hacked contact sensor to operate hot water recirculator pump
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10 posts in this topic

Just a fun note:

 

My domestic solar hot water system includes a hot water recirculation loop that keeps a long leg of pex tubing hot in the attic with a return line back to the storage tank. All of my household plumbing fixtures are 1/2" drops from this leg. Automating the operation of this pump vastly improves efficiency since there is no reason to keep the loop hot when nobody is home or it isn't in use (energy loss from pipes, and energy loss from the pump).

 

There is a flow switch on the cold inlet to my hot water system, a Johnson Controls paddle switch. It has NO/NC contacts, and the paddle switch has adjustable tension. I opened up the Iris/Alertme contact sensor and carefully removed the magnetic reed switch, and attached wires that run to the NO contacts on the flow switch.

 

Whenever there is hot water demand, the contact sensor detects the switch closing as cold gross-flow enters the system and signals Iris. Magic rule turns on a smartplug for ten minutes to run the hot water recirculator pump and warm up the pipes. If use of the hot water continues, it keeps activating the rule to run the pump for ten minutes.

 

Magic rules also schedule warmups via the smartplug in the mornings, evenings, and whenever the system changes to home mode. Away and Vacation defeat the schedule.

 

I'm trying to get the temperature sensing chip to accurately read water temperature in a pipe or tank... somewhat challenging. But I can trend hot water usage through the care status (see attached).

 

 

post-112-0-10985600-1405053322_thumb.jpg

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That's awesome!  I've hacked 3 of my contact sensors as well, but your implementation into an existing system is more elaborate and definitely more creative.

 

I got tired of the standard IRIS motion sensors very occassionally false alarming, so I've hacked three contact sensors to detect the NC relay operation of a far more advanced wired motion detector (Honeywell DT7435).  For the last year they've been in operation, I've had no false alarms with the 3 motion detectors around my house.

 

A bit excessive, but definitely a fun project!

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I wanted to add a development to this:

 

I filed a quarter inch aluminum bar stock to match the rounded shape of the copper pipe wall, and super glued this "heat sink" to the pipe. Then I super glued the flat end of the bar to the temperature sensing chip on the contact sensor board. Now it can see pipe temperature pretty accurately, so it another magic rule can shut down the pump when the recirculation gets too warm (my thermostatic mixing valve struggles to manage water temperature when recirculating too long).

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Hey guys I was wondering if you could let me in on how you were able to hack the contact. I am thinking I want to be able to connect this to a RIB (relay in box) to do.....well almost what ever I want that involves a contact closure. Thanks for any info.

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I have a post where I did this and used the contact sensors to tie into my existing ADT home system wiring.  Now my old " zones" are on Lowes Iris.  actually pretty easy.

 

But what I need now is a magic rule that tells me when a contact is open for a period of time - any way to do that?  I want to put it on my garage freezer - if the door is open longer than " x" minutes it will send messages.

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I have a post where I did this and used the contact sensors to tie into my existing ADT home system wiring.  Now my old " zones" are on Lowes Iris.  actually pretty easy.

 

But what I need now is a magic rule that tells me when a contact is open for a period of time - any way to do that?  I want to put it on my garage freezer - if the door is open longer than " x" minutes it will send messages.

Apparently if you pay an extra $4.99 /month you get that capability with the care package.

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