Another question about Heat Pumps

Sorry about so many posts... I am new to C-Bus

What additional wiring is required to integrate a heat pump with a C-Bus network?
Do cables usually need terminating?

I know that wiring may differ from model to model and manufacturer to manufacturer but can anyone tell me what most of the installations have in common?

 

All heat pumps have 5 dry contacts for remote control (as far as I know).
For example if you terminate together:
1-2 --> Works as a chiller (cooling mode)
1-3 --> Works as a heat pump (heat mode)
4-5 --> Indication of fault - alarm

The best way is to use 2 channels of a changeover relay.
However you can use a standard C-Bus relay. If you set contact 1 (common as the input in 2 channels of a C-Bus relay) and contacts 2,3 as the output you will get the same result. Of course you will have to use a little programming for avoiding that both channels will switched on at the same time.
For the fault-alarm indication, if a C-Bus network is close enough you can use a bus coupler otherwise a general input device is needed.

You can use ordinary 1,5 mm2 cable for connecting heat pump's contacts to C-bus devices (although this depends on the local regulations).

I hope this is what you were looking for.

 

Another common configuration is:

• 1 Circuit to turn the compressor on
• 1 Circuit to control the reversing valve - Sometimes you energise this circuit to select heat, sometimes cool
• 1 Circuit to activate the fan in the inside fan/coil unit
• The internal fan may also have a high/low control circuit.

With this configuration the typical control scheme would be:

Cool mode: Energise the fan/coil unit, energise the reversing valve (if requied) and energise the compressor. When the set point is reached turn off the compressor and reversing valve but leave the fan running.
Heat mode: energise the fan/coil unit, energise the reversing valve (if required) and energise the compressor. When the set point is reached turn everything off.​

When they are released, the C-Bus thermostats will take care of this for you (and do more, like enforce compressor re-start delays etc)

Many newer systems use 24Vac control circuits (You can switch this with C-Bus relays or the in-built relays in the still-to-be-released C-Bus thermostats). Older systems use direct line-level control (110V or 220/240V) - This can only be switched by standard C-Bus relays.

Many really modern systems use dedicated electronic control panels that are difficult to integrate with C-Bus. You may be able to use infrared control or the manufacturer may offer an optional automation control interface.

Paul