hvac estimates and choices, help!

joan1953

14 years ago

Could really use some opinions on whether we are selecting the right system for our situation, and which quote we have received is more reasonable.

Our situation: 3,000 sf 2 story house in Southern California. Presently we have a 30 year old gas 110,000 btu furnace, one 5 ton AC condenser, and a basic Honeywell programmable thermostat. We are looking at putting in 2 systems because there is always a large temperature difference between the 2 floors for heating or cooling seasons with only one system. We presently use the AC only occasionally in the summer. My guess is that our gas bill from heating is about $315 annually, and electric from the AC use and blower is about $690 annually.

Right now we are looking at:

Carrier Performance Boost 80 furnaces 58PHX, 90,000 btu on 1st floor, 70,000 btu on 2nd floor, both with ECM blowers and 80% AFUE and single stage

Â Carrier Performance Series high efficiency Cased N-Coils

Â Carrier 3 ton Performance Series Condensing Units 24APA736003 R-410A Puron R-410A system. BEL rating as low as 6.7. Rated SEER up to 17+. Same for both floors

Â Totaline Thermostats P340

Â Replacement of all ducts and registers, R6 insulation and adjustable bar style grilles

We are down to two contractors who have excellent reputations. Before Fed rebates and Carrier rebates, one bid is $17,893, the other $20,666. Rebates will knock each down $2,000, therefore to $15,893 and $18,666 respectively. The more expensive contractor is implying that the other price is too low to do a quality installation. Any thoughts on that? It is a $2,773 difference.

Also the more expensive contractor suggests two different upgraded systems:

Â The first changes the Performance Boost 80 furnaces to Infinity 80 furnaces. 66,000 btu for both furnaces with 2 stage heating and variable blowers. This would add another $1,826 to his estimate bringing the price after rebates to $20,492.

Â The other upgraded system would change the Performance Boost 80Âs to an Infinity 95 AFUE 56,00 btu downstairs and an Infinity 80 AFUE 66,000 btu upstairs. Add to that two Infinity 17 series condensing units, 3 ton, 17 SEER and Edge thermostats. That would add still another $1030. This system has higher Carrier and a Gas Company rebates, bringing our cost after rebates to $21,522.

In summary it is the system with the Boost 80 furnaces for $15,893 or $18,666 depending on which contractor, and/or upgrading to partial Infinity equipment for $20,492 or full Infinity for $21,522. The less expensive contractor thinks those upgrades are overkills for us.

I am leaning to sticking with the Boost 80Âs because our utility bills do not justify the added expense of the other systems (though we plan to be in this house for 30 years). Also the claim is the ECM blower uses 80% less electricity than a standard blower. While the Boost 80 is only one stage I am not sure with our climate and use it will be that important to justify spending more. Also we were reasonably happy with our old pretty standard builderÂs equipment except for the big temperature difference between floors.

Any opinions on the systems and quotes would be very appreciated!!!

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Comments (5)

mike_home
14 years ago
last modified: 9 years ago
Joan,

You have posted a lot of information here. I will try to hit the key points.

Did either of the contractor do a load calculation? You currently have a single 110,000 BTU furnace. The contractors are recommending going to two furnance with a combined input of 160,000 BTU. That is a lot of BTUs for your climate in Southern California. At 80% efficiency, that is 128,000 BTU output. I live in Central New Jersey in a 3200 sq. ft. house. I have two Carrier Infinity 95% 60,000 BTU furnaces. This is 120,000 BTU input, and 114,000 BTU output. I am confident your furnace are way oversized considering my winters go into the low 20s. I also question why you need to replace your single 5 ton condenser, with two 3 ton units. I would think 2 1/2 tons upstairs, and 2 tons downstairs would do the job.

If you really only spend $315 to heat your home, then you will never see a pay back on anything above an 80% efficiency furnace. I do suggest you get a quote on a condenser which meets the $1500 federal tax credit (16 SEER/13 EER rating). You may consider going with a heat pump. The rating required for a the federal tax credit is a little lower.

I don't follow the Carrier rebates you quoted. For a Performance furnace and condenser system, the rebate is $250 per system. But you must get a Carrier branded thermostat. For an Infinity system, the rebate goes up to $1000, but you must get the Infinity controller.

I suggest you add the 10 year labor warranty from Carrier. Since you plan to live in your house a long time it is a good investment.
joan1953
Original Author
14 years ago
last modified: 9 years ago
Hi Mike,
No neither contractor did a load calculation. They both live close to me and claimed that for my house the 5 ton condenser I had was barely adequate. For that reason they recommended two 3 ton. It was also claimed to me that for a 3 ton condenser paired with a 80% AFUE furnace, the furnace size must be either 90,000 or 70,000btu. ??? Also in my house, I find in the summer frequently my upstairs gets hot enough that I would like to run the AC, but the downstairs is still quite comfortable. The reverse is true in the winter. Since I have a 2 story entryway smack in the middle of the house, I think the theory is that at those times I could run the system on the floor that needs it, and just run the fan to circulate the air on the other. The rise of hot and fall of cold air will benefit the other floor. Of course there will be times when both systems will have to run. We do go below freezing at times, and hit some 100 degree days. Does this sound like good reasoning to you?
Concerning the Carrier rebates. The Totaline thermostat is apparently made by Carrier. I looked it up on the web and on the bottom of the page it has: copyright Carrier Corporation 2008, so I am hoping that is OK. I will email Carrier directly. Also according to the chart given me by one of the contractors, for the Infinity Systems both the Infinity or EDGE Control thermostats qualify for their $1,000 per system rebate, hence $2,000 for 2.
Both contractors have said their combo of Boost 80 furnace and Performance 17 series condenser will qualify for the Fed Rebate of $1,500.
Thanks for the tip on the additional 10 year warranty from Carrier. I will look into that.
Any thoughts on whose price for the Performance system is more reasonable?
Thanks for your help!
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mike_home
14 years ago
last modified: 9 years ago
Joan,

It sounds like you are more up to date on the rebate requirements than I am.

It's hard to judge about your pricing since you are having a considerable amount of duct work done. Are either of these contractors Carrier Factory Authorized Dealers? The Carrier FAD has a gurantee that if you are not satisfied Carrier will do whatever it takes to fix the problem.

I would not discount the lower priced contractor. If you feel good about him, then why spend the extra money? I assume you got other quotes and you have narrowed it down to these two. If not get a third quote and see if someone will do a load calculation.
joan1953
Original Author
14 years ago
last modified: 9 years ago
Hi Mike,
Yes both are Carrier Factory Authorized Dealers. Does their thinking about unit sizing seem reasonable to you?
mike_home
14 years ago
last modified: 9 years ago
Its hard to tell if the proposed systems are oversized or not. You say you had heating and cooling problems in the past on the second floor. This is common problem with two story houses as large as yours. It is usually a duct problem and not so much not enough heating and cooling capacity.

Have each contractor explain to you in detail how they arrived at these sizes and not something smaller. Also have them explain how they are solving the heating and cooling problem on the second floor.

hvac estimates and choices, help!

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