Pump working or not?

[Notebook64]

Hi
hadn't had to use the ch since last year, and due to the motorised valve breaking, had to change it and also the pump due to water shorting it and subsequently burning it out (possibly needs drying out)
Fitted a new valve and pump

When I put the central heating on, the pump appears to run and the boiler fire when it is demanded. This to me appears correct.

However
With just hot water selected the pump appears to run all the time - is this correct?

Thanks

 

[seco services]

your pump will run all the time till hw satisfied.

 

[Notebook64]

your pump will run all the time till hw satisfied.

ok - so what your saying is that when the boiler is firng, to make the required temp, the pump runs to circulate it to the tank etc?

when the temp is reached, does it run for a while after the boiler stops firing? its just that every time I check it in hot water mode, the pump is hot and running.

Thanks for your help

 

[seco services]

if your stat is satisfied useally all will shut down.

if your boiler has an overrun where as the stat is satisfied the boiler etc will shut down and the pump will run for a few mins to remove any hw from the boiler.

if you say you pump is still running say 5 mins after everything is satisfied
then something wrong.

 

[jacobball]

pump overrun removes residual heat from the boiler's heat exchanger when the boiler has stopped firing - this protects the boiler and stops "kettling" sounds happening also.

usually found with modern, low-water content boilers. will be pre-wired up to the boiler's pcb when boiler is purchased.

 

[Notebook64]

if your stat is satisfied useally all will shut down.

if your boiler has an overrun where as the stat is satisfied the boiler etc will shut down and the pump will run for a few mins to remove any hw from the boiler.

if you say you pump is still running say 5 mins after everything is satisfied
then something wrong.

are all the pumps the same? I know the flow rates may vary, but all do the same job? - this was from B and Q

saying that I bought the correct pump, there are only 3 wires if I remember, how could I get this incorrect?

any pointers as to what could be wrong - if I am correct in what I initially said.

There is no excess noise coming from the boiler (apollo) so I dont think it is overheating in there - any ideas?

The central heating appears to be ok as in the pump definately shuts down if the wall stat is turned to a lower setting

thanks for the help so far