This is a tough couple questions to ask. Please forgive the length of the post. This message is spurred by a call-in to the Tom Tynan radio show in Texas. The caller complained of AC monthly bills in the $350-400 range (meaning 3500-4000 kwh) while living in a 2700 sqft home using 3.0 ton AC system. He said the system ran "all the time".
Now Tynan has more experience than I will ever have, on building matters in general. I would buy a home built by him and trust in his craftsmanship and good construction methods, as much as any builder I know of -- even when they are not what Lstiburek would do. But occasionally Tynan sounds off his strong opinions that don't seem to reflect education.
Tynan came down hard on this guy's AC sizing, saying the long runtimes were the source of high bills. He strongly advocated a larger unit which would cycle even during the hottest days, saying the shorter runtime would result in lower bills -- he strongly suggested a similar house built by him would see summer bills no higher than $160/mo.
Tynan exclusively uses Central City Air for his AC systems, so I am very confident he gets a quality install even if not exactly to Manual J specs. And I am confident CCA would make sure the ductwork was well sized (Tynan's apparent awareness of ductwork is nil). I am hoping Airman would be willing to say why Tynan might be believing a larger system would be better for energy consumption. Would anyone else care to argue in favor of Tynan's claim that a larger system with shorter runtimes, would result in lower energy bills?
Question for the other board experts -- At 900 sqft/ton this does not seem to be the classic old leaky Texas house. It seems as if someone tried to use modern building practices and botched it. What would you think would be the LEADING CAUSES TO SUSPECT for high energy bills in a case like this one?
While I would *like* to believe all the answers can be found with Lstiburek and Manual J etc., it seems necessary to look and see if answers can be found elsewhere as well. Hence the devil's advocate type of question.
Thanks -- P.Student