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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> What causes shower temp. to be effected by taps? https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1326031696 Message started by Shevek on Jan 8^th, 2012, 2:08pm

Title: What causes shower temp. to be effected by taps?
Post by Shevek on Jan 8^th, 2012, 2:08pm

Hi, what is it about the way plumbing is done that causes the shower to change in pressure and/or temperature when others taps in the household are used? And what's the best way to avoid this problem?

Title: Re: What causes shower temp. to be effected by taps?
Post by Lectrician on Jan 8^th, 2012, 5:20pm

What type of shower are we talking? Electrically heated?

If so, by their nature, they heat the water to different temps by adjusting the flow through the heater. Opening a tap somewhere will reduce the flow and cause the shower temp to rise.

You can get thermostatically controlled electric showers these days, designed mainly for the infirm, they are costly but do away with the scalding issue.

If it is a mixer type shower, it is likely a thermostatic type anyway which will keep the temperature constant by adjusting the hot and cold accordingly.

Title: Re: What causes shower temp. to be effected by taps?
Post by thescruff on Jan 8^th, 2012, 10:41pm

Combination boiler also has the same problem, usually low mains pressure.

How to get over the problem, install a cylinder or educate the household to not use another outlet when your in the shower.

Title: Re: What causes shower temp. to be effected by taps?
Post by CWatters on Jan 9^th, 2012, 10:17am

Plain shower mixer not thermostatic?

Long pipe runs of wrong bore?

Scaled up pipes or valve not fully open?

High flow rate shower on otherwise adequate pipes?

Poor flow rate from the mains?

How to avoid...

Buy house in area with good mains pressure and flow rate.
Soft water area to avoid need for water softner (which looses some pressure).
Large bore, short pipe to the house.
Mains pressure stored hot water system.
Dedicated >22mm pipes from tank to the shower (Separate pipe runs for other outlets such as bath and taps).
All valves to be full bore types.
Thermostatic mixer shower.
Shower head with moderate flow rate. (Special care needed for high flow rate "rain" type heads and body jets).

Title: Re: What causes shower temp. to be effected by taps?
Post by Shevek on Jan 9^th, 2012, 1:46pm

Thanks guys. I'm talking about any type.

Thermostatic shower sounds like minimum we need.

I've just moved into a 2-storey 1930s terraced house which currently has a cold water tank in the loft and a hot water cylinder at 1st floor in a cupboard. The bathroom is currently on ground floor.

We're going to move the bathroom to 1st floor and add an en suite to a new loft conversion.

We want to hook up to solar hot water panels and maybe wood burner, along with a new boiler to a HWC to supply hot water and underfloor heating.

I don't think we'll be able to fit the HWC higher than the loft conversion floor level.