Adding a secondary return to a system

[mutley racers]

Hi, what do people a think is the best way to add a secondary return to an unvented cylinder install.

The scenario is I am quoting to replace a gravity system with an unvented. The bathroom furthest away takes around 2 minutes to get hot water. The problem is all the floors are glued and screwed tongue and groove chipboard so not easy to take up and run the return.

Cheers

 

[Scott_D]

Up into the loft and back?

 

[mutley racers]

Up into the loft and back?

Do you mean run new supplies into the bathroom from the loft?

 

[Scott_D]

Do you mean run new supplies into the bathroom from the loft?

Just tee into the hot and run a return back to the cylinder

 

[mutley racers]

Just tee into the hot and run a return back to the cylinder

Tough unless I start removing tiles. Guess that will be easier than the floor though. Thanks Scott

 

[Scott_D]

10mm copper is big enough

 

[EvilDrPorkChop]

Is there any plastic on the system? If there is it's a big no no.

Also you'll probably find that under pressure the hot water will come a lot quicker anyway.

 

[Aire]

Is there any plastic on the system? If there is it's a big no no.

Also you'll probably find that under pressure the hot water will come a lot quicker anyway.

Is there an issue with secondary returns and plastic?

 

[Scott_D]

Is there an issue with secondary returns and plastic?

Manufacturers say it can’t be used

 

[Aire]

Manufacturers say it can’t be used

Really? We've just done a new build with about 90% plastic. It was installed with a secondary return. Which manufacturer, the pump or cylinder manufacturer?

 

[EvilDrPorkChop]

Really? We've just done a new build with about 90% plastic. It was installed with a secondary return. Which manufacturer, the pump or cylinder manufacturer?

Owch, the get the towels ready.

All the plastic manufactures. Circulating return has to be copper then the branches have to be 1 metre in copper then can go to plastic.

 

[Scott_D]

Really? We've just done a new build with about 90% plastic. It was installed with a secondary return. Which manufacturer, the pump or cylinder manufacturer?

The pipe manufacturer.
I worked for a company that did the hot water in plastic and the return in copper. They seemed to think that was ok.

 

[Aire]

Oh dear . Well you learn something new. Do we know the reason behind this? Surely it can't be because of heat.

 

[Scott_D]

Oh dear . Well you learn something new. Do we know the reason behind this? Surely it can't be because of heat.

It’s not suitable for constant high temperatures

 

[Aire]

It’s not suitable for constant high temperatures

But central heating runs hotter than a hot water return and there's no issues with that.