jsharris, on 03 August 2015 - 08:41 PM, said:
You are a star! that information alone is gold dust.
The controller doesn't do much, it just reports on a few parameters via an RS232 (I think) link and allows dome parameters to be set using the time clock in the controller. It's main job is as a programmer for setting the heating curves, without it you are stuck with the default settings (unless you borrow a controller, using to make the settings, then hand it back). AFAIK, the unit doesn't deen the controller to work, all the vital stuff, like turning it on and off, setting heating or cooling mode, setting quiet "eco" mode and setting hot water mode nd cooling mode, don't need the controller. The controller does offer some useful diagnostics (pump flow rate inadequate, pressure head too low etc, but these same errors codes can be read ou by a flashing Led connected to the low voltage connections.)
My view is that I'd be inclined to hack the RS232 protocol and see what is being communicated. It's quite complex, as the controller/programmer has a timer and the ability to displaye variius system parameters and sensors (for example I have mine set to show the flo temp and well as the current day and time, plus the outside temperature and the mode (heating or cooling - the hidden pin 7 function I'd already found and works like a dream).
I could try and see if disconnecting the controller/programmer from my unit stopped it working. My guess is that is may not, in which case I could send you mine, you could programme up your units, then send me the controller/programmer back. What would be smarter would be for someone with some spare time to sniff the RS232 comms and see if a simple programmer could be replicated. My guess is that it could. Of the top of my head this controller/progammer has a a 0V, 12V, Tx and RX connections, that's all.
Thanks very much for the offer - I think I have a couple of other options to investigate before we resort to posting your controller around the UK.
Firstly I have had a bit of a dig into the protocol being used, it is something called CCN (Carrier Comfort Network) running over RS485. CCN is a propriety protocol extendable to full scale building management of large HVAC installations. Unfortunately it seems to be pretty well tied down with no documentation that I can find. I have a feeling that given the scope of the protocol reverse engineering may be big job.
There seem to be a couple of other options open to me :-
I could replace the external temperature sensing themistor in the ASHP with a resistor and effectively lock into a single point on the default climate curve to provide 35C heating at all times. (This would be equivalent to defining a flat curve using the controller). Alternatively I could buy the Carrier heat pump controller (33aw-cs1). This is the all singing+dancing version so a bit of an overkill for setting a few parameters and displaying a few temperatures but I can get one for less than £100 from Germany. (£200+ in the UK!). As I am fairly certain I wont be happy until I can see exactly what the heat pump is doing in terms of inlet and outlet temperatures I will probably go with this option.
EDIT - The German option was too good to be true an vanished when I tried to order. Looks like a new resistor may be the solution.
Edited by Alphonsox, 05 August 2015 - 12:39 PM.