Lay-Z Spa Remote Control

extended control of heater/pump/blower, costs tracking and preview, alert up-on fault, LED lights add-on

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using cellular network, based on rapidM2M

Remote control of
* Heater schedule (start/end, temperature)
* Fallback temperature (e.g. hold 10°C during winter)
* Instant blower control (on/off)
* Instant pump control (on/off)
* Instant LED stripe color selection or turn off

See current status
* Water temperature
* Monthly costs estimation
* Pump/heater/blower activity
* Pool Exx fault indication
* Connectivity

See history
* day / month / year
* temperature, costs, power consumption, faults, pump/heater/blower activity


some more features:

* email/SMS alarm when pump signals fault condition (Exx)

* "silent mode" to turn all noise (blower, pump) temporarly off

* local button for blower on/off and "silent mode" on/off

* 10 schedule-able programs (target temperature or pump only)

* freeze-protection at any selectable temperature (i use 10°C)

* pump runs only while heating or if scheduled

View all instructions

Enjoy this project?



ricoghardforth wrote 10/01/2020 at 08:32 point

Hi I'm looking for a wifi solution to the four wire lazy spa controller/display.  Does any one know any one whos used a esp2866 for this model yet,  I'm lucky and my wifi goes all the way down my garden.  I've found ximon  3 wire project and visualapproach 6 wire on github but can't find any one working on or done a solution for the four wire models yet on wifi.

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visualapproach wrote 08/03/2020 at 17:50 point

hi, Funny they have so many different communication solutions.

Regarding the 6-pin pump- I made a WiFi remote;

Pins are 5v, gnd, clock, data, enable and sound. Not nescessarily in that order but it is described in the code on github.

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mrQ7 wrote 08/14/2020 at 07:54 point

great project! - and yes, seems that these are really creative guys ;) 

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smithl100 wrote 07/31/2019 at 02:19 point

Hi! great project. I have a Sundance 850 circuit board with 10 pin interface with the LCD control. I put an oscilloscope on it, but need help with trying to parse what it is doing. Would love to see how yours worked so I can start heading in the right direction.

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mrQ7 wrote 09/06/2019 at 18:15 point

pls read comments below to find link to full set of docs on github  and google.

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mrQ7 wrote 07/02/2019 at 17:46 point

Sand filter upgrade for Lay-Z Spa - just a few simple steps to improve filter performance dramatically. All you need is some sand filter /w pump as you may have it around from some old larger pool. For description and fotos see here ->

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John wrote 06/16/2019 at 17:27 point

My lay-z-spa (Helsinki) has a 6 pin connector between the IOC and DSP rather than the 4 in this project.

Anyone  come across this? Are some wires un-used?

Luckily I checked it out before ordering the components

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mrQ7 wrote 06/17/2019 at 03:48 point

i know that there are units with 3wires out in the field. but 6 sounds a bit scary... definitely not enough lines for direct signalling (e.g. parallel itf) ... possibly a serial interface with handshake signals (RTS/CTS) ?

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John wrote 06/23/2019 at 20:26 point

Mine seems very different to yours. I'm trying to identify the protocol. See this thread - seems that the Laz-Y-Spa internals are very different despite externally looking similar.

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John wrote 06/16/2019 at 16:00 point

Can I ask what the p6ke6.8 diodes are doing in your circuit before the tx/rx input?

Are they acting as a level shifter with the resistors?

If I am not going to implement the RGB lights do you think I could power the M3 off the 5v from the flexband connector?

Do you know if the M3 gsm connects to UK networks? (I have wifi in where the Spa is but I can't find a WiFi board which seems to be compatible with your code)


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mrQ7 wrote 06/17/2019 at 03:23 point

die diodes (and their 100R resistors) should not be necessary. i put them in just for safety, to dampen any unexpected signal peaks (since i do not know the internal circuits of the DSP/IOC). anyway, i would recommend to keep at least a single 100R per signal line to softly de-couple your controller from DSP/IOC circuits.

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mrQ7 wrote 06/17/2019 at 03:33 point

M3 supply: i would not recommend to power it from the lay-z supply, since it may drag peak currents of >1A with sharp signal edges. even if the lay-z supply is able to provide the current, the sharp signal edges may cause heavy electromagnetic interference over the thin flexband (which is unshielded and may act as antenna...).

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mrQ7 wrote 06/17/2019 at 03:42 point

M3 footprint: the integrated SIM chip operates on most cellular networks in Europe, detailed list to be found here

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John wrote 04/24/2019 at 17:48 point

can’t find this on GitHub or codepen.

Do you have links?

Very interested in what the protocol looks like as I would like to use a spare a Particle device I have knocking about 


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mrQ7 wrote 04/28/2019 at 05:37 point

all related information ist listed here:


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[this comment has been deleted]

mrQ7 wrote 04/20/2019 at 19:47 point

details are to be found on github and codepen - just search for lay-z there.

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troels wrote 04/16/2019 at 04:52 point

This is great!
What do you use to parse signal on the RXD / TXD from the control panel of the spa ?
I opened my spa controller yesterday to look into this idea also

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mrQ7 wrote 04/20/2019 at 19:48 point

think my PM solved your question?

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troels wrote 04/20/2019 at 19:54 point

I am sure you did! Thank you once again

now I just need to lock my self inside with the control unit and a few hoses of water!

Can't wait to start writing a sketch for Arduino

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asgeirholms wrote 05/23/2019 at 20:43 point

Could you send me that PM as well? I would like to know what you used to parse the signal :)

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