Replace Aging HVAC or Install Additional System


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Old 11-22-21, 10:43 AM
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Replace Aging HVAC or Install Additional System

Hi everyone

I just reread my post from when I had a Manual J calculation done. There was some terrific info there.
Here is the LINK

Background:
  • Moved here about 5 years ago: Split level home, relatively tight, built in the 1960s, in north NJ
  • Current Furnace/AC Condenser dates to 2005
    • Lifespan, as I understand it, is 15 years at high end (translation: could last another 15, could die tonight)
    • Lennox G60UHV, 80k BTU furnace
    • Lennox model HSXB15 condenser, 3 ton
  • Some family members have developed significant allergies since moving in to this home, but HVAC salesperson said its unlikely that new system would change that (he wasn't sure that my hypothesis would be correct, that dust in the basement is being drawn in to ducting)
  • Upstairs tends to be 5-8 degrees warmer in summer than main living area
So, today I had vendor #1 in to provide a proposal to replace my HVAC system.

His proposal:
  • Bryant Legacy 3 ton 16 SEER condenser and matching evaporator
  • Bryant Preferred 96% AFUE ECM Condensing Gas Furnace 2 stage variable speed furnace

At my request, He ALSO suggested considering a ‘ducted, ductless’ new system on my second floor. It would provide AC in summer for this living area, and it would also be a heatpump, so we wouldn’t have to heat the whole house while sleeping during much of the heating season--at a minimum, on the shoulder seasons. It would have a better chance at ameliorating allergy issues as it would be new ducting on that level.

With budget as no obstacle, I would consider doing both. But this is real life, and cost IS important

So, my questions to the experts here:
  1. Should I stick to the plan, and pro-actively replace the current HVAC system?
    • Other than requiring annual flame sensor cleaning (we discovered that last year-- those sensors get DIRTY. Wonder if the allergen issue is related?)
  2. Should I consider 'if it aint broke, dont fix it' approach and focus on the option that has the highest likelihood of improving comfort in the home? ie: Do the ducted/ductless unit. It has the best chance of reducing allergens that we suspect are being drawn into the existing system, as we would use ductless for the bulk of our cooling and possibly much of our heating needs
    • Proposed unit: Carrier 18000 BTUH Heatpump Condenser
  3. Is Bryant a good name for HVAC equipment? We are already at nosebleed pricing level. Not sure if I should request Carrier brand proposal....?

Thanks in advance for any and all advice!
--K
 
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Old 11-22-21, 11:30 AM
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You simply never know when the system will go so there is no right answer to that.

Dust is everywhere in a house, not just "basement" dust, a furnace system is useless in removing airborne dust regardless what is installed. Think about how often the furnace runs in a 24 hour period, simply not enough run time to make any noticeable difference.

Upstairs is always hotter, further from the furnace, heavy cold air, heat from the roof.

You want a balanced system, look into zoned ducting, one HVAC system, two zones, upstairs and down stairs. Having had that in one house it's the most cost effective way to go, if it can be installed into the existing structure?
 
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Old 11-22-21, 12:46 PM
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Bryant is owned by Carrier, so if you go with Bryant, you essentially have a Carrier product. FWIW, I have a Bryant split A/C that was installed in 1995 (R22) and it's still running. It maybe doesn't get as cold as it used to, but it is sufficient to cool the house. Nothing has been done to the A/C system since it was installed.
 
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Old 11-22-21, 01:32 PM
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Lifespan, as I understand it, is 15 years at high end

>Assuming 95% ("two sigma" in the Normal Curve) of the cases are covered by this, your chance is 95% that your unit is "done".

But DIY'ers keep & repair things way beyond their "normal life for risk-averse homeowners".

I have repaired my '82 relay-logic NG furnace several times, but the maker was kind enough to provide me a Theory of Operation [& we have a gas fireplace]. It's very unlikely that I can repair a computer controlled unit.

You could search
"Repair or replace decision"
& put a dollar value on your time & inconvenience.

Split level home, relatively tight
>Average house is 6 BTU/(sq ft x heating degree day), a tight house is 2, our 2200 sf '64 house is 12 or so, even with new windows.

Your NG gas bill will tell you.
 
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Old 11-22-21, 02:03 PM
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Hi Marq1!

Alas, reducting my split level home would likely be quite an invasive project. That said, adding a heatpump/ac, separate unit for the upstairs would only be 'mixing' the air from that level, no? Would that not help to alleviate the dust from the lower levels?
 
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Old 11-22-21, 02:33 PM
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Thanks as well, Bob and Bulova!

My energy bills are pretty reasonable-- $150-190/mo for electric in summer, about the same in winter for the NG.

House is 1700 sq ft, and we installed blown in cellulose to get to R-49 when we moved in
 
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Old 11-22-21, 04:01 PM
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1700 sq ft
>if avg temp for 24 hrs for a windless, sunless period = 40F
if CCFs used during this period = 62
your Tightness Index is 6.1

For 10F avg, TI = 2.8.

Don't count the gas WH consumption if you have one.
 
 

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