We recently had the landlord and plumber round to replace our immersion
heaters (plural - we're on economy 7) as both had packed up - the elements
had split and shorted.

When the plumber replaced them, he put in new thermostats. Ever since, the
hot water hasn't been as hot as it was before. It's most noticeable with
the shower. The plumber reckons it's a venturi-style mixer, and before the
work we used to have the dial about halfway round for a hot shower, now it's
just hot enough when turned to the hottest setting.

This is with the immersion thermostat turned up full.

We had the plumber back, and he flushed through various pipes in case there
was scale blocking the hot water pipes, all to no avail.

I've swapped the peak and off-peak thermostats (we never use peak), but it's
no better. I had the landlaord round, he ran his hand under the tap and
declared it fine. I brought home a digital thermocouple-type thermometer
from work and the hot tap gets to a maximum of 55.8°C in the morning when
the immersion heater is still on (running the tap for a few minutes).

The landlord brought round another thermostat to try, but the hot water gets
to the same temperature.

The thermostat is a Heatrae Sadia 7-inch one. The instructions say it comes
with the dial preset to 60°C, and it was somewhere in the middle. With it
turned all the way up, we get no hotter than 56°C.

We now don't know what to do - the landlord's getting annoyed at calling out
the plumber and not finidng out what's wrong, and we're getting annoyed with
warm showers.

Can anyone suggest something to try? Are there different sorts of
thermostats - could we get a hotter one? The ones we have audibly click in
the middle of the dial range at room temperature (i.e. out of the water
tank) - is that right?

--
Ian Cowley
Bishop's Stortford/Cambridge, UK

www.iancowley.co.uk/contact