HW pump

Hello,
I was browsing through some old posts (there are so many here; how do you choose what to read?) and I read about hot water circulating pumps that are supposed to get hot water to the taps quicker.
This sounds very good. In our house the HW goes from the cylinder to the bathroom, then drops into the kitchen, where it goes into the concrete floor and over to the sink. None of it was lagged. I have tried to lag various parts when I have had different floorboards up but obviously the run under the kitchen floor is inaccessible. It takes ages to get hot water to the kitchen sink. One of these pumps might be a good idea.
However, I am unsure how they work. Do you need to run a return pipe? Do they constantly circulate hot water around the house? If so that would be very impractical because surely you would need to plumb the hot water in a ring main, rather than the traditional radial style and have a return pipe? Also wouldn't this be uneconomical because you would constantly be losing heat through the pipe work rather than keeping it in a well insulated cylinder?
Or is it that the pump only comes on when a tap is open and just increases the flow so that the hot water gets there quicker, like a power shower?
Is there a special pump for this purpose and what are they called?
Thanks.
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On Sun, 03 Feb 2008 10:18:07 +0000, Fred wrote:

Yes, typically smaller than the main feed pipe so you could run it in 8mm or 10mm copper or 10mm plastic.

Well, that's what you have to do if you want such a system. It's more commonly used in larger, commercial or industrial premises.

Yup, but then you don't throw away heat and water running off warm water to get it hot.

No it runs constantly (preferably on a timer so at times of low demand you can still get got water (if it's available) but you have to run off the cold.

Usually bronze pumps (though plastics and stainless steel might be used)

You'd lose even more heat circulating constantly-hot water through uninsulated pipes in screed. Since you'd have to run new pipework for the return ayway, I'd suggest scrapping the existing pipe and installing a new, more direct run of well insulated pipework. You could use plastic for easy installation.
--
John Stumbles

Fundamentalist agnostic
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A pipe stat can be fitted when the loop is up to temperature and it switches off the pump. IF a mains pressure loop the instant hot water can be used for kettles reducing the electricity bill, so offsetting the running cost of the pump. If on a water meter it also reduces water waste and again cost offset. Also instant hot water into a washing machine. Many just fill up the machine with cold water from the dead-leg DHW draw-off pipe and then the expensive to run electric element kicks in. And the great convenience of having instant hot water at taps. So,they are not financial dead loss.
Well worth doing as long as the loop is very well insulated and a pipe stat fitted.
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Must be an old washing machine. Almost all washing machines now are cold fill only -- as is generally true of dishwashers also.
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contains these words:

The more economical machines are hot and cold fill to use cheaper gas heated water.
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I know the reasoning perfectly well. The question which new model designs are using h and c fill?
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Doctor Drivel wrote:

I just checked on the John Lewis web site - a random selection of four washing machines (3 A+ and one A rating) - all cold fill only. Are any new washing machines hot & cold fill?
They (JL) say that cold fill is better because the hot water fill would normally be at too high a temperature so would require cooling down (for many programs).
That said, if they are available, hot and cold fill might be more economical for those who do a large proportion of hot washes for some reason.
--
Rod

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contains these words:

Decent machines do not allow hot in on settings below 60C, so that is crap.
I know most dishwashers are cold fill only, but some will allow hot fill and this means a hot rise too. It is more economical overall even though the rise is hot, that heating the water with electricity all the way. It is also quicker as the machine does not stand while the element heats the water.
In the USA most machine many w/machines have no internal heaters relying on the water temp from the house, so it makes the product cheaper. Makes sense.
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Most US washers are top loaders wasting both water and detergent, weed.
--
*If a pig loses its voice, is it disgruntled?

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

Please eff off you are a total plantpot.
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Think it's been shown yet again that you simply don't know what you're talking about, weed.
--
*The problem with the world is that everyone is a few drinks behind *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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wrote:

Please eff off you are a total plantpot.
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wrote:

Change the record, Dribble.
--
Regards, Paul Herber, Sandrila Ltd.
http://www.sandrila.co.uk/ http://www.pherber.com /
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wrote:

Do you mean this man should not eff off and he is not a plantpot? Gosh!
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Is there anybody left who hasn't been described as a "total plantpot?"
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wrote:

Keep going and will qualify.
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>Doctor Drivel wrote, <>

killfile him and you're not tempted to respond to his posts
--
Si

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writes

That is right. Plantpots should be killfiled.
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Send for a straightjacket at once! This man thinks that everyone who disagrees with him or even questions his statements is a plantpot! :-)
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wrote:

I tried that, it made no difference. He still remained a plantpot.
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