On Thu, 09 Mar 2006 22:22:35 +0000 someone who may be AJH wrote this:-
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the unit promoted by one supplier. In addition to this box there is just the panel, cylinder and some piping/wiring.
The drainback system does depend on the valve working, just like human life depends on valves in the heart working. I suspect that the valve in the unit is chosen to have a very large number of working cycles, as it will be operating a minimum of once a day and so the possibility of it failing and the panel to freezing is remote enough to be placed with the other remote possibilities, like the panel being hit by a meteorite.
Thanks I was considering a more simple open vented system. In general I have a preference for sealed systems (only just becoming common in UK and then almost never for wood burning). Once the option for sealed system is taken I can see little advantage in drainback over a glycol or food grade antifreeze system.
It has to be "in" the tank. The pump will squirt water everywhere. Best to have say 15mm into the tank, then immediately up to 28mm (1"). This pipe drops into the tank water. In this section have a 28mmx15mmx28mm tee, then the water will just drop down the larger bore and not squirt out of the side of the 15mm port in the tee. You could put an isolator on the end of the
15mm so that you can turn up or down to keep water going down the 28mm route, or have a 15mm elbow and a short piece of pipe pointing upwards.
Some do. Mine does and it is pretty new. Dishwashers now are cold fill only as they now use more advanced detergents. In yea olden dayes the dishwasher was a large tray of water with powder like sand. It sand blasted the dishes clean, hence why you could not put patterned plates in the things. They use a hell of a lot less water now, so heating up via electricity is viable. Also, some dishwashers can be just a hot fill. This saves on electricity to heat up (electricity is ~4 times more per kW than gas), but it uses hot water for the rinse cycles. Even so it is still cheaper overall using the hot only fill.
Nice one Mary, spoken like a true Yorkshire Lass. Bitters are supposed to be drunk at just below room temperature, not with ice forming on the top. One way to ruin a bitter, is over chill it. The Yanks are more into fine beers these days, as pale ale is big over there, so all is not lost. The Aussie are still way behind though. They don't know the meaning of beer that is why they call it XXXX.
The message from "Doctor Drivel" contains these words:
Mine certainly does.
The trouble is they draw water from hot /and/ cold when hot is required
- for two reasons. 1) There may be no hot water connected 2) The hot water may be too hot.
I've throttled the cold supply right back on mine so it fills preferrentially from the hot supply 'cos I know there's always hot water. One day I might play with the innards and a relay or two such that when /both/ valves are intended to be on, only the hot supply is opened, and when only one of the other is on things are as expected.
On Fri, 10 Mar 2006 09:54:57 +0000 someone who may be AJH wrote this:-
In general I have a preference for open vented systems, in small installations. In such installations the advantages of a "sealed" system largely fall to the installer and maintainer. The occupier gains little with such systems, in many/most cases. Large installations (I have been responsible for some very large heating systems) are a different matter.
However, for solar water heating the disadvantages of an open vented system include the trouble of placing the header tank high enough, then maintaining it and the inability to heat water above 100C. In this case I think the advantage lies with a "sealed" system.
The system at
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has a number of advantages. One of these is that it does not use mains electricity, which can exterminate 20% of the savings gained by using solar hot water heating [1]. The control system is very simple, if the sun is shining it pumps water into the panel and starts warming up the cylinder. If the sun is not shining, or there is snow on the PV panel, then the pump is not running and the panel is drained of water.
The system at
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more sophisticated and so will extract more heat from the sun. On the other hand it needs mains electricity 24 hours a day, because the controller might need to turn on the pump occasionally to warm up the panel header a bit on cold nights (assuming it is run without anti-freeze). Mains failure means possible freezing in winter and overheating in summer, though these are rare in most of the UK.
The system at
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involves much less plumbing, so is easy to fit and has simple PV powered controls. Provided that the existing hot water cylinder is well insulated and of an adequate size this has great advantages.
These are just three possibilities, but they do show a range of possible solutions in one small part of the world.
[1] - "Side by Side Testing of Eight Solar Water Heating Systems" DTI/Pub URN 01/1292
On Fri, 10 Mar 2006 13:00:40 GMT someone who may be Guy King wrote this:-
This could easily be solved with more complicated controls, which would measure water temperatures. They would then use as much hot water as possible, only adding cold if the hot was too hot for the programme selected. No doubt manufacturers think this would cost too much.
Equalising the pressure on the hot and cold sides, by feeding them from the same source, can also reduce the enthusiasm of the cold water.
A neighbour saw that on a 50C wash hot an cold came in and mixed making the
50C tap water about 30C, then the electric element cut in to heat the water to 50C. She realised that at the very hot wash (90C?) only hot ever came through and the cold was off. So she made sure hot water was at the tap, selected the 90C wash and the drum filled with 50C water, then she would switch off and then select the 50C wash. It worked, also the wash was quicker.
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