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David Hearn
 
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Default Installing boiler thermostat question

Received my new thermostat today and planning on fitting it this evening.

Couple of quick questions...

Firstly, the old thermostat had marked on it 16A 250V~ and T107oC. I assume
that means that it can switch 16A at 250V AC and switches at 107oC. The new
one (the part suggested by Baxi Spares and KeepTheHeatOn.com) has lots of
figures on it (with what appear to be first 3 chars of part number) but the
one for this part says 2(2)A 250V~ 90oC. Can I assume that this switches 2A
@ 250V AC and switches at 90oC? Seeing as Baxi said this was the part, I'm
tending to believe them that 2A switching is okay - and I guess that it just
means that the water reaches 90oC rather than 107oC now? Does this sound
okay?

Secondly, I drilled out the old siezed probe and the hole is now nice and
clear. I used an 8mm drill and it fitted fine. 7mm was too small and 8mm
was tight, but not too tight. This new probe is just under 8mm in
diameter - so it should fit. My only question is whether I just insert it
or whether I need to put anything like heat transfer stuff. From memory,
when a similar probe was removed from a similar Baxi boiler it was dry
without anything on it - so I'm assuming that's right - but I just wanted to
make sure!

Thanks again.

D

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BillR
 
Posts: n/a
Default Installing boiler thermostat question

David Hearn wrote:
Received my new thermostat today and planning on fitting it this
evening.

Couple of quick questions...

Firstly, the old thermostat had marked on it 16A 250V~ and T107oC. I
assume that means that it can switch 16A at 250V AC and switches at
107oC. The new one (the part suggested by Baxi Spares and
KeepTheHeatOn.com) has lots of figures on it (with what appear to be
first 3 chars of part number) but the one for this part says 2(2)A
250V~ 90oC. Can I assume that this switches 2A @ 250V AC and
switches at 90oC? Seeing as Baxi said this was the part, I'm tending
to believe them that 2A switching is okay - and I guess that it just
means that the water reaches 90oC rather than 107oC now? Does this
sound okay?

Should be ok and its unlikely to have to switch much current anyway.

Secondly, I drilled out the old siezed probe and the hole is now nice
and clear. I used an 8mm drill and it fitted fine. 7mm was too
small and 8mm was tight, but not too tight. This new probe is just
under 8mm in
diameter - so it should fit. My only question is whether I just
insert it or whether I need to put anything like heat transfer stuff.
From memory, when a similar probe was removed from a similar Baxi
boiler it was dry without anything on it - so I'm assuming that's
right - but I just wanted to make sure!

Thanks again.

D

The boiler thermostats I've replaced were just push fit into the hole.
Any heat transfer compound that doesn't set hard is likely to run out in a
short time...


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Roger Mills
 
Posts: n/a
Default Installing boiler thermostat question


"David Hearn" wrote in message
...
Received my new thermostat today and planning on fitting it this evening.

Couple of quick questions...

Firstly, the old thermostat had marked on it 16A 250V~ and T107oC. I

assume
that means that it can switch 16A at 250V AC and switches at 107oC. The

new
one (the part suggested by Baxi Spares and KeepTheHeatOn.com) has lots of
figures on it (with what appear to be first 3 chars of part number) but

the
one for this part says 2(2)A 250V~ 90oC. Can I assume that this switches

2A
@ 250V AC and switches at 90oC? Seeing as Baxi said this was the part,

I'm
tending to believe them that 2A switching is okay - and I guess that it

just
means that the water reaches 90oC rather than 107oC now? Does this sound
okay?

Secondly, I drilled out the old siezed probe and the hole is now nice and
clear. I used an 8mm drill and it fitted fine. 7mm was too small and 8mm
was tight, but not too tight. This new probe is just under 8mm in
diameter - so it should fit. My only question is whether I just insert it
or whether I need to put anything like heat transfer stuff. From memory,
when a similar probe was removed from a similar Baxi boiler it was dry
without anything on it - so I'm assuming that's right - but I just wanted

to
make sure!

Thanks again.

D

--
To send email to me - remove references to NoSpam, and Spammer from my

email
address.



