Recirculating Hot Water Systems

exactly. One in bathroom, one in kitchen, so the pump only runs when someone comes into the room. But is it worth it?

NT

Reply to
NT
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I think I go into my kitchen far more often than I run the HW so a room PIR would be a bit wasteful. If it was just over the sink, it wouldn't save you any time, just water.

As to "is it worth it?" almost certainly not but who cares? ;-)

Tim

Reply to
Tim

Ah, but there would be no flow in the 22mm becuase the thermostatic mixer woudl shut it off until the 10mm ran hot.

Robert

Reply to
RobertL

For a fully open tap, hot water will arrive quicker on a 22mm pipe run that it will on a 10.

Reply to
fred

I think it's worth saying that for us, the biggest issue is wasted water, not the time taken. We'd like to have a meter, and reduce the water bills, but not at the expense of the electricity or oil costs.

If it also means that sometimes the delay waiting for washing-up water can be avoided, then that's a bonus. And it can, because we wash up after a meal, and there is plenty of time while clearing dishes to the sink area for the system to 'run to hot' - and that without the current waste.

This has been an interesting thread, I'm glad I started it. I've learnt a lot, it's particularly interesting that OSO planed for it in the design of the cylinder.

I estimate that it would cost at least =C2=A3250 to install though, and that's a lot of water to save! Payback is not a quicky. More thought required. Mind you, if I can find a potable-OK pump for under, say =C2=A360, then it becomes much more do-able.

R.

Reply to
TheOldFellow

In article , TheOldFellow writes

Moving the cylinder is out of the question I suppose?

Reply to
fred

Or perhaps a multipoint gas water heater in the kitchen?

Tim

Reply to
Tim

In my kitchen, the tap, a mixer has 10mm ss-flexy tails, and so that is the limiting factor. Even if the pipework to it was 28mm, it's still got to get through the 10mm flexy. I don't like the tap much, but SWMBO loves it :-(

If I do the re-circulator, then the limiting factor will be the smallest bore in the circuit. ATM that's the 15mm from the bathroom.

The rising main is also 15mm, but that's at full pressure. The feed to the pressurised tank is limited to 2.1 bar - it's permitted to take that to 5 bar if I fit an external expansion vessel (potable, sized to system, charged to 5bar). We are getting into diminishing returns here.

R.

Reply to
TheOldFellow

Does it *need* to be potable-ok? We never drink anything that comes out of the hot tap because the water has previously been in an unsealed tank in the attic.

Reply to
Roger Mills

In article , TheOldFellow writes

Bear in mind that the length of each restriction is important too, a 40m run of 22mm followed by a 30cm length of 10mm tail will flow a lot more than a 40m run of 10mm (you'd get barely a trickle from a full length of

10).

If you have an electrical or electronic bent then thin and thick cables (or large and small resistors) in series are a good analogy.

Reply to
fred

Electric heating tape along the hot pipe may be a lot cheaper to install, plus good pipe insulation.

NT

Reply to
NT

Electric heating tape along the hot pipe may be a lot cheaper to install, plus good pipe insulation.

NT

At my last house I installed a circulating hot water system to avoid the cold leg, and it worked fine by gravity for the 23 years I was there. I had 22mm feed from the top of the cylinder to all the services and a 15mm return pipe back to about 18" down the cylinder, with a gate valve to shut it off if needed. It worked fine - I'd expected to have to install a pump but never did. Needless to say the loop was very well lagged. This was in a 7 bedroomed four storey Edwardian pile so there was a goodly chance of gravity working in my favour!

AWEM

Reply to
Andrew Mawson

Hmm? Yes, well I live in a Bungalow, the maximum I can get is about 2 metres from return boss on the cylinder to the run of pipe on the flat in the loft. So with 80 metres of pipe to manage (flow and return) do you think a thermal-only system would work? Is it worth trying?

R.

Reply to
TheOldFellow

I haven't done one, but my house has one. Whoever fitted it failed totally on the "well-insulated" part, so the potential saving in not having to run the hot tap is more than balanced by having to run the cold tap to get rid of the water which has warmed up being alongside the hot pipe (along with wasting heat in summer)...

It uses a combined pump and time switch, and tees back into the cold feed to the heat exchanger on the tank (it's a thermal store system, with mains pressure hot water). For the reasons above, the time switch is generally just left to "off" (I did turn it on while there was no heating upstairs).

Reply to
Alan Braggins

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