G1, G2, G3 (Y1, Y2 / W1, W2) thermostat out/inputs

Not sure if this is the right forum for this - but I guess it would be :wink:

I am trying to figure out the wiring for my new AC unit. Which has a “generic thermostat aux module”. This module exposes the standard connections to link up a thermostat (like Nest). Y1, Y2, W1, W2, G1, G2, G3 etc…

the question is now, how a “regular” thermostat would switch these… and Y1, and Y2 to be switched in AND mode
Y1 + Y2 == boost

or exclusive mode (OR)
Y2 == boost – Y1 == OFF

This as the Velbus thermostat kicks in the heater + booster channel for “booster mode”

And would the same principle apply to G1, G2, G3?
G1 AND G2 AND G3 == Full speed
G3 ==Full speed


Hi Roelf

Can you post a picture of the device or connection details please.

I think it’ll be a case of using a VMB4RYNO and testing some actions with the thermostat.

It certainly shouldn’t be difficult.

This is in the manual - I think I found it out… essentially I have to short the R to the Y1/Y2/etc… the manual states either to link the G or use the individual fan speeds on G1, G2, G3… which is my plan

This is my proposed design - to drive the control for 2 AC’s

and if I can get input (error messages) as well…


I think you need to look closely at your drawing.

You don’t need to connect anything to the N terminals on the VMB4RYLD modules, you’re only using them to switch a signal.

Volt free error return outputs (I think) should connect to a VMB7IN

yeah… its a labeling thing… the middle one is a RYNO…

And I probably will configure it like

4 alarms (mode’s for the thermostat)
1 = X = Off
2 = I = on demand compressor (Y1) / fan G1 (low speed)
3 = II = on demand compressor (Y1) / always fan G1 (low speed)
4 = III = on demand compressor (Y1) / always fan G2 (medium speed)

Booster channel (Y2) relay + fan (G3) high speed

but if the fan needs to go high-speed - I need to force the medium/low speed fans to off (to prevent mixed signals) - I’ll probably use the “Forced off when initiator closed” for that

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After some feedback from a very knowledgeable man… I configured the AC to:

Alarm 1 == Day (II) or Comfort (III) mode
Alarm 2 == in Night (I) mode
Alarm 3 == if set temp + offset < +3C
Alarm 4 == if set temp + offset < +5C

And I’ve configured the channels as:
Cooling ==
Y1 follow
G1 on when initiator closes, delayed off when initiator opens + 1 minute

Y1 forced off while initiator is closed
Y2 follow

Then on the alarm channels I’ve put
1 == nothing
2 == enable Silent Mode (an option on the roof unit to make less noise)
3 ==
G1 forced off while initiator is closed
G2 on while initiator is closed
G3 forced off while initiator is closed
SM mode forced off while initiator is closed
4 ==
G1 forced off while initiator is closed
G2 forced off while initiator is closed
G3 on while initiator is closed
SM mode forced off while initiator is closed

That way the fan should go into medium (3) and full (4) upon those items… - and the silent mode can be disabled in this case (to get more power from the unit) - while on normal nights we have a pre-set temperature + silent mode and during the day - normal operation and day temperature…

Now my feedback to @velbus is - can we please replace the icons on the thermostats for the cooling mode of the thermostat. having fan blades representing day/night mode is a bit silly - as they might not represent the actual usage of the fan or the set temperature compared to the fan speed…

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okay… back to the design board… it seems the booster channel only kicks in for the heater… not the cooler… - guess I’ll add it to alarm 4… or something

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