Geofence the wife?

dpilati

Member
So I'm back to an old problem of mine, the recirc pump on the hot water.
 
The wife insists that the pump be on all the time but it is pretty wasteful of energy. We have solar hot water but on a cloudy day or in the winter, the backup has to come on.
 
I have the pump as an output on Elk M1 Gold. I need to use a motion detector in the bedroom to activate the pump in the morning. I usually shut it off manually at night or it shuts off at 11pm. 
 
What I'd like is for it to shut off when she is out of the house. Lots of ways to do that but it needs to be on for 5+ minutes before she gets home. What I would love to do is shut the pump off when she leaves the house and then turn on when she is 2 miles from the house (ie returning home). She carries a droid and I can get her to keep GPS on if needed.
 
The other thing I'd like is a low circ mode - like run the pump 2 minutes every 15 when someone less sensitive is at the house (think babysitter) to give reasonably hot water most of the time but not 120+degrees within 5 secs from every tap like my wife wants.
 
I'm thinking a software HA add on to the ELK could do this but which one?
 
There are probably other more sinister uses of geofencing the wife but I assure you mine is pretty clean.....
 
I have a HW recirc pump as well so I have faced the same problem. I can tell you there is no easy answer.  First, I would be very careful of anything that turns it on for a while, then off, then on, etc.  If you do this relatively fast on a faster schedule, that is probably O.K. but you don't want the pipes to get hot, then cold, then hot over and over because that stresses them. 2 or 3 times a day is O.K. but all day and night is not too good.
 
Second, as you probably know, when you turn the pump on, it takes a fair bit of energy and hot water to get to your faucet. Doing this a lot will use lots of extra energy.  There are solutions where you might press a button and then wait a few minutes for your hot water.  That seems reasonable if you can wait for the water to reach you. 
 
We decided not to do this. Instead, ours turns on in the morning when we wake for an hour or so, then shuts off, and that is it.  That is all we need 90% of the time. 
 
If you REALLY must have hot water at a faucet all the time, you might want to get a small hot water heater under your sink and then you'll always have hot water there, and this might be cheaper to run long-term.
 
Here we have a recirc line with a recirc pump, but we never have to turn on the pump because it turns out there's a thermosiphoning effect which does the work.  It's basically because the hot water into the recirc line travels UP, whereas, the return water (cooler and therefore heavier) re-enters at the base of the hot water heaters.  Not sure if your situation could be adapted to do the same, but if so, it might be an answer to your problem of not wanting to run your recirc pump all the time.  Depending on your setup, it might just require some relatively minor re-plumbing of the connections.
 
Of course, it would still lose heat through the pipes, so maybe it's not the total solution you're looking for.  The only energy it saves is the electricity from running the pump, plus it saves potential erosive wear on the pipes from running a fast stream of water through them over lengthy time periods, as might happen if the pump were on.
 
I've actually thought about inserting an electric valve to programmatically turn OFF the thermosiphoning effect, for the middle of the night when it's not needed, but it's pretty far down the to-do list.  Our NG bill is rather minimal.
 
I'm not positive but I thought Tasker (Android app) could trigger an event based on GPS location.
 
As far as 'who' is home, perhaps separate disarm codes, though off-hand I'm not sure how to detect differences in them.
 
Does Tasker interface with Elk? 
 
The pump runs about 50% duty cycle for 16 hours a day at 30 watts. At my rates, $5 a year. Definitely not my concern.
 
The house is new with Pex plumbing. I'm not sure the heat/cold stress is a big issue. Typically the pipes don't get cold for several hours - they are mostly insulated. Even still, the heat loss is pretty significant.
 
Or use monitoring at the house to detect when her devices are near enough to be detected.  Bluetooth, Wifi or even a RFID module on the car would be usable for tracking. 
 
That and most logic conditionals shouldn't be used alone.  Thinking the phone is 'gone' wouldn't help if its battery went dead.  But using location-based tracking puts more drain on the phone's battery.  Not to mention the "you did WHAT to my phone!" argument that's sure to come up when you slip-up and reveal you knew a location somehow...
 
dpilati said:
Even still, the heat loss is pretty significant.
I'm not disagreeing, but I'm  wondering how you're gauging that.  Maybe it's more significant (especially during the winter, when it would get conflated with other NG expenditures) than I realize.
 
The easiest way I can think of would be to pick a couple  days (if you can) when the NG won't be used for anything other than just maintaining your hot water at standby temperature.  Then, compare NG expended while running your recirc on one day with the NG expended on another day with the recirc off.
 
Or, you could try calculating your predicted standby losses for just your water heater (without the recirc), and then subtract those BTU's from the actual BTU's consumed with the recirc running.  Not sure how accurate it would be though.
 
The most accurate would be comparing the temperature of the return circ water against the outgoing recirc water.  Then, if you know the actual flow rate, I guess you could calculate the loss of BTU's that way.
 
geofencing the wife
 
Homeseer does allow for a nice little mixture of whatever addition hardware stuff and software integration.  Here I have some ~20 pieces of hardware connected to the mothership (HS) which do integrate a bit with the HAI OPII panel.
 
The above noted though; wife and mostly related to WAF; she keeps her phone off unless she wants to talk to me.  That is just the way it is.
 
You can though monitor though less invasively and more intuitively these days just using many automation pieces of hardware.
 
Too she hard sets the AC on hold at 68F in the summer.  Never deviates.  I use a blanket when she cranks on the ceiling fan at 3AM.  She is happy that way. 
 
Here though automation involves much WAF while concurrently I am able to justify the spends on whatever I automate.
 
HERE are some rather innovative ways of detecting when someone is home.
 
I've used my broadcast car monitor for over seven years and it has also been in my wife's vehicle for over four.  I get over 650 ft range with it using my home made antenna for the W-800 X-10 receiver.
 
My issue is not detecting when she is home, I need to know when she is 2 miles away because the pump needs 5 min (at least) to heat the pipes. 
 
The heat loss is easy to detect. It is electric hot water heater and I have a monitor on it. It runs just at a kw of losses or 16 kwh a day if I run it 16 hours a day. The loop is about 200 ft of 3/4 in pipe - insulated where I could. I have run the pump when the house is empty and no one using hot water and compared to not running the pump with an empty house - the tank itself does lose about 1 kwh per day
 
I'm thinking the safer way of running it is to detect she is 3 miles away and send a 10 minute shut off command every 10 minutes. That way failure leaves the pump on. 
 
How are you going to set up the logic that allows keeping it running if someone else is at home?  As in, guests, you, cleaning service, etc...
 
Yup here was going to the direction of an APRS station and the use of APRS tracking. 
 
There is one Homeseer user using it today with his setup.  Its free except for the hardware.
 
 
This would a DIY geotracking of your automobiles not dependant on your cellular service.
 
APRS-1.jpg
 
http://board.homeseer.com/showthread.php?t=111387
 
attachment.php
 
5 minutes is nothing if you figure in parking the car (pulling into the garage?) then grabbing a purse and coming in the house and unloading. - is she really going to sprint for a hot water faucet to test you?
 
Maybe a cell phone app that checks GPS and  sends a message when she crosses the 5 minute geofence?  The alternative is one that allows constant GPS/other tracking, which a PC/mcu or cloud app monitors and then triggers when she crosses the geofence.
 
My wife tried a few different apps/services, and the accuracy varies from plus or minus ~50 feet to plus or minus miles (when it's a service that's triangulating off cell towers instead of GPS).
 
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