Secondary return necessary?

[Nick Pain]

Hi all
Re-plumbing a 4 bed, 3 bath house as part of a renovation and I am trying to figure out of a Secondary Return loop is worth the extra work?

The longest pipe run from the tank to outlet would be about 18m. If we made up a secondary return loop the total pipe length would be approximately 75m.

What is the maximum recommended pipe length from the loop to the outlet?

Thanks for any help in advance.

 

[Roger928]

At 18m you should fit the return pipe. And insulate it well. Only needs to be 15mm.
And insulate the distribution section to the same standard.

 

[Steelmasons]

At 18m you should fit the return pipe. And insulate it well. Only needs to be 15mm.
.

Providing the circulator can provide enough head....22mm would be the norm.

 

[Doggit]

As Roger says, do the maximum insulation that you can (take into account where it goes through walls etc) as you've effectively got a giant radiator heating the underfloor spaces. You'll still lose a lot of heat and gas to run it, but you'll save on wasted water and gas waiting for cold water to travel 18M. Your other option would to fit a combisave on the boiler, but you'd still wasting water and time waiting for the hot water to arrive.