Vaillant System Boiler Q’s ...

[Old Account]

hello guys,

I am wondering if anyone of you could tell if that makes any difference if you connect the flow and the return of the boiler the other way around on a uniSTORE unvented indirect cylinder?

Just came across an installation which some builders have done. Customer is complaining that the recharge is well over 1,5h for the hot water cylinder and therefore the boiler runs well too long - gas bill well too high.

Weirdly the builder has installed the flow with the zone valve for hot water at the bottom rather than at the top. Also the mains cold water pipe is very hot due to the fact that the pipe is right next to the flow.

I also noticed they did not install the vr10 sensor from the cylinder to the boiler which means the boiler will run almost continuously due to the controller setting on hot water constant.

Will that be one of the issues too?

The ufh is a joke too but see for yourself.
Any advise and tips are greatly appreciated.

Kind regards

Ron

 

[Old Account]

Also too he is saying sometimes when heating is off and hot water is on constant he gets warm radiators. I have been there and checked if the zone valves working properly. They seem to open and close without problems but could that be that it’s letting by?

 

[Riley]

If the hw isn’t the last tee back into the return then it could be back feeding some rads

 

[Riley]

Also f &r should be the right way round. I’d doubt that it would make 1.5 hours difference but if the flow goes in the return the water will cool as it works up the coil

 

[Aire]

Where's the boiler in relation to the cylinder? The return does appear to be piped wrong allowing for backfeeding into the radiators as Riley has said. Also I can't see the wrong piping of flow and return into the cylinder making that much differnece, but I haven't came accross it before. Simple enough to repipe though and see if it makes a difference.

Fix the prv while your at it too

 

[Old Account]

Where's the boiler in relation to the cylinder? The return does appear to be piped wrong allowing for backfeeding into the radiators as Riley has said. Also I can't see the wrong piping of flow and return into the cylinder making that much differnece, but I haven't came accross it before. Simple enough to repipe though and see if it makes a difference.

Fix the prv while your at it too

The boiler is in the kitchen which is about 5m away from the hallway where the cylinder is ( under the stairs.)!

 

[Old Account]

If the hw isn’t the last tee back into the return then it could be back feeding some rads

I’m sorry Riley, any chance of simplifying this for me? As the flow is coming from the bottom the first T is the HW then CH. Are you saying it should be the other way around?

 

[Riley]

HW should be the final tee into the return before it goes back to the boiler

 

[Scott_D]

I wouldn’t think the F&R round the wrong way would mean it takes hours to heat up.
Is the flow temp set low?

Any auto bypass?
D2 not 300 before the bend
Does it goes into a washing machine upstand?

 

[Old Account]

I wouldn’t think the F&R round the wrong way would mean it takes hours to heat up.
Is the flow temp set low?

Any auto bypass?
D2 not 300 before the bend
Does it goes into a washing machine upstand?

Flow temperature is set to 65c
Yes it goes into wm stand / wrong I know as well as the D2.