Why do 230v programmers have batteries?

[Zebra579]

I am looking for a 230v, 7-day programmable thermostat. I have wired a 3-core-and-earth to where the thermostat will be, so want a mains voltage one, to prevent having to have batteries.
Why then when I search for 230v programmers, do they say in the specs "battery powered?" Do they have batteries as well for back-up?
Can anyone recommend a good model to choose?
It is for a combi boiler.
Deborah

 

[Dan Robinson]

Honeywell or Drayton.

 

[Zebra579]

Yes, OK, those are good brands, but can you answer the question about why mains ones seem to have batteries?

 

[hertsboilers]

Batteries to keep the programs and time clock / day.

 

[Zebra579]

But doesn't the 230v power do that?

 

[hertsboilers]

But doesn't the 230v power do that?

Back up, to save your pre-setting.

 

[Zebra579]

Aha! Thank you.

 

[flameport]

Why then when I search for 230v programmers, do they say in the specs "battery powered?"

The mains powered versions are also available as battery only, presumably the descriptions for both have been mangled together by the dubious websites selling them.

There is no reason for any electronic device to need separate replaceable batteries to maintain settings in the event of power failure.

Another option - Danfoss Randall TP7001M, which is a programmable thermostat (replaces both thermostat and programmer), it definitely does NOT have any batteries.

 

[hertsboilers]

Why then when I search for 230v programmers, do they say in the specs "battery powered?"

The mains powered versions are also available as battery only, presumably the descriptions for both have been mangled together by the dubious websites selling them.

There is no reason for any electronic device to need separate replaceable batteries to maintain settings in the event of power failure.

Another option - Danfoss Randall TP7001M, which is a programmable thermostat (replaces both thermostat and programmer), it definitely does NOT have any batteries.

But I can give you more samples that have both batteries and mains power.