What is a secondary return?

[jacko]

I've just had an unvented hot water system fitted. The plumber said that the secondary return inlet is not required and has been capped off.

Can anyone tell me what this is for, is it correct that I don't need it?

Cheers,

Jack

 

[COG]

generally not used unless you have a large house or small hotel say.its a return leg from the furthest tap back to the cylinder ,that way the pipe work wont end up full of cold water and the guest wont have to waite 1/2 hour to get hot water out the tap.

 

[jacko]

Thanks for the information.

Does that mean that the pipework loops from the top of the cylinder, feeds all the relevant appliances and then returns to the cylinder? By my reckoning this would ensure constant hot water rather then a leg of cold water (that was once hot!), or am I jumping ahead of myself?

Jack

 

[ChrisR]

Yes you got it right. Often it needs a brass pump - you do calculations based on the relative densities of hot vs cold water, the heat lost in the loop etc to work that out. Then you need to time the pumping so it aint going all night, then you have to spend a small fortune on the correct grade of insulation, or put electric trace heating on the pipe.

Or you decide its a hell of a lot easier to just wait for a few seconds, and cap off the secondary return...