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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22678
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how many btu is needed for a 1600 square foot ranch home that

Resolved Question:

how many btu is needed for a 1600 square foot ranch home that is 14 years old very well insulated i have had 3 quotes from lennox dealers 2 say 70000 and one says 90000
Submitted: 6 years ago.
Category: HVAC
Expert:  BillyHvac replied 6 years ago.




The traditional way without using the accurate manual J format, was to allow 40 btu's per sq ft. In your case this would be 64,000 btu. Given your additional information I feel the 70,000 would be an accurate choice.


Of course though the best way is to have the load caluclation done which takes into account, insulation, windows, exposure, climate etc....





Customer: replied 6 years ago.
i had more questions and i thought i paid 15 for the month the additional question is what if i add a 14x14 family room would 70000 still be enough
Expert:  BillyHvac replied 6 years ago.


Depends on how you have duct available for future use...but yes....that scale you very close to the 70,000 btu, and if amply insulated the 70,000 will be sufficient.



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Customer: replied 6 years ago.
i thought when you paid the 15 it was for a month
Customer: replied 6 years ago.
is 15 for the month of questions
Expert:  BillyHvac replied 6 years ago.




If you have the $15 month subscription, you can click "accept" all you like and still pay just the monthly fee.


The site still wants the experts who take their time to be here to be able to still garner accepts. If they didnt the experts would be answering hundreds of questions for free.


If you have subscription questions please contact [email protected] . I am a heating/cooling technician and am not fully versed in the administrative side of the site.



Customer: replied 6 years ago.

billy is the 90000 over doing the btu that are needed in michigan


Expert:  BillyHvac replied 6 years ago.


Depends if it is 2 stage or variable. Now Michigan is a Hot/cold state. So if this was "loose construction" I would err towards a 90,000. But your home is fairly new....and well insulated, I would stick with 70,000. Furnaces have oversized for many many is hard for us to scale down. In your situation 70,000 would be the choice I would offer.


I am from the the same I am taking climate into consideration.



Customer: replied 6 years ago.
it is the G61 two stage high efficiency furnance
Expert:  BillyHvac replied 6 years ago.


Ok....that changes things....


A 2 stage is like having 2 furnaces....a small one when it is not that cold, and a big one when it really needs it.


Since this is 2 stage I withdraw my opinion and submit the 90,000. The 90,000 now becomes a "it is there if you need it"...but is not running 90,000 btu all the time.


The beauty here is the first stage will handle a good portion of the heating...especially early season and late.


Therefore, seeing how it is the given model...I change my mind. Sorry.



Customer: replied 6 years ago.
so you would recommend the 90 000 btu 2 stage unit well i did not understand and my friend wanted the 90000 and the two other dealer said the 70000 would handle up to 1800 square feet so you are saying the 90000 would no t be over load because the one dealer who i did not go with said that would be way to much i sent you the model of the furnance because that is what i got off the quote it said lennox two stage g61mp36b 071
Expert:  BillyHvac replied 6 years ago.


Given it is a 2 stage furnace means it will run at even less than 70,000 when a lot of heat is not needed. The 90,000 is like insurance.


The big thing here is it just like buying 2 for keeping up and standard temps...and another furnace just in case.


I amyself put in a 2 stage...I already had a single stage 90%...but the 2 stage saved me even more on my gas bill.

Customer: replied 6 years ago.
so you would feel comfortable with the 90000 2 stage in my 1530 square foot home plus it also has vaulted ceilings i am just spending money and the furnance in the home works well but it is 70000 single stage and 17 years old and i think it is a tempstar and is real loud presently the house is 1530 but we will be adding at leat 55 more square feet so i dont know if it is a little under 1600 would make a difference
Expert:  BillyHvac replied 6 years ago.


I still stick with 2 stage 90,000. If it were single stage I would not.


The sizing is so close around the if you add sq ft.


Look at it as buying a new car that runs on the highway on 4 cylinders....but if you need has 8 cylinders....

Customer: replied 6 years ago.
i appreciate all your answers i just got such negative responses from the other lennox dealers when i said well why not the 90000 they said you can damage your home from having too big of furnance and it could create too much humidity and mold they kept saying bigger is not better
Expert:  BillyHvac replied 6 years ago.



I agree with their statement.....IF it were single stage.


The humidity and mold would be products of the air conditioning.....but this G61 has multiple speed blower so it can be dialed in for proper ac operation.


I also looked ast the unit specs here


Page 2 will tell you that low fire runs at 60,000.....and high fire is actually 88,000, they just round it up.



Customer: replied 6 years ago.
so the 700oo would be running more because of the lower btus my friends have a heil 90000 2 stage furnance in a 28000 square foot home is that to low for their house i wanted to remind you my house is very highly insulated he used fiberglass and i inch dow foam board on the outside i just dont want to make a mistake
Expert:  BillyHvac replied 6 years ago.


Most of the time it will run at 60,000 btu, not 70,000. and then when on high fire it is 88,000 btu.


There is really nothing I can do to make you feel comfortable in the decision. If you want to be certain, ask the contractors to supply a manual J sizing form.


This will take all information and mathmatically tell you what you need. Any quality contractor can/will be able to do this for you.



Customer: replied 6 years ago.

i respect your knowledge you have given some of the best answers not only that we will be heating the basement in the winter which is 800 square feet so if you feel the 2 stage 90 is the best i will do that

Expert:  BillyHvac replied 6 years ago.


Given the basement sq ft makes an even stronger case for the G61 90,000.


I really do think you would be happy with it. The 2 stage is what makes all the difference.



Customer: replied 6 years ago.
ok thank you you have given me some peace of mind my husband said we will never go over the 1600 square foot but he would like to heat the basement as the man cave i just did not understand everything so well and with different opinions it was hard can we contact this site anytime or text messages my text is(NNN) NNN-NNNN
Expert:  BillyHvac replied 6 years ago.

Sorry for delay....


you can return to this site or even this question anytime you wish.

Customer: replied 6 years ago.
billy i talked again to a contractor who gave me a bid on the furnance for g61 70000 he has the computerized program and went over the whole thing with me and stated with the air purifiying system i am getting etc the 90000 is to much for the house he must have the j program or what ever you call it i was not there at the time my husband was so he did not get all the information they totally back that program and the basement to heat was only 400 square feet my mistake so even though i am going with a different contractor 600 cheaper i guess i should have went with the one who had all the most up to date information