PSA about Thermostats

[Exterous]

I ran into an issue where my furnace wasn't turning on clearly evidenced by the rather low temperature in the house. 49 according to the thermostat. Went down to check the furnace. Went through the motions of turning it off and then back on. Pilot light was on but it still didn't fire up to heat the house. Diagnostic lights were green.

Went back up stairs and lowered and then upped the temp again. Nothing. Turned the fan from auto to on just to see if the thermostat was sending signals to the furnace. The fan turned on. Checked the wired connections for the thermostat. Everything looked good

Lacking nothing better to do other than despair over a malfunctioning furnace I decided to change the batteries on the thermostat as it was blinking the 'battery low' error message.

The furnace turned on the instant I replaced the batteries.

So... be aware that just because your thermostat's LED screen is functioning and it will trigger the fan it may no longer be able to trigger the furnace if its low on batteries

 

[rsd]

Seems like changing the batteries would've been the first thing I'd have tried if it says battery low

 

[Fear No Evil]

Seems like changing the batteries would've been the first thing I'd have tried if it says battery low

Its like if your oil light comes on and you are checking the tire pressure. LOL.

 

[feralkid]

I decided to change the batteries on the thermostat as it was blinking the 'battery low' error message.

Wow, that's thinking outside the box.

 

[calvinbiss]

Since when do thermostats take batteries?

 

[ShawnD1]

Since when do thermostats take batteries?

Wellfare housing. The one in my house is wired, as it should be. I gave a battery powered door bell though, and no it doesnt work worth shit. Batteries suck.

 

[Exterous]

Seems like changing the batteries would've been the first thing I'd have tried if it says battery low

To be fair - the indicator isn't in the most visable location and it wasn't my immediate thought as the LED screen lite up when I pressed the buttons and the Fan controller was still, apparently, getting enough power from the batteries to control the fan. I would have thought lighting the LED screen would use more power than sending a signal to the furnace

Now if my thermostat was dead and the furnace wasn't turning on I would think the issue would be a tad more obvious

 

[Exterous]

Wellfare housing

And I use mah welfare checkz to build mah Home theatre! Thanks Obama!

 

[Rubycon]

Lesson learned here is a liquid crystal display can still switch on a very weak power cell! When that low batt icon is displayed it's important to replace 'em because they will eventually get too weak to close terminals calling for heat/cooling etc.

If you don't need setback, etc. T87F FTW. No batteries, no worries.

If you're freezing you can also pull the 'stat off the sub base and get out a few "roach" jumpers...

The R terminal is "hot" and when jumped to other terminals will bring on the heat. When R+G are jumped you will have your fan. Jumping to W will give you heat, Yellow cooling. If you have a heat pump and need cooling you will need to jump O as well (for the reversing valve to energize) or otherwise you will still get heat. This is a fail safe as it's generally better to fail in heat mode than cooling mode, etc.

Don't worry about these wires/terms because it's all 24V and you won't feel a shock unless you lick them. :biggrin:

 

[imagoon]

Mine has batteries because it was a replacement for the 1960's mercury switch. Granted I prob could have grabbed the 24V of the existing wiring but... at the time I didn't care, the AA batteries lasted 3 years and I keep a spare set for it in the drawer.

 

[Exterous]

Lesson learned here is a liquid crystal display can still switch on a very weak power cell! When that low batt icon is displayed it's important to replace 'em because they will eventually get too weak to close terminals calling for heat/cooling etc.

Heh - yeah, lesson well learned. I thought either the fan controller or the LEd would use at least the same amount of power as the heating/cooling but obviously I was wrong there.

If you're freezing you can also pull the 'stat off the sub base and get out a few "roach" jumpers...

The R terminal is "hot" and when jumped to other terminals will bring on the heat. When R+G are jumped you will have your fan. Jumping to W will give you heat, Yellow cooling. If you have a heat pump and need cooling you will need to jump O as well (for the reversing valve to energize) or otherwise you will still get heat. This is a fail safe as it's generally better to fail in heat mode than cooling mode, etc.

