ratflinger
Well-known member
I didn't comment on what labor cost is or should be, only what equipment cost is.
Temporary a/c fix?
- Thread starter ybnormal
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well, I finally managed to go thru all the estimates and sort thru all them , so now I have a good idea of what it will cost me; somewhere between $12k and $8k. it remains to evaluate each proposal for the differences such as 1-stage vs 2-stage, variable speed air handler, etc.
I also decided to read up on exactly what Manual J is and what data is required. It's not that difficult but since I don't feel like going that deep into the details of each item (double paned glass, e-coatings, etc), I decided to use the basic formula and got the following:
It would appear that I'm going to need a 2.5-ton unit and not a 2-ton. So it's probably been undersized for the last 40 yrs. I'll have to get in touch with the one company I will probably select and have them give me an updated quote.
As has been posted by other GJ members here and elsewhere, it will probably boil down to the company itself and their reputation as all the prices are so close. In this case, it is the American Standard bidder. Not the cheapest but he seems to be offering a competitive quote based on the HVAC specs given.
I also decided to read up on exactly what Manual J is and what data is required. It's not that difficult but since I don't feel like going that deep into the details of each item (double paned glass, e-coatings, etc), I decided to use the basic formula and got the following:
| Manual J calculation | |||||
| (House surface in square feet) x (height of the ceiling) | 1230*9.5 | 11685 | |||
| (Number of occupants) x 100 BTU | 4 | 400 | |||
| (Number of exterior doors) x 1,000 BTU | 4 | 4000 | |||
| (Number of windows) x 1,000 BTU | 14 | 14000 | |||
| 30,085 | btu's |
It would appear that I'm going to need a 2.5-ton unit and not a 2-ton. So it's probably been undersized for the last 40 yrs. I'll have to get in touch with the one company I will probably select and have them give me an updated quote.
As has been posted by other GJ members here and elsewhere, it will probably boil down to the company itself and their reputation as all the prices are so close. In this case, it is the American Standard bidder. Not the cheapest but he seems to be offering a competitive quote based on the HVAC specs given.
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Wrench97
Well-known member
As mentioned in another thread you can't up the size of the unit and expect better results if the air flow(duct sizes) don't support it.
I hope your "manual j" included a lot more parameters than what you shared.
https://loadcalc.net/ is a pretty good option
https://loadcalc.net/ is a pretty good option
as you may know, there are a buttload more parameters you can input but if you don't have the necessary data, or the ability to calculate it, the basic dataset I used is adequate for determining. I used Block Load calculation method.
yes, I have double pane windows (or should I say 'fenestrations'?) but they are 40 yrs old with no lowE coating or gas-filling. also trying to figure out how much sun or shade each window receives and a peak load each day on each one would have been getting too deep into the weeds for me. since I am not re-modeling or replacing sheetmetal ducting on the first floor of this two-story house, there was no point in doing a Room-by-Room calculation, especially since all of downstairs is essentially an open space that flows thru. as for the number of windows, my house faces east. I have an equal number of windows facing east and west that get approximately the same amount of sun each day, so that calculation would even out anyway. I also have no way of knowing how much insulation my outside walls have.
I did not mention it but, yes, I will be asking the winning "bidder" to do a proper Load Calculation as part of the job as it looks like we will need to do that to: 1) be sure we have the right numbers to get the right size unit, and, 2) my basic Block Load calculation shows that it may be necessary to re-size.
You have a couple options. You can continue with your guess, because that's all you are doing, and hope it works. Some people can do this pretty successfully.
Option two is either do the load calc yourself or pay someone to do it. If you want a load calculation it needs to be done before you accept any bids.
Hopefully if you pay to have it done they can also look at your duct and determine if it's even capable of flowing enough air for 2.5T. If the duct won't support it you will still have cooling issues.
Option two is either do the load calc yourself or pay someone to do it. If you want a load calculation it needs to be done before you accept any bids.
Hopefully if you pay to have it done they can also look at your duct and determine if it's even capable of flowing enough air for 2.5T. If the duct won't support it you will still have cooling issues.
finally got the estimate data spreadsheeted so I can look at it in a way that makes sense, being able to see the system specs and prices. prices are all similar within each group (1-stage vs 2-stage)
Carrier has a weird warranty option: 10yr parts only, or 5yr parts w/3yr labor
American Standard is happy enough to charge $99 to transfer the warranty to a new homeowner (we plan to sell the house in another year or so)
numbers are SEER2, EER2, HSPF
interestingly, company #1 seems to be offering a higher performance for slightly less money for each category. I guess a bigger question is: do I really need a 2-stage unit vs 1-stage? we won't be seeing any longterm savings since we'll be selling.
Carrier has a weird warranty option: 10yr parts only, or 5yr parts w/3yr labor
American Standard is happy enough to charge $99 to transfer the warranty to a new homeowner (we plan to sell the house in another year or so)
numbers are SEER2, EER2, HSPF
interestingly, company #1 seems to be offering a higher performance for slightly less money for each category. I guess a bigger question is: do I really need a 2-stage unit vs 1-stage? we won't be seeing any longterm savings since we'll be selling.
| 1 | 2 | 3 | 1 | 2 | 4 | ||||||||||||||||
| Goodman | Carrier Performance |
| Lennox Merit |
|
| ||||||||||||||||
17.2 | 2-stage | 16.5 | 2-stage | 16 | 2-stage | 15.8 | 1-stage | 15.2 | 1-stage | 15.2 | 1-stage | ||||||||||
12.5 | variable | 12.5 | variable | variable | 13 | variable | 12.5 | stepped | 12.5 | stepped | |||||||||||
8.2 | 8.1 | 8.1 | 8 | 7.8 | 7.8 | ||||||||||||||||
| $ 10,719 | $ 10,943 | $ 10,750 | $ 8,319 | $ 8,729 | $ 7,927 |
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danski0224
Well-known member
2 stage is more comfortable. It's never about "saving money".
Snapped-off
Well-known member
danski0224
Well-known member
Same thing, it's about comfort.
Snapped-off
Well-known member
I meant equipment wise. I'm not knowledgeable on 2 stage systems.
danski0224
Well-known member
Two stage AC would be less $$ than inverter/variable.
Same with a gas furnace (usually called modulating).
There may not be energy savings from variable speed or modulating equipment, but if it's done right, it will be more comfortable.
Of course, the comparison has to be limited to "properly sized" equipment. If an oversized AC or furnace is replaced with a high zoot variable/modulating piece of equipment, of course there's gonna be "energy savings".
In my area there isn't one contractor that will do an honest load calc on a house. Nobody does them.
I had one contractor mention he was in a home to do a price quote and the customer asked if he was going to do a load calc like the previous contractor. He asked if the previous contractor had gone into the attic, asked about insulation in the walls and information about the specs on the windows. All needed for a proper load calc. The customer said "no" to all the questions and said the guy just asked the square feet and filled out an official looking form. He then asked what size system the previous contractor recommended and it was the same size this contractor recommended.
He did explain to the customer that a proper load calc will take some time, maybe 2-3 hours and not 15 minutes and without specific information anything that was done was the same as he had done, a good guess, based on years of experience.