Need furnace help

[AMink]

I have an older model Night and Day gas furnace that was installed when the house was built in the mid-80's. Recently the furnace fan has been coming on after it shuts off after the fire shuts off and the fan has removed the residual heat. It turns on for a couple of seconds, off, then again once or twice. I doesn't do it more than three times. I've cleaned the filters and installed a new limit switch but it continues to happen. Nothing else has changed since this has started to happen. Any ideas/suggestions?

 

[p-Bar]

Sounds like something in the computer module is bad . Try unplugging it and let it sit a couple minute and plug it back in. Good luck

 

[AMink]

Sounds like something in the computer module is bad . Try unplugging it and let it sit a couple minute and plug it back in. Good luck

I'll give that a shot. This thing is so old I'm not sure it has a computer!

 

[seafish]

CHeck out these GREAT short vids on fan cycling with Honeywell limit switches--

https://www.youtube.com/watch?v=r0LUzC4JTiQ

https://www.youtube.com/watch?v=C1cE8hubfys

https://www.youtube.com/watch?v=QpHfFdk04u0

 

[AMink]

CHeck out these GREAT short vids on fan cycling with Honeywell limit switches--

https://www.youtube.com/watch?v=r0LUzC4JTiQ

https://www.youtube.com/watch?v=C1cE8hubfys

https://www.youtube.com/watch?v=QpHfFdk04u0

Those are good. I know I have power to the fan because it does come on. Unfortunately, the limit switch in my unit is set; there is no adjustment. I'm going to try the unplug/plug and see if that jolts anything. With a unit this old, pushing 30 years, it might be time to get a newer, more efficient unit. It's only money!

 

[SVick]

Hello, I've got over 30 years in the residential and light commercial HVAC business and own a company now. The first thing I would check is the heat exchangers, if you have a rupture it will cause the same effect. A 30 year old furnace is at 1.5 times its expected useful and safe life, please replace if you can. If the heat exchanger is cracked, it is unsafe to operate and must be replaced. I don't know where you are, but let me know if you want more info.

 

[AMink]

Hello, I've got over 30 years in the residential and light commercial HVAC business and own a company now. The first thing I would check is the heat exchangers, if you have a rupture it will cause the same effect. A 30 year old furnace is at 1.5 times its expected useful and safe life, please replace if you can. If the heat exchanger is cracked, it is unsafe to operate and must be replaced. I don't know where you are, but let me know if you want more info.

I think replacement is the way we'll go. Any suggestions on brands? Lennox and Carrier seem to have good reviews but there are lots of others.

 

[AMink]

Thanks for the suggestions. I had an HVAC guy come out and take a look. The brain is going, the bearings on the fan are going, and the piece that supplies the power to the fan motor is going. New furnace. D'oh!

 

[Jim W]

I think replacement is the way we'll go. Any suggestions on brands? Lennox and Carrier seem to have good reviews but there are lots of others.

I would stayaway from the Carrier units. There has been a class action lawsuitagainst Carrier with their ceramic heat exchangers failing prematurely andnot being warrantied. I found this out when I did research to replace myfurnace in my house.
I ended up buying an American Standard furnace and new AC unit. I purchased a95% energy efficient furnace with a DC variable motor, witha new furnace thermostat that controls everything. This unit is a setbackmodel were the temperature can be changed as one wishes with the furnace fanrunning 100% of the time. My heating and cooling bills have changed significantlyover the older 80% efficient furnace that I had. The savings has been about 50%in gas/electrical usage combined over what they use to be. I am very pleasedwith the unit. I do have the furnace inspected and clean every year by thecompany that installed the unit. Air filters are changed every other monthsince the fan runs contentiously, filters a lot of dust.

 

[SVick]

Everybody has there own opinions on the brand and we all know what opinions are like. That said, I am an Amana dealer for the last 6 years and have had the lowest amount of warranty issues by far from the other brands I have used which are Trane/American Standard, Rheem, and Lennox over the years. Funny thing is that Rheem/Ruud has been at the top of the Conumer Reports list for years and was by far the most problematic brand I have ever used, and I mean by faaaaaaar! Amana has the best heat exchanger in the business and the best warranty to back it but the most important part of the project is the design and INSTALLATION!!!! Get the best person to design, size and install whatever brand he offers and likes. The duct system is the most important section of the system, so make sure it is designed and sized correctly for the house and the machines.