When to consider replacing furnace / ac

Old 04-15-21, 12:16 PM
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Question When to consider replacing furnace / ac

Hi everyone!

Sorry, as this isnt a true 'DIY' question, but I feel that I would get better advice here than I would by getting companies in my home for quotes on a system I may not yet need..

We moved into our home about 5 years ago. We were told that the furnace would eventually need replacement due to age. My question is: how does one know if a furnace failure is oncoming?

The furnace in question, a Lennox G60UHV, 80k BTUs, was put into service on or around 2006--per the sticker on it. Its paired with a Lennox condenser, model HSXB15 (3 ton, I think-- I was told to 'never replace that condenser' as it was well made, and meets/exceeds current requirements. That thread is here: Posts 32 and 27 refer to my AC )

So, I am trying to wrap my head around risk here. I have two young kids, and would prefer to 'be in the drivers seat' when it comes to needing to replace this--versus an 'emergency replacement' where I am at the mercy of whomever shows in terms of what we put into service.

  1. 1. Do natural gas fired furnaces, like mine, give any warning when failure is coming?
    • Is there anything that I can check, proactively? Right now, the only 'trouble' it gives me is an almost yearly need to have flame sensor cleaned
  2. 2. How does one educate themselves on what to look for in a new furnace? I know I want:
    • -energy efficiency
    • -quiet operation
    • -better air filtration (we are all suffering from allergies when HVAC is in use-- we have a MERV 8 filter in there); maybe one of those bulb type air cleaners?
    • -and two stage (or variable?) system
  3. 3. Should I stick with Lennox? Are there brands/models known to be well made and others known to be 'builders grade' or basically garbage?
  4. 4. Given the advice in that old thread, I am loathe to replace my condenser should my furnace be replaced--is this a bad idea?

Any advice on this is really appreciated! I am hoping I am way ahead of myself on this, but I would really like to be informed when it comes time make a (costly) decision.

I should mention: last year, I had a well-regarded HVAC company out for a Manual J Heat Loss assessment. They charges hundreds of dollars to provide a copy of the report. He told me that my system was sized appropriately (if I do go forward, I will have another done before final selection of equipment). Right now, I will be using sizing of my existing equipment as a benchmark for estimating costs.

Thanks again for the advice!

Last edited by sirk98; 04-15-21 at 12:17 PM. Reason: bullet numbers didnt appear. Manually added
Old 04-15-21, 03:05 PM
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You will never know and there typ is no notice.

I just had my every 4 year inspection on our GEO last fall and this winter a capacitor went bad. Nothing they could have predicted but it happens.

Honestly for a regular old gas furnace they can easily be replaced in a day so fearing an extended period of time without is not really an issue.

Your furnace is not all that old, after 20 years I might start thinking about it but your years away from that!

Old 04-15-21, 03:32 PM
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I am in a similar situation with my 20 year old system. This spring my AC compressor has started occasionally making a nasty sound when starting. I have my HVAC person coming out tomorrow and probably put on a hard start kit before it gets worse. We will also inspect everything and get some idea when I need to replace. I want to replace before it dies catastrophically especially since many things are not in stock like they used to be. I don't want to be forced into buying what's available if my AC should die before life and inventories fully return to normal. If I have anything new to add after tomorrow inspection of my system I'll post back.

1. Yes and no. Many failures like a bad ignitor or control board tend to happen without warning. A rusted through or cracked heat exchanger will often give warning (and is why you should have a few CO detectors). Sometimes when it goes the unit will light and then it quits shortly after and may blink an error code for a flame rollout. Also, listen. Many problems with blower motors and AC compressors will telegraph a warning with unusual sounds.

2. I think it is good to talk to others and see how they like their systems. Everyone has high seer and quiet two stage and variable speed options. I really don't like putting the air filtration burden on the HVAC system unless you choose carefully and install a system that can handle it. I've seen many problems caused by people putting restrictive filters in a system not designed for it. In your case keep in mind that higher MERV filters create more resistance to airflow so your system will have a harder time moving air which can strain components and may suck in more outside air if the ductwork is not completely sealed. A good talk with some reputable HVAC companies would be wise so you can get some professional advice.

3. Most major brands in my experience are similarly reliable. Sure there are some that are better than others but they are all (that I know of) are pretty good so I wouldn't get hung up on Amana vs Goodman vs Rheem vs Lenox... so much. I have seen a difference among each brands "tiers". The lower seer inexpensive units may have some failures more often but from what I've seen the parts are readily available and inexpensive. More premium high seer, two stage or variable speed have some higher quality components but they are more complex with more to go wrong and the parts sometimes/often have a lead time and can be quite expensive.

4. No clue what old thread you are referring to but... this is one thing we will discuss tomorrow. I know my condenser is having troubles but I think my furnace is OK. But the AC portion of my system is the big part of the expense and the furnace is 20 years old and I think 80% efficient so there is room to upgrade in efficiency. Plus, If I'm spending many $k on the AC portion of the system I don't want to have to tear everything apart to replace the furnace or air handler in a few years.
Old 04-15-21, 04:37 PM
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thanks for the replies!

in reply to your reply on question #4, this is the thread:
Lennox furnace: only wired single stage

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