On 09/10/2013 12:47 PM, Tony Hwang wrote:
Nate Nagel wrote:
On 09/10/2013 12:10 PM, Tony Hwang wrote:
wrote:
On Monday, September 9, 2013 10:14:34 PM UTC-4, bob wrote:
My old house has a 3-wire thermostat, and I can either use a
mechanical
thermostat, or one that uses AA batteries.
I want to put in a smarter thermostat that requires power supplied by
the
furnace.
Another option is just get one of the thermostats that will
operate off of batteries and change them once a year. Most of
the programmable ones work like that. I have a Honeywell VisionPro,
which is a really nice one that I recommend. It will work with
either battery or furnace power. The advantage to furnace power is:
1 - You can set it so the display is backlight all the time.
With battery it only lights when you touch it to use it.
Lithium batteries last ~3 times longer.
2 - You don't have to worry about changing batteries, or having
dead batteries in winter when you're not there, etc. Some
thermostats have a backup mechanical that closes at 40F or so
to prevent freezing.
Some Vision Pro comes with RTA(return air) sensor.
Drill one hole into return air plenum to mount it. One wire
from it to thermostat to use this fall back freeze prevention feature.
Being a Honeywell retiree, I am always for Honeywell 'stats.
I've had good luck with them myself. Only complaint being the latest
one I purchased - which appeared to be the updated version of the same
on that I had in my last house - only runs off batteries, the directions
tell you not to connect the 24VAC wire from the furnace controller. Now
it's been in use for several months now with no apparent issues and no
battery changes, but just on principle I would prefer that the batteries
be for backup only as they were on my old thermostat. Also
reprogramming after a battery change is a pain in the keister (it's a
5/2 programmable deal, part of the reason I got it. The other being
that it has an "Auto" mode for the few times a year that you may need to
switch from heating to cooling or vice versa in the same day.)
All in all, if I'd known that it didn't tI always liked 7 day
programmableake the 24VAC input, I'd have
purchased a different model. (ordered it online as it was $20-something
vs. $60-something locally.)
nate
Hi,
If you must, there maybe a unused battery compartment in that 'stat.
Jury rig to put in rechargeable batteries in there and build a small
charger/regulator on a breadboard and hang it behind 'stat and drive it
with 24V AC coming from the furnace. I'll be 73 next month. My brain
still works pretty good but little slow. Always looking for some thing
to do or I still play my euphonium driving family crazy(just better half
now), LOL! I never used 5-2 programmable one.
That would actually be a great idea, if I didn't have 20 more important
projects to do as well. That's how I would ideally like to have the
thing work, have the power actually charge up rechargeable cells which
kick in only when AC power goes out for a true zero-maintenance (until
the cells actually die 10 years or so down the road) system.
I'm assuming you could just maintain a constant voltage on the cells,
that way you could piggyback right on the terminals of the cells and
make a crappy little power supply to keep them trickle charged. It
wouldn't actually power them up if they were run down, or at least not
quickly, but it'd be cheap 'n' sleazy.
nate
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