[mjllewellyn]

Hello all, new here.

Having difficulties with my heating system at home, bad timing too in the winter...

Basically it acts irratically, so hard to explain exactly but. For example, we notice its getting cool in the house. I check the thermostat and the room temperature is 1.5-2 degrees below the heat set point. I have it on the HOLD mode to override the program. The little heat icon shows as being on, but the fan isn't running at all. If I turn the heat setting down until hearing the relay click, the icon goes off. If I turn it back up above the set point, the relay clicks again and it starts up. Sometimes the fan will kick on with the heat as its supposed to and work fine. Problem is, at times it only kicks on for about 5-10 minutes then shuts off, leaving the heating icon on the screen but no heat.

I've tried resetting it and everything else I can think of, it used to work fine but in the past little while its been acting up. Other times we put the set point very high and it wll stay on and heat the house, usually going above the set point before shutting off, at times a full 1+ degrees above that.

Also, I can turn the fan on manually by taking it off "Auto" so that part works.

Furnace is about 10 years old now.

I've heard the Noma units aren't the best, so I bought a new Honeywell WiFi unit to install. Haven't done that just yet, just hoping I have a wonkey thermostat and NOT more expensive furnace problems happening.

[talaniman]

There can be many other outside factors that affect your thermostat including the weather, where its located, and how and when it was set up. If there are hot and cold spots in your home, all these and more affect the operation of your thermostat and when the weather is wonky, so will it's operation be a bit wonky. I think you explore these other factors before you decide to fiddle with the thermostat.

Heat & Cool Efficiently : ENERGY STAR

http://www.energystar.gov/index.cfm?c=heat_cool.pr_hvac

A one or two degree fluctuation is not necessarily a thermostat problem.

[mjllewellyn]

There can be many other outside factors that affect your thermostat including the weather, where its located, and how and when it was set up. If there are hot and cold spots in your home, all these and more affect the operation of your thermostat and when the weather is wonky, so will it's operation be a bit wonky. I think you explore these other factors before you decide to fiddle with the thermostat.

Heat & Cool Efficiently : ENERGY STAR

Heat & Cool Efficiently : ENERGY STAR

A one or two degree fluctuation is not necessarily a thermostat problem.

Thank you for the reply. I am in Southern Ontario, very cold outside right now. Was just concerned because if I have it set for 26 for example (just to test it), the heat icon comes on for a bit then shuts off. But the heat icon stays on for hours, but the temperature isn't increasing all the time. Seems to happen most at night, late.

[talaniman]

Where is your thermostat located? The ambient temperature around windows AND oft used doors can keep a room cold, and colder at night once the temperature falls. When is the last time you cleaned and inspected your duct work? If you can operate your thermostat manually, chances are its NOT the root cause of the problem.

A more accurate test would be monitoring the temperature in different locations around the house at different times and seeing a pattern. You may be losing heat as fast as you produce it.

[mjllewellyn]

Its located on the main level of the home. I understand there could be hot and cold spots. But.. If I have the temperature SET to say 24, why isn't reaching 24? Why is it shutting off early and just sitting there dropping the temp? That tells me its just not working properly. When it doesn't decide to work properly, it pounds out the heat and works well. It almost seems like there is a relay problem in that thermostat, signals not clicking over when they should. Just never done this prior to now, everything in the furnace is cleaned and maintained.

[talaniman]

I don't know your skill set or level, but here is the procedure to check your thermostat.

http://www.ehow.com/how_7893559_noma...tructions.html

How to Troubleshoot a Thermostat | eHow

Or have a handy man that you trust go through the process. It might be an easy fix, it may NOT.

[mjllewellyn]

I don't know your skill set or level, but here is the procedure to check your thermostat.

Noma Thermostat Instructions | eHow

How to Troubleshoot a Thermostat | eHow

Or have a handy man that you trust go through the process. It might be an easy fix, it may NOT.

Ok so it happened again yesterday. Got home from work to a cool house, turned up the stat and it came on for about 10 minutes then shut off. The heat symbol still showing on the stat as active, but the furnace not running. I then dropped the temp on the stat in order to get that flame icon to disappear and "Click" off. Then when I ramp it back up it comes back on.. sometimes it will shut back off again, other times it will keep going. House got nice and warm last night once it decided to stay on, so the temperature was about 24C last night before bed, furnace was still running. I dropped it to 23.5 before bed. Woke up this morning to 20 degrees, heat symbol still showing on the stat but obviously not working.

