What type of pipe stat do I need to control secondary circulation pump

[dilalio]

Great ( inventive ) minds think alike.

That said I would not consider the idea for use with a combi hot water supply, firing up the combi every time the loo was flushed would be a waste of gas.

But so would a guest running the hot tap in the bathroom in order to wash their hands after using said loo! And giving up after a minute with no hot water... Would waste water too

 

[Harry Bloomfield]

Supply the toilet cistern from the hot supply. Then after the toilet is flushed the cold water in the pipe fills the cistern allowing hot water to come along the pipe ready for when the tap is turned on.

The problem with that, is that you use the toilet, flush and whilst its still flushing, you go to wash your hands. There just wouldn't be enough time for the hot water to get to the washbasin.

It would still suffer exactly the same timing issue, but you could sense the cold water flow, at the main stop tap and use that flow to trigger the circulation pump for a few minutes. I suppose you could (if you intend to need the hot water), deliberately turn the cold tap on for a second, as you walk in the bathroom.

I'm convinced the PIR sensing someone walking into a bathroom and triggering the pump for a few minutes, is the best compromise and not that involved to install.

 

[bernardgreen]

Is this the solution ?.... The cistern stays empty until the toilet lid is raised at which time the cistern starts to fill.

 

[dilalio]

I'm convinced the PIR sensing someone walking into a bathroom and triggering the pump for a few minutes, is the best compromise and not that involved to install.

Agreed. Have done it on a few jobs and used same ceiling mounted PIRs to also trigger low level task lighting in the same room.

 

[dilalio]

Is this the solution ?.... The cistern stays empty until the toilet lid is raised at which time the cistern starts to fill.

Which will exacerbate the "seat up vs seat down" discussion between the sexes
Self-closing seats perhaps... Starts getting expensive no

 

[dilalio]

The ideal solution is to have a centrally located hot water store and a manifold to direct hot supplies to each outlet over shortest distance possible with heavily insulated pipes. No recirc required.

 

[bernardgreen]

The ideal solution is to have a centrally located hot water store

With that I totally agree

Self-closing seats perhaps... Starts getting expensive no

True, maybe a contact on the door that fills the cistern when the door is opened.

 

[sirocosm]

Another possibility if you had a thermal store, might be to locate plate exchangers close to the points of use, and keep them "warm" by using a pressure modulating smartpump and thermal balancing valves on the returns of the primaries close to the exchangers.

Disclaimer: I said might. I am not a plumber nor a heating engineer.

 

[competant guy]

Resurrecting this thread - anyone got a link for a suitable PIR pls?
Want to have dual switching. - both timer and PIR independently being able to switch the pump. Thanks in advance.

 

[martygturner]

https://www.screwfix.com/p/zinc-thea-indoor-white-microwave-recessed-sensor-360/4277r is failry good...it does not need a swtich to set the duration all done on the unit.

If you want to control the pump remotely consider using a https://www.rfsolutions.co.uk/blog/...mp+Overrun+Solution&utm_content=MAINSLINK-PRO

Saves any wiring from the pir to the pump, just make up your own wiring box.

Power to timer out to pump
Power to pump from remote switch