Originally Posted By: jwortham This post was automatically imported from our archived forum.
I’ve got a Bryant furnace I am looking at. Has NO product labels or anything to tell me the Model, serial, BTU ratings. (Other than a handwritten note on the iside of the door and how do I know the author was not insane?)
Originally Posted By: tallen This post was automatically imported from our archived forum.
That would work if the unit was sized properly in the first place I guess but, I am not a HVAC tech and I really don’t know how they determine what size furnace to use. I understand they take in to account the # and size of windows wether or not they are insulating ,and I would imagine there are many other factors involved. That’s why I just go by the burners if no other info is available.
Just my 2.5 cents 
-- I have put the past behind me,
where , however, it now sits, making rude remarks.
Originally Posted By: Blaine Wiley This post was automatically imported from our archived forum.
Although the 20K btu rating per burner is usually close, I would not put the gross or net BTUH rating in a report unless I knew it. You don’t want to put guesswork in your report. Just suppose it turns out to be undersized…
Originally Posted By: jpeck This post was automatically imported from our archived forum.
I wouldn’t estimate anything.
Simply put in your report what you told us:
"Bryant furnace ... NO product labels or anything to tell me the Model, serial, BTU ratings", recommend having HVAC contractor determine brand, model, size, age and condition, or replace it.
If you start "estimating" sizes and you are wrong, you could end up buying a new heater for your client. I guess I am not as generous as you are.
Originally Posted By: dbowers This post was automatically imported from our archived forum.
Standard Comment on My Matrix Checklist is:
"Data Tag Missing, Size and Age Unknown".
"Data Tag Worn and/or Damaged, Size and Age Unknown".
It then has a brief sentence telling the client to consult with a licensed and competent HVAC contractor prior to closing if further information is desired.
Originally Posted By: bkrautter This post was automatically imported from our archived forum.
Actually if you tell the client to contact there utility co. who ever serves the gas ,they can ask them to clock the meter ,which will tell exactly what the furnace is rated at. This is something that should be done at initial installation ,but unfortunately no one does it.It takes about 10 minutes to do,most heating a/c guys probably do not even what this is.
Originally Posted By: jpeck This post was automatically imported from our archived forum.
Jeff,
In that case, Bill K. gave the best way to do it.
Actually measure it at the meter.
I've never had it done, or seen it done, but if EVERYTHING else gas was turned 'off', then you could easily clock the usage at full burn, calculate the Btu being used, take the 10 minute usage x6 or the 15 minute usage x4 and you would have the Btu per hour input reading (note: I did not say 'input rating', because I am sure that could actually get much more complex, to determine what the "rating" is, this would just determine 'input usage' under those conditions - how close is this, Bill K.?).
Originally Posted By: bkrautter This post was automatically imported from our archived forum.
you are close,in fact you need the gas value ,from the gas co. and a stop watch,like you said with all other gas appliances off,you simply clock the meter,use your multiplier and vioala,it is actually a tool to get the furnace to burn at its correct firing rate,you use a manometer at the gas valve also,and make adjustments there and clock again to see if it is firing correctly. This is also something that is done to try to stop a condensating chimneybefore suggesting a liner.
Originally Posted By: John Furr This post was automatically imported from our archived forum.
Wow I had a great post written only about 10 thousand words giving you massive amounts of information on furnaces, types, how to tell efficiencies, how to tell age and a whole lot of extras…
I wrote how to do a proper meter clock test and the value of heat in a cubic foot of natural gas (1000 Btu/ft3) and a whole host of interesting facts about natural gas and transmission of gas to the consumer, mercaptan ordourizer added to the gas such as its composition and true energy value etc...... all about the necessity for temperature rises and comissioning furnaces...
All to help any inspector confidently determine the rated input and output of a natural gas furnace... given a few simple guidelines... and provisos related to 2 stage furnaces and modualting furnaces...
I also had a comment regarding the remark about heating installers knowledge... and one that inspectors shouldnt guess at sizing due to the many factors that could cause you to be in error buy a few hundred percent on your sizing...
I also concurred that you shouldnt supply anything in your report without a disclaimer and that you should really just comment that the ratings were missing from the furnace and recommend the client seek assistance from a certified gas technician....
However, this was all lost due to the system timing out since it did take a while to write that post.... and when I logged back in the post was not in the local memory of my computer and was lost...
Someone do something about the idle time-out period for your connection login, or god you guys will miss some really neat stuff you can learn through the use of applied sciences... I will not hang around to post if the post gets lost frequently.
I will try to rewrite the post later, but right now I have to get back to work and finish a residential air system design due tomorrow morning.
-- John Furr
Residential Efficiency and Training Resources of Ontario
Originally Posted By: rray This post was automatically imported from our archived forum.
Hey, John.
I solve the time-out problem by copying into Word the post I want to respond to. Then I write my respond in Word. Then I spell check it in Word. Then I save it in Word. Then I copy it from Word to the NACHI message board.
Can you tell that I like Word? Been using it since version 1 for DOS. I think I'm getting old. 