Does anyone have any experience with using PIR to control hot water flow and return ?

 

Our nearly completed conversion is very long and thin and we have a hot water flow and return setup to reduce delays in getting hot water to the furthest taps.

 

My builder has suggested the possibility of using PIR sensors located near certain HW taps to avoid having the pump on all the time.

 

Any advice or thoughts ?

Some of these strapped to the pipes might work better. You will need to get the correct temp and hysteresis for your application though. 

 

https://uk.rs-online.com/web/p/thermostatic-switches/2282557?cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Switches_MOB_Whoop-_-Thermostatic+Switches_Whoop+(2)-_-2282557&matchtype=&pla-330742918010&cq_src=google_ads&cq_cmp=9765532031&cq_term=&cq_plac=&cq_net=g&cq_plt=gp&gclid=Cj0KCQjwpPKiBhDvARIsACn-gzCal-PfS3eUj6c7kHhc9NGEGX2IGLGBP_By_yl0lyh7sgzJ7hzJNS4aAlklEALw_wcB&gclsrc=aw.ds

Or a pump like this, it has an built-in timer and thermostat. You set the times you want it on and the thermostat lets you adjust the temp, it then only pumps until it sees the temp required etc...

 

https://www.anchorpumps.com/lowara-ecocirc-pro-15-1-110-u-1-2-bronze-circulator-with-timer-240v?gclid=CjwKCAjwx_eiBhBGEiwA15gLNzmQxn4_qdy-fiCkBdn3Tc0KHsKkZP2lE_2PoClhsJwYmVXOy7r5QBoC9dQQAvD_BwE

Thanks for these suggestions.

 

If I understand them correctly they are similar in that they both are about temperature control but John's one also gives you the option of timing as to when the pump runs.

I am also taking from this that the PIR concept is not a main stream accepted solution. I guess also the question is how big of a problem is the pump running most of the time going to be ?

 

Looking at the pump John suggested, the biggest version is 27w, which would be about £80ish pounds a year if you ran it 24/7.

I use mine a couple of hours in the morning and the same in the evening, I have have it set at a low temp, so it not a cold hand wash in morning, more a warm one.  In the evening when showers are more likely in our house, its just keeping the pipes warm, so hot water doesn't take that long to arrive.

 

So costs are more like 4 x 0.027 x 0.34 x 365 = £13.40, possibly lower