Residential energy calcs.

[energy911]

Im on my last year of apprenticeship. and my teacher is going over hand loads. Now i have been doing energy calcs for my company for 2 years and the teacher and i had a debate about lights in a residential load calc he says you have to add up every single light in the house and find the btuhs and add them in by using watts x 3.41 well in a 2240sqft. house he came up with 13000btuh for all the lights. total house load was 57,000 btuhs i came up with 39000btuh with out the lights who is right.

[cehs]

I don't know the answer to your question, but
most people do NOT use 100 watt lights, nor do they have all the lights on at the same time.....
.

[jimj]

Im on my last year of apprenticeship. and my teacher is going over hand loads. Now i have been doing energy calcs for my company for 2 years and the teacher and i had a debate about lights in a residential load calc he says you have to add up every single light in the house and find the btuhs and add them in by using watts x 3.41 well in a 2240sqft. house he came up with 13000btuh for all the lights. total house load was 57,000 btuhs i came up with 39000btuh with out the lights who is right.

You are!

[jimj]

Here ya go. Pay special attention to the part about not making assumptions about every thing is going full blast about internal loads!

[mgenius33]

Im on my last year of apprenticeship. and my teacher is going over hand loads. Now i have been doing energy calcs for my company for 2 years and the teacher and i had a debate about lights in a residential load calc he says you have to add up every single light in the house and find the btuhs and add them in by using watts x 3.41 well in a 2240sqft. house he came up with 13000btuh for all the lights. total house load was 57,000 btuhs i came up with 39000btuh with out the lights who is right.

Considering the fact they won't be producing incandescent bulbs in the near future. That would be about 165, 23watt bulbs all lit at the same time.

[energy911]

Its hard to put every thing on here without going to far into detail. my teacher has never been a tech. he is under the presumption that loads are to be done at absolute worse case.

[jimj]

Wrong........Wrong...........Wrong

See my attachment! See if he recognizes the authors names. If he doesn't have him look in the front of Manual J.:whistle:

[jimj]

If were talking about Manual N for commercial, thats a different subject!

[energy911]

yes if commercial the light could possibly run 24hr. a day but no way in residential

[energy911]

Here ya go. Pay special attention to the part about not making assumptions about every thing is going full blast about internal loads!

you completely proved my point thank you

[jimj]

you completely proved my point thank you

:cheers:

[hvacker]

There are a lot of goofy assumptions when it comes to loads.
I knew a salesman that when selling a heat pump he would add up all the amp ratings on the circuit breakers and assume they are all drawing the rated amps. From that he would tell the HO's they would need another 200 amp panel installed. Glad he didn't sell many.

[54regcab]

I don't know the answer to your question, but
most people do NOT use 100 watt lights, nor do they have all the lights on at the same time.....
.

Especially in the middle of the afternoon on the hottest day of the year... If the homeowner is hot they can just turn some heaters (aka lights) off. Agreed, there needs to be some common sense in sizing for peak internal loads :)

[Tech it out]

Its hard to put every thing on here without going to far into detail. my teacher has never been a tech. he is under the presumption that loads are to be done at absolute worse case.

No disrespect to your teacher as I'm sure he is a fine man and very knowledgeable but, no HVAC or technical school should ever hire a teacher that doesn't have at least 5 years field experience. Seems like that just shortchanges the students IMO.

[54regcab]

A Journeymans should be required to teach HVAC classes.