Boiler not maintaining hot water

edwardmluk · 18 August 2015 at 11:49AM

I've just moved into a property which has an Ariston gas combi boiler (any sticker with the model number has been removed...helpful).

When any hot tap is turned on full power, it is unable to maintain the temperature. It will fire up, get up to temperature and then switch off the heat. And then fire up as soon as it drops. And switch off when it gets up to temperature. And repeat. However if I have the taps half turned on, it's able to maintain the temperature for a lesser trickle of water. I've tried reducing the max water temperature on the boiler, to no avail.

The problem is that the shower has a mixer tap, and to maintain the heat (e.g. lessen the hot water flow), you end up with a pretty cool shower. Not ideal.

It's a rented property, so it's up the landlord to fix it. But I don't want to call up and get someone out, if this is the expected behaviour of an older boiler.

Any plumbers got thoughts on this? Should this be the behaviour of a boiler? Or should it be able to maintain the highest temperature for the largest flow of water a tap allows?