Depends if the radiator side has has trvs on all rads , if so then the (automatic) bypass keeps the flow rate through the boiler constant.
Has the pressure of the cold dropped lower than the hot ?
At a guess I reckon you have a stuck non return valve causing cross over between the hot and cold, usually its a shower valve or mixer tap,
Try recharging the expansion vessel on the pump.
The bottom "thing" in the pic is a remote sensor for a rad, its just a thermostatic rad valve with the sensing element remote from the rad its...
Easy enough, put one of these on the pipework and wire the main feed to boiler through the switch.
Potterton 910026 Pressure Switch Kit Water...
F83/f72/f23 are all temperature related so check water pressure and then pump before anything boiler related.
Where is the expansion vessel plumbed in for the cylinder ?
Can you post a pic of the wiring centre ?
You will have to replace the stack from the tee your replacing upwards, you wont get away with "adapting" what is there now.
Is there no way you can replace the whole stack ?
Is there a bypass fitted and if there is does it work ?
No I think I can manage without the straws, so going with your theory the more rads I have the smaller the pump, grundfos could bring out a 15/1...
That's interesting, could you expand on that pet theory ?
The resistance of the heat exchanger and pipework to 19 rads will kill a 15/60, I would be looking at a 25/80 or as you have bought a 15/60...
I reckon the vr65 is kaput, if you have a multimeter you can check the voltages coming from/to the 3 port valve in the vr65.
Not what I asked o_O I there a two port valve fitted on the unvented cylinder flow ?
Do you have a two port valve on the hot water cylinder ?
Be aware it can be a bit of a slog getting work as all employers want experience, the diplomas on their own a almost worthless.
Sounds like a stuck relay in the vr65, turn the power off and open the front of the vr65, you will see a row of relays just gently tap the tops...
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