On-demand hot water recirculation
Curtis_Homan
| Posted in General Questions on
Does anyone have experience with AutoHotUSA? I want to use their DR099A system with dedicated return line. I like the AutoHot because I can use wireless motion sensors to activate it instead of having to fish low voltage wires down to the basement. It looks like a similar pump and control set up to other on demand system like Taco Genie.
Unfortunately, I cannot find any reviews.
Thanks in advance
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Replies
9 years ago, I could not find an off the shelf on demand hot water control system.
I built one myself. It uses hot water flow to start the loop heating. Turn on any hot water faucet for a few seconds that will trigger the system and the system will heat the loop even if you close the faucet like I normally do. I put the temp sensor in the return line near the heater and control box too avoid the long run of control wiring.
It has worked well and I would not change a thing if I had to do it again.
Try asking Autohot if they could give you a flow sensor option. Someone likely has a patent on it.
Walta
Flow sensors have been around for a long time. We commonly use them in the commercial world on glycol systems as part of lead/lag controllers for redundant pump packages. I haven't ever worked with one small enough for a residential hot water system, but I'd be very surprised if you couldn't get one that would work.
I doubt you'd have patent issues with the flow switch, but the Autohot system might not have a way to integrate the switch into their system. That would be where you'd need to reach out to the Autohot people.
Bill
You can use wireless motion sensors with any system using home assistant.
Home assistant is free, but you need a raspberry pi or inexpensive micro pc.
Then, you can buy inexpensive motion sensors and program them to control a smart plug that the circulation pump is connected to.
I did it this way for a while but i switched to controlling the pump with wireless zigbee buttons in each bathroom and the kitchen.
Just curious why you switched methods? I was planning on doing the HomeAssistant method triggered by Aeotec motion sensors. And, the circulator pump will also have a built-in thermostat so it won’t run if the loop is already warm enough.
It was wasting energy since most of the time one enters a bathroom it's not to shower and don't always need hot water when one enters the kitchen .
By switching to the wireless buttons the pump only runs when someone specifically calls for it, usually to take a shower or wash dishes .
I still have my guest bathroom on a motion sensor so they don't have to think about it, bit I disable that automation when we don't have guests.
I also have zigbee temperature sensors and the automation doesn't run when the water is already warm.
If you get a multifunction button you can also have various heat settings . Eg short press run for 30 secs, long press run for 1 minute.
There is a company called Smart Recirculation Control https://smartrecirculationcontrol.com/ that has a flow based on-demand control for domestic hot water recirculation. It can be triggered from any hot water fixture in the home as well as via their smart phone app and it supports webhooks so it can be triggered from home automation systems like Home Assistant.