Fix the IP units in the OS Results

asked 2021-03-02 09:57:42 -0500

TheEnergyTutor gravatar image

updated 2021-03-29 08:53:02 -0500

These units are wrong. image description

M is roman numeral for 1000, and does not mean a million, unless using the SI system. For representing a million BTU in the IP system the abbreviation is MMBTU. Technically, this chart units are 1000 BTU, but the data is actually million.

Additionally KBTU/HR is not an IP unit. The correct units are MBH (pronounced one thousand BTUs per hour). k=kilo in the metric system.

image description

I've been a mechanical engineer for 23 years. This is factual information that is used by industry. What will it take to fix this?

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I disagree. It is common to use M=million and k=thousand with IP units, and MBtu and kBtu/hr are used often. See this Wikipedia note for example: "Energy analysts accustomed to the metric "k" for 1,000 are more likely to use MBtu to represent one million, especially in documents where M represents one million in other energy or cost units, such as MW, MWh and $."

shorowit gravatar image shorowit  ( 2021-03-02 11:23:28 -0500 )edit

Personally, due to the ambiguity of "MBtu", it is best just to not use it.

JasonGlazer gravatar image JasonGlazer  ( 2021-03-02 11:35:43 -0500 )edit

Making an excuse that, "everyone else does it wrong" doesn't make it ok. If you look at any gas burning appliance in the US, there is a metal nameplate or sticker always in rated in MBH. It's been like this for 40 years. It does not mean million. I think we should do something to make it clear. If I size a customer system wrong because the report is unclear, it will be very disappointing. I agree with Jason we should get rid of it and use something that can't be mistaken.

TheEnergyTutor gravatar image TheEnergyTutor  ( 2021-03-15 14:47:53 -0500 )edit

Every residential software tool I have ever used asks for equipment capacities in kBtu/hr. Here are more examples: BEDES, EnergyStar, ANSI Standard, Carrier heat pump, etc. Just because AHRI does it one way doesn't make it the only/correct way.

shorowit gravatar image shorowit  ( 2021-03-15 15:04:40 -0500 )edit