What is minimum reasonable head of water for a shower

[Keefiedee]

When we moved into our new (v. old) home some 4 years ago one of my first jobs was to replace the seemingly dodgy mixer valve with a thermostatic bar type mixer shower (Triton Altair). This worked reasonably well for about 11 months, after which time to get a decent temperature we had to turn the temperature control knob hotter and hotter. I assumed the new mixer was in some way faulty and Screwfix replaced it.

All was well for a while, and then the same thing started happening - to get a decent temperature the temperature control knob had to be set hotter and hotter again. At the same time the temp control knob became very sensitive so that very small changes in the position of the knob created excessive changes in water temperature.

I have checked out the mixer valve as best I can - cleaning the filters being the main task - but they were not particularly clogged. I am wary of calling out a technician as I suspect call-out fees are horrendous, and thought I would check with the newsgroup to see if anyone has any ideas or suggestions.

I have been doing a bit of googling and realise that there may well be an issue with water pressure, in that the bottom of the cold water tank is 28 inches above the shower head and the water level when the tank is full is 16 inches above that. I understand this is pretty borderline and may not be helping the situation. I also noticed that some people advocate 22mm pipework as far as possible, whereas everything around the shower is 15mm.

I feel I'm on a bit of a losing wicket here, and may have to install a shower pump for a decent shower. However they obviously use a lot more water.

If I do end up going down the shower pump route can anyone recommend a pump which is sufficiently controllable to just increase the pressure enough to make sure the mixer valve works properly - i.e. can be adjusted so to be not unduly powerful?

Keith

[Keefiedee]

On Aug 19, 3:29=A0pm, Keefiedee wrote: see above

Sorry guys, have just checked the archives and in one post it was suggested that the shower in question worked better when the feeds were swopped. Crazy I thought - but decided to check my instruction book anyway and find that I have indeed fitted the shower with the feeds swopped!!!!

I shall now go and quietly hide my head in shame.

Keith

[Hugh - Was Invisible]

Yes the head is borderline. 22mm with swept bends rather than tight right angle fittings would give a slightly better result but that would need to go from the cold tank to the cylinder and on to the bar.

I am however puzzled why a new valve works but changes after a while. Could limescale be affecting it?

I installed a horrendously expensive Aqualiser pump and shower fitting but cannot recommend a pump.

[Old Codger]

My shower has around 9ft head and the pressure from the shower head is possibly greater than the pressure from a shower I installed for my daughter using a Wickes shower pump.

Don't understand your concern about the amount of water used. You are correct in that the potential flow increases with the pressure. However, the actual amount of water used is controlled by the shower control. There will be a minimum flow (probably defined as pressure drop across the pump) to cause the pump to operate but ISTR that is quite small.