I know this is long, but if any of you have time to read through it and give your feedback, I would SO appreciate it. I've included a link to the HVAC plan and also the summary from the HVAC guy after our meeting this week. I'd like opinions on: a) Is it possible that the unit is short-cycling because it is oversized and in an attic? If so, will a 45 btu unit be large enough and will it solve the problems? b) Should we add a floor-level return air duct on the 1st floor? Our closets are already very small and I hate to lose the space, but will do it if it will help significantly. c) Other thoughts or comments. - - - - - - HVAC design plan and floor plan: Click here or go to: https://www.evernote.com/shard/s2/sh/6b0b0d4d-66f6-4e2c-8ace-e58fd14979f9/dda0a92615d4f6fd - - - - - Summary from HVAC guy: Heating and A/C Systems are designed on the coldest and warmest day of the year. Looking at the original design of your system and the heat load, your system would require 40,000 BTU’s of heat and the cooling needs are 3 tons. At the time the furnace that fit the home was a 90,000 BTU furnace as your home required 3 tons of cooling. To our knowledge of Lennox, this was the smallest furnace with a 3 ton drive. We struggle with this, as every day homes are being built better and the heating and A/C industry has not offered more cooling with less heating system. Your home has a zoned system, which causes issues, since your system and every system, has a start and stop which is designed around your whole home. When one zone is calling, the furnace has to relieve or bypass the rest of the heat. This, in a normal home with a cold basement, is not an issue. Your system is located in your attic where all the heat rises, not allowing to dissipate the extra heat as a basement would. A heating system is designed to allow the heat to rise 2 degrees an hour. Your system raises the temperature 5 degrees in about 10 minutes which is telling us that your system is oversized. Lennox at this date offers a two stage 45,000 BTU furnace with 3 tons of cooling to work with a modern home likes yours. I would like to move forward with changing out your furnace to allow for proper heating of your home. Atlantic would also like to get a return duct down to the floor of your first level. This will require us to take space from your spare bedroom closets.

"They hit 120 degrees a couple weeks ago. She has 2 AC's and said they didn't shut off all day." "Run-time varies from 30+ mins during heat of the day to 10-ish mins in early morn hrs" This varying equipment behavior is to be expected, isn't it? I would believe that a lot of people "set it and forget it" at their thermostat. I do. 73F from May to September, no setbacks programmed. With this in mind, how can one expect their system to do anything else but have cycle times of very different lengths? When does the thread topic change from "it's short cycling!" to "it runs 24/7!"? After all, isn't the purpose of HVAC to provide comfort? I'm comfortable at 73F. If I were to have a bigger droop set in the stat, or agree to raise or lower the set point as outside conditions change, I guess I would have uniform, perfectly long cycles. No thanks, I'll leave it as is. Comfort does come at a price sometimes.

" Let me start by saying this entire system is from 1970 and was more than likely never serviced by a professional. " It's time to call a professional. If you don't like the quote, get another. It may also be time to replace it.

I agree I shouldn't have to pay, or just a fraction of the total bill, but how do I argue that? They are just saying that it just happened to break on its own when they were cleaning it. Like a fluke or something.