Thermostatic shower not holding temperature

[Martin Pentreath]

Dear all

I have recently had a thermostatic shower fitted. It's an Aqualisa Aqarian (sorry for the long link):

runs off an Ariston Microgenus combi.

It seemed to work fine at first, but recently the temerature has started wandering. It gradually cycles from the set temperature down to tepid and back up to warm and so on. It's driving me mad. It's well within its guarantee, but before I call Aqualisa out I want to check something.

When I run the bathroom tap by itself the water temperature is steady. But when I run the bathroom tap with the shower on as well the temperature of the tap water cycles in sync with the shower. What's going on? Is it the boiler? The boiler is burning constantly, even when the water goes tepid.

Thanks for any ideas,

Martin

[john]

> It runs off an Ariston Microgenus combi.

I find with my Worcester Combi that the residual hot water initially flows quite hot - then the thermostat realises (perhaps a bit late) that it needs to fire the boiler and it takes a little while to recover from the sudden loss of some hot water. Could it be a similar issue? I get around it by 'warning' the boiler that I want a shower by running off a bit of hot water to make the boiler fire.

[Pete C]

Hi,

How are the hot and cold fed, directly off the mains?

Have you tried calling Aqualisa to see what they say?

Basically the boiler will likely dump a finite amount of heat into the water regardless of flow, so if the shower is varying the demand for water through hot then the temperature of hot from the boiler will go up and down and the shower will have to react to this giving the cycling effect.

The colder water temperature to the boiler and mixer as winter approaches could exacerbate this I'd expect.

If the installation is fine the solution might to restrict the cold or hot, but see what Aqualisa recommend. In the meantime running the shower with a reduced flow might cure the problem, try turning it on and gradually reducing the flow to see if the cycling stops.

Also which (ie hot or cold) tap are you running when the problem persists?

cheers, Pete.