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Andrew Smith
Andrew Smith, Plumber
Category: Plumbing
Satisfied Customers: 3757
Experience:  City and Guilds qualified plumber
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Jaguar 23 boiler overheats on heating but dhw works fine...pump

Customer Question

Jaguar 23 boiler overheats on heating but dhw works fine...pump seems to be running ok.put cleansing fluid in but made no difference. Flushed main heat exchanger but also made no difference .. Any ideas ?
Submitted: 3 years ago.
Category: Plumbing
Expert:  Andrew Smith replied 3 years ago.
***** ***** : Can you confirm the pump is spinning?
***** ***** : How long is the boiler on for heaing before it overheats?
JACUSTOMER-n28hxr4x- : Pump spinning comes on a warms up within a couple of minutes..stat set to 80 and cuts off when reaches 88. But doesn't get chance to heat all rads.. Only a few upstairs
***** ***** : How far is it the heating getting, can you follow it along the pipework using your hands?
JACUSTOMER-n28hxr4x- : It's get to furthest rad upstairs but not getting downstairs..think because boiler shuts of b4 it gets chance..or maybe pump not strong enough ??
***** ***** : The pump would be strong enough if it has been working previously, yours just sounds like it is wearing out
***** ***** : Can you confirm it is on speed 3
***** ***** : Can you turn off all the rads except the furthest away downstairs
***** ***** : Lets see if it can push it that far to start with
JACUSTOMER-n28hxr4x- : Pump in boiler only 1 speed as far as I no
***** ***** : ok, can you turn off all the rads except the furthest away and see if the heat gets there
***** ***** : It could be a pump problem
***** ***** : or a water qulaity problem
JACUSTOMER-n28hxr4x- : Overheats and comes up f 3 boiler overheating .. It's almost like pump no moving water fast enough
JACUSTOMER-n28hxr4x- : Flushed system and emptied / cleaned all rads...
***** ***** : ok, pointing to the pump then
JACUSTOMER-n28hxr4x- : Even took main exchanger of and des sled / flushed it
JACUSTOMER-n28hxr4x- : Descaled*
***** ***** : I think it will be worth swapping the pump, but 9 times out of 10 you can get away with swapping the head
JACUSTOMER-n28hxr4x- : Will the pump run slower than normal if it's knackered
***** ***** : yes before it eventually fails all together
JACUSTOMER-n28hxr4x- : Could it be overheat thermostat or is that working ok if cuts boiler off
***** ***** : The overheat thermostat shuts down the boiler if it gets too hot
***** ***** : If it was faulty it would just shut the boiler down at a lower temperature
JACUSTOMER-n28hxr4x- : Problem has only occurred since I changed the diaphragm in diverted valve as had no hot water .. But hot water fine now
***** ***** : Perhaps the divertor is stuck in hw mode, so when you try and put the heating on it has nowhere to go
JACUSTOMER-n28hxr4x- : What does the diverted valve pump do
JACUSTOMER-n28hxr4x- : Sorry motor
JACUSTOMER-n28hxr4x- : And how do I no if that's working
***** ***** : if you disconnect it then you should see it push the pin in
***** ***** : once you have taken it off
JACUSTOMER-n28hxr4x- : There's a black block switch on the end of the valve with 2 wires I believe when water called for it pushes pin into block as though it's some sort of switch
***** ***** : With it removed but still connected can you see it moving?
***** ***** : What happens if you run the tap now - do you get heating?
JACUSTOMER-n28hxr4x- : Can't remove as water flows into the motor
JACUSTOMER-n28hxr4x- : Does seem to heat water in heating while demand is for hot water
JACUSTOMER-n28hxr4x- : Doesn't *
***** ***** : The divertor is not working correctly
***** ***** : You may have to strip it down again to make sure