Can the Motion Sensor be used to trigger on demand water pump?

In a residential application, I plan on installing a motion sensor to assist in turning lights off (and possibly on if it doesn't get annoying). I'm now looking into various plumbing solutions for the home, one of which is an on demand loop system which uses a motion sensor to trigger a high-velocity pump that automatically moves hot water to the faucet, and after a set time the pump shuts off.

So here's my question:
Assuming all of the motion sensors need to control their regular day jobs of controlling the lights, can they also be setup to control another group, "water heater pump" that would trigger a relay contact which would ultimately be turned off after XX seconds?

 

Great concept... is this a fulltime function?? or lights @ night Water @ day??

Id keep it simple and use a single key input in each required location as a retrigger timer, no need to reinvent the wheel...

 

Circulation Pump Control

I have a circulation pump at home and find timed (schedule) control works fine. odd shower times just mean running water longer. You need to match the pump flow rate to the pipe size to minise noise and cavitation of the pump plus the pump if normally on the return side and not the flow side so that flow is not impeded when the pump is not running.

 

Hi Poldim,

Just adding a little info here but I'm no plumber.

I have seen several recirculating hot water systems over here in Australia using Grundfos recirculation pumps and I know they are also used quite extensively in Hydronic underfloor heating systems etc in UK and Europe. These pumps seem to be very 'low impact' looking at the impellers, and low flow rates so hardly 'High Velocity'.

I think Fredinver's warning of cavitation is probably going to haunt you here more than the C-Bus side, but I see why you want high-velocity because the area movement in a bathroom suggests a need for hot water almost immediately.

As for the C-Bus side of the question, no real problem. Just use some logic watching the PIRs assigned day, night or all movement group address and do a logic operation something like:

Once GetCBusLevel("Local Network", "Lighting", "PIR_All_Times_Movement") = 100%

if (time >= "6:30AM") and (time <= "5:00PM") then //(* or whatever times you want the pump to do its recirc duties)

SetCBusLevel("Local Network", "Lighting", "RecircPump", 100%, 0);

Delay("0:0:45"); // (* or whatever time the pump should run - 45 secs?)

SetCBusLevel("Local Network", "Lighting", "RecircPump", 0%, 0);

end;


or instead of an on/off sequence with delay you can just pulse the pump group address using:

PulseCBusLevel("Local Network", "Lighting", "RecircPump", 255, 0, "0:00:45", 0);

I prefer the on/off method myself but both should work.

I think that should do it (or might need some tweaking!!).

On a plumbing note again, There was a system that you could fit to a sink etc that reacted when you turned it on and didn't let water out until it was hot using a pressure bladder in a canister to take the cold water before the hot came through. Not sure who makes it but a possible non-electrical solution.

Kind Regards,

Brad

 

Hi Poldim,

In my brochure files I found a system similar to the one I was talking about in my earlier mail. It is the Chilli-Pepper and it uses a small pump to redirect cooled hot water ie cold water back into the cold circuit line without a need for a separate ring main back to the water heater.

see http://www.chilipepperapp.com/Motion-activated.asp for details on how they suggest setting it up when motion activated.

Just run the 'switch' circuit to a C-Bus relay and you have a working system

All the best,

Brad