New two-port valve - water hammer on opening

[dilalio]

there is nothing I can think of that can create a system pressure imbalance that can create a 2 port valve, that doesn't have any issues, to clunk

Me too, unless there's a serious feck up in the piping!

 

[Johntheo5]

Perhaps it is?
Can only assume that's where it's been teed in... As it should be.

Probably allready suggested but maybe run with the 2 port actuator removed and the valve left manually opened for a few days.

Also, the Spirovent is installed between the pump discharge and the MPV, maybe better to have it installed before the pump inlet.

 

[dilalio]

Probably allready suggested but maybe run with the 2 port actuator removed and the valve left manually opened for a few days.

Good shout to avoid drain down.
Am Sure OP can try that one

 

[DylanT42]

Is the above EV in addition to the Megaflo air bubble?? so has nothing to do with a (red) EV installed if a heat only boiler.

Yes, that’s the cream one to assist the Megaflo. The original on the heating side was red (which makes sense) got replaced with the gray one (less so).

Looks like it, so should have been installed downstream of the expansion valve on the cold feed to the Megaflo.

It is, as per IMG_1488, there’s big 22mm t-off from the cold feed to the Megaflo after the pressure control unit. Glad that aligns with expectations.

Probably allready suggested but maybe run with the 2 port actuator removed and the valve left manually opened for a few days.

I don’t think that has been, but makes sense & we’ll test for a while. My expectation is that with the NC valve held open we won’t have the issue.

Also, the Spirovent is installed between the pump discharge and the MPV, maybe better to have it installed before the pump inlet.

I don’t think there’s enough space above the flow pipe from the boiler to do that. It’s too close to the ceiling.

 

[DylanT42]

Couple/three other things which we’ve considered:

* Is there an Integrated Flow Check valve in the Wilo Pico pump that might allow a pressure difference
- No evidence the PICO pump has such a device; plus hard to see how it would have this effect

* Might the pump benefit from a run of the de-aerator function?
- Pressed the button & waited 10 mins while it ran, will advise IDC

* Could the old Califei(?) air-vent at the top right of IMG_1490 be holding some air?
- We were told to keep the black plastic bleed screw locked down to avoid air being sucked into the system

PS: And thanks for the continued input. Very much appreciated by both of of us.

 

[Johntheo5]

Couple/three other things which we’ve considered:

* Is there an Integrated Flow Check valve in the Wilo Pico pump that might allow a pressure difference
- No evidence the PICO pump has such a device; plus hard to see how it would have this effect

* Might the pump benefit from a run of the de-aerator function?
- Pressed the button & waited 10 mins while it ran, will advise IDC

* Could the old Califei(?) air-vent at the top right of IMG_1490 be holding some air?
- We were told to keep the black plastic bleed screw locked down to avoid air being sucked into the system

PS: And thanks for the continued input. Very much appreciated by both of of us.

No, no check valve, I have one of those pumps myself.

I've also installed a few of these pumps in relation's and I didn't use this air venting function in any of them, no harm in using it, it just varies the pump speed up and down for this 10 minute period.

What you might try, even though not the recommended mode, is PP (proportional pressure), note the pump power in watts, W, in whatever CC mode you are now running on, CC2?, then turn the setting knob anticlockwise into the houses, stop turning it occasionally, it will then flash the selected PP head and then display the power in watts, keep adjusting it until the power is exactly the same as it was in CC mode, see does it make any difference.

Just open the Caleffi AAV blanking cap now and then to check for any air.