Robert11 wrote:
Hello:

Have a gas, forced hot water heating system.
Was about to order a Honeywell thermostat over the web, but had the
following concern which
just dawned on me.

Am interested in their digital model RTH 5100 which is
non-programmable.
It says on their ad sheet that it maintains the set-point if there is
a power outage.
O.K., that's great.

But even if there is house power--

These units require a battery or two.

What happens if the battery runs down while you are away ?
I know, use new, fresh, batteries, etc. But-

Will the furnace shut off if battery runs down ?

Or, is the battery only for the display, and the circuitry still
works ? If so, how, as there's no current when
the circuit is calling for no heat thru the 2 wires.

e.g., with no thermostat battery voltage, does the curcuitry default
to a circuit closed condition, which would
keep the furnace active, or... ?

A bit worried about this.

Thanks,
Bob

I don't know about all models, but many if not all just use the battery
as backup to remember your settings. If the battery dies and if the power
goes out, you will need to rest your preferences.

--
Joseph Meehan

Dia 's Muire duit