Having just spent the weekend replacing the hot water cylinder,
immersion heater and thermostat - it was all working lovely last night
and this morning, but I've just come in from work to discover the
thermostat has tripped and I've had to reset it.

Why does this trip exactly? The thermostat is set to it's maximum
setting on the dial, so surely it's impossible to set the thermostat
too high?

Under stand it trips because it gets past it's maximum temperature -
although I thought the themostat measured the temperature from the tip
of the device, not the top of it - and the idea was to stop the heater
being stuck on should the thermostat fail on......yet it seems to be
this saftey thing that causes the problem!

This is the second thermostat that's done this and it's going to get
bloody annoying if I have to constantly keep checking the immersion
heater has come on when I get up or get in from work.

I know it's supposedly safer to have this rest thing, but the old
thermostat had been in the tank for the many years without the tank
'exploding' or whatever it's supposed to do if the heater is left on.

Starting to thing a surface mounted thermostat that sits on the outside
of the tank would be better.

In an earlier contribution to this discussion,
Russ wrote:

Having just spent the weekend replacing the hot water cylinder,
immersion heater and thermostat - it was all working lovely last night
and this morning, but I've just come in from work to discover the
thermostat has tripped and I've had to reset it.

Can we be absolutely clear just *what* has tripped. Is this the safety stat
in the immersion heater itself - or is it tripping something in the Consumer
Unit next to the electric meter? Just what do you have to do to reset it?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Russ presented the following explanation :
Having just spent the weekend replacing the hot water cylinder,
immersion heater and thermostat - it was all working lovely last night
and this morning, but I've just come in from work to discover the
thermostat has tripped and I've had to reset it.

Why does this trip exactly? The thermostat is set to it's maximum
setting on the dial, so surely it's impossible to set the thermostat
too high?

Oh yes it is!

If the set point of the regular stat is higher than the safety stat,
then the safety will trip. That is its designed purpose. Set the
regular one a little lower until it doesn't trip.

Health and safety concerns over the hot water being too hot mean that
HW stat temperatures have been lowered anyway, so don't expect your
water to be as hot as it used to be.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

Hi Set!

It's the safety stat in the immersion heater thermostat...if that makes
sense!

In article . com,
"Russ" writes:
Having just spent the weekend replacing the hot water cylinder,
immersion heater and thermostat - it was all working lovely last night
and this morning, but I've just come in from work to discover the
thermostat has tripped and I've had to reset it.

Why does this trip exactly? The thermostat is set to it's maximum
setting on the dial, so surely it's impossible to set the thermostat
too high?

Not sure if this is possible, but if you had a short heater and
a long stat in the top of the cylinder, I could imagine the stat
would never switch off.

--
Andrew Gabriel

hi again Set!

Yes, it's the safety stat built into the immersion heater
thermostat....if that makes sense!

Andrew Gabriel was thinking very hard :
In article . com,
"Russ" writes:
Having just spent the weekend replacing the hot water cylinder,
immersion heater and thermostat - it was all working lovely last night
and this morning, but I've just come in from work to discover the
thermostat has tripped and I've had to reset it.

Why does this trip exactly? The thermostat is set to it's maximum
setting on the dial, so surely it's impossible to set the thermostat
too high?

Not sure if this is possible, but if you had a short heater and
a long stat in the top of the cylinder, I could imagine the stat
would never switch off.

The stat fits into a pocket built into the heater element matched to
the element size, so it would only be possible to fit a shorter stat.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

which I haven't done.

The old immersion was approx 32" with an 18" stat.

I bought a 27" immersion initially, which had an 18" stat.

The new immersion heater is 36" with an 18" stat.

I can't put any longer than that in there.

Russ wrote:

hi again Set!

Yes, it's the safety stat built into the immersion heater
thermostat....if that makes sense!

then your safety stat is set to a lower temp than the adjustable stat.
Turn adj stat down till it works ok. If water not hot enough when it
works ok, the safety stat can not be used. A bolt on external stat can
then be used to provide a secondary safety backup stat.

I can see overriding the safety stat becoming popular, since some
systems simply wont work usefully at the preset safety stat temp.


NT

On 9 Jan 2006 12:19:30 -0800, "Russ"
wrote:

which I haven't done.

The old immersion was approx 32" with an 18" stat.

I bought a 27" immersion initially, which had an 18" stat.

The new immersion heater is 36" with an 18" stat.

I can't put any longer than that in there.

Hi,

How hot is the water with the new heater and stat? Bear in mind that
heating the water over 60C makes the scale form in the cylinder much
quicker.

cheers,
Pete.

On 9 Jan 2006 12:19:30 -0800, "Russ"
wrote:

which I haven't done.

The old immersion was approx 32" with an 18" stat.

I bought a 27" immersion initially, which had an 18" stat.

The new immersion heater is 36" with an 18" stat.

I can't put any longer than that in there.

Does the safety stat always cut out before the adjustable one when
it's on maxium? If so set the adjustable one as follows:


Turn the adjustable one up to maxium and switch on immersion. Wait
until the safety stat cuts out.

Turn the adjustable one down and carefully listen for a click when the
contacts of the adjustable stat open.

Turn it down a little more. Reset the safety stat.

The adjustable stat should now be set so it opens just before the
safety stat. If the safety stat still cuts out just turn the
adjustable one down a bit more.

Once it works reliably without the safety stat cutting out mark the
position of the adjustable stat for reference.

cheers,
Pete.

Cheers Pete

I sort of discovered/experimented with that yesterday, and it seems to
be ok now.

Thanks for your advice.