Thermostat question
 

We have a Honeywell T-stat for controlling our Heat/A/C unit.
We don't usually use the 'programable' feature of it as it's easier for us to just turn it on when we want it and off when we don't.
Lately it's been acting weird as it comes on for about 15 minutes and then shuts off, before it reaches the set temperature. Starts up again and runs....for a while.

I think the lastest power outage may have fried it. Guess I'll break down and call the man to come look at it.

Thanks for listening.
http://forums.pelicanparts.com/uploa...1640105127.JPG

They are really cheap, and pretty easy to install....

have you tried replacing the batteries?

Single stage or multi stage furnace?
The 15 minute thing gets me thinking that it is calling for a second stage of heat, and that's not happening. When the furnace shuts down does the thermostat still indicate that it is calling for heat, or no?

Also, how's your filter?

Batteries are new as of yesterday. Blew it out with canned air too while I was in there.
Don't know if it's a single or multi stage furnace. It's got the A/C system integral to it and is a Carrier unit.
Yes, the thermostat is still calling for heat when it shuts down as it hasn't reached temp in the room according to its readout.
I cleaned the filter a couple weeks ago in anticipation of us using the heat more this winter. It was cleaned for A/C use which lasted until early Nov this year as we had some hot days.
I think the power outage we had recently might have messed with things, either in the t-stat or in the furnace itself.

Are you using the "hold" button on the front? (I think I have the same one)

Yes, using the 'hold' button to get 'out' of the program and to raise the temp setting from 68 to 69 because you have to hit the 'up' button at the same time as the 'hold' button to get it to work.

http://forums.pelicanparts.com/uploa...1640114086.JPG
Here's a really quick pic of it hanging on the wall.

Your A/C is working great!
;)SmileWavy

T'stats (electronic) don't last forever. I keep an old merc bulb two stage stat around just incase the White Rogers Big Blue stat packs it in. I am on my second Big Blue in 22 years.

I like this particular stat because it is very configurable in the service menu. Programmable for time.

Emerson has purchased White Rodgers and I believe the thermostats are still available. Not cheap.

http://forums.pelicanparts.com/uploa...1640120409.jpg


turn switch to HEAT



:p

YOU FIGURED IT OUT!




















C'mon man.;)

I didn't want to be a smartazz .... just yet :D. I've had that model for a few years now ... didn't even know it had batteries....

Saved me from starting a thread eventually ;)

So fun aside I think you should just go to the Depot and grab a fresh one and see what happens. Take it back if that's not it.

Mine you don't have to 'hold' the hold button, you just click up or down and push hold and there's a "HOLD" indicator in the display. dunno.

SmileWavy

Since you posted a pic of the t-stat, it's only capable of single stage heat. So not that. However, there should be a "Heat On" that shows up on the screen when it calls for heat. If the room is colder than the set point, does the furnace eventually come back on all by itself, or do you have to do something after the 15 minute shutdown?

One thing if there was a power outage and the batteries were suspect - go through the setup again and make sure none of the settings are set weird.

http://www.kele.com/Catalog/22%20Thermostats_Controllers/PDFs/TH4110%20Installation%20Sheet.pdf

Page 8, go into setup and verify. You probably want the default (in bold) for your configuration.

One other thing, when the furnace does its 15 minute shutdown, are there any errors showing on the furnace controller itself? It may or may not have warning lights, and you may need to remove a cover to see them.

Is is plugged in? :D

Really appreciate the help and suggestions.

Thermostats are simple stupid to replace. I like the non programmable just because less to go wrong. The 60 dollar home depot honeywell one is pretty slick. Easy diy instructions.
As long as you're not running a two stage pump. All the wires are color coded. Recommend taking picture of the wiring to the back of the original thermostat just in case.


Also might be low on coolant and the evaporator might be frosting over.

If you have a voltage meter, put the leads on W and C. You should see 24 volts if the thermostat is calling for heat. If not you'll get no voltage. You want to make sure the call for heat is ending and it's not your furnace cycling off of the limit switch. And easy way to test the thermostat is to put a jumper wire between R & W at the furnace circuit board. If the furnace just keeps running, it's the thermostat. If it cycles off again, it's cycling off limit and you've got some looking to do to figure out why. Typically a dirty air filter but I've seen dirty evaporators cause the problem and a blower wheel that is slipping on the motor shaft too.

This morning's T-stat adventure is being attacked a little more scientifically thanks to you guys.
Here's a pic of it this morning.
http://forums.pelicanparts.com/uploa...1640184660.JPG
It ran @10 minutes from start up this morning before shutting down. I looked and it had a 'Heat On' showing on the T-stat. It started back up within a minute. Has run about 20 minutes and I took the picture. About a minute after the picture was taken it shut down, still 'Heat On' showing and 3 degrees short of the goal. It started back up within a minute.
I didn't look at the basic setup yet so I still have to do that. Sorry, got lazy after wrestling trying to get the printer going with the switch I bought.
I'd be more motivated to get this straightened out if we didn't have any heat at all. I've called the electrician, hopefully they can work us in sometime today.
The furnace just shut off again as I'm typing. 'Heat On' still showing and we're at temp too. It started up again and I just heard a 'click' from it. 'Heat On' is now off, so I think it's in the cool down phase that it goes thru.
More to come...and thanks to all for helping.

