
daestrom

Mine can too ( I think its upto 80C though). It is cheaper to run on cold and has no effect on cleaning ability. It may save a few minutes.

The prewash and rinses are usually cold. The final rinse is usually hot to speed up drying.

Reply to
dennis

Wrong. Eric Hawkins at Powertech Ltd (UK) has been done this for years in lots of systems with no loss of prime (the vacuum in the Apricus evac tube header loop above the unpressurized tank) after initial priming. Then again, they don't shut off the pump at some max water temp. So a "slow draindown system" with a small hole in the return pipe above the tank water line should work fine, with a lower flow and higher head to start with and higher flow and lower head after the pump has pushed all the bubbles out of the underwater return pipe.

Nick

Reply to
nicksanspam

Although it would take three pipes. A foolproof way is have a tee inside the tank on the hot pipe from the panels. From this tee take a small bore pipe up to the same height as the top of the panel and back to the tank. Vented and no pump over at all. If there is a problem it goes back to the tank. Pipe is cheap.

Reply to
Doctor Drivel

There's no need to go that high. A foot would suffice.

Nick

Reply to
nicksanspam

I was on about a sealed system, any system whether hearting or whatever. Hawkins vacuum is not new.

Eric Hawkins is pushing product that is clear. In his house:

- He stripped out the copper pipe in his house and installed plastic. Most new homes are fitted out in plastic these days, with copper where pipes are seen. What he thought he would gain with plastic is beyond me,

- He fitted solar panels fitted to a thermal store in his loft/attic. I have a thermal store in my loft too. Nothing special there.

- He insulated pipes in the loft. All new homes require that exposed pipes are insulated. Nothing new there.

- He fitted solar panels to heat his thermal store. Nothing new there.

- Now! He stripped out his NG boiler and fitted an air to water heat pump in the loft. In the UK gas is approx 4 times cheaper than electricity. And the condensing boilers are very small in physical size and highly efficient. So a heat pump that "averages" COP 4 would equal a NG boiler in running cost. NG condensing boilers are cheap (some 26kW version were available from B&Q for £300 [same as your Home Depot]), heat pumps are not cheap at all. NO GAIN THERE at all, except a very cold loft, as that is where he is moving the heat from. No wonder he needs to insulate the hell out his pipes up there.

- He fitted low temperature underfloor heating in his house. One hell of an upheaval in an existing house. But nothing new there. Low temperature UFH is ideal for solar panels.

What he has done is have a thermal store heated by solar panels that heats wet underfloor heating. For backup he has an air to water heat pump.

He would have been wiser to keep, or update to, a NG condensing boiler. Much cheaper and guaranteed to give heat when needed, which the heat pump is not, and then insulate the hell out of his house. Cavity wall insulation is cheap enough. We have cavities in the UK and this is now very popular with recent energy price hypes, with government grants too. It is pumped into the cavity. So a wrap round blanket of insulation. He then could have had

400mm of Warmcell celluloid insulation sprayed on the floor of the loft (this seals up the ceiling/loft too). Then did some air tight measures around the house. That would have dropped his heating bills further than his £180 per ann, with the heat pump and wind turbine. Service for NG boilers is comprehensive, not so for heat pumps.

The rainwater harvesting is off the shelf stuff. Mandatory in the BenNeLux countries in new builds. It is worth it I believe with a 7 year payback. Nothing special there.

PV panels are not new and so far not worth it. Micro turbines in a built up area are difficult to get permission to erect. They also have long payback periods, but fine in off-the-grid locations.

His point is: Has the Traditional Boiler Had Its Day? A long time to go yet. Heat pumps are fine for off the gas grid systems. Even then you have to do your arithmetic well to justify one. The capital cost of them is horrendous in the UK. Solar panels a thermal store and low temperature UFH could be worth it. Unless the air to water heat pump is the same price as a NG boiler, I would think very hard.

Reply to
Doctor Drivel

It "probably" would, but I said "foolproof".

Reply to
Doctor Drivel

Nick

Reply to
nicksanspam

No accounting for those who doubt gravity :-)

Nick

Reply to
nicksanspam

yes, beside it is fine

I'm not really following you there, but theres no need for any valve or air hole on the pump side. The pump will be an impellor type, not a piston, so the water drains back through it once stopped.

not many lofts that high :)

With drainback the panels empty themselves when the pump stops. Draindown stays full much of the year, but when frost threatens theyre drained, and stay dormant until refilled in spring.

it seems either can, I'd not heard of sealed drainback before. Cant see much good in it though.

=A363 per panel? Use a few, space heat in winter, water in summer. Run the numbers to see how many gets you best result.

You wont get 75% efficiency for hot water, but can for hot air.

NT

Reply to
meow2222

a mild abrasive maybe, thrown out by the pssive plastic arms sure, but a fair way from sandblasing :) Maybe if I motorise the arms the ovenware will come out better!

NT

Reply to
meow2222

You also need to wake up before posting. Read the bit you snipped. Honestly!

NT

Reply to
meow2222

LOL.

To each his or her own I guess. I drink beer occasionally to refresh myself not foam at the mouth.

supposed to

Reply to
Solar Flare

Figure WHAT out? You posted upside down and so provided no trimmed context.

Reply to
Andy Luckman (AJL Electronics)

On 10 Mar 2006 16:49:59 -0800 someone who may be snipped-for-privacy@care2.com wrote this:-

Not only can you read my mind, but you can read it back in time. That would be fascinating, if you were able to do it.

I did. However, the figure remains a low one, no matter where it came from.

Reply to
David Hansen

It's a bit like those bird drinkers where the reservoir of water is inverted and the column of water only allows water into the drinker when the level in the drinker drops and allows a bubble of air in. In this case we have a loop of pipe and panel filled with water, the legs of the loop will not drain as there is nothing to replace the water column, so you need a way of bleeding air into the top of the loop to break the stagnant syphon.

No but you may be tempted to house the pump and F&E tank on the ground floor or basement with the panels at the top. As someone pointed out if pumping power is high the electricity cost could negate the value of the solar input.

OK understood

Erratum ^ triple wall^

Yes that's what I thought, maybe worth considering for a new build, pitched roof with a few cms of celotex underneath, I'd have to review the nuances of "warm" roofing again.

It looked like this was possible from the SAP pdf, what makes you think it will be worse on water and better on air?

AJH

Reply to
Andrew Heggie

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