Pumped shower / hot water

Hi,

I am currently refitting my bathroom and planning to move from an electric shower to a pumped shower. However I have now discovered that all the coldwater outlets in my house are mains. The house is effectivley a bungalow and the hot water cylinder is level with the shower.

Can I fit a pump just to the hot water side? I have seen posts on here that say the hot and cold water needs to be at the same pressure to work correctly. Is this correct can I not just use a manual shower mixer? The currnet basins seem to cope fine with a simple mixer tap despite the huge differences in hot and cold water pressure.

Regards

Mark

Reply to
markjenneson
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You can (but twin is safer), but the cost-benefit of fitting a high pressure hot water system may not be as bad as you think.

In the cottage I have just been advising on, the plumber was mist reluctant to put a pressure pump on a small hot water tank due top potential problems of draining it faster than it would refill.

The final solution was to retrofit a 150L mains pressure hot water cylinder, and convert the CH to sealed with anther expansion vessel and pressure gauge added to it. And add some sorely needed motorised valves (the old system had been bodged with twin pumps, one of which had failed)

Total cost including labour and extra pipe runs was 1400 notes. The flow rates even with mostly 15mm pipework is very good. Probably far better than a pump.

The tank and pipework occupies no more space than the CH header tank and old HW tank it replaced.

Reply to
The Natural Philosopher

On Tue, 05 Jun 2007 03:11:57 -0700 someone who may be snipped-for-privacy@gmail.com wrote this:-

That is one possibility.

Other possibilities include fitting a venturi shower and taking a separate cold supply from the cold water storage tank to a pump that pumps both hot and cold.

Fit a thermostatic valve if you go for one of the pumped options.

Reply to
David Hansen

You can - single impeller versions are available.

It works best if they are similar - they can cope with some variation. You may find a pressure balance mixer would work better than a thermostatic one in these cases.

The other option you have if there is decent mains pressure is a venturi shower. These don't require a pump but are driven from the cold water pressure instead.

Reply to
John Rumm

Is there a large tank in the roof feeding the cylinder or is the cylinder a combined ("Fortic") type? If it's the latter your choices are:

1: replacing the cylinder with either an unvented (mains pressure) cylinder or a thermal store or heat bank - see
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fitting a venturi shower.

If you have a standard cylinder fed from a tank in the attic you can fit a pump. You then have the choice of

1: an all-in-one-box 'power shower', looking a bit like your electric shower but containing a pump and mixing valve (thermostatic or otherwise). 2: a separate pump and shower mixer valve

All-in-one units are relatively cheap and easy to fit but when it eventually packs up it will be more expensive to repair or replace than separate parts. Also if you later upgrade your hot water system to mains pressure the pump in the unit will be superfluous, at least, and you really ought to replace it with a normal mixer valve.

With either approach you would normally fit another tapping to the cold water storage tank, a bit lower than the existing tapping (or higher, and swap over the pipes) to supply cold water at low pressure to the pump. However with a separate pump you can, with certain shower mixer valves, pump just the hot and have mains pressure cold water. For this you should really use a single-ended pump, but could probably get away witha twin one (which are actually cheaper than single ones). The Salamander pumps Screwfix does for about £100 are very good for budget priced pumps, unlike the dross B&Q, Wickes et al do (Newteam etc).

There's a wide variety of mixer valves around but the bar-type ones are relatively cheap and have the advantage that if/when they pack up they can easily be replaced (if they can't be repaired) since they all(?) have 3/4" female fittings at 150mm centres.

These valves are, however, a PITA to fit, especially with the usual fittings supplied with them. For easier ways see

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Reply to
John Stumbles

My recent experience suggests that you can't use a mixer tap with mains pressure cold, and gravity fed hot (I live in a bungalow conversion & the gravity tank for the hot supply is about 3' above ceiling level). While mixing the taps with the water coming out of the spigot is fine, engaging the shower causes cold water to back-flow up the hot feed. Reducing the cold flow makes control virtually impossible.... I suspect that even installing a hot water pump would still make the correct balance difficult to achieve.

The other posters evidently know what they are talking about :-(

Bramblestick

Reply to
Bramble-Stick

Reply to
Stephen Dawson

Fancy name for a pressurised HW tank?

Reply to
The Natural Philosopher

In message , The Natural Philosopher writes

I know this has cropped up before but are there known drawbacks to using this system in a flat intended for letting? Also is hard water any more or less of an issue?

regards

Reply to
Tim Lamb

On Wed, 06 Jun 2007 20:03:26 +0100 someone who may be The Natural Philosopher wrote this:-

No.

The shell of the store is at low pressure. What is at mains pressure is the domestic hot water, which is heated as it passes through the heat exchanger in the store.

No bureaucracy or annual inspections.

Reply to
David Hansen

On Wed, 6 Jun 2007 21:14:55 +0100 someone who may be Tim Lamb wrote this:-

Not that I know of. Obviously a thermal store has the great advantage of no annual inspection and the rest of a pressurised hot water cylinder.

Hard water is a good reason for going with the type of store with an external heat exchanger. The plates of this can then be replaced as necessary.

Reply to
David Hansen

Or removed and descaled easily.

Reply to
Doctor Drivel

And no explosions and when coupled to the CH a superb CH buffer that improves efficiency.

Reply to
Doctor Drivel

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