yo i dont think you understand how pump overrun works or how its wired because what you are saying does not make sense\!
If the boiler and pump are connected to the switched live through the mv, the switched live is getting its power from the permanent live
if its wired like this then you cannot have pump overrun as the mv will close opening the micro switch breaking the connection between permanent live and switched live.
sorry mate no! the pump is wired back to the boiler and is controled by the pcb & thermister keeps the pump running when the zone valves close.
like i said the boiler puts 240v on the pump not the external controls.
Hi wink.
You will probably find that the system has two motorized valves, the pump gets it`s power from a permanent live feed through the orange and grey wires connected to either of these valves when they are open. If they are both closed then the pump should not continue to run.
It appears that the the MVs is not closing correctly, the only way to test these valves are to check them each for continuity across the orange and grey wires, there should be no continuity when the valve is closed but continuity when it is open.
Cheers
spraggo
errrr emm it kinda looks like you said the pump is controlled by the external controls here, I still think we should hit you with a brick anyway
piccaso is correct; if the pump is connected through the MVs then the circuit would be broken when the MVs close. Unfortunately I was not able to reply to piccasso before I had a few ha ha`s etc. So I thought I would lie low hoping that someone else would enter the argument the sort of query as follows:ha ha
pump runs during the night every so often, blr doesn't fire tho.
5. "Functional Wiring Diagram"
"Boiler Lighting Sequence"
1. Supply external voltage to boiler terminal connections L and N, 230 volts, 50 HZ.
2. Supply external voltage to boiler terminal connection, switch line SW 230 volts, 50 HZ.
3. Pump live from boiler energised, diverter/zone valves operate in accordance with system demand.
4. Boiler control checks, air pressure switch for No Air Condition (red light "On", green light "Flashing").
5. If "No Air" the control switches on the fan.
6. After ten seconds air pressure switch proves fan is on.
7. Gas valves open and ignition for 3 seconds ("green light flashes rapidly).
8. Boiler firing (green light "On" only).
9. If the flame is not "detected at this "time, the boiler will turn off.
10.The above sequence wil repeat for a further two ignition attempts before going to lockout (indicated by the red light flashing).
11.Pressing the reset button will re-start boiler at No. 1.
12."The control will continue to run the pump for several minutes after any firing of the boiler.
13.The control will run the pump automatically for a few minutes every twenty four hours to maintain the free running of the pump.
14.The standby position on the thermostat control knob will prevent the boiler firing but will permit operation of the pump for sequences 12 and 13.
matt, sorry mate the pump is running on its own for hours! not mins!
Check that you have not got a blocked cold feed. It will be the pump overrun control which is keeping the pump running. Any suggestion that the pump and not the boiler is controlled by the end switches on two port valves is nonsense.
If it is an installation with two 2 port valves [known as an S Plan], there should be a bypass before the two valves so there is still circulation through the pump during overrun. It is commonly omitted.
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