Boiler noise after converting to s plan

[notfocused]

Hi, I have just updated my dhw circuit to include a 2 port motorised valve, a automatic bypass valve and a cylinder stat, previously my hot water was controlled by boiler water temp.
Whilst waiting for electrician to change wiring I had 2 port valve set to manual and all was ok, since getting wiring changed to s plan and swtching the 2 port valve to auto I have noticed a bubbling type of noise when I have the dhw switched on, if I turn on the central heating the other 2 port valve opens and noise fades away,does anyone have any suggestions ?
Thanks in advance

 

[mysteryman]

Have you vented the new fully pumped circulation at the cylinder?

You should have a radiator or heated towel rail branched off before the 2 port valves as a bypass.

 

[jackpike]

could be a wiring issue, in a s plan, there is a live wire to the valve, when heat is called for the live wire distributes live to the pump and boiler when the valve opens and hits the micro switch in the valve, could be that the pump and boiler are getting live before the valve fully open,
to check if this is the case, turn your hot water on at the programmer, there should be a delay while the valve opens, if there is no delay, then the wirings wrong,

 

[snb]

You should have a radiator or heated towel rail branched off before the 2 port valves as a bypass.

afraid this is not true or adhering to building regs.

Has the circuit for the hot water got a gate valve to reduce the flow (balance for when both rads and hot water)?

If it has just open it up 1/2 turn futher. The noise you are getting is most likely to be high veocity water passing through the bypass valve.

 

[ChrisR]

You should have a radiator or heated towel rail branched off before the 2 port valves as a bypass.

Not necessarily - it depends on the boiler.

Notfocused - what IS the boiler?

could be that the pump and boiler are getting live before the valve fully open

No way. He'd hear the noise change as the valve opens.
And he wouldn't have separate CH and HW.

 

[notfocused]

Thanks for the replies, ok to answer some of the question there is a bottle air vent on the flow in at the cylinder, It's not a wiring issue as there is a delay before the boiler fires up after being switched on at the programmer.
I don't have a gate valve on the hot water circuit, do I need to add one ?.

Thanks again for the quick replys

 

[notfocused]

Hi Chris R

the boiler is a ferolli optimax he 31 s system boiler

 

[mysteryman]

You need a bypass with a boiler with pump over-run and an S Plan. The purpose of the pump over-run is to dissipate residual heat. Just bypassing it back to the boiler does not achieve this. Therefore you should have a small radiator or heated towel rail in the bypass circuit.