BTU Rating


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Hi Joe,

Last time I checked they used a BTU rating for Window AC units. They may also use them for Mini split systems but I am not sure.

I believe if you search on google you can find that a one ton AC unit is rated @ 12,000 Btu per hour.

Forgive me but I don't know about permitting in California, but Who is asking for this information?

When I'm submitting for permits I sometimes use the IC3 compliance calculator https://esl.tamu.edu/terp/code-compliance-calculator/

When I have issues like this come up when i don't have enough information I consult with my HVAC contractor and HERs rater. 

You might also post your question on an HVAC forum like HVAC-Talk.com.

 

 

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  • 2 weeks later...
7 hours ago, Alchemyjim said:

Not sure why this is viewed as some "big government" intrusion.

I didn't say that.  OTOH, I'm not sure it's something the Bldg Dept really needs.  But it is appropriate for the home owner to know that the system is adequate.

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  • 3 months later...
On 9/19/2020 at 8:06 PM, Joe_Carrick said:

I didn't say that.  OTOH, I'm not sure it's something the Bldg Dept really needs.  But it is appropriate for the home owner to know that the system is adequate.

 

Looks like Joe's question was never really answered and I have a similar question so I will add to this.

I have been doing research HVAC sizing and was wondering if I can depend on this "AC Tonage Calculator" to give my customers adequate information for the size of system they should need. Also, it looks like measurements are taken from the interior area (Thermo Envelope) of each room and not total square feet with walls .
Any thoughts and opinions would be great.
https://learnmetrics.com/ac-tonnage-calculator/

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1 hour ago, builtright3 said:

I have been doing research HVAC sizing and was wondering if I can depend on this "AC Tonage Calculator" to give my customers adequate information for the size of system they should need. Also, it looks like measurements are taken from the interior area (Thermo Envelope) of each room and not total square feet with walls .
Any thoughts and opinions would be great.
https://learnmetrics.com/ac-tonnage-calculator/

While there is some good information on this website, I would not be willing to use this calculator. It does not account for insulation or glazing area, so it provides only a rough approximation. If you have a highly insulated house, and carefully designed glazing with a high-efficiency AC unit, using this calculator will probably lead to the AC unit being oversized and therefore cycling too often, with a resulting loss of efficiency. 

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5 minutes ago, Richard_Morrison said:

While there is some good information on this website, I would not be willing to use this calculator. It does not account for insulation or glazing area, so it provides only a rough approximation. If you have a highly insulated house, and carefully designed glazing with a high-efficiency AC unit, using this calculator will probably lead to the AC unit being oversized and therefore cycling too often, with a resulting loss of efficiency. 

 

This particular project that I'm doing it calls out for a 3.5 Ton unit in the Title 24 for 2275 square feet of living space. Using this calculator it calls for 4.59 Ton.
Also if you do the interior area it is actually around 2000 square feet so I'm thinking 4 ton should do it.

I don't need exact, I just need to be close for budget purposes. The expert will come in and access the scope of work before the final decision is made.

Also, I believe I understand enough about the thermo envelope and climate zone to figure this stuff out myself. I just want to be a little more accurate and feel good about my estimate and that I'm close.
 

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  • 6 months later...
On 9/6/2020 at 6:29 PM, Joe_Carrick said:

Plan Check is asking for the BTU rating of the existing AC system on a remodel/addition project.

How and where do I get this information?  I don't see it on the label of any piece of equipment.

Hi Joe,

I found a very good resource for your question. You can check the resource here: https://top10gears.com/ac-tonnage-calculator/ 

This article has an AC Tonnage calculator along with factors and parameters that need to be taken care of while calculating the AC tonnage capacity. It also has a stepwise guide and the AC tonnage formula for calculation. 

 

I think it is a complete resource on the topic. 

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