Open vented system Hot water working but heating is not - getting really annoying now!

[TexanRob]

Hi all

I am i need of a bit of help.

i have an oil boiler - working fine. Hot water is running, heating normally however the sequence of events has meant no central heating

1 new pump fitted - damaged due to contamination
2 heating working fine for 3-4 days
3 drained system , put x800 sentinal cleaner in, bled radiators
4 boiler ran for 4 mins , no heat to rads and then cut off
5 check rads all have water, put the motorised heating valve into manual - s-plan system - same result
6 flipped pump 180 - reversed flow direction and rads heated up
7 returned to normal flow direction heating ran for 2 hrs to temperature
8 heating came to restart and came back to the 4 minute run time

Any ideas/help gratefully received

Thanks

TexanRob

 

[Stuckinarut]

So, have you definitely fitted the pump in the correct orientation? Any airlocks?

 

[TexanRob]

Hi Stuckinarut,

I am with you - I think it could be an airlock. When I have the pump in the original installed condition then hot water is fine but not the heating. Checked the motorised valves too they are working. I am completely baffled at this point in time

 

[TexanRob]

Pump is installed correctly flowing to the motorised valves too- I have bled each radiator - clear water in the header tank etc

 

[terryplumb]

When you run central heating does the pipe that comes out the 2 port valve to heating circuit get hot along any of its length,during the 4 minutes that the boiler is running ?

 

[TexanRob]

Hi Terry - yep it is short run before pipes disappear under the floor. There is heat maybe 3-4 inches past the valve but the pipe just before it goes under the floor is noticeably cooler. I reckon the total run from valve to floor is around 8-10 inches of pipe work

TexanRob

 

[terryplumb]

Your issue seems to be a lack of circulation through the heating circuit ,and the hot water from the boiler isn't getting past the 2 port valve. I would remove the body from the pipework for inspection / replacement.

 

[TexanRob]

Hi Terry - If I put the valve into manual the system still does the same - I have removed the motor from the valve and can confirm that it is rotating when i call for heat and I have also then moved the valve manually and it seems free - Also the heating did run for two hours when the pump was put in the correct flow position.

 

[terryplumb]

You manually moved the lever to open the valve,but the gate inside the valve body may not actually be opening.
It's obvious that the motor is working and triggering the internal switch that sends voltage to the boiler because the boiler is working.
With the actuator head removed from the valve body ,exposing the spindle in the body ,have you tried to move the spindle by hand ? Also examine the underside of the actuator where the spindle sits in, to see if it is in good condition and would actually turn the spindle .

 

[TexanRob]

Hi Terry - I will take a look at the valve and see what is going on - I get the logic - May take me a day or to sort out - I will come back to this thread. If there any other ideas out there then please feel free to add to this conversation - Thank you for the help

 

[TexanRob]

Thanks Terry for making take a second (proper) look. Your diagnosis was spot on. Got a new valve body and now up and running. Great advice!

 

[terryplumb]

Well done ,thanks for letting us know the result.

 

[TexanRob]

first time I have used the forum and it turned out to be really useful! Properly at my wits end and you guys helped! Thanks again