I have this vague memory of seeing a TV program many years ago about Hot Water Systems (from Europe?) that didn't use big storage cylinders like we do yet had a central heat source that somehow provided hot water at the various points round the house that we all need. I have a memory of small cylinders immediately next to the hot taps.
Anybody able to enlighten me?
=============== I don't know about the continental system but we have 'multipoint (gas) water heaters' which require no storage at all as they work directly off the water main. Some people swear by them - others swear at them. I have used them for the past 30 years and I'm quite satisfied with them. Do a 'google' for 'multipoint water heater' and you'll find plenty of information.
Cic.
Thanks for the suggestion but that's not it, I'm afraid. My son has one of those in his flat and that's not what I remember.
But then my memory could be mistaken.
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On the continent they are no so conscerned about water loss, so the have unvented hot water systems with no expansion vessel or bubble top The expansion of water on heating is discharged from the expansio valve. To them this is not an issue. It is against UK builkding reg. G England and Wales.
There are available small unvented storage devices below 15 litre which don't require you to have special training to install, and tha allow for expansion by expanding up the supply pipe.
As someone else said there are available gas heated multipoint an single point instant water heaters.
There are also instant electrical single point and multi point wate heaters
-- Paul Barker
This is a common way of providing hot water in German appartment blocks. They tend to have a communal central heating system with usage meters and if they were to provide hot water the metering is not easy (as the temperature needs to be taken into account as well). So in the kitchen will be a small 5 litre cylinder heater and in the bathroom will either be a UK sized cyliner or 30Kw instant water heater (requiring three phase supply) which heats the water up about as fast as a combi gas boiler.
tim
I recall one Continental system that was similar. It went "something" like this: There was a large output boiler around 50kW. I think fresh water was heated directly by a glass lined boiler, or similar. The heated fresh water was pumped around a circuit set out like a rad circuit. Where the rads would be there were small cylinders, sized to suit the application at that draw-off point, larger for bath, etc. Cold mains water fed the cylinder at the bottom and hot water out the top. The loop was kept at around 55C. It was a distributed storage system, that also used instantly heated water from the boiler too.
So, if water was drawn from one cylinder it was immediately fed with 55C water, heated quite rapidly by the large boiler. If the boiler could not cope, the stored hot water at other cylinders/taps was fed back to the boiler return to keep the flow temperature high. It worked well enough and did save space, giving instant response at the taps. My memory is vague on it, but one version was similar to what I described.
Today plate heat exchangers could be used under each tap. Plate Heat exchangers are small. Small plates are available and are used in small combi's, these could be used for basins, and large plates for a shower and bath. Primary water could be continuously pumped around a similar rad type loop at 70-80C. This also acts in a similar way to a secondary hot water loop to give instant hot water at taps. When water is drawn off the plate is immediately heated by 70-80C water.
Alternatively, a large plate heat exchanger or a couple of them at the large boiler on a pumped loop, keeping the plates at 70-80C. Cold mains into the plates and hot out to the DHW draw-off. There will be a pumped loop blended down to 50-55C back to the plates, and a pipe stat at the return maintaining the loop at approx 5C below the blended temperature setpoint. So when hot water is drawn off the large boiler maintains the plates at 80C. Envisage a large cylinder with a secondary circulation pumped loop to the taps. Just replace a large cylinder with a couple of plate heat exchangers. Simple. No large cylinder to take up room and instant response at the taps.
That sounds right. The question now is what are the benefits/disbenefits of such a system and why don't we use them in this country. My reason for asking is the house I've just bought. The run from the tank to certain frequently used taps is long resulting in a wait for hot water. I'm not impatient, but the house also comes with a septic tank. Now, I'm probably overeacting but I've become rather aware of the amount of water I use these days, not wanting to overload the septic tank. So, I thought, as things need replacing, I might plan to move to this "continental" system.
- Instant hot water at the taps.
- No large cylidner taking up masses of space.
- No tanks in the loft
- mains pressure
- The fullpower ofthe boiler is used to provide DHW
- Distributed storage used for backup.
We are backwards.
Use a secondary circulation pump. This pumps DHW around a hot draw-off loop back to the cylinder. From the furthest tap run a 10-12mm pipe back to the cylinders side shower tapping. Have a pipe stat on the pipe at the cylinders return, set below the cylinder stat and have a time clock on the pump. Lag "all" of the draw-off pipe. Instant water at the taps.
Fit 10 of them ;-)
"IMM" wrote | > There are available small unvented storage devices below 15 litres | > which don't require you to have special training to install, and that | > allow for expansion by expanding up the supply pipe. | Fit 10 of them ;-)
That would be a win, win, win, win, win, win, win, win, win, win situation.
Owain
IMM, how much would you charge to install such a system for me? :-)
I always remember getting instant hot water from every tap in scandinavia - though unbelievably there was a **monthly charge for hot water**! So you could stay in the shower all night and still pay the same. No meter and no fuel bill. A friend of mine in Finland tells me the system is the same for most flats there still.
I get the impression the local water companies don't like any system that might encourage you to use more water. Even just installing a shower pump requires you to have a water meter installed.
M.
On Mon, 10 Jan 2005 10:46:00 +0000, Markus Splenius strung together this:
You can do it yourself for a fraction of the cost. The end job will probably be the same even if you've never seen a pipe before. All you need is a rusty hacksaw, some Speedfit pipe and fittings and you're on your way.
I only design and consult now on mainly big stuff. A secondary circulation pump should do the trick. No so much alterations and understood by some of the locals. Grundfos make a dedicated pump for this purpose.
They have local gas fuelled power stations. The waste heat is piped to the homes. The total efficiency is 90% plus and there is little waste. Scandinavians lead the world in respect.
No. the water companies want you to pay more. They are geared for maximum profit first, service levels second.
Another billiant suggestion from uk.d-i-y.
"Speedfit pipe"?
I thought you could use "normal" pipe. :-)
I don't know what a plate heat exchanger looks like though I can conjur up some kind of mental image!
M.
Meaning that people actually pay for this?
Please let me know who they are so that I can sell them Tower Bridge.
Generally the size of a small book. A collection of stainless steel plates with gaps between. Hot water goes in one way in every other gap, and cold water in the other direction in every other gap (the two bodies of water do not mix) . It gives a large surface area and imparts heat from water body to the other very efficiently.
Some plates are very small, can fit in your hand, some very large, about 6 foot high. Combi's generally have them fitted to instantly heat cold water.
They don't do bridges.
It's essential to use Speedfit pipe, not follow the manufacturer's instructions and then claim that the product is faulty. :-)
Another excellent suggestion from uk.d-i-y.
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