The thermostat switches the gas valve on your boiler** - which is very
unlikely to require more than 2 amps - so the one you have should be fine. I
don't think that you can deduce anything about the switching temperature
from the hieroglyphics in the part number - the old one certainly didn't
switch at a water temperature of 107 degC, by which time it would be well
and truly boiling! If it's a boiler stat, and if it fits, it should do the
job. I assume that the end with the electrical contacts has a knob which you
can twiddle to set the switching temperature?

It's a long time since I fitted one of these, but I seem to remember that
you are supposed to use some conducting paste to make sure that the bulb
makes good thermal contact with the pocket in the heat exchanger.

** The term "boiler" is somewhat of a misnomer - since if it *boils* the
water it is malfunctioning! A flow temperature of around 80-85 degC is what
you need for the central heating.

Roger


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David Hearn
 
Posts: n/a
Default Installing boiler thermostat question


"BillR" wrote in message
...
David Hearn wrote:
Received my new thermostat today and planning on fitting it this
evening.

Couple of quick questions...

Firstly, the old thermostat had marked on it 16A 250V~ and T107oC. I
assume that means that it can switch 16A at 250V AC and switches at
107oC. The new one (the part suggested by Baxi Spares and
KeepTheHeatOn.com) has lots of figures on it (with what appear to be
first 3 chars of part number) but the one for this part says 2(2)A
250V~ 90oC. Can I assume that this switches 2A @ 250V AC and
switches at 90oC? Seeing as Baxi said this was the part, I'm tending
to believe them that 2A switching is okay - and I guess that it just
means that the water reaches 90oC rather than 107oC now? Does this
sound okay?

Should be ok and its unlikely to have to switch much current anyway.

Secondly, I drilled out the old siezed probe and the hole is now nice
and clear. I used an 8mm drill and it fitted fine. 7mm was too
small and 8mm was tight, but not too tight. This new probe is just
under 8mm in
diameter - so it should fit. My only question is whether I just
insert it or whether I need to put anything like heat transfer stuff.
From memory, when a similar probe was removed from a similar Baxi
boiler it was dry without anything on it - so I'm assuming that's
right - but I just wanted to make sure!

Thanks again.

D

The boiler thermostats I've replaced were just push fit into the hole.
Any heat transfer compound that doesn't set hard is likely to run out in a
short time...


Well, I replaced the thermostat and it is working fine now. Noticed that
its short cycling far more than it used to. Its not a room thermostat
problem as it was constantly calling for heat, its that the new thermostat
is switching off when it reaches temperature and then switching on again
about 1 minute later. Still, not bothered too much with it.

Anyway - I noticed when I inserted the thermostat probe that there were
small droplets of rusty water clinging to the sides of the hole. Either its
condensation or its leaking slightly. Seeing as the old one siezed in
there, I guess it was doing it before, and just was kept hot so water never
had a chance to sit there. I'm planning on removing the probe every so
often and cleaning the hole so this new probe doesn't seize as well. Sound
sensible?

Thanks

D


  #5   Report Post  
Ed Sirett
 
Posts: n/a
Default Installing boiler thermostat question

On Wed, 03 Dec 2003 09:46:19 +0000, David Hearn wrote:


"BillR" wrote in message
...
David Hearn wrote:
Received my new thermostat today and planning on fitting it this
evening.

Couple of quick questions...

Firstly, the old thermostat had marked on it 16A 250V~ and T107oC. I
assume that means that it can switch 16A at 250V AC and switches at
107oC. The new one (the part suggested by Baxi Spares and
KeepTheHeatOn.com) has lots of figures on it (with what appear to be
first 3 chars of part number) but the one for this part says 2(2)A
250V~ 90oC. Can I assume that this switches 2A @ 250V AC and
switches at 90oC? Seeing as Baxi said this was the part, I'm tending
to believe them that 2A switching is okay - and I guess that it just
means that the water reaches 90oC rather than 107oC now? Does this
sound okay?

Should be ok and its unlikely to have to switch much current anyway.

Secondly, I drilled out the old siezed probe and the hole is now nice
and clear. I used an 8mm drill and it fitted fine. 7mm was too
small and 8mm was tight, but not too tight. This new probe is just
under 8mm in
diameter - so it should fit. My only question is whether I just
insert it or whether I need to put anything like heat transfer stuff.
From memory, when a similar probe was removed from a similar Baxi
boiler it was dry without anything on it - so I'm assuming that's
right - but I just wanted to make sure!

