tp9000 with remote sensor

11 Feb 2024
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United Kingdom
hi, I have a Danfoss tp9000 with a remote sensor for the heating can anybody tell me how this programmer and sensor are wired to an S plan system using a Honeywell 10 terminal junction box?
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That's a good question and the answer in reality is: According to the preferences of the original installer and the location of the various parts of the heating system in your home. It may also change if the system has been modified, extended or updated at some point.

Having said that, the generic installation is as below. Often now the boiler requires a pump overrun so the pump is wired directly to pump terminals provided at the boiler, instead of as shown below.


The Danfoss TP9000 corresponds to the TIME CONTROLLER shown above and the terminal marked CH corresponds to Danfoss TP9000 terminal 4 (ON HTG) and the terminal marked HW corresponds to Danfoss TP9000 terminal 3 (ON DHW) Terminals 1 and 2 won't be used with an S-Plan.

You won't have the room thermostat as the TP9000 has this built in so wiring centre terminals 4 & 5 would be linked.



The question I have is why are you asking? If you are planning on changing the Danfoss TP9000 for another device or smart thermostat, then it's can be done without disturbing the TP9000 connections at the wiring centre.

The sensor would normally be wired straight to the TP900 terminals 5 & 6 as shown above.
Here's a modified drawing showing the TP9000 terminals marked and without a room thermostat. There may be a link between the wiring centre terminals 4 & 5 as I've shown, or more likely, the wire from TP9000 terminal 4 and the brown wire to the CH Zone Valve may simply just be inserted together into the same terminal.

should the programmer remote sensor connection number 5 have voltage going to the remote sensor
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It will have some voltage, not sure what though. It's an integral part of the TP9000 circuitry but is just remote from it.
Thank you Stem for your help appreciated. At present, I do not have the sensor so I cannot see if I wire it to the programmer that when I either call for heat or turn off the heat power is either enabled to HTG connection 4 or disabled. When wired with a temporary 240v and no sensor connected the heating connection 4 is live even if I bring the temperature as low as possible. So I assume from your advice that once the sensor is fitted it should either give power to 4 if required or no power if no heating is required.
It's possible that the sensor is an NTC thermistor. This is a device where the resistance decreases as the temperature increases. If that is the case, with the device missing the TP9000 will think it is extremely cold and turn the heating on.

Screenshot 2024-02-16 143528.jpg
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when I get hold of a sensor I will connect it to the programmer power it up and see if switching occurs through the HTG connection 4 on the programmer when I call for heat or not call for heat. I did put a multimeter on the sensor connections 5 and 6 to see if there was voltage I got some sort of reading around 1.6v but this reading would fluctuate up and down without a steady reading.

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