Smart Hot Water Recirculation Solution

Just bought one. Thanks for turning me on to it.

Funny last major ST outage a few months ago I railed about the cloud failure leaving my circulator pump on (I caught it in 20m or so, but still) and called for a community supported local processing engine with a port of webcore.

Seems these guys were already way ahead of me.

off topic but to save you a little time
to make SmartThings DH work in Hubitat

  • copy the DH (ctrl A and copy) into notepad
  • select edit and replace physicalgraph with hubitat and replace all
  • copy the modded DH into the Hubitat interface
    (it uses web browser but goes right to the hub just like if you logged in your router)
  • not all DH will work it may take a little trail and error or a search on the forum. Support will usually get you a DH in a few days.

This next bit might be over kill and really applies to SmartThings as well (most people will not bother doing it)
Like SmartThings, Hubitat when you fist set it up scans your zigbee channels and chooses the channel with the least noise on it. This is normally fine. But I did have a GE switch that would not pair to the channel it choose. but paired to another channel fine. But then you have remove and pair all your previous zigbee devices to that channel (you could try leaving them for 24 hours and they may find the hub by themselves depends on the device).
others say zigbee devices will find the new channel automatically but I have found not all devices have that feature.

  • turn off any 2.4 wifi your router has that you do not need (for this test) after the test if you need the 2.4 WiFi change it’s channel away from the zigbee range.
    zigbee and 2.4 uses the same band and 5g is faster anyways.
  • power off SmartThings and remove the batteries (just for this test)
  • Then go through each channel one at a time and try to pair a zigbee device 3-4 times. If it does not pair after
    3-4 attempts move to the next channel. If it does pair you will have to remove it or use another device for the next channel.
  • After you have completed all channels from 11-26 you will notice only a handful paired in the first few attempts.
  • go back and repeat the test on those few channels and narrow it down to one.
  • If it is the same channel as SmartThings is using (found in the hub info on ide) then you will have to contact SmartThings support and have them change the SmartThings zigbee channel so it does not cause any interference.
    (SmartThings does not allow us to change the channel ourselves)
    Some people have found the lower channels to work better.

Over kill but may save you a lot of headaches down the road.
This should probably be done for SmartThings as well if we had control of changing the zigbee cahnnel.

I have not had any issues with zwave devices.

Thanks for the info. My hubitat should be arriving this weekend. I plan on integrating it very very slowly, given that my ST install is working pretty well at this point.

In other news, I finally went to install my brew pi thermostat, only to discover that those stainless barbs don’t fit 1/2" pex. I know you had trouble ordering them, and frankly you’re better off for it. They fit 1/2" ID hose, which is not the ID of either 1/2" or 3/4" pex. I thought they looked a bit funny but didn’t give it much thought beyond that. I’m glad I didn’t do this project late last night. I’m off to the big box to buy some 1/2 barb to 3/4 male npt fittings.

This is a great thread. I have been looking for a better pump and noticed that some people were using the BACOENG pump. This does not seem like a good option is it is not designed for drinking water and is not NSF rated as far as I can tell.

I did find another pump which is made by Taco and sold by Rheem( Homedepot) and Richmond (Menards) with part number RH17920 or RP17920. This pump is designed to run for 2 minutes every 30 minutes which makes me think it has much higher flow compared to the Watts pump. It could easily be wired for on demand. It is designed for tankless systems

This pump would need to be used with some sort of valve between the hot and cold lines if no dedicated return line is available.

Also noticed that Taco has a hot to cold water control valve. It is a different design than the Grundfos valve. The Taco valve is part of the Taco HotLink system. Seems like a beefier design.

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It looks like there is a stainless and a cast version. They seem to recommend the stainless for this sort of use.

It looks like the Rheem/Richmond pump is based on a Taco 0015. The Taco 0015 seems to have slightly better specifications although it is much more expensive compared to the BACOENG.

Taco 0015 - 18 MaxGPM/17 FT Max Head 17 FT
BACOENG is 13 MaxGPM/20 FT Max Head

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. :rofl:

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!!!

