[SOLVED] Wiring thermostat to gateway

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larsvdvoorden
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[SOLVED] Wiring thermostat to gateway

Post by larsvdvoorden »

Hello,

I'm trying to install an opentherm gateway at home for controlling my CH-system. 4 months ago I tried the gateway and I was able to receive messages from my Remeha Avanta. My Honeywell Chronotherm (Modulation CMT937 ) didn't work. The thermostat starts but said 'Bedrading fout' / Wiring error) I thought I'd made some mistakes when soldering the gateway so I decided to make a new one with new components. Yesterday I soldered the new gateway and tried it for the second time. Unfortunately I get the same message from the thermostat. The Avanta is still working and generating messages.

Is there someone who can tell me what I'm doing wrong?

Thank you.

Kind regards,
Lars
Last edited by larsvdvoorden on Thu Mar 12, 2015 10:46 am, edited 1 time in total.
hvxl
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Re: Wiring thermostat to gateway

Post by hvxl »

What does the gateway report on the serial interface?

Did you go through the troubleshooting instructions?
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larsvdvoorden
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Re: Wiring thermostat to gateway

Post by larsvdvoorden »

The gateway reported 'Thermostat disconnected' on the serial. I measured all resistors and I found out that I was using 4.7 resistors instead of 4K7 (stupid me :roll: ). It seems to work now. I can receive messages from the thermostat, but I have a new question now;
When I set 'TT' (Temporarily temp) to eg. 20C, it will takes a minute (or two) before my CH-system starts burning. Is this normal? (without gateway it will take 10 to 20 seconds)
Also nothing seems to change on my thermostat and about 5 minutes after I fired the TT-command, the gateway (or my thermostat) will put the setpoint temperature back to 18C.
hvxl
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Re: Wiring thermostat to gateway

Post by hvxl »

Either the thermostat accepts the override setpoint, or it doesn't. In the former case, it may take a minute or so. The thermostat only queries the gateway about an override setpoint periodically. Then you get the standard 10 to 20 second delay on top of that. If the thermostat doesn't accept the override setpoint, nothing happens on the thermostat and the gateway stops its attempts after a while.

On some Honeywell thermostats the tele function needs to be disabled for the remote override setpoint function to work.

If none of that helps, examine the otmonitor logs to see exactly what is going on. If you're not sure what to look for, I can help with that if you provide logs of an unsuccessful TT attempt to me.
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larsvdvoorden
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Re: Wiring thermostat to gateway

Post by larsvdvoorden »

The Equipment matrix on otgw.tclcode.com tells me that the Honeywell Chronotherm Modulation CMT937 should accept the override setpoint, right? When I send a TT-command, the TELE-symbol is shown on the thermostat. Maybe that's the problem?
Do you know how I can disable (?) the tele function on the thermostat? There seems nothing in the manual about it. (exept how to wire your phone to your thermostat).

I put a copy of my OTGW logfile ( 7 minutes) on my server:
http://vdvoorden.nl/otgwlog.txt

As you can see; I send a TT-command for 20.5. the thermostat seems to accept 20.0 and set the themperature back to 18.0 on 09:54:31.
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Re: Wiring thermostat to gateway

Post by hvxl »

People have reported in the past that certain Honeywell thermostats only accept override setpoints of full degrees. That appears to be going on for you as well. The gateway requests a setpoint of 20.5 and the thermostats only goes to 20.0. That's too much of a deviation and the gateway gives up after a couple of tries. At that point the thermostat falls back to its regular schedule. Things will probably work fine if you restrict your override setpoints to full degree values only.
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larsvdvoorden
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Re: Wiring thermostat to gateway

Post by larsvdvoorden »

That seems to be the problem. When I round my setpoint, the thermostat won't jump back to its own programmed value. Thank you!
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