Check your thermostat batteries?

Bret · #1 10/15/14, 09:25 AM

Saw the low battery indicator this morning. Replaced them during banjo workout.

(no banjo). Reply when you check yours. I do not get a battery kick back.

Nimrod · #2 10/15/14, 09:49 AM

My thermostat works like this, when my body says it's cold I throw another log into the stove.

There are no batteries, it runs on chocolate.

arabian knight · #3 10/15/14, 10:06 AM

Yes I make sure before the heating season starts I put in a set of new AA's in my setback thermostat. And at the same time I change the batteries in the smoke detector as well as the methane/propane detector even though that is a plug in model, it has a 9v battery back up.
Good advice for anybody that has battery operated things for safetys sake.

Rectifier · #4 10/15/14, 05:30 PM

As an electrician and motors tech. I have long maintained that any "modern" thermostat with batteries should have another bimetallic thermostat installed in parallel with it and set to a safe temperature for the house as a failsafe.

However, I still haven't got around to doing this in my house yet

It really annoys me that these stupid things run off batteries instead of draining their tiny current demand from the 24v circuit, like an X10 switch does.

lazyBum · #5 10/15/14, 09:33 PM

Last winter somebody at work went a few days without heat. The repair man finally showed up. And their thermostat batteries were dead. I can't remember if he charged them or not.

nosedirt · #6 10/16/14, 12:17 AM

The batteries in a modern thermostat are only to maintain the program if the electric goes out. The t-stat should be drawing power from the unit itself on the 24v side like Rectifier said. If your unit is not running this way, it is most likely installed incorrectly. Older units were set up to run with a two or four T-stat wire. To Pull power from the unit to the t-stat, you need five wires. Some HVAC guys don't want the hassle of pulling a new cable when they install a new unit or the homeowner didn't want to pay the extra cost of pulling the wire.

It would suck paying the HVAC tech for changing batteries, mostly because my wife would go all warpath on me.

How do you have banjo workout with no banjo?Drums are cool.

The only thing better than Nimrod's setup is if I could train my wife to do it. Well, maybe that's not a good idea.

Bret · #7 10/16/14, 05:25 AM

Nimrod. I have a banjo but not a banjo emoticon. Yes, drums are cool too.

bja105 · #8 10/16/14, 02:16 PM

Quote:

Originally Posted by nosedirt

The batteries in a modern thermostat are only to maintain the program if the electric goes out. The t-stat should be drawing power from the unit itself on the 24v side like Rectifier said. If your unit is not running this way, it is most likely installed incorrectly. Older units were set up to run with a two or four T-stat wire. To Pull power from the unit to the t-stat, you need five wires. Some HVAC guys don't want the hassle of pulling a new cable when they install a new unit or the homeowner didn't want to pay the extra cost of pulling.

Not true, usually. 90% of the digital thermostats I see can only be powered by the batteries. I don't mind pulling new stat wire, customers don't always want to pay for it. Ok, actually I despise pulling new wire more than anything! It stinks when the old wire is stapled in the wall. One of my nightmares is pulling a new stat wire at 3:30 on a Friday.

Both of my thermostats are powered by 24v circuit, but thats what I installed. I also am loving my wifi stat at the farm.

nosedirt · #9 10/16/14, 09:16 PM

Wifi stat is cool.

Rectifier · #10 10/16/14, 10:03 PM

Nail on the head bja105. What personally disappoints me is that we shouldn't need to pull new wire (hate pulling new wire in a residential setting too... can get so frustrating). The thermostat needs about as much power as a watch does (except for the momentary pulse when it throws the relays, probably equivalent to pressing the backlight on the watch).

This type of device should be capable of running off "parasitic power" - allowing several microamps leakage current through the gas valve, and using this to charge a capacitor to throw the relay. This type of setup is common for sensors etc. and was probably best known to the consumer as the way the X10 2-wire light switches were (and still are) powered.

The wireless age has resulted in far too much reliance on batteries in my opinion

nosedirt · #11 10/23/14, 05:53 AM

A couple years ago I took over a facility that is utilizing a rather cheap wireless t-stat setup (runs on a Zigbee network) and they were having trouble keeping the batteries changed. Turned out that the techs that installed them did not set them to pull power. Some of them also required pulling new wire. That required some creativity for a 30 year old, four story building but they got it completed. Anyhoo, I stopped in to talk to one of the techs while he was pulling the t-stat wire on one of the units and I noticed it was set for 240v instead of 208v. We assumed it was a simple mistake on one out of 450 units installed but curiosity got the best of me so we checked the unit next door. It was 240v also. We checked the next unit, 240v. I ended up devoting one tech to reverting all 450 units. After he was finished, he found only three set and wired to 208v. Hmmm

bja105 · #12 10/23/14, 02:01 PM

Rectifier, there are 'power stealing' thermostats, powered through r and w. They just need an isolation relay or a resistor at the furnace to prevent short cycling the inducer on a modern furnace.
Carrier and Honeywell make wireless stats I have used, but are expensive. There is a wireless transmitter that can be mounted on a wall in the space, and a receiver wired into the equipment.

As far as the 208/230v thing I don't think installers can read. Two out of 450 is about the ratio our guys hit, too.

nosedirt · #13 10/23/14, 02:54 PM

For flips and giggles, I ran a cost comparison on that building against a couple others that I had of the same age/type. Almost double the replacement of blower motors, transformers, relays. One of the supers from the company that had done the original installs said, "It doesn't matter. it will run the same on 230 as it will 208." One of my techs was in the meeting and said, "You can kill a deer with a baseball bat but that doesn't make it right." and walked out. Priceless!

bja105 · #14 10/23/14, 03:12 PM

I believe you! Lots of problems with with voltage. I have also seen someone try to kill a deer with a baseball bat. I don't recommend it, but it is preferable to pulling stat wire.

Rectifier · #15 10/23/14, 10:00 PM

I figured that modern furnaces might be the problem with parasitic power. Modern lamps don't get along with the old parasitic remote switches either - A CFL, even dimmable, will flash every minute or so when the ballast caps trickle-charge up enough to attempt to fire the lamp.

It's good to know they are out there, the question now is why they are not on the shelf beside the battery ones at Home Depot. I guess the consumer can't be expected to install something in his furnace.

What is to run the same on 230 or 208, heater circuits (no) or the control power for the T-stats (maybe)? Odds are the switching control supplies in the T-stats would do just fine on either voltage, though the fact that the option was provided implies otherwise... super embarrassing for the installer...