[OpenTRV-dev] ELV offerings

Mon Feb 10 15:50:28 GMT 2014

On Mon, Feb 10, 2014 at 10:44 AM, Thomas Hood <EMAIL ADDRESS HIDDEN> wrote:
> From ELV I recently ordered and received (within two days) a "FHT 80b
> + Ventilantrieb + FHT 80 TF-2, ARR-Bausätze" which is a kit consisting
> of semi-assembled FS20 wireless thermostat, valve head and window
> sensor "almost ready to run". Cost 55 EURO. I have started assembling it,
> taking pictures as I go. Has anyone else already purchased one of
> these ELV ARR sets? The instructions are well written, assembly is
> easy and the kits are cheaper than the assembled sets: the assembled
> FHT8V-3 [1] and the seemingly equivalent Conrad FS20 part [2] cost
> 40 EURO. The some-assemblly-required ELV ARR kit is only 25 EURO.
> [1]http://www.elv.de/elv-fht8v-funk-stellantrieb-mit-adapterset.html
> [2]http://www.conrad.de/ce/de/product/570056/FS20-Funk-Stellantrieb
> [3]http://www.elv.de/ventilantrieb-fht8v-2-arr-bausatz-inkl-batterien.html
> If OpenTRV is going to be making use of ELV RVs for a while then this
> is a way to lower costs slightly.

I've been surfing around the labyrinthine ELV website. The FHT system
has more possibilities than I realized. The FHT8V valve head which is
normally controlled by the FHT80B wall thermostat can in turn be
controlled either by the FHZ1000 (control panel) or by a FHZ2000
gateway which in turn can be controlled by a HomeMatic CCU2 or by a
PC. Although the FHT system has a boiler controller (the FHT8W), it
has no occupancy sensing; but as part of a HomeMatic system I imagine
occupancy detection could be used to make heating decisions. That's
more than can be said even for the 2014 Honeywell Evohome system which
overall is the most versatile and polished commercial offering (and a
lot more expensive).

Further surfing led me to realize that the HomeMatic system is also
rather versatile. The old HomeMatic TRV is HM-CC-VD valve head +
HM-CC-TC wall thermostat. The valve head looks exactly like the FHT8V
but has a bidirectional radio that employs the so-called BidCoS
protocol[1]. This combination has been discontinued (although it's
still listed for sale at Conrad) and has been replaced by the
HM-CC-RT-DN TRV which looks more like other eTRVs. The HomeMatic
system proper includes occupancy sensors but no boiler control.


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