In article , says...
We recently had the landlord and plumber round to replace our immersion=
=20
heaters (plural - we're on economy 7) as both had packed up - the element=
s=20
had split and shorted.
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When the plumber replaced them, he put in new thermostats. Ever since, =
the=20
hot water hasn't been as hot as it was before. It's most noticeable with=
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the shower. The plumber reckons it's a venturi-style mixer, and before t=
he=20
work we used to have the dial about halfway round for a hot shower, now i=
t's=20
just hot enough when turned to the hottest setting.
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This is with the immersion thermostat turned up full.
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We had the plumber back, and he flushed through various pipes in case the=
re=20
was scale blocking the hot water pipes, all to no avail.
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I've swapped the peak and off-peak thermostats (we never use peak), but i=
t's=20
no better. I had the landlaord round, he ran his hand under the tap and=
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declared it fine. I brought home a digital thermocouple-type thermometer=
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from work and the hot tap gets to a maximum of 55.8=B0C in the morning wh=
en=20
the immersion heater is still on (running the tap for a few minutes).
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The landlord brought round another thermostat to try, but the hot water g=
ets=20
to the same temperature.
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The thermostat is a Heatrae Sadia 7-inch one. The instructions say it co=
mes=20
with the dial preset to 60=B0C, and it was somewhere in the middle. With=
it=20
turned all the way up, we get no hotter than 56=B0C.
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We now don't know what to do - the landlord's getting annoyed at calling =
out=20
the plumber and not finidng out what's wrong, and we're getting annoyed w=
ith=20
warm showers.
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Can anyone suggest something to try? Are there different sorts of=20
thermostats - could we get a hotter one? The ones we have audibly click =
in=20
the middle of the dial range at room temperature (i.e. out of the water=
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tank) - is that right?
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=20

=09In my experience, the newer thermostats with the built-in=20
manually resettable over-temperature cut-outs, are made to control at a=20
much lower maximum temperature setting.

=09I suspect that it is to do with the recommendation that domestic=20
stored hot water is not maintained at a temperature higher than 65=B0C, to=
=20
minimise energy wastage due to heat losses.

=09The older type thermostats used to control upto about 85=B0C, so=20
the chances are that yours was set higher than recommended. The lower=20
temperature that you are reading at the tap is likely to be partly due=20
to heat losses in the delivery pipework.

=09The thermostat should not switch in its mid-point at room=20
temperature, perhaps it had not fully cooled from its time in the tank?=20
The fact that you have two stats that operate very closely to each other=20
indicates that they are unlikely to be faulty as such, unless they both=20
came from a faulty batch...

--=20
Regards,

Will.