Somfy Vertical Blind Automated Control with openHAB

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The vast majority of the window blinds are roller blinds with mains motors wired back to MDT blind and shutter actuators using 4-core cables (Live for Up; Live for Down; Neutral; Earth).

The exception is the blind for the large West-facing window in the office, which is trapezoidal (with a sloping top) so the only practical option is a Vertical blind with slats of different lengths.

Large window in second floor office
Large West-facing window in second-floor office, with Vertical Blind in ‘Slats Open’ mode

Good hard-wired control options for this sort of blind proved elusive so it’s got a permanent live mains feed and uses the Somfy RTS system for control. Manual control works very well using the battery powered Somfy Telis 1 Mod/`Var RTS Pure remote control handset, which provides options for:

  • ‘Up’ (fully open, with the slats retracted) using the ^ button
  • ‘Down’ (fully closed, with the slats closed)
  • ‘my’ (which has been configured to the ‘slats across the window but open’ configuration – as shown in the photo above)
  • Fine adjustment of the angle of the slats using the black ‘scroll wheel’
Somfy Telis 1 Mod/Var RTS Pure remote control handset

So manual control is all good; the challenge is automated control from openHAB or a similar home automation control hub.

What’s been working well for years is integration via an RFXcom RFXtrx433E-USB-43392MHz-Transceiver which is managed via the openHAB RFXCOM binding – with just a slight niggle that Open means ‘all the way open, with the slats retracted’ and Closed means ‘all the way closed’. The ideal would be having some way to automate moving to and from the “my” position – so that the slats always remain across the window and only the angle of the slats changes. On the rare occasion of needing the slats retracted to the ‘parking’ position on the left of the window, that can be done with the manual control.

I had been thinking it would necessary to configure a Dimmer-type controller rather than a Switch-type controller, which I’d tried a few times but never got to work. Then I spotted this post on the openHAB forum which explains that the RTS handset uses a custom protocol for the scroll-wheel interaction and using the standard protocol via the RFXcom transceiver there’s no way to say things like ‘close the blinds to 50%:

https://community.openhab.org/t/venetian-blinds-with-somfy-lift-tilt-25-only-no-tilt/43672/2

However, that same forum post highlights it is possible to say ‘go to the “my” position’ by having openHAB send the STOP command rather than the UP or DOWN commands.

In the end it was simply a question of changing “UP” to “STOP” in the rule that opens the Home Office blinds at sunrise (the roller blinds (_01 and _02) still need the “UP” but the vertical blind (_03) gets a “STOP”.

Screenshot of the openHAB rule editor for the Home Office blind automation

(The check for ShadlingLogic <> 2 is so the blinds stay closed when the Shading is set to “Maximum”, where the blinds stay closed all day.)

Paul Novus MVHR Fan Bearing Replacement

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Woke up to a vague, persistent ‘mechanical’ noise somewhere in the house. After opening the door to the Plant Room it was immediately apparent the fan bearings on the Paul Novus 450 MVHR unit had failed – slightly surprising after only 6 years, but then they are running 24×7. The fans were still working and there were no errors on the control panel, but the noise wasn’t good – and I have enough experience with bearings to know they only ever get worse, not better. What was good was the sound attenuation on the MVHR ducts – the noise was only really obvious in the Plant Room and in Bedroom 2 immediately beneath it, so the noise was not being transmitted to other rooms via the ducting.

A quick Google search turned up the service manual for the Paul Novus with guidance on getting to the fans and the advice to replace the complete fan units: centrifugal housing, fan rotor, motor, electronics etc. (Estimated cost of £280 per fan.) I was hopeful it would be possible to just replace the bearings instead and proceeded with some dismantling.

I was very pleasantly surprised by the specification of the fans: embpapst units with part number G3G160-AD54-22. Really good build quality and the prospect of not being too difficult to repair. YouTube turned up an excellent video showing the dismantling and bearing replacement procedure.

Bearings are generally standard and pretty cheap and one of the great things about living in Derby, with its rich heritage of railway and aerospace engineering, is that there are some excellent suppliers of these sorts of spare parts located within a few miles. Derby Bearings Ltd don’t win any prizes for inventive business naming but they do offer an excellent service and carry good stocks – they had a couple of options in the correct size for only £4 each (£8 per fan).

The fans are now running quietly again and peace is restored. I’ve written a Technical Article with some hints and tips to make the job easier next time – or for other people attempting it for the first time.

I do wonder if the exceptionally hot summer weather contributed to the premature failure – could the heat have softened the lubricating grease in the bearings, causing it to leak out, making them more prone to rusting when the cold and damp weather returned?