Heating Control with an X10 AWM2 MicroModule


Submission by Steve Edwards – I recently changed my central heating boiler and took the time to set it up to be controlled by X10 via homevision, for local control I had a X10 Maxi controller in the kitchen.

This worked fine but during our kitchen refit I decided I needed something a bit neater than the maxi controller.  As well as buttons to control the heating I also wanted a visual indication of the current state of the heating, I’ve used clipsal faceplates, their modular design allows for a lot of flexibility. An AWM2 appliance module was used to convert the switch to X10.

The AWM2 is an X10 micromodule and so fits behind the switch, the only things required are a deep back box and a power supply. I fitted it next to an existing power outlet so that I could get power to it easily.

The AWM2 allows two external switches to be fitted, one controls the internal appliance module and another just transmits on and off on an additional x10 code, yep thats right, the AWM2 is 2 way, this means that every local change to the state of either switch is transmitted on the wire so that your home automation controller always knows the true status.

Fitting was a doddle, although the deep back box is required as things get a bit tight in there with 2 switches connected up.

Programming was not quite so easy. The micro modules don’t have the usual house code wheels that are on the old modules, instead they have a single button that you press to set the module into programming mode. Sequences of x10 commands are then sent to the module to set the house code and various features.

The AWM2 would simply not acknowledge the commands, now I was using an old Maxi controller so it could have been that which was causing the problems, but in the end I had to send the same commands about 10 times one after the other and suddenly the AWM2 blinked in acknowledgement. This shouldn’t be a problem as you should only need to do it once, but it made me long for a simple code wheel.

I have set the AWM2 up so that it is on the same house code as my heating appliance module so it controls it directly, this means that if homevision were to go down we could still control the heating.

With homevision working the button works as an override, homevision detects that the button has been pressed and kicks of a timer for an hour which disables the normal heating control routine which is based on the current temperature.

The only thing remaining was a visual indication of the status, now as the internal appliance module is on the same house code as the boiler one I fitted a Clipsal green neon indicator (30NGR) to it, this initially caused problems as well. The appliance module leaks just enough current when off to light the neon indicator, so you get dim when off and bright when on, not quite good enough.

A trip to the clipsal website turned up the following:  “Note: Inductive loads occasionally cause neons to glow in OFF position. To prevent this, place a 47k., 0.5W 240V resistor across the terminals.”

So, a quick maplin order later and it was installed, it does indeed cure the problem and the indicator now works as intended.

Overall I am happy with the result, and the micromodules are certainly easier to retro-fit into an existing wiring setup than standard DIN modules, I just wish they had used the damn code wheels.

[UPDATE] Two months and two blown resistors later, it appears the 0.5W resistor isn’t up to the job.  I have just replaced the latest one with a 2W version, I’ll report back if this cures the problem.

Clipsal Faceplates   :   AWM2 Appliance Module

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2 Comments on "Heating Control with an X10 AWM2 MicroModule"

  1. Did the 2W resistor fix the problem ?

  2. Yes, the 2W resistor did the trick, still running with the same one over 2 years later.

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