Second opinion on replacing our HVAC system

jplee3

Hi all,

Wanted to get your opinions on sizing for our home. We are located in South Orange County California (Laguna Hills area - San Diego Gas & Electric is the electric provider and SoCal gas is the natural gas provider. SDGE supposedly has the highest electricity rates in the nation). It's a 2-story home 2680sq ft built in 1980. Spanish clay tile roof (no solar or intention of putting solar up there let alone us avoiding people walking the roof and breaking tiles), stucco exterior, double-paned windows throughout most of the home except a couple french doors in the back and one window in the back as well), ceramic tile flooring on the first floor and carpeting on the stairs and upstairs.

Current furnace Lennox G12Q4E-110-8 and condenser HS16-511-V-5P - I believe this indicates a 4ton system (I confirmed the condenser is a 4ton unit per this thread - https://forum.heatinghelp.com/discussion/126561/lennox-condensors. I'm guessing the furnace is also 4ton)

I got some help from over at HVAC-talk and the recommendation was a 3ton unit (and 2-stage heat pump) based on this:



Heat pumps don't seem like a great idea considering the high electricity costs out here (again, SDGE reportedly has the highest in the nation). If we had solar then maybe but that's not the case and no plans to go solar in the near future.

I've had a few contractors already recommend and push 5ton, even after asking about manual J. One actually said I could go with 4ton but it would be at the upper range based on his "Manual J" assessment (not sure if he was using loadcalc or what). Another contractor also was pushing a whole house fan or gable exhaust fan as a means to keep it cool and run the AC less. The same one told me that personally he pulled the 3ton from his 1700sq ft home and installed a 5ton + gable exhaust and he likes this setup - it allows him to cool his home down faster so that he can stay off the grid. He also said that this is OK because humidity isn't crazy out here like it is in many other places.

We just moved in to the place back in October so don't know what a full summer is like but so far (even on hot days) it seems to stay relatively cool inside. The other day it measured 87F and inside it was 72F. On the flipside, when it's colder outside, it tends to get pretty cold inside. We know we need to replace our furnace as there are probably many things wrong with it (the biggest concern with it right now, outside of getting it to fire up and stay lit, is that the heat exchanger may soon be developing a crack or hole so it seems to be a ticking timebomb if were to continue using it), and so I'm thinking we should probably just replace everything at once including the ductwork. I was contemplating trying to get home warranty to help (at least with the furnace) and even opened a claim but once I found out who the service provider was (horrible reviews on Yelp and elsewhere) I canceled the claim lol. I think we're just going to have to suck up the cost of a brand new system in our case.



Anyway, wanted to get some specific advice as far as sizing is concerned. At this point, I'm inclined just to stick with the same sized system that we have (4ton)? Going down to 3ton seems a bit risky unless we were to double-check the insulation and perhaps consider adding either a whole house fan and or gable exhaust fan.
Was also curious about brands to go with: Goodman, Bryant, Carrier, Rheem, Payne? Any to avoid? And in terms of cost, the ballpark estimates I've been getting range from $10k-13k at least currently. I hear the best time to replace systems is generally beginning of Spring or Fall? Should I try to hold out until then? On the other hand, I hear supply chain disruptions aren't helping either and it may not be a great idea to try to hold out for a "deal"...

TIA