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Old 05-28-2013, 11:13 PM   #1
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spend $400 on heat gain calc for 2nd floor A/C?


spend $400 on heat gain calc for 2nd floor A/C?

I contacted three companies for a/c quotes. Two gave them to me right away. the third company said I needed to spend $400 dollars to get a heat gain calc so he could properly quote the right system ie 2 1/2 ton, 3 1/2 ton. etc.

The quick question is, is the third guy right? and the other two companies shooting from the hip? Or is the third guy overdoing it? $400 isn't a trivial amount.

We're only looking for a/c for the second floor bedrooms thru the attic thru the second floor ceiling, (we have radiators.) we don't' want ductless units in each room thru the wall.

Its an 1930 old house with no insulation and original bad windows. We know its a leaky house.

Master bedroom 14x18
other three bedrooms, 12x10
2nd floor hallway 14 x 10
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Old 05-28-2013, 11:17 PM   #2
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spend $400 on heat gain calc for 2nd floor A/C?


as with all quotes, you'd need three heat load calculations to get an average. what one guy inputs could be completely different than what the other two guys do. I've yet to hear of any two contractors coming to the exact same conclusion on any one dwelling.

but if the home is older and you've done work to it to seal the envelope such as insulation and/or double pane windows than it wouldn't hurt. you definitely do not want an over sized system.

what we need to know is the whole house heat load. that or simply ask the home owner how the past a/c system(s) worked and for how long, how many years? any mildew or mold issues? what were the run times inbetween cycling on and off? things like that to get a "feel" for if they were sized properly. Any whistling at the returns or supply vents? etc., etc.,...

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Old 05-29-2013, 02:25 AM   #3
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spend $400 on heat gain calc for 2nd floor A/C?


Quote:
Originally Posted by Doc Holliday
as with all quotes, you'd need three heat load calculations to get an average. what one guy inputs could be completely different than what the other two guys do. I've yet to hear of any two contractors coming to the exact same conclusion on any one dwelling.

but if the home is older and you've done work to it to seal the envelope such as insulation and/or double pane windows than it wouldn't hurt. you definitely do not want an over sized system.

what we need to know is the whole house heat load. that or simply ask the home owner how the past a/c system(s) worked and for how long, how many years? any mildew or mold issues? what were the run times inbetween cycling on and off? things like that to get a "feel" for if they were sized properly. Any whistling at the returns or supply vents? etc., etc.,...
So, what does the company that you work for do when installing a system? Have three different employees do a load calc, or have the customer request this from two additional companies? Sounds odd to me.
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Old 05-29-2013, 02:49 AM   #4
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spend $400 on heat gain calc for 2nd floor A/C?


People charge for heat loss calculations? Really?

A lot of supply houses do them for free for the contractors.
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Old 05-29-2013, 07:08 AM   #5
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spend $400 on heat gain calc for 2nd floor A/C?


thanks for the reply and my original question still stands..

should I spend $400 on heat gain calc for 2nd floor A/C? And is the third guy right, and the other two wrong, or vice versa.

The system is only to do the 2nd floor, the house has no a/c installed now.


from before......
I contacted three companies for a/c quotes. Two gave them to me right away. the third company said I needed to spend $400 dollars to get a heat gain calc so he could properly quote the right system ie 2 1/2 ton, 3 1/2 ton. etc.

The quick question is, is the third guy right? and the other two companies shooting from the hip? Or is the third guy overdoing it? $400 isn't a trivial amount.
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Old 05-29-2013, 08:03 AM   #6
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spend $400 on heat gain calc for 2nd floor A/C?


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People charge for heat loss calculations? Really?

A lot of supply houses do them for free for the contractors.

Absolutely-we charge for the calculations if the homeowner wants the results WITHOUT a signed contract for the replacement.

I know our calcs are highly accurate room by room and I would question a "supply house" doing an accurate calc from their office desk.
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Old 05-29-2013, 08:03 AM   #7
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spend $400 on heat gain calc for 2nd floor A/C?


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So, what does the company that you work for do when installing a system? Have three different employees do a load calc, or have the customer request this from two additional companies? Sounds odd to me.
what's odd is that with all the science involved in a heat load, hard headed hvac techs and contractors don't ever see eye to eye on the calculation and NEVER come to the same conclusion.

it is printed on our service tickets that heat loads are strongly recommended for COMPLETE system change outs but no one ever goes for it as no one is willing to pay for it and no, it's not free. We simply change out like for like in most instances but I can't say how many times a complete system has been installed, mostly and on my end it's one piece, no heat load required.
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Old 05-29-2013, 08:28 AM   #8
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spend $400 on heat gain calc for 2nd floor A/C?


so the other two hvac contractors are wrong not to do a heat gain calculation I take it, even thought its just for the second floor bedrooms...?
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Old 05-29-2013, 03:55 PM   #9
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spend $400 on heat gain calc for 2nd floor A/C?


the ones that don't do a heat load calc. probally doesnt know how.
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Old 05-29-2013, 06:37 PM   #10
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spend $400 on heat gain calc for 2nd floor A/C?


$400 sounds high. Even if his company charges $100/hr it does not take 4 hours to do one. 2 max. DIY at this site and see how close you come.

http://www.hvaccomputer.com/gtarget1...Fe4-MgodPF4AoQ
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Old 05-29-2013, 10:12 PM   #11
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spend $400 on heat gain calc for 2nd floor A/C?


While the other 2 are some what wrong. Your talking bout 512 sq ft. Doubt it needs more then 1.5 tons. And you won't find a 1 ton conventional split unit. Save the 400 bucks.
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Old 05-29-2013, 10:17 PM   #12
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spend $400 on heat gain calc for 2nd floor A/C?


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While the other 2 are some what wrong. Your talking bout 512 sq ft. Doubt it needs more then 1.5 tons. And you won't find a 1 ton conventional split unit. Save the 400 bucks.
GOOD advice!
Take it.
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Old 06-04-2013, 06:41 PM   #13
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spend $400 on heat gain calc for 2nd floor A/C?


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Originally Posted by yuri View Post
You cannot expect (HVAC contractors) to have laptop computers with expensive heat load calc software and take the time to satisfy a very few tech savy customers.
I never said it should be their job to do this.
If anything... I'm saying that the HVAC contractors are the LAST ones to be doing this.

Homeowners need an objective 3rd party to write the spec.
Someone who doesn't have a $5-$15,000 job on the line.
Armed with the spec... they can knowledgeably shop the work.

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