Advice needed. Issues with underfloor heating and hot water system for new build

[diamondgas]

Effectively when the heating is on the flow does not go through the T to the cylinder, but when the heating is off it does and therefore heats up the water.

Just re-read your post and find this strange! It doesn't go through the 'T' to the hot water when the heating is on ... the way it's piped it should pi$$ through the hot water circuit ... I'd concentrate on the hot water circuit, from what you've said! The fact that it "heats up" is incidental as it will if its the only thing on! However if the flow through the circuit is restricted then it'll be bi-passed, virtually, when everything else is calling! IMO

 

[Carrera]

I will try and answer some of the points.
Area is south bucks, I would happily pay someone to look and advise me, as I would like to give the plumber the opportunity to put right, and they are trying!

there is a bronze pump for secondary hot water return, just not in the picture it's above the cylinder.

One of the upstairs manifolds sideways!View attachment 16405

Not signed off by building control as the rest is not finished, however we have been living in the house for just under a year, heating was working fine, just not in tandem with the hot water

For the time being the magna pump has been removed and replaced with the old pump, as it isn't working properly, as they are also trying to overcome a flow issue introduced with the recent messing around

Also the non return valve on the flow out from the cylinder has been removed to reduce resistance, however, what is happening now is if the heating is on and the water is switched on, the flow is being pulled backward through the cylinder and cooling the flow up to the heating

 

[Ermintrude]

They do houses this size all the time, and say they haven't had this issue crop up before. I have had the same guy, their senior guy, from first fix to final and they have a good reputation.

re bringing hot water online with the system hot and one zone at a time, can you confirm whether you mean one zone or complete manifold?

Pull one manifold at a time

 

[Carrera]

Just re-read your post and find this strange! It doesn't go through the 'T' to the hot water when the heating is on ... the way it's piped it should pi$$ through the hot water circuit ... I'd concentrate on the hot water circuit, from what you've said! The fact that it "heats up" is incidental as it will if its the only thing on! However if the flow through the circuit is restricted then it'll be bi-passed, virtually, when everything else is calling! IMO

thats precisely the piece that's baffling the plumber and he has been concentrating on the resistance aspect.

 

[Gray0689]

Just re-read your post and find this strange! It doesn't go through the 'T' to the hot water when the heating is on ... the way it's piped it should pi$$ through the hot water circuit ... I'd concentrate on the hot water circuit, from what you've said! The fact that it "heats up" is incidental as it will if its the only thing on! However if the flow through the circuit is restricted then it'll be bi-passed, virtually, when everything else is calling! IMO

From what I can see of pipework if the umber on site can't see how it not a simple fix the cylinder Is a metre away can't be that many things

 

[Gray0689]

thats precisely the piece that's baffling the plumber and he has been concentrating on the resistance aspect.

What exactly has he tried
Has he checked pump is running when on hot water only
Has he checked pump running on heating and hot water
Has he checked the 2 port is opening when the above Is on
Has the electrical side of things been checked

 

[diamondgas]

thats precisely the piece that's baffling the plumber and he has been concentrating on the resistance aspect.

Temp difference between F&R on hot water only? ... There may be something within the coil of the cylinder itself or , as mentioned, a man made restriction on installation ... PTFE across the pipe opening? A temp check of the flow through the cylinder will quickly tell you whether or not you have a restricted flow. It's then a strip down to find out where it is I'd imagine

 

[Gray0689]

Your always going to have a flow problem imho as the massive load you will be trying to get out of that 28mm pipe to flow to 6manifolds for that size of a house is just silly

 

[Carrera]

What exactly has he tried
Has he checked pump is running when on hot water only
Has he checked pump running on heating and hot water
Has he checked the 2 port is opening when the above Is on
Has the electrical side of things been checked

All of the above have been checked and checked again

 

[Gray0689]

Did he try blowing out the coil with mains