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

[Gray0689]

Guys, look at the picture, this isn't undersized, its 35mm and 28mm. The picture is deceiving but it is larger Pipework than you think.

It's undersized it needs a low loss header and re piped properly
As already said big drop at flow meters is a big giveaway

 

[Carrera]

Carrera, the flow to hot water cylinder valve tees off the main run as it were, then before it gets to the hot water zone valve it tees off again, what's that for?

this is a Pipework issue, I'm sure of it, somewhere in that plant room, maybe with a combination of balancing chucked in as well.

That next T leads to the small basement manifold which is also located in the plant room

 

[Gray0689]

And putting the smaller pump back in and it still working the same as it was is proof of that.

The manifolds are pumped the magna is acting as a shunt pump
It can't get enough flow through that 28mm IMO

 

[Nostrum]

Yes I agree I wouldn't have installed it anything like that and agree with you, always fit it right the first time dare than go back replacing the corners you have cut.

but just saying rip it out and start again is not a great help, and this fault is due to a different fault IMO.

He reality is no one really knows how well it's going to work once sorted, but when you are as balls deep as this now, it's worth trying to rectify before chucking the towel in completely. It's not the O.P's fault, whatever the price someone has been contracted to carry out this work. If they are confident they can get it running with this design then give them the benefit of the doubt.

if the O.P decides once/if it is running that it's not good enough, that is the time to question the design.

Whilst it's not our job to rectify, the post is asking for advice.

Its one of the more interesting posts anyway!

 

[Gray0689]

That next T leads to the small basement manifold which is also located in the plant room

I know it's not what you want to hear mate but we are just trying to help where not just slating your plumbers work you have a problem I'm sure you paid big money for this job

Plumbing is a funny thing it could be plumbed crap but it can work as far as the customer is concerned as long as he turns the heAt on he gets heat it's grand but unfortunately that's not the case
For a smaller house your set up probably be grand but not a house that size
It really should of been designed by a M&E consultant with spec they would not do it that way I can guarantee that

 

[Nostrum]

The manifolds are pumped the magna is acting as a shunt pump
It can't get enough flow through that 28mm IMO

are you sure, where's the pump for the cylinder , the bypass circuit and why is the pump wired directly to the boiler?

 

[Gray0689]

Yes I agree I wouldn't have installed it anything like that and agree with you, always fit it right the first time dare than go back replacing the corners you have cut.

but just saying rip it out and start again is not a great help, and this fault is due to a different fault IMO.

He reality is no one really knows how well it's going to work once sorted, but when you are as balls deep as this now, it's worth trying to rectify before chucking the towel in completely. It's not the O.P's fault, whatever the price someone has been contracted to carry out this work. If they are confident they can get it running with this design then give them the benefit of the doubt.

if the O.P decides once/if it is running that it's not good enough, that is the time to question the design.

Whilst it's not our job to rectify, the post is asking for advice.

Its one of the more interesting posts anyway!

Looking at a bad picture of half an installation don't think where going to see the full picture
Yes he ha asked for advice and I do believe he has had good advice
The bet seems to have checked all the normal causes that it could be so now need to look at it deeper
As all were doing is just guessing now but as almost everyone has stated already it looks undersized

 

[Gray0689]

are you sure, where's the pump for the cylinder , the bypass circuit and why is the pump wired directly to the boiler?

The magna is the pump for cylinder
Ps I'm not an electricians ask me one I know lol

 

[Nostrum]

Well, maybe that's where we disagree, looks like 35mm and 28mm UFH circuits with 22mm towel rail circuit to me. Can't be sure but the hw circuit looks like it could be 28mm as well.

 

[Gray0689]

Well, maybe that's where we disagree, looks like 35mm and 28mm UFH circuits with 22mm towel rail circuit to me. Can't be sure but the hw circuit looks like it could be 28mm as well.

Yes there is some 35mm but coming off 28mm from boiler the 35mm is useless