Not warm

Good afternoon, The furnace size appears to be ok for a house with "typical" insulation for approximately 15 year old home. But if you did mention that you had a 80% efficiency furnace in your home which makes us believe that your home might be approx 40+ years old. This could also reflect the current insulation value that is in your home as well. A couple of questions on our end would be has your home been renovated within the last 15 years, have you upgraded insulation, have you upgraded doors & windows? These are all things that play a large role in your homes heat loss and heat gain. This could possibly be deeper than just a thermostat offset. We would be able to provide more information if you'd like to reach out. Thanks Costas from Omega Heating & Air Inc

You were right to bring up your concerns. With a J load calculation of 72,000 BTU, even though a 96% efficiency 80,000 BTU furnace could be considered slightly oversized it would most likely have been a better choice. That being said, if you have a local HVAC contractor you trust and can come and do a proper site/equipment inspection there might be a couple of simple adjustments that can be made with this new installation to help a little: sometimes even a swap of what filters are being used can make a difference - In older homes and ductwork designs, a higher MERV rated filter can be detrimental to the needed airflow with unnecessary restriction. I normally recommend a MERV 8 pleated filter where this is a concern. There could also be an issue with with how the furnace was initially set up to jump from 1st stage heating to 2nd stage heating - I was at a service call recently because a homeowner had said that a newly installed furnace was not keeping up and he needed a second opinion. It turns out, that the furnace settings, by default, would require that the thermostat should be set-up to determine when 2nd stage heating would kick-in. However, because the thermostat was only wired for single stage communication, a simple setting on the furnace needed to be adjusted to allow the furnace itself to initiate the second stage of heating after 10 minutes - otherwise the furnace would only ever run on the single stage heating, never stopping on colder days as it could never reach the desired temperature because of a significantly reduced heating output. For that Trane model - if the thermostat is only wired to the the one heating terminal (w1) on the furnace control board and is not set for 2 stage communication with it also being wired to W2 and the thermostat settings adjusted to 2 stage heating needs - the furnace will only run on 1st stage heating unless the W1 and W2 terminals are jumped together at the furnace board allowing the furnace itself to initiate 2nd stage heating after a set-time. If your Trane is only ever running on 1st stage heating, then your 60,000 BTU furnace will only run at about 38,000 BTU's I hope this helps

Good afternoon As you mentioned your house in older than 19 years. So insulation ,windows and doors are not in good shape . Anyway you were happy before while using 80000 Btu furnace with 80% capacity that is equal to 64000 when your furnace was new and after 19 years it should be around 60000 or less but I think that one was single stage furnace . And new one is 60000 Btu with 96% efficiency and that efficiency is a kind of laboratory efficiency real one should be less so new one has 57000 in best condition and it is double stage so it seems you have two problems less capacity and maybe your second stage is not operating at all so it is better you call some expert come and check your furnace performance