Don't worry about these wires/terms because it's all 24V and you won't feel a shock unless you lick them. :biggrin:

Good to know! Thanks!

 

[Modelworks]

Most thermostats that have batteries also have a 3V relay for switching the unit on and off.

 

[Squisher]

Ruby knows 10 times what I know about HVAC, but every thermostat I've seen that used batteries used them only to hold programming info in case of power outages. I've taken the batteries out and not replaced them for days.

 

[feralkid]

Wellfare housing. The one in my house is wired, as it should be. I gave a battery powered door bell though, and no it doesnt work worth shit. Batteries suck.

They are all wired; the batteries are for programing.


edit; I guess wireless is available...I stand corrected.

 

[Rubycon]

Ruby knows 10 times what I know about HVAC, but every thermostat I've seen that used batteries used them only to hold programming info in case of power outages. I've taken the batteries out and not replaced them for days.

You would think that's what the batteries are for but apparently some are using them for "holding" which means too feeble of a current means no tack and loss of call for heat/cool.

Lots of cheap offshore stuff these days.

 

[AyashiKaibutsu]

Wellfare housing. The one in my house is wired, as it should be. I gave a battery powered door bell though, and no it doesnt work worth shit. Batteries suck.

I live on a military base and they use wireless thermostats. It completely ceases functioning when it gives the low battery warning. Probably to make sure something like it signaling the heater to go on then running out of battery and having the heater stay on (just a wild guess on my part).

 

[Mixolydian]

Since when do thermostats take batteries?

Just about all electronic and programmable thermostats use batteries.

 

[kranky]

Our digital thermostat is about 10 years old and we found out early on that replacing the batteries solved erratic furnace/AC operation. It doesn't even have a Low Battery indicator.

There have been a couple times when my wife insisted the batteries could not be the problem because they were only a couple months old, but new batteries always solve the problem.

 

[ShawnD1]

Just about all electronic and programmable thermostats use batteries.

Your thermostat sucks.
One in my parents house looks a bit like this

Been running for over 30 years. No batteries needed.


If you don't want to dick around with batteries, what you can do is use an AC adapter. Thrift shops sell any voltage you want. 3v, 5v, 6v, 12v, 14v, 18v.

 

[Rubycon]

Your thermostat sucks.


One in my parents house looks a bit like this

Been running for over 30 years. No batteries needed.

That's a T87F.
When utilities have programs to replace them for free you should follow the trucks and collect all the old ones. Lots of mercury switches = lots of fun.

 

[ShawnD1]

That's a T87F.
When utilities have programs to replace them for free you should follow the trucks and collect all the old ones. Lots of mercury switches = lots of fun.

Is this you?

Mercury switches are often used in motion sensitive bombs. The bomb sits on the porch completely safe until someone tilts it, the switch closes, and detonates the bomb.

 

[imagoon]

Your thermostat sucks.
One in my parents house looks a bit like this

Been running for over 30 years. No batteries needed.


If you don't want to dick around with batteries, what you can do is use an AC adapter. Thrift shops sell any voltage you want. 3v, 5v, 6v, 12v, 14v, 18v.

I had that one, the new programmable one dropped my utility bills enough that I could buy a few thousand batteries. I wouldn't want it on a wall plug, why would I want to lose the programming each time the power fails? Is it really a big deal to spend $1.49 every 2-5 years?

 

[Rubycon]

Mercury switch on moving vessel at sea = probably biggest epic fail of all. Well until terrorists started using cell phones for triggers and spam texts KIA's them before reaching their intended target. :biggrin:

Mercury is fun to play with. Tossing a handful (a good kg worth) up in the air and listening to the metallic rain that follows.

Imagine finding one of these and tossing a few hundred kgs down it!

http://www.youtube.com/watch?v=vLNbzZmBOmI&

Yes I played with mercury when I was young - in the '60's

 

[Mixolydian]

Your thermostat sucks.

Not really. I only had to replace the battery once in the 6 years I've had it. It only uses 2 AA's.

 

[ShawnD1]

How does the programming lower your bills?