Hello friends,
It is time to replace our aging gas furnace/AC. The furnace is 23 years young and AC is about to be 15 this summer.
Attempted my own load calc (not entirely confident here), came up with 43k cooling BTU, 53k heating BTU. Although only 23 years old, our house is pretty leaky/drafty. and has some brutal exposure. The main living area which has a 20' high vaulted family room (directly under 45-degree pitched, black asphalt shingle roof (joists, no attic there) which opens to the adjoining kitchen - all both with full western exposure.
Current equipment is a 92% 75k BTU gas furnace with a 3.5 ton AC condenser/evap coil.
Heating is no problem currently when the furnace isn't broken. The only issue I have with the current system (other than age) is that in the dog days of July and August, the AC cannot maintain 76 degrees set point in the main living space – as explained, that side bakes in the mid-afternoon. The current unit will run from about 2-3 pm through after dinner once cooking is done and can maintain at about 80 degrees minimum until the sun gets lower in the sky. It’s not horrible, but not exactly comfortable either. We aren’t that picky, just a little picky.
I am trying to compare recommended equipment of our 3 bid options which are all within about 10% cost factor (negligible). Furnaces appear to be oversized to me but from reading this site, it is apparently very common for contractors to do this, and in my mind, the 2 stage units will compensate for this by likely running nearly full time in stage 1. Contractors were not playing ball talking about smaller furnace sizes, one mentioning that the larger unit would be needed for cooling CFM. Despite these factors, between my personal Manual J attempt and the one contractor’s referenced “proprietary” load calculation, all systems are relatively in the same ballpark as far as sizing is concerned. I am trying to compare like equipment to get opinions of quality, as I believe that all 3 of these contractors will do a good job with install. I likely trust Contractor 2 the most due to previous relationship and repair work performed, plus their outstanding labor warranty offer.
I am intrigued by Contractor 3Â’s bid for the 2-stage outdoor unit because the other two contractors offered 2-stage units as an option but those quotes are way outside of our budget. The 2-stage 4-ton unit makes me wonder if most of the time the unit could operate at 70% capacity in stage 1 (2.8 tons if my math is correct) and then during those dog-day afternoons that I mentioned, it could compensate for the load by ramping up into stage 2 to keep the house closer to the setpoint. And by running longer most of the time at 2.8 tons, it would do a better job with dehumidification?
Here are the bids:
Contractor 1
Located via HVAC-Talk map, only one in my area I could get to bid. No apparent load calc done.
Bryant Preferred 96%, 80k BTU input, 2 stages, variable speed
Bryant Legacy 16 SEER 3.5 ton
Bryant Cased coil CNPVP4217ALA
2-year contractor labor, 10-year manufacturer parts, lifetime HX
Contractor 2
have used several times for service over the last 10 years. Always reliable. Referenced load calc but keeping proprietary.
Rheem Prestige 96%, 84k BTU input, 2 stages, variable speed
Rheem Classic 16 SEER, 3.5 ton
Rheem Alum cased coil, 4.0 ton with elec. TXV
16(!!) year contractor labor (with a yearly maintenance plan that we will do regardless), 10-year manufacturer parts, lifetime HX
Contractor 3
Good local references, been in the community forever. No load-calc done.
Trane S9X2B080U4PSBA 96%, 80k BTU input 2 stages, 9 speed ECM
Trane XR 17 4TTR7048B1, 2 stage
Indoor cased A-coil model 4PXCBU48BS3
5-year contractor labor, 10-year manufacturer parts, lifetime HX
This contractor also gave a 1-stage outdoor unit bid that was a 3.5-ton like the first two, as a less expensive option
Thanks in advance for any feedback you can share :putergreet: The name on the box is more important than the name on the truck, right? Right?! :oops:
It is time to replace our aging gas furnace/AC. The furnace is 23 years young and AC is about to be 15 this summer.
Attempted my own load calc (not entirely confident here), came up with 43k cooling BTU, 53k heating BTU. Although only 23 years old, our house is pretty leaky/drafty. and has some brutal exposure. The main living area which has a 20' high vaulted family room (directly under 45-degree pitched, black asphalt shingle roof (joists, no attic there) which opens to the adjoining kitchen - all both with full western exposure.
Current equipment is a 92% 75k BTU gas furnace with a 3.5 ton AC condenser/evap coil.
Heating is no problem currently when the furnace isn't broken. The only issue I have with the current system (other than age) is that in the dog days of July and August, the AC cannot maintain 76 degrees set point in the main living space – as explained, that side bakes in the mid-afternoon. The current unit will run from about 2-3 pm through after dinner once cooking is done and can maintain at about 80 degrees minimum until the sun gets lower in the sky. It’s not horrible, but not exactly comfortable either. We aren’t that picky, just a little picky.
I am trying to compare recommended equipment of our 3 bid options which are all within about 10% cost factor (negligible). Furnaces appear to be oversized to me but from reading this site, it is apparently very common for contractors to do this, and in my mind, the 2 stage units will compensate for this by likely running nearly full time in stage 1. Contractors were not playing ball talking about smaller furnace sizes, one mentioning that the larger unit would be needed for cooling CFM. Despite these factors, between my personal Manual J attempt and the one contractor’s referenced “proprietary” load calculation, all systems are relatively in the same ballpark as far as sizing is concerned. I am trying to compare like equipment to get opinions of quality, as I believe that all 3 of these contractors will do a good job with install. I likely trust Contractor 2 the most due to previous relationship and repair work performed, plus their outstanding labor warranty offer.
I am intrigued by Contractor 3Â’s bid for the 2-stage outdoor unit because the other two contractors offered 2-stage units as an option but those quotes are way outside of our budget. The 2-stage 4-ton unit makes me wonder if most of the time the unit could operate at 70% capacity in stage 1 (2.8 tons if my math is correct) and then during those dog-day afternoons that I mentioned, it could compensate for the load by ramping up into stage 2 to keep the house closer to the setpoint. And by running longer most of the time at 2.8 tons, it would do a better job with dehumidification?
Here are the bids:
Contractor 1
Located via HVAC-Talk map, only one in my area I could get to bid. No apparent load calc done.
Bryant Preferred 96%, 80k BTU input, 2 stages, variable speed
Bryant Legacy 16 SEER 3.5 ton
Bryant Cased coil CNPVP4217ALA
2-year contractor labor, 10-year manufacturer parts, lifetime HX
Contractor 2
have used several times for service over the last 10 years. Always reliable. Referenced load calc but keeping proprietary.
Rheem Prestige 96%, 84k BTU input, 2 stages, variable speed
Rheem Classic 16 SEER, 3.5 ton
Rheem Alum cased coil, 4.0 ton with elec. TXV
16(!!) year contractor labor (with a yearly maintenance plan that we will do regardless), 10-year manufacturer parts, lifetime HX
Contractor 3
Good local references, been in the community forever. No load-calc done.
Trane S9X2B080U4PSBA 96%, 80k BTU input 2 stages, 9 speed ECM
Trane XR 17 4TTR7048B1, 2 stage
Indoor cased A-coil model 4PXCBU48BS3
5-year contractor labor, 10-year manufacturer parts, lifetime HX
This contractor also gave a 1-stage outdoor unit bid that was a 3.5-ton like the first two, as a less expensive option
Thanks in advance for any feedback you can share :putergreet: The name on the box is more important than the name on the truck, right? Right?! :oops:
source https://hvac-talk.com/vbb/threads/2236535-Bid-evaluation-My-Apples-to-Apples-1-Orange-attempt?goto=newpost
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