small heatrae megaflow pipework query

[howy1]

Hi all , i came across a heatre mega flow today and couldn't get my head round something , it was heated via a boiler through the coil but the puzzle is that there was a secondery return from the hot water circut that also acted as the cold feed in seprated by a NRV to stop the hot going back up the cold
Has anyone come across this before .
Cheers
Howy

 

[ShaunCorbs]

Yes de stratification pump

 

[howy1]

Yes de stratification pump

Hi Shaun , would you mind elaborating , i am assuming the systems all one pressure and when hot water is drawn off its just replaced .
Howy

 

[ShaunCorbs]

Hi Shaun , would you mind elaborating , i am assuming the systems all one pressure and when hot water is drawn off its just replaced .
Howy

I read it as hot water secondary is connected to the cold feed to the cylinder correct ?

 

[howy1]

I read it as hot water secondary is connected to the cold feed to the cylinder correct ?

That's right , the only thing I couldn't get my head round was the fact that the secondary has a pump for obvious reasons
and I thought the in coming pressure and the pump would be out of kilter but I guess it all runs at the same pressure as set by the
incoming cold through the reducer ?

 

[ShaunCorbs]

That's right , the only thing I couldn't get my head round was the fact that the secondary has a pump for obvious reasons
and I thought the in coming pressure and the pump would be out of kilter but I guess it all runs at the same pressure as set by the
incoming cold through the reducer ?

It’s to maximise the capacity of hot water instead of having thermocline layers eg say 30% of hot hot water etc with a destrat pump you would get 75-80% of hot hot water

 

[Ricky]

if the non return valve is on the secondary return before it enters cylinder or cold feed in, it is there to stop colder water being drawn off when a hot tap is opened