Ironically, the entire reason I started looking at home automation was because I needed a remote ability to turn on and off my hot water recirculator in my home. I acquired a vera lite, hooked it up to a ton of things in my home including creating a schedule for the hot water pump as well as a scene so the iphone could run the pump for 5 minutes to get hot water to all of the water supplies.
Now, I would like to be able to sense that the hot water line is flowing as if someone has turned on a sink or shower or started a washer. If a flow is sensed, I would like it to report to vera and trigger the pump to start and run for some number of minutes.
Does anyone have a good solution that I can install on my hot water line and communicate with vera? I don’t need for it to be able to be a valve for shutoff, I just need to know when it has started to flow. The hot water line is either 3/4 or 1 inch. In a nutshell, I am ready to move toward automation and away from remote control.
My RV’s 12VDC water pump starts to run when the pressure drops (someone opens a tap), and I’m sure the same concept exists in the household 120VAC version. You could put a power-metering Z-Wave plug in line, and when the wattage goes above a threshold, it’s telling you the pump is running, i.e., someone opened a tap. There may be more intelligent solutions than this…
I actually trigger my circulation pump by the motion sensors in the wet areas (kitchen, bathrooms, utility room).
I leave it running for about 10 minutes …
I actually have an all electric instant on hot water system … But I have a 20 Gal storage tank in front of it … for warm water feed.
The circulation pump returns to this tank … So if it runs a little longer that needed … it just warms up the water in this tank for later use.
The idea being that heat loss in the tank is a function of delta-temperature. So since this warm water tank is NOT at 120+ … there is not much heat loss.
The tank is insulated. Actually it’s a normal electric Hot water tank that is not usually powered on.
In the winter I run the circulation pump a little more often. It’s quite a load to raise my 40 deg water (from rain water collection) to a warm shower temp.
So pre-warming the 20 gallons eases the peak load.
And I always have hot water (minus about 4 ft of tubing from circulation loop to the faucets). In drought stricken Texas … minimizing flushing cold water down the drain is more important than the cost to heat the water.
Thank you richard. I certainly agree. My house is about 100 feet long and the hot water line just does a loop across the front, turns and goes to the back, and then another 100 feet to my shower. Seriously, this takes more than five minutes. Also, I fear that my heat loss is in the lines more than in the hot water tank.
Right now I have a scene that we can access on my iphone to run the hot water for five minutes and then turn off the pump. When we have house guests, I have another scene that runs the pump every 20 minutes to keep it warm at least. May be useful to state that we have 5 bathrooms, and 1.5 kitchens, a dishwasher, and clothes washing machine. I thought about using motion detection but I think there would be so much motion around the wet areas all of the time that it would run most of the time anyway. I guess it would help at night but if motion turned it on, then just brushing my teeth with cold water would set off the hot water pump.
So, I was hoping to identify some way to recognize that hot water has flowed. Even within a minute some useful sinks get hot water. Or in other situations, I could tell people that if they turn on the hot water and turn it off and wait a bit, they will have nice hot water. Basically telling them where the hot water trigger is.
Anyone think there is a flow sensor out there for residential use that could provide some sort of signal to any vera capable sensor? I suppose I could try to test the hot water line coming out of the hot water heater for an increase in temp and go from there.
Use the arduino plugin with the temperature sensor sketch. You could place 16 or so sensors at positions around your hot water circuit.
Then you can use pleg for advanced logic in controlling your pump.
I put a micro switch in the wiring box that powers the pump motor. I think it is an aeon. So, I can talk to that switch and turn the pump on and off using my iPhone app via a vera lite. So, I have the ability to do schedules, and scenes and things. I just thought that if I had a way to connect a flow sensor to something that talks to vera then I could have control based upon someone turning on the hot water anywhere in the house.
Yep … I have a small pump (rated for potable water) to circulate the Hot water from the end of the line back to the hot water tank.
All lines are insulated to minimize heat loss.
The pump is controlled from a Z-Wave duplex plug … I have the pump plugged into it. It’s a small pump … does not need an appliance module.
My problem with flow sensors is that it will turn the pump on when the water starts … for me letting cold water go down the drain is worse then heating water when I do not need it.
We are in a drought … and all of my water is from Rain Water … So I do not want to waste water.
Another approach is to put a temperature sensor on the line and always measure the temperature of the return line.
Motion to start … temp and/or time to stop.
Cool… thanks guys. honestly, i HATE trying to set that little dial timer on the pump as it is. Mine is in a very awkward spot, coupled with my aging eyes… it’s a total pain. I’d do this just to save me the hassle.
Richard, when I start my pump, it doesn’t run into the sewer, it just starts hot water into the line from the hot water heater and the water that is being pushed through the line just returns to my hot water heater. This is what solved my original problem of turning on the shower and watching ten minutes of cold water do down the drain. If I could detect that someone actually wanted hot water as shown by the fact that they turned the hot water on at any sink, then I could help them along by turning on the pump and getting the hot water to them faster. In fact, they could turn off the water for a couple of minutes and when they turned it back on, it would be hot. I wouldn’t lose any water, just the heat from the pipes in the line when they turn off the hot water.
Ah, good point. I guess it is that loss that the recirculation system is meant to avoid. This is like the hotel systems that keep hot water coming on immediately. I’m just wishing I could find a balance between running the pump 24/7 and minimizing the cold water down the drain. I will check out the gems sensors. Thanks for all of the thoughts.
I am just starting to work with arduino. I think initially I will put a temperature sensor on the pipe coming out of the hot water heater and if it rises significantly then I know someone is using hot water and I can initiate the pump to speed it up. Even with the pump starting up, it takes minutes to get hot water to the last shower.
My favorite automation in my VeraLite is turning on the hot water recirculating pump for 5 minutes when the front or back deadbolt is opened via PIN. So anytime someone comes home, start heating the water because you know they are likely to wash up shortly after arriving…
Again… this is just never an idea I would have considered, and may go a HUGE long way in the WAF situation. Not really an HA question per se, but if you guys run your recirculater for say 10 minutes, how long will that keep the water hot in the pipes? on days I know we are home more, like sat/sun, i’m wonder if you can “pulse” it, so to speak.
Weekday mornings I run mine for 5 minutes every half-hour, and that works well…
I plan to move to a mostly on-demand trigger via motion detectors soon, but I will still keep a few runs scheduled (like a few minutes before we normally get up)…
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