I have ducted air conditioner with a control panel in both bedrooms and the living area that only has a thermostat. Is it possible to replace each of these easily (and inexpensively) with a timer to switch off and on at certain times?

It's a Siemens model if that helps but not permitted to post pictures yet!

Edit: A couple more questions:

  1. Can I buy from the US (thinking Amazon as I'm visiting next week) if I'm in a 220V country or would I have to buy locally?
  2. Any recommendations for a replacement thermostat? Can you pretty much buy any one with the desired features and it will be compatible?
  • You can put in a link to your picture and someone can edit it in for you. – Aaron May 30 '13 at 18:02

It should be possible in theory to use a generic timer switch to electrically disconnect the 'stat from the aircon during certain time periods so the 'stat cannot call for cooling. Whether it's inexpensive or easy (or attractive) depends on the details of the current installation and the style of timer switches available.

A better solution would be to replace the 'stats with a more sophisticated controller that has timer functions. This solution is unlikely to be inexpensive, but shouldn't be prohibitively expensive either. It is typically easy to do this, disconnect the old 'stat from the wiring and attach the wiring to the new 'stat. Once again, the ease depends on the details of the current installation and the replacement 'stat.

  • Thanks bcworkz. I opened up the thermostat and found it was a Siemens RDF 60.1 thermostat. See my additional questions in my edit above. – Deon O'Brien Jun 2 '13 at 17:58
  • Your aircon supplies 24v to the 'stat. This is very typical in the US and world wide. What the mains voltage is at your location makes no difference. I don't think you'll have trouble finding a compatible 'stat with a timer function. To be extra sure, count how many wires come into the 'stat from your aircon, and if possible, what each wire does. The linked PDF should help you determine this. As long as the new 'stat has appropriate connections for each wire and is for a 24v supply, it will work for you. – bcworkz Jun 3 '13 at 22:24

A programmable thermostat does this, there are only a few wires depending on if you have AC or not or a heat pump. Essentially take a pic of what you have and make a diagram and replace the same way, turn off the power to be sure you dont hurt anything by letting the Red wire touch ground or common. enter image description here

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