Before replacing the stat (which I already have new one) if I remove the current one and connect the white with the RH wire, then turn the furnace power back on, this will show if my stat is working properly correct? From what I read it should kick right on with those wires tied. If it stays on like this then maybe the stat is bad? Really strange behavior.

[mjllewellyn]

I don't know your skill set or level, but here is the procedure to check your thermostat.

Noma Thermostat Instructions | eHow

How to Troubleshoot a Thermostat | eHow

Or have a handy man that you trust go through the process. It might be an easy fix, it may NOT.

Since my last post, I've disconnected the STAT from the wall to see which is the problem. I tied the red wire to the white, turned the breaker back on. The furnace came on almost immediately, ran for about 10 minutes then shut off. I'm not sure if that really tells me anything or not. I have however seen this furnace do that before even on a good day before any of these issues, it will usually come back on after that, is that a normal thing for them to do? Got chilly again last night. Seems to work to get the house warm, but when I set the temp lower for overnight and it drops.. I wake up to see the room temp well below the set point, flame icon on the screen going, but nothing happening constantly. Seems to come on, but not stay on.. So it just hovers below the set point. I'm going to try replacing the thermostat tonight as I've already purchased the new Honeywell WiFi unit, so at least I can see it on my smartphone what is happening with the temp when I'm not there.

I did notice the circuit board with the LED on it, but when the cover goes on and closes the switch I can't see it. There is no little window for me to see what is happening, or if there is an error code...

[talaniman]

If your furnace shuts off while direct wired you have another issue that's not thermostat related. It may be as simple as a flame sensor, or a bad connection, but a furnace inspection is indicated.

With the furnace on you can observe when it shuts down after removing the burner door and you should be able to see red blinking led light that will tell you what the fault is. I will say at this point not knowing your skill level, or knowledge of a furnace system this may e best done by a professional, but for sure if the same results of your new stat remain, then you know for sure it wasn't the stat in the first place and you have to move to the next step.

If it is as I suspect, NOT the stat, then your furnace is cycling on the built in safety limits, but you should be able to get to the problem from your LED indication lights that are visible from either the furnace door, or the blower compartment door. Try your new stat first, that's the easiest route to go, and you have one handy.

Please let me know what the results are. Do you have a service manual for this furnace? How old is it? Is it still under warranty?

[mjllewellyn]

Thanks for the reply. Regarding my skill level, I am an engineer. Just haven't worked directly with a furnace before, so I like to be well prepared. But working mechanically with things isn't a problem for me. Regarding the flame sensor.. That's the "L" sort of shaped part I've seen people cleaning on YouTube correct? I am going to try to locate that later on, remove it and clean it. This unit is about 11-12 years old now. Believe the brand is Diamond 80 series.

[talaniman]

Why does the gas furnace short cycle - YouTube

This one? I look the codes up before I monkey around with anything.

[mjllewellyn]

There are many videos out there. It had service done to it about 3 years ago, I did notice a lot of new parts in there when I was looking inside. Just thought that nothing bad can come from a simple inspection of this sensor, the symptoms caused by its faults are similar to mine. But I know its not limitted to just that, at least the heat does work when it gets going and won't shut off until I drop the stat temp.

[talaniman]

Back to the stat huh?

Thermostat Temperature Calibration | DoItYourself.com

I only assume you have gone through this process. Its quite tedious as was programming the 7 day, or 5+1+1 day times and temperatures from the default settings.

Glad you have heat, but be prepared for higher heating bills.

[mjllewellyn]

Back to the stat huh?

Thermostat Temperature Calibration | DoItYourself.com

I only assume you have gone through this process. Its quite tedious as was programming the 7 day, or 5+1+1 day times and temperatures from the default settings.

Glad you have heat, but be prepared for higher heating bills.

Ok so everything is now functioning 100%. In fact its much better than its been running for years now. Maintains the temperature bang on. Problem is I don't know which of the two was the problem... I removed the flame sensor last night and cleaned it with a VERY light grit sand paper. Even then I barely put any pressure on it at all. Sensor rod was black and white towards the center. Cleaned that outside material off and wiped it after with a clean cloth.

Then rewired the furnace (Didn't have a "C" at the stat) the Honeywell WiFi unit needed the common wire. Everything went perfect, EASY setup on that stat, can control everything remotely from my smartphone.


Thank you very much for all the advices, glad I took the time to learn from others rather than spending $$$ on having it done by someone else. Had my hand on the phone a couple times ready to call them in, but didn't.

[talaniman]

Glad you had a positive outcome. Being warm and saving a few bucks is well worth the efforts.