Is this motorised valve in the correct position?

[Charlie_Powell]

Hi all,
I have a plumbing system with an unexplained bang that occurs when the heating is switched off. I heard that this can occur if the valve is placed backwards. Can anyone explain to me if the example in the picture is backwards? The arrow on the brass ware appears to point towards the Joule cyclinder when I think it should go the other direction?

 

[cross thread]

Can’t see the photos but it should flow in the direction of the water ,easily checked from cold

 

[Charlie_Powell]

Thanks. Here are the pics. The arrow is visible in the first

 

[Madrab]

Yes .... the 2 port valve is pointing in the correct direction.

 

[CBW]

That’s the hot water valve, you mentioned it happens when heating is turned off - the bottom 2 will tell you.

 

[Charlie_Powell]

Thanks. That is surprising because I thought the water leaves the cylinder from the the part marked 'boiler flow' and returns at the part named 'boiler returns' which is lower down.

The other two valves are for downstairs and upstairs heating. Both of their arrows point downwards. I guess the upstairs heating goes downstairs before returning up again.

 

[Madrab]

Nope other way about, the 'boiler flow' is the flow from the boiler and the 'boiler return' is the return to the boiler.

 

[Harry Bloomfield]

Thanks. That is surprising because I thought the water leaves the cylinder from the the part marked 'boiler flow' and returns at the part named 'boiler returns' which is lower down.

Flow is the hot(ter) output coming out of the boiler, Return is the cooler water going back/ returning to the boiler.

The hotter boiler flow, always goes to the top of a cylinder, because the got water content of a cylinder stratifies - hot will always rise up, cold will drop to the bottom. As more heat is applied to the cylinder, the stratification hot/cold level will progress downwards in the cylinder.

 

[CBW]

The filling loop also appears to be fully open, so could be a prv operating?

 

[Madrab]

so could be a prv operating

Hopefully not @ 0.75 bar

 

[Charlie_Powell]

Cheers! In the first picture, the arrow with letters on the brass tee should be just about visible. The arrow points towards flow. Isnt that backwards? Pardon me for repetition but I hope it is clearer now. The bang that I hear is not extremely loud but it is annoying. I had a plumber out to look at it and he just said it was the actuator and that he would leave it alone.

CBW, should the filling loop be less open?

 

[CBW]

CBW, should the filling loop be less open?

The filling loop shouldn’t be open at all

 

[Harry Bloomfield]

The filling loop shouldn’t be open at all

The fill loop is there just to top up the pressure, should the pressure drop - a drop in pressure will mean you have a leak somewhere, so the ideal is never needing to top it up. In practice some slight loss is to be expected. Needing topping up once per season is not unreasonable, or if air has been bled out of the rads. If the pressure drops too low, the boiler will lock itself out, to prevent damage.

So the normal is to have both top up valves turned to off, some also advise disconnecting the fill loop as well.

 

[Madrab]

see that more and more where the mains pressure is lower (1-1.5bar) or the PRV is set to 1.5bar and it's left turned on, basically it keeps the systems automatically topped up. Bad practice of course as if there was a leak it would just keep going.

That being said if your filling loop is open at both ends, as it seems to be, then either your mains pressure can't be the best (0.75 bar) unless or it's on a PRV set to that pressure. If that is your mains pressure then there shouldn't really be an unvented cylinder installed.