Hot water return circulation

[Alex-b-93]

Hi,
was wondering if anyone could help, I am currently working on a big new build retirement home, at the moment I am piping the new build up, with my hot and cold going into each plot from the corridor. I have also got a hot water return, the bit im not sure about is that does the hot water return just circulate in the corridor or do I need the hot water return to link into the hot water at a certain distance away from each outlet as the run offs to each outlet from the corridor are over 10 meters. Also the runs from the cylinders to the corridors are over 30 meters.
If any one could give me some advice on this would be much appreciated. Thanks

 

[Jay The Plumber]

not sure what you mean mate, the return usually just goes back to the tank.

 

[snowhead]

Take the return to 300mm / 600mm from outlets.

Some of the Commercial buildings I work on have DHW pipework (42mm) over 100mtrs from the Calorifier or Hot water boiler with a single return pump.

 

[Knappers]

if your going to have multiple branches you may need to consider balancing valves too

 

[Alex-b-93]

Is there any other reason for this apart from hot water on demand?

 

[Alex-b-93]

And I have also thought about balancing valves, just not sure o the correct positioning of them?

 

[Knappers]

Not aware of any regs regarding distance from outlets?

 

[ShaunCorbs]

There should be m and e drawings/ consultant as if you get this wrong it its big

and sounds like you haven't done anything this big before and commercial

 

[snowhead]

Balancing valves are essential, fit Balancing on return and shut offs on hot and cold, in the corridor ceiling if they'll be accessible when completed or just inside the units.

It's no different to aCentral heating system, flow will favour the path of least resistance.
The remote legs may not circulate.

 

[Knappers]

accessible lockshield on return side of branch?
Easier just to loop round corridor but 10m is a fair stretch if instant hot is expected.

 

[Knappers]

unless you want to run it in 10mm - JOKING

 

[Alex-b-93]

What balancing valves do you recommend?

 

[Knappers]

just lockshields will do - shouldn't be delicate enough to need proper ones.

http://www.leengatevalves.co.uk/images/product_images/big/LV2458.jpg

 

[Worcester]

Is there any other reason for this apart from hot water on demand?

Yes, Legionella, it's a killer in hospital, care homes, etc

It's also covered by regs.

 

[Knappers]

Dont stress about legionella, you couldnt get the return close enough to the outlet to keep a regs man happy.
Mostly dealt with in commissioning flow and return temps risk assesment and flushing routines.
Just lagg pipes to keep return temps up and make damn sure there's no dead legs!!!