Want to install secondary hot return - need advice please

[minmax89]

Hello everyone!
I'm finally getting to do my own bathroom renovation (spend most of my time doing everyone else's). The bathroom is on the ground floor and the hot water cylinder is at the other side of the house on the first floor. The house isn't huge but I'm sick of running the hot tap and wasting considerable amounts of water to get hot coming out of the tap so I'd like to install a secondary hot return.
Access is limited. but I think I have a good run through the pitched roof rafters (above bathroom and kitchen) to get most of the run that way. I had initially planned to use 'Qualpex easy lay' pipe as I need the flexibility. But then after researching found out it must be done in copper or appropriate multi layer pipe. Copper would be near impossible to do I think or be a right PITA. It seems my only other viable option is to use 16mm multi layer pipe. This would then be meticulously lagged in Armaflex pipe insulation. I plan to fit an appropriate brass pump.
I will certainly not want the pump running constantly. The timer option doesn't really suit either so I was thinking of (tip from another plumber) connecting the power for the pump to a motion sensor in the bathroom, via a pipe stat on the return pipework.

If all that sounds okay (please tell me if I've missed anything fundamental) I'm then thinking of a few different set ups. I've attached a pic with options:

Option 1 (preferred): to install the pump and pipe stat under the bath (I can route the pipework to pass this way)
Option 2: install pump in cupboard with cylinder upstairs (although this is in my daughters room and pump noise may be undesirable!).

Questions:
I thought the pipe stat might be best positioned at the START of the return pipework (see pic) so it switches off sooner without filling the return pipe with hot water unnecessary?
My cylinder is 48" copper insulated vented and has no inlet for the return pipe so I plan to retro fit one. How easy is this to do? It there a special fitting for this (I can come in with 1/2" copper)? The cylinder has two side immersions.
Or is it an option for the return pipe to continue up into the attic and dump into the CW storage tank? or dump into the feed from CW tank to HW cylinder?
Do I need check valves or none return valves anywhere in the above set up?


Many many thanks for any sound advice.
Adam

 

[Peterdevon]

You need a single check valve, the PIR idea works well I have done it several times. Don't use a timer as it can waste a lot of heat and you won't need a stat.

 

[minmax89]

You need a single check valve, the PIR idea works well I have done it several times. Don't use a timer as it can waste a lot of heat and you won't need a stat.

Thank you!
Why dont I need the stat? And where exactly does the check valve go in the diagram? Is it a flap type valve?

 

[exedon2]

First you need to check with pipe manufacturer is it can be used on secondary returns , all the manufacturers i no off stopped use of it stopped use on secondary returns some years ago.
You can use one of the plastic/aluminium types textile metal is one used with correct fittings and inserts works very well and comes in 25m and 50m coils.
Pump must be a bronze one we always install next to cylinder you could install Essex flange in cylinder that would be my option or tee it into cylinder cold feed.
Have tried various control options the only way we have found to guarantee hot water out of every tap every time is to have pump running! Time it off at night and when property unoccupied.

 

[ShaunCorbs]

Option two for install

copper or mlcp pipe only and has to be insulated 15mm / 16mm max dia

 

[king of pipes]

Could you use trace heating if the hotwater supply is copper a self regulating heating tape strapped to the pipe with glass tape and then insulated works well and can be timed if necessary. Kop

 

[EvilDrPorkChop]

Or change it to an Unvented system and your water will come through x2/3 as fast without the need of a return

 

[minmax89]

Or change it to an Unvented system and your water will come through x2/3 as fast without the need of a return

The want of a secondary return is primarily to stop the waste of water, secondary is the speed. I measured it yesterday when I got up (so not been used all night) . It takes 30 seconds to get hot water out of the hot tap from cold but I have to run off nearly 3.5 litres of cold.
Also, our mains pressure is quite poor most of the time. Its around 1 bar of pressure.
[automerge]1603611907[/automerge]

Could you use trace heating if the hotwater supply is copper a self regulating heating tape strapped to the pipe with glass tape and then insulated works well and can be timed if necessary. Kop

Sorry @king of pipes what does trace heating mean? And what is self regulating heating tape?