I know you guys probably think 'Why doesn't he just get a new stat and put it in? It's simple.'

When I was young a cousin of mine went fishing on a private lake in Texas. Story goes that there was some kind of bridge or something that they passed under with the aluminum boat they were in. My cousin, Geoff, reached up to help guide the boat and was electrocuted when he touched the bridge which was steel. Somehow something got mis-wired and the bridge was 'HOT'.
Ever since then I've been very leery of messing with electrical stuff. I just haven't been schooled enough in the 'how to do it right' to trust that I wouldn't end up killing someone.

As Cab had mentioned, it could be a problem at the furnace, not the T'stat.
To eliminate the T'stat completely, turn the heat cool switch to "off" and at the furnace terminal board, jumper R to W and see if the same thing happens. It is only 24 VAC but be careful not to short while trying this.
Gas heat? Check your outlet temperature and see if it is high. This would indicate a lack of airflow due to closed registers/vents, restriction through the air filter, dirty fan wheel etc.

Lol, I see the fear of electricity post after I had posted my response.

Turn the furnace off while jumpering R-W and that should eliminate any possibility of getting zapped!

Yeah, our furnace is up in the attic. I'm not as spry as I used to be so I'm not about to go up there to mess with it.

I am with you there! I avoid the attic space in the house and haven't been up there for years.
Did you have the T'stat off the wall for the photo? You could also jump R to W at the thermostat.
Don't want to talk you into doing something you are not comfortable with.

Okay, turn the furnace off at the breaker. Tie the R and W wire together at the thermostat. Turn the furnace back on at the breaker and see what happens. If the furnace runs and the house warms, it's the thermostat. If it short cycles, limit. And no worries about zapping anyone if you follow my directions. Plus you're on the low voltage (24v) side when working at the thermostat. Just make sure you turn the breaker off, remove the red (R terminal) wire from it's terminal, Remove the white (W terminal) wire from its terminal, twist the two together and turn the furnace back on. You'll probably hear the fan cycle for about 30 seconds when you power it back on then it'll start going into a heating cycle.

If you're not comfortable messing with it I get it. But with the breaker off for the furnace you shouldn't have any worries and 24v just gives you a nice little tingle. If you'd feel better, I can PM you my phone number and talk you through the whole process. I even promise not to yell DON'T DO THAT while you're messing with the wires.

Based on that, you're cycling off of limit. The Heat on indicates you've got a call for heat. The fact that it remains on when the furnace turns off tells me you're cycling off of limit. I'd call a heating contractor (well, I wouldn't because I am or was one) and have them check the system out. Make sure you check your air filter or filters before you call someone to come look at the system. I've seen some attic systems have a primary in the wall or ceiling of a home but also have one at the furnace.

Edit: One more thing. Make sure all of your supply registers are opened and none are blocked off too.

OK, got a call from the local electrician/heating/a/c company we've used for electrical stuff. They are swamped with calls from people without heat so we slid down the totem pole on getting them here before Christmas, which is fine with me. We have heat and I'd be in a world of hurt if we didn't. They said it sounds like the heater is working as designed. It may just need a thorough cleaning, which it's never had in the 10 yrs we've had it since it was put in. We don't use it like most people do/would. It only gets run if it's really hot or cold. It's not a set it and forget it system as far as how we run it. I doubt it has 1 full years worth of run time on it. So they'll call us after Xmas and set up a 'thorough service cleaning' to make sure everything is OK.
Thanks again for all the help.

Yours may not have batteries. It's possible for a thermostat to get power from one of the wires coming from the HVAC unit. If that wire isn't there, then you must have batteries. If the wire is there, then I think you can have batteries anyway which might (can't remember for sure and may depend on thermostat) help with settings in the case of a power outage.

Understandable. I probably need some sort of event, because 9 times out of 10 that I do work on electrical, I don't even turn off the breaker. I've recently rewired lights, switches and outlets in 2 bathrooms with the breakers on.

yeah. "Ground" is not automatically ground.
It's often several circuits connected to the same path of least resistance. The breaker box.
Something else along that same path can be considered "hot" and back-feed to a point inside above the final termination sink, i.e. the earth.
Pipes and copper rods are usually used afaik but are not guaranteed.

I heard a story of some neighborhood household electrical problems in SF that were next to an electric train station. Big electricity. We are talking tens or hundreds of thousands of volts. There was an engineering ground problem. The earth in the whole vicinity became energized, which disrupted all the other grounds nearby.

When I moved into my new (to me) house last spring, mine was acting the same way. After some research I found out that the filter was SO clogged that the heat would back up into the furnace and it would auto shutdown due to high temps.. Assuming your filter is clean, make sure you are getting sufficient airflow though the system.

and then buy a WiFi enabled TStat. You can turn it on/off/adjust it from your phone... I use that feature every single day.