Is there any reason why a regular contact sensor with builtin temperature couldn’t be taped or stuck to the raw copper pipe coming out of the wall? Even if it doesn’t read the actual temperature of the water, wouldn’t it serve as a benchmark as to how how the pipe is “relatively speaking”?

Yes, doing this basically upgrades it to an under-sink system with a smart timer (https://www.homedepot.com/p/Undersink-Instant-Hot-Water-Circulating-System-ACT-E1/100037011). It’s not much more expensive that the basic Watts. You save time and headaches with a system that does what you want out of the box.

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Yep, I can see this as being a more streamlined solution. Would still need a Smart Plug/Switch to make it “Smart” but at least it’s “Smart” enough to know when to turn on motor and when not to. Also having the added benefit of one less part to fail.

I have the Watts installed so it is what it is. I’ve created the Piston below to see if I would need to install a separate temp sensor. In essence, it would limit the amount the pump runs by at least 1/3 of the daily operations. This should lead to less energy both in electric and gas…Maybe…

We will see.

wasting money

If added up all the time & money spent and the sleep lost making it so that I can, say, turn off a light without getting my fat ass out of bed … well, it just will never make sense that way.

However, my smart hot water recirculating solution does make sense to me because, in my perpetual drought-plagued state, I don’t piss away a whole lot of water waiting for it to get hot.

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Makes a whole lot of sense to me as well! This thread is the reason why I purchased the pump in the first place.

What doesn’t make sense about the “Pump”, which you pointed out, is that that the sensor and the pump does not work as a team. What’s the point of the pump being on if the valve is closed! Your solution is simple and great!!

Peace of Mind? Yes. Economically sound…Nope. :rofl:

Even without the sensor installed, waiting on the parts to arrive, the water doesn’t take 2 minutes to get hot any longer. More like 10 seconds now. The downstairs bathroom which has a low flow faucet, is still taking forever to get hot. Think I’ll just have to deal with that or pay an extra $60 to add another sensor under that sink.

Thanks for sharing!!!

Just wondering. When using the re-circulation pump, how long does it take for cold water come out of the tap?

When using the re-circulation pump, how long does it take for cold water come out of the tap?

Good question!
It depends but it kind of just inverts the problem.

When a hot water recirculation system does not have a dedicated return line, it uses the cold water supply instead.
In that case …

A temperature sensitive valve (strategically located at the end of a run) opens between the hot and cold supply lines when the the hot supply line is below a hard threshold (for the Watts valve, this is around 90F).
If the pump is turned on, the tepid water in the hot line will be recirculated through the valve, and cold water return line, until the valve shuts off.

If hot water is used at the sink, the hot water supply temperature will eventually rise to the temperature the water is heated to.
While this is happening, the recirculation valve will remain closed and the cold water supply temperature will slowly drop.

The cold water supply at the valve will never be over the valve temperature threshold.
While the valve is closed or the pump is turned off, the cold water line temperature will slowly drop.
Cold water temperature will also drop when water is used but in this case the tepid water is dumped down the drain.

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So far, it seems like we have no issue with cold water being “hot” it takes about 3-5 seconds for the cold water to be at the temperature that we have been accustomed to.

The hot water at most faucets is either hot…well hot enough… or takes about 10 seconds or less for the water to become hot enough. It still takes about 30 seconds to 1 minute for the hot water to be hot hot.

Got the devices to install a “Smart” probe sensor but so far it seems like a simple Smart Plug and rules have been good enough. It takes about 45 minutes for the water to cool off to a temperature where the valve opens. The Smart Plug is program to turn on the pump if it’s been off for 2 hours or if it has not been on in the last 45 minutes and motion is detected. It only runs for 15 minutes through regular hours and 30 minutes during peak use. If the Mode is Night, it only runs for 5 minutes.

The Piston below has all the rules and is working great!

Will cost about 5 US dollars a year to run the pump based on 12 cents/kWh. Hopefully the gas bill will not increase too much. Hoping the water and sewage bill goes down because we’ve been wasting a LOT of water waiting on the water to get hot.

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