Thanks again.

D

The boiler thermostats I've replaced were just push fit into the hole.
Any heat transfer compound that doesn't set hard is likely to run out in a
short time...


Well, I replaced the thermostat and it is working fine now. Noticed that
its short cycling far more than it used to. Its not a room thermostat
problem as it was constantly calling for heat, its that the new thermostat
is switching off when it reaches temperature and then switching on again
about 1 minute later. Still, not bothered too much with it.

Anyway - I noticed when I inserted the thermostat probe that there were
small droplets of rusty water clinging to the sides of the hole. Either its
condensation or its leaking slightly. Seeing as the old one siezed in
there, I guess it was doing it before, and just was kept hot so water never
had a chance to sit there. I'm planning on removing the probe every so
often and cleaning the hole so this new probe doesn't seize as well. Sound
sensible?


I'd make sure the water is moving around well in the system.
How long do you intend keeping the old boiler going?
If you do have a small leak in the sensor pocket on the main heat
exchanger this is all reason to change it next summer.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html




  #6   Report Post  
David Hearn
 
Posts: n/a
Default Installing boiler thermostat question


"Ed Sirett" wrote in message
news
On Wed, 03 Dec 2003 09:46:19 +0000, David Hearn wrote:


"BillR" wrote in message
...
David Hearn wrote:
Received my new thermostat today and planning on fitting it this
evening.

Couple of quick questions...

Firstly, the old thermostat had marked on it 16A 250V~ and T107oC. I
assume that means that it can switch 16A at 250V AC and switches at
107oC. The new one (the part suggested by Baxi Spares and
KeepTheHeatOn.com) has lots of figures on it (with what appear to be
first 3 chars of part number) but the one for this part says 2(2)A
250V~ 90oC. Can I assume that this switches 2A @ 250V AC and
switches at 90oC? Seeing as Baxi said this was the part, I'm tending
to believe them that 2A switching is okay - and I guess that it just
means that the water reaches 90oC rather than 107oC now? Does this
sound okay?
Should be ok and its unlikely to have to switch much current anyway.

Secondly, I drilled out the old siezed probe and the hole is now nice
and clear. I used an 8mm drill and it fitted fine. 7mm was too
small and 8mm was tight, but not too tight. This new probe is just
under 8mm in
diameter - so it should fit. My only question is whether I just
insert it or whether I need to put anything like heat transfer stuff.
From memory, when a similar probe was removed from a similar Baxi
boiler it was dry without anything on it - so I'm assuming that's
right - but I just wanted to make sure!

Thanks again.

D
The boiler thermostats I've replaced were just push fit into the hole.
Any heat transfer compound that doesn't set hard is likely to run out

in a
short time...


Well, I replaced the thermostat and it is working fine now. Noticed

that
its short cycling far more than it used to. Its not a room thermostat
problem as it was constantly calling for heat, its that the new

thermostat
is switching off when it reaches temperature and then switching on again
about 1 minute later. Still, not bothered too much with it.

Anyway - I noticed when I inserted the thermostat probe that there were
small droplets of rusty water clinging to the sides of the hole. Either

its
condensation or its leaking slightly. Seeing as the old one siezed in
there, I guess it was doing it before, and just was kept hot so water

never
had a chance to sit there. I'm planning on removing the probe every so
often and cleaning the hole so this new probe doesn't seize as well.

Sound
sensible?


I'd make sure the water is moving around well in the system.
How long do you intend keeping the old boiler going?
If you do have a small leak in the sensor pocket on the main heat
exchanger this is all reason to change it next summer.


Well, everything appears to be working fine - rads are getting nice and hot
and the house is warm, so I doubt there's any problem in the water flowing
around.

How long to keep it going? Well, the truth is as long as possible. I have
no plans on replacing the boiler for another few years - though that doesn't
mean it won't give up the ghost before then!

Obviously, if I had the money to do it, I'd get it changed ASAP - however
our situation is that we just don't have the money to spent on it - at
least, not unless it died and wasn't repairable. I guess that's the joys of
a mortgage in Guildford and a baby on the way...

D


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