DIY Doctor

Thermostat Wiring Advice Needed

Postby ian54 » Wed Jun 04, 2008 7:41 pm

I am trying to replace a Honeywell T6360 room thermostat with a Siemens RDD10 (not 10.1) digital thermostat.

The Honeywell wiring has 4 wires, I have identified from the wiring diagram inside the cover; Earth, Live (red), Neutral (Blue) and Neutral/Load (Yellow).

The Siemens requires four connections, however, none of them are Earth, so I have 3 wires for four connections.

Here is a manual for the RDD10, page 7 shows the wiring diagram for the RDD10 on the left (the right is the RDD10.1 which is the battery model).

Can anyone suggest what I should wire, I guess Neutral (Blue) goes to "N" and Neutral/Load (Yellow) goes to "Q14". I've tried Live (Red) in both "L" and "Q11" separately but in "L" I get power but the control is not working, in "Q11" there is no power at all.

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Simply Build It

Postby plumbbob » Thu Jun 05, 2008 7:52 pm

The two pins marked "L" and "Q11" need to be joined together and to the "Live" (Red) wire

The "Neutral"(Blue) needs connecting to pin "N" and finally the "Load" (Yellow) should be to pin "Q14"

But you may have a problem here, because the stat is a mains variety and requires constant live on the (Red)"L" to maintain settings so if you have a time clock fitted before the stat, when the timer switches off, the stat will lose it's memory.

If you look at the pdf you posted, the live is split at the top into two; "L" and "Ln". "L" being permanent live and "Ln" being switched live.

Of course this won't arise if you do not have a timeclock.
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