Mixer tap temperature issues

beckym123

Hi

Me and my boyfriend recently bought our first house and are having issues with the bath/shower temperature. The mixer tap is pretty useless, we basically have either scalding or freezing water. It takes a good few minutes for the hot water to kick in, but when it does it's boiling and the cold water doesn't seem to mix with it. We're wasting so much water trying to find a happy medium and I wondered if there was any sort of fix for this?

We have a combi boiler that was just serviced and the pressure is fine. No other taps are being used at the same time as the shower. Any help would be much appreciated!

Crinkmeister

If you turn on the hot tap on it's own and then do the same with the cold tap, are the pressures equal? What sort of tap is it, just a simple deck mixer or thermostatic?

beckym123

Hi, it's a deck mixer tap. The hot and cold seem pretty similar, the hot is lower pressure but not by much.

cyclonebri1

You need a thermostatic mixer:T

beckym123

Oh is it that simple?! Everything else so far has needed major upheaval so that's great, thanks!

adandem

We have the same set up as you and it works really well?

Moss5

I had the same symptoms after replacing the bath taps with a bath/shower mixer. I did not realise the importance of equal supply pressures.

Do you have a hot tank and a cold tank?
Do you have a combi boiler or unvented hot water tank?
For a bath/shower mixer to work, both hot and cold water must be at equal pressure.
Combi boiler/unvented tank houses have equal pressure by default.

If you have vented tanks, the cold supply to the bath mixer must come from the cold tank, not the mains.
An easy test is to run the bath tap on cold only and turn off the cold main stop-tap.
A. If the cold supply to the bath tap is from the cold tank, the tap will continue to flow and you have equal pressure.
B. If the cold supply to the bath tap is direct from the mains, the flow will stop and you have unequal pressure.

If a deck mixer is connected to unequal pressure, some cold water will push the hot water all the way back to the hot tank and could cause the tank overflow to run. Almost impossible to get a shower at an even temperature.

The cure is a bit disruptive. A dedicated cold supply must be connected between tap and cold tank.
Another solution is to fit an electric shower.

Be careful when buying taps. Some require a minimum pressure of 1bar or 2bar. If you have a cold tank supply it will be at a pressure of 0.1bar or 0.2bar (1 to 2 meters above your head)

beckym123

We have a combi boiler, I just did your test and the water went off so the cold water is from the mains.

I'm confused now as to what the solution is! So getting thermostatic taps won't make any difference? Am I doomed to a life of scalding hot showers?

(We already have an electric shower in another bathroom, that's a whole other story that I won't bore you with!)

southcoastrgi

OP this kinda thing is what you need

although Moss has given a good explaination I'm not sure why they are confusing things when you have already said you have a combi

cyclonebri1

beckym123 wrote: »

Oh is it that simple?! Everything else so far has needed major upheaval so that's great, thanks!

Yes it is, see SCG link above

beckym123

Thanks all, there was a sale on at Victoria Plumb so I took advantage, fingers crossed for a normal shower!