Baxi solo 2pf noise when HW switched on & top of rads wa

[Sunnydiy]

Just wanted some info on the problem as the HW is switched on the boiler or pipes decide to make a noise about 1 min after coming on. I read in the D.I.Y manual that the mid position valve can be at fault but how do I check this?

ps. I switched the heating on and it works ok.

Cheers Sunny.

 

[meldrew's_mate]

Turn all your rads OFF except 2 small ones. Does the symptom repeat on heating now?
The reason for this could be that the flow rate through the cylinder is restricted compared to that through the CH circuit, and this could be due to the restricting (flow control) valve on the cylinder primaries being almost closed, if one is fitted (?). This valve, usually a 22mm gate valve, should be approximately 1.5 turns from CLOSED as a guide only.
Is the pump speed appropriate? Turn it up a notch and retest.