Do we need a new furnace?

Our furnace has been going out a few times over the last few weeks. The plumber told us after the first visit, that it wasa bad sensor. But then it happened again and we were told that if it keeps on happening it can be an internal problem and we need a new furnace (old one is 14 years old). Now, whenever the furnace goes out, my husband shuts off the power, moves the wires around on the furnace, turns the power back on and it works fine .. at least for a while, sometimes a day, sometimes 10 days. Any suggestions?
  11 answers
  • The furnace is no where near needing replacement. As long as the heat exchanger is intact all the other parts can be changed out. However you must determine what is really going on before you decide to simply replace parts or replace the unit. There are benefits of a new unit however, more efficient more quite and much smaller in size to save some space. If the furnace is working once the power is turned off then back on the gas flame sensor is going bad. This sensor triggers off the gas valve if it does not light the pilot correctly. When you turn off the power switch and then back on, you reset the control that keeps it from running once tripped. Most likely the sensor may be installed incorrectly, or a vibration has caused it to come loose or crack the glowing element. Replace the glowing sensor with a new one. Be sure to keep from touching it or bumping it. Then if there is a small thermocouple attached to the pilot area, this is a copper tube that is connected to a long smaller tube or wire that goes back to the gas valve. That also should be changed. Once done, you should be fine for several more years. If your husband is handy, this is a repair that can be done with just a little effort. A side note on furnace replacement, Based upon what I have been hearing and due to the new energy laws that are taking effect this coming summer, People will no longer be allowed to purchase any low efficiency furnaces only those of over 90% will be allowed to be installed. This means you will be spending much more money then you would if you put in another 80%+ furnace.
  • HomeSpot HQ HomeSpot HQ on Jan 09, 2013
    I agree with Bob. It is incredibly expensive to remove and install a new unit. It sounds like something is shorting out. Check the wires to see if there is any exposed metal or damage.
  • Karin W Karin W on Jan 09, 2013
    Thank you both very much. We are looking into buying a higher efficiency furnace before they get really expensive. Thank you for your advice!
  • Before you spend a few thousand on a new furnace you need to evaluate your air supply duct system. As an energy auditor I often find new furnaces, although in the 90%+ range installed, the delivered overall performance out the ducts is in the low to mid 70's This makes your current 80% unit somewhere around low 60%. By simply fixing the duct supplies and returns by sealing and properly sizing them you will see a tremendous increase in comfort and much lower utility bill overall. By simply changing to a new furnace, which I think you do not need. And NOT fixing air duct supplies and returns for proper performance, You will only get what your current unit is supposed to supply once the ducts are fixed. So your choice is to fix ducts for about 20% of the cost of a new furnace and get another 8 to 10 years out of the one you have, or spend the thousands without doing the ducts and end up where you should be with the one you now have installed with just spending the cost to fix the ducts and nothing else. Ideally doing both new furnace and ducts is ideal. But that overall cost can be quite expensive and most if not all do not go though all that work. Main reason is that the sales person installs a larger fan (cost more) to overcome the inefficiency of the current air supply system.
  • Jeanette S Jeanette S on Jan 10, 2013
    Have a company with a good reputation in your area come out and check this out...get a referral from friends or neighbors. Ours shut down the Sat. before Christmas. Luckily we had alternate heat for our family gathering. Hubby turned it off and after the holiday A1 HVAC came out and a sweet gum tree ball had dropped down into the unit. We learned it was a Mr. Sparkey franchise...we have had several positive experiences with Mr. Sparkey! The service call and repair was just over $200! Our unit was only 13 years old so we knew it should have years left in it.
  • HomeSpot HQ HomeSpot HQ on Jan 10, 2013
    To Bob's point, make sure you use foil tape to seal up duct work. Ironically, duct tape is not good for these applications as it will become brittle with heat and fall off.
  • Even foil tape is not really all that good as once the heat dries out the glue on the tape it will come off, Not to mention any dust makes it impossible for it to stick. They make a duct sealing paste that you can purchase at the big box stores that is designed just for that. You can use a stiff short brush to apply, or get down and dirty and use your fingers. Just be careful you do not cut yourself. Caulking also works, but it is much more expensive and the duct needs to be dust free or it will not stick.
  • Karin W Karin W on Jan 14, 2013
    I changed my mind about getting a new furnace. Just can't afford it right now. The furnace stopped again last week and my husband got it started again. I guess we will have it fixed sooner or later, probably sooner, because I think they will stop selling parts for the lower efficiency furnaces. I want to use the duct sealant paste, which was mentioned. Can you recommend a certain brand? I saw that they have just one brand at Homedepot and it is allot cheaper than the brand I saw online, which was called Mastic. Which one are you familiar with, that is easy to apply?
  • Jeanette S Jeanette S on Jan 15, 2013
    Karin W, I hate to be an alarmist, but when an electrical thing is giving you trouble, please keep in mind that fires can get started this way! Dangerous to all of you so pay the professional to come out and fix cannot replace your loved ones! Do it today!
  • Karin, they are all about the same. As far as duct sealing compounds. HD brand is fine. As far as getting the parts, they will be around a long time. But you really should replace the ignitor because one day it will not restart. If money is the issue, they really do not cost all that much.
  • Theresa Stewart Theresa Stewart on Feb 24, 2015
    I hope you meant electrician and not plumber. Call an electrician (another one) and have it re-checked out.
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