Hacking a Grundfos Comfort AutoAdapt recirculating hot water pump for ESPHome

ESPHome
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I’ve seen a few other posts on here about integrating hot water recirculating pumps with HA, so I thought I’d share my solution.

Some time ago, my original pump broke and I replaced it with a Grundfos Comfort AutoAdapt pump. Supposedly, this pump learns when you use hot water over a 2 week period and then automatically runs the pump when it thinks you’re going to need it. This has never worked very well for me, and I wanted to get it under HA control so I could do things like set it to come on early on days when I’m getting up early. Plan A was to put it in “always on” mode and use a Shelly relay to control it, but this was scuppered by the fact that the pump defaults back to “Auto Adapt” mode every time it it turns on.

So, I decided to take it apart and see if I could force it to be in “always on” mode. After a bit of reverse engineering, I realised that simply removing the control PCB would do exactly that, but by that point I had a better idea: replace the control board with a custom PCB with an ESP32 on it. The advantage of this over an external relay is that it can get access to the internal temperature sensor of the pump, and also the external temperature sensor that measures the water flow temperature.

The pump is actually a pretty nice design: it has three PCBs - a power supply board, a driver board for the brushless motor, and this control board. This makes it quite easy to create a drop-in replacement for the control board, re-using the existing PSU and motor controller.

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On the right is the original PCB. This has a PIC microcontroller on the other side.

On the left is my custom PCB running an ESP32C3. The pump runs at 14V, and the stock control board uses 5V from a regulator on the pump board, but I was concerned that the ESP32 would be drawing too much current from this (from what I could tell, it was rated at 100mA) so I put in a separate switching 3.3V supply.

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Status LEDs upgraded from orange to blue :slight_smile:

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I’ve set it up so that it can be turned on and off by HA, and when it’s on, it runs the pump until the return temperature is within 10°C of the flow temperature, and then stops until the difference is more than 15°C. The button on the front activates a 30 minute boost that overrides the normal control.

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If anyone is interested in doing something similar, or wants more details, I’m very happy to share the PCB design and ESPhome config.

3 Likes
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I have the same pump, and have been logging temperature data from a bunch of sensor to try and figure out why it turns on and off randomly throughout the day. I’d be very interested in swapping out the control board in the pump. Do you have any more details on your design?

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hi @pdw,

I’m facing the same issues as you are with “auto adapt” feature of Grundfos and would like to take control in my own hands.

Could you please share your solution, so I can enjoy automation with home assistant the same way you are enjoying.

Best regards,

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Agree with everyone here!!! Any chance I can buy one off you?

I am using one for hot water circulation, but I have found that is wasting me alot of energy… Obviously as hot water leaves the tank it starts cooling down as it circulates through the house.
As a result the hot water system is running much more than it should be.

My plan is to turn this off whilst we are sleeping, not at home, etc.

My grand plan was to use this “Smart” Grundfos pump, but it seems in the rush of building the house I overlooked the details of what can actually be controlled.

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Apologies for the lack of reply on this thread. I thought I was setup to receive notifications of replies, but obviously not!

I’ve just published full details of the board to a project on github including my ESPHome config.

If anyone is still interested in a board let me know. I do have some spare blank boards, but they had a couple of mistakes. Given that they cost around £5 for 5 delivered, it’d be easy to get some fixed ones.

2 Likes
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Hey @pdw,

This is amazing! Great work on this! This is exactly the problem I am having / trying to solve with this pump.

What’s the best way for me to get my hands on one of these? I would love to either buy one from you or have a completed one (front and back) printed from JLCPCB. Would you be able to help me with either of these options? I noticed you have the schematic, but I would need the BOM and position files to get them printed.

Thank you in advance!

1 Like
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Thanks so much for your efforts

I would love to grab one from you as well!!

But in the meantime in going to check out that GitHub repo

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@opendba @meekju1339 @guiddruid

I am looking to get a batch made by JLCPCB, but the setup costs are not insignificant for a single unit.
If I purchased the batch and split the costs evenly + postage, would you be interested?

At the moment they seem to be about USD$30-35 each + postage.

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It’s been a while since I’ve used JLCPCB’s assembly service, but from what I remember, the bit that gets you is the $3 charge for “non-standard” components, and components with a high minimum quantity. If that’s the case, it’s possible that there are some components that can be swapped.

Whereabouts are you? I’d be happy to help put one together, but I’m in the UK so international postage might make it not worthwhile.

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I’m on the other side of the world in Thailand, but postage these days isn’t too bad.

The big cost increase in the ESP32 in package format, this automatically converts the order from economic to standard with a $50 setup fee. I assume because the soldering method is different.
I thought about changing it to module but that is a huge redesign of the board

Do I need to solder the pad that is in the bottom middle of the package?

(sorry this is my first time soldering package type components…)

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Ah, interesting. I don’t know exactly why that adds to the cost, but it doesn’t surprise me that it does.

I’m not sure whether it’s essential to connect the central ground pad, but I don’t think skipping it helps, as none of the other solder pads are accessible either. Unfortunately, I think it’s impossible to do these with a normal iron, but not too hard to do with a hot plate, or hot air (from underneath).

Looks like postage to Thailand would be around $5-6. I’m about to place a digikey order so could easily get the few components that I don’t already have at a sensible price so I’d just need some PCBs. Drop me a PM if you’re interested.

1 Like
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I would be interessted in two boards, as well! I am based in Germany.

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I’ve sent you a private message.

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is there any chance I could buy one already built? I live in Italy and own a 15-14 BTA model (97916757).

Thank you :smile: