Which control system? Control heating/ventilation/air conditioning with an app

  • Erstellt am 2017-12-25 18:02:20

ruppsn

2018-01-01 13:10:02
  • #1
Happy New Year everyone! I don’t want to hijack the thread, but since the OP also asked about lighting: how have you implemented the lighting topic? I am currently facing the decision between DMX or DALI, with a current preference for DALI due to the simpler wiring (5x 1.5 NYM versus “special” bus cable) and the main requirement to be able to dim or switch our exclusively LED lighting on/off. RGB(W) strips and light sources are not our thing and therefore not a requirement. Since DMX comes from stage technology and has advantages due to the higher bus speed for synchronous (color) light control of many light sources simultaneously, I wonder what else would speak in favor of DMX. By the way, the lighting will be completely implemented in 24V with central drivers in the technical room – according to the electrician. How have you done it?
 

ruppsn

2018-01-01 13:13:52
  • #2


That means to be future-proof, you would then wire in a star topology and use a CAT-7 cable instead of the green one as the KNX bus cable? Wouldn't that be the conclusion from what was said? One could then also use a green CAT-7 for nostalgic reasons [emoji6]
 

ONeill

2018-01-01 13:49:00
  • #3
Lighting completely centralized with power supply and MDT LED controller. Wiring always simply with 5x2.5, we didn't calculate here. Partly, 5x1.5 would probably have been sufficient.

Where exactly do you see the advantages of DALI? For me, only the price would come to mind, but I'm not quite up to date on whether that is still current. Although the price would of course be a good argument. KNX, however, has made significant progress recently in terms of actuators.

Regards
 

ruppsn

2018-01-01 14:12:18
  • #4
Hello! Well, the price would definitely be a very weighty argument [emoji4] Otherwise, converting the dimming values into a logarithmic dimming curve in the EVG would be a point. Where do you see disadvantages with DALI compared to KNX actuators? Did you then pull each light source individually into the UV? If yes, that would be a greater effort compared to DALI. The latter is a bus, i.e. more flexible when relocating the luminaires with less material effort (cabling from the UV to the room or floor, then open ring-shaped vs. each individual light source into the UV). But it depends on how often the "rewiring" occurs. What still doesn't quite convince me about DALI is that "off" is not without current, but 0%, meaning a small residual current might flow. I hope it doesn't cause any squealing when off. However, if there are no other advantages with KNX dimmers and "only" the price advantage remains, that would certainly be enough for me. Why invest more money than necessary (with the same or marginally "better" quality)? But I'm not yet decided and open for arguments [emoji4]
 

Tom1607

2018-01-01 14:40:15
  • #5
Hello everyone,

first of all, a healthy and successful 2018 to you all from me as well.



NO!!

KNX cable is certified with a test voltage of 4KV and may be laid parallel and even in the same conduit as 230V cables without special protection (also in the distribution board!!). CAT cables must be laid separately from 230V cables and in a separate conduit. So if bus cable, then the green KNX!! (And that has nothing to do with the color, KNX cables also come in purple)

I would still lay CAT cables parallel. There are now several devices that do KNX via IP (Gira G1 just as an example) and of course you are allowed to lay them in the same conduit as the KNX cable. Just not together with 230V.
 

Tom1607

2018-01-01 14:56:29
  • #6
Since a gateway from KNX to Dali is needed, Dali currently only pays off if you really dim many LED loads. The channel prices for KNX LED dimmers are currently around €45/channel. Dali is at about €30. A KNX Dali gateway is likely to cost around €300. That means Dali pays off from about 20 dimming channels for LED.

You just have to look at the details to see if two systems are still really worthwhile.
 

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