Trying to figure out correct BTU size for purchasing new furnace. Total living space of my 15 year old ranch home (including finished basement) is 2800 square feet. I currently have York Stellar 100,000 BTU single stage 92% efficiency furnace. Heating contractor wants to replace with Lennox G61 36B071 two stage 70,000 BTU 95% efficiency furnace. I am questioning reduction in BTU. Contractor is adamant 70,000 BTU is adequate. 70,000 or 100,000 BTU? Which is adequate? Thank you.

I would get another contractor for a 2nd opinion, maybe even a 3rd.
A good contractor should do a manual J to see exactly the size needed, if he doesn`t do manual J it is guess work and you will foot the bill,,
Also ( one contractors opinion ) Lennox is close to the last unit I would put in my house,, get estimate on other brands,look at warranty`s and good installation is a must

Again make them do a manual J,, they will know what it is

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