Remote Control Switch - RF doesn't work

[kristen]

I want to have push-switches in the bathrooms (well, just outside will do) to trigger the DHW circulation pump.

I tried an RF Doorbell but it doesn't get through our walls.

So I reckon the next-best would be something that sends a signal over the mains?

I'd appreciate your advice, thanks.

Background:

Currently the DHW circulation pump is triggered by a pressure sensor, which detects the drop in pressure when a hot tap is turned on. That triggers a 5 minute timer, and there is a pipe-stat on the return in case the DHW loop gets up to temperature before the timer finishes.

So in the morning you flick the hot tap on for a few seconds, turn it off, wait 4 minutes or so, and then there is hot water at the tap.

However, the pressure switch triggers for no reason at times (middle of the night), possibly because of pressure drop on the cold side.

Also, the pipe run to the kitchen is short, it represents the majority of day-time hot water use, but it still activates the pressure-drop switch and the pump warming the whole circuit , thus I want to change to a "personal demand" system.

[guydewdney]

two one way valves, from the pump, one 'isolating' the kitchen, the other the bathroom. Reduce pump time to min required for kitchen. have two switches, one in the bathroom leg, the other in the kitchen leg, with the bathroom leg acrtivating a longer timer?

[profp]

I want to have push-switches in the bathrooms (well, just outside will do) to trigger the DHW circulation pump.

I tried an RF Doorbell but it doesn't get through our walls.

Ceiling mounted passive IR sensor (burglar alarm movement sensor)?

Not sure if you are worried about inadvertent triggers due to other carrying on in the bathroom...

[wyleu]

X-10?

[profp]

X-10?

Bit of a power hog though IME -- 5W+ in the idle state for a lot of the modules. Obv not such a concern if you're on grid.

[kristen]

Separate legs for the Kitchen is an option. However, for now I just want to only have the pump come on when there is a "demand request" from the bathrooms (which are on the longest-leg).

Don't really want PIR as I want to reduce the number of false-trigger events.  However, it would be easiest to cable as I could take a cable through ceiling into the loft, whereas anything else would have switches at chest-height with the problems/mess of routing cables up to the loft.

So X-10 looks like a runner.

I couldn't find a push-switch (like a door bell) though, only on/off switches.

By understanding is: I would have a switch outside each bathroom, each consuming no power unless pressed? (assuming wired into the mains, rather than battery operated), and a sensor by the pump that would be using power in order to detect an "On" signal?

Or, perhaps, I could have a control box and that (amongst other things) would have a wire to the pump timer. The control box is then using power, but it could be configured to do additional Home Automation tasks. Maybe the existing timers would be replaced by some programming logic in the control box.

Am I on the right track?

"5W+ in the idle state for a lot of the module"

I reckon that 1W used 24/7 is about £1.50 a year ... so 10 of them would be 10 * 5W * £1.50 = £75 just to run some switches.  We've worked hard to cut out power usage, so I'm not keen on things that are on "standby"

[Baz]

The switches you mentioned above if connected to the mains & X10 would be consuming power. However if you are prepared to run mains to the location ie do some wiring why not run a low voltage wire from the switch point to the control box which can be much simpler and use unobtrusive bell wire.  You might be able to pinch some power for the timer from something that is already on, like your alarm system or modem if it has a USB port. However in low power mode I would suggest an electromechanical timer like a small 3v battery motor, gears, cam and microswitch.

[wyleu]

Think isolation. if it's anywhere near a bathroom.

[dhaslam]

Does the RF switch have to  work through walls or ceiling or both?    Foil back plasterboard is able to stop signals but you just need to  scrape the foil off if it is accessible.   The  RF  device shouldn't be deterred by normal walls or ceilings.   

[kristen]

Long runs for bell wire I'm afraid. Lots of potential for mess and demands for redecorating. Hence sending a signal over the mains would be nice. 

"if you are prepared to run mains to the location ie do some wiring ..."

Sorry, wasn't clear about that. I was thinking that if the light switch for the bathroom has Live and Neutral (probably not) then I can add a box alongside with a push-button X-10 switch wired in; if no Neutral I can run a wire from the nearest ring-main point.  Its fairly non-intrusive compared to running wires all the way from bathroom to the hot water pump. With hindsight I should have put the hot water pump close to the bathrooms, rather than next to the hot water tank!

The cable run-length from bathrooms to boiler room is about 50M (paced-out thus not including going around door frames etc, and assuming that I can T the switches from the 3 bathooms into a single cable run). That's quite a lot to "make tidy" (and to pay the sparky to do 'coz I ain't got time)

Up to the "loft" may be somewhat easier than around the skirting board.  But the house had a block-and-beam flat room on which has been added a pitched slate roof.  There is no access to the "loft" from within the house, only from a narrow hatch on the roof itself. So not as simple as a normal house I reckon

Walls are very solid. WiFi signal, and wireless RF doorbell, don't propagate to more than the room next door. Dunno what the walls are made of - probably just blocks (built in the early '60s). It is very solid though. There is no sound transmission around the house, no floor boards, lots of poured-concrete I expect ...

"Think isolation. if it's anywhere near a bathroom."

Thanks, light switches are on the wall outside the bathrooms, and I was thinking of adding a switch next to that.

[Solal]

A bit late  maybe  but a DMB51 multi function  timer/relay (or similar from other manufacturers))  will do what you want  with  the function set to In (interval)...
http://elcodis.com/datasheet.php?c=2234738&c_name=DMB51CM24&doc=256662

 A push button switch (available from rs components  or any electrical  controls suppliers, cef etc) energises Y1 which will latch and 18 will energise  for  the desired time set by  the  micro switches.
You can set it for  45 seconds  which is  sufficient  for most domestic  secondary  circulation loops.

Or alternatively use something like this.....
http://www.farnell.com/datasheets/51994.pdf