So, I’ve installed the Watts pump and have it on an Iris Smart Plug that also measures energy usage. From what I’ve gathered, the pump uses a little less than 27 Watts when on. This is true if it is pumping while the valve is open or not. I used the below information to help me with my tendency to throw the “Law of Diminishing Returns” right out of the window when it comes to “SmartThings”.
27 Watts X 24 Hours = 648 Watt Hours or .648 kWh (Daily Use)
.648 kWh X 365 Days = 236.52 kWh (Yearly Use)
236.52 kWh X $0.12 (Energy Cost per kWh) = $28.38 (Yearly Cost)
Yep, that’s less than $30 a year if the pump was always on. Now, something else to consider is recirculating water when there is no demand! The cost to reheat that water, although is not calculated, has to be more than $30 a year…
So, how important is it to know if the water is hot or not versus if the pump should be running or not? From my understanding, it takes about 1-2 minutes for the water to recirculate through the pipes, of course longer or shorter times depending on how much linear foot of piping you have. If there is a motion event triggered in the bathroom, then more than likely, someone is going to be in there at least 1 or 2 minutes before they wash there hand or get into the shower…
I also considered just letting the pump run 20 minutes each hour while the house is in Home Mode. (Simple Button)
So, I can already cut 6 hours off of the run time of the pump just by having the pump off during Night Mode. That leaves 18 Hours of just 1/3 of that time on to equal 6 Hours per day.
Pump being on 6 Hours per day = Less Than $8/Year to operate! Spending $60 on a temperature sensor will take 7 Years to recoup the cost. By that time, the pump and the valve will probably went bad.
So…As I hit the order button on Amazon, I just can’t help myself even though I know that I am just wasting money.
Side-Note, I hope my Wife doesn’t see this post!!!