How would you report this system's BTUs?

I am not an HVAC expert but depending on the orifice size it could be 64,000 or 80,000 BTU furnace.

It says Natural gas on the data plate.

Below is some Googled info on the topic:

A furnace is sized according to the amount of heat it can produce.
This is known as a BTU rating. A furnace will have two BTU ratings. One for INPUT and one for OUTPUT. The BTU input rating is the gross amount of BTU produced.
The BTU output rating is the amount of usable BTU. In other words, Input is how much heat produced and Output is how much of that heat can be delivered to your house.
The difference between Input and output is the efficiency rating.
A 100,000 BTU input furnace with an 80 percent efficiency rating will make 80,000 BTU of heat available for your house. (Eighty percent of 100,000 = 80,000)
A 100,000 BTU input furnace with a 95 percent efficiency rating will make 95,000 BTU available for your house.
Both furnaces will use the same amount of energy, one will simply waste more.

Yup, could be…:slight_smile:

David, this is for SC, NC is similar to TN.

SC has a different SOP, very few inspectors truly understand it even when it is fairly simple, some employees for the state HI office refuse to admit it even exists but they send it to you when you ask for an application.

NC has had some changes since TN used it as a template, I wonder how many NC inspectors know that we have been required to move insulation and inspect in certain places for a long time now.

You would have to know if the unit has a #44 or a #42 burner orifice installed to determine whether it is an 80,000 or 100,000 btuh input.

Thanks for the update Bruce!

I now incorporate the Tennessee law into my home inspection report so that everything that is required is covered. I always perk up when I hear SC, NC changes.

That goes for inspectors in any state. Many seem to latch on to inspection standards taught in school or where discussed by associations but do not seem to pay attention to the actual requirements for their individual states. Every inspector should know their state law or subscribed SOP verbatim.

If you were to order a replacement unit, you would order a ___,___btu:D

Sorry if this sounds stupid, but would a two stage gas valve have anything to do with amount of heat produced?

Below copied from: http://www.ccht-cctr.gc.ca/projects/2stage_e.html

High-efficiency 2-stage furnaces have been promoted using the promise of lower operating costs for gas and electricity, thanks in part to the brushless DC variable speed blower motor. 2-stage gas furnaces are simply gas furnaces with 2-“step” gas valves that operate at two distinct heat input rates. One example control strategy used responds to a call for heat by firing at a Low heat input first and if the call is not satisfied within a set time-frame the gas valve increases to the Hi heat input rate. Control logic determines the lag time between Low and Hi input based on a number of system conditions. The Low firing rate can be 50-75% of the Hi firing rate (e.g. 20 000btu/hr-40 000btu/hr or 50 000-75000btu/hr).
Combined with a variable speed blower, the manufacturers claim that this system will increase comfort, reduce noise and save money on operating costs. Electricity savings were expected due to the BLDC (brushless DC motor, aka ECM) blower and improved gas conversion efficiency were expected as well. The purpose of this project was to use the CCHT to shed some light of the “real” performance of a two stage system in comparison to a single stage system in order to enlighten Canadians, utilities and HVAC contractors. The purpose was not only to identify the potential benefits in comfort and savings but also to determine the source of any savings (e.g… better efficiency, BLDC motors, etc.).

As I read the post, it amazes me how wonderful an organization we have. All types of people from all walks of life, give their input to a person with a similar profession for no reason but to be kind. Just my two cents. Just happy to be an Inachi member I guess

Ditto. Inachi is an invaluable resource!

The quesiton was accurately answered early on in this post. The correct answer is:

Drum roll please…

drdrdrdrdrdrdrum

Input 100,000 output 80,000 or an 80% efficiency.

This answer is correct because of the little * beside the correct preset elevation. I might go so far as to note this is the factory present condition.