pump staying on

[pistol89]

heading to a job tomorrow and have been told the pump for the central heating is staying on all the time?
anyone ever come across this issue before? pretty sure its a "s" plan heating system with motorized valves!
any info appriciated!

 

[Richard Burns]

Initially my thoughts are: One of the valves is stuck open or one of the microswitches is jammed on, probably.
A quick continuity test at each section should show the fault location.

 

[davesparks]

Apart from the obvious advice to test the circuit and establish why the pump,is running constantly there is very little advice to be given.
As long as you understand how a boiler control system works and not just a wire by numbers approach then it should be an easy task to diagnose the problem. If you don't understand how a basic boiler system works then I feel sorry for your customer who will be paying you to spend hours looking for a fault which should be identifiable well within half an hour.

First I would be wanting to know if it is just the pump running or if it is the boiler which is also firing. Also it would be important to know the make and model of the boiler and if an external frost protection circuit has been installed. It is not uncommon to see a frost stat connected without a pipe stat which leads to the (hopefully) obvious problem with modern well insulated high efficiency boilers.


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[Leesparkykent]

If one of the micro switches were stuck in one of the valves then the boiler would also be firing up. The boiler probably has pump over run and something internal in the boiler is playing up like the pump over run thermostat or similar.

 

[PEG]

A simple addition,of knowing the boiler still functioned,would cut the guessing in half,the customer must have mentioned this...

 

[davesparks]

A simple addition,of knowing the boiler still functioned,would cut the guessing in half,the customer must have mentioned this...

A simple bit of actually going to the site and doing a bit of testing would cut all of the guessing out!

 

[nunthe wiser]

Could well be sticking valve, boiler cutting out on hi limit stat but pump continuing to run. Do plumbers install a radiator to bypass the heating valve, for heat dissipation in the event of closed valve. Just a general question, it seems to ring a bell. Or maybe I'm just havering.

 

[pistol89]

ended up being a micro switch stuck!..accept criticism but just wanted a head start before i got there,not that experienced in this area.. thanks for all the help!!

 

[Leesparkykent]

ended up being a micro switch stuck!..accept criticism but just wanted a head start before i got there,not that experienced in this area.. thanks for all the help!!

so the boiler was on to?

 

[PEG]

Could well be sticking valve, boiler cutting out on hi limit stat but pump continuing to run. Do plumbers install a radiator to bypass the heating valve, for heat dissipation in the event of closed valve. Just a general question, it seems to ring a bell. Or maybe I'm just havering.

They would do this,on a solid fuel fired gravity system,or,as i suspect you are referring to,a radiator or even two,would have two lock-shield valves,left balanced,but on,to provide a functioning loop.

Some of the modern hi-spec boilers,have a myriad of features fitted internally,which can second guess what the rest of the system is up to.

The Vaillant i have just fitted,is very chatty,and gives you more information than most plumbers can...

It reminds me of the talking screen,on Red Dwarf :heart: