HVAC

One of the downsides of living in a 4000+ square foot home and having temperatures hovering in the 100 F range is that it is increasingly difficult to stay comfortable.

I am not sure if it is a function of more frequent extreme weather or if people just have a lower tolerance for discomfort, but more and more homes in Colorado tend to have air conditioning.

We bought our house in 2021 and in 2022 we decided to replace the furnace and primary air conditioning.  The furnace was original (1994) and though well maintained, was getting increasingly expensive to repair.  We opted for a equivalent units to what were installed and ended up with XX BTU Furnace (xx% efficiency) and a 5 Ton Air Conditioning unit.

The air conditioning unit was struggling to keep up.  Part of the problem was air flow.  Apparently return air needs to be coming through on the order of 400 cubic feet per minute (CFM) per ton for the air conditioner to work.  Our 5 ton unit was essentially starved at roughly 1000 CFM.  One fix was to add an additional return in the basement which got us to 1400 CFM.  This return air would have been sufficient for a 3 ton unit.  The 5 ton unit was overkill.  

Costs from Alpine Home Air for condenser (air conditioning) unit show:

1.5 ton - $1668

2.5 ton - $1710

3.5 ton - $2392

4.0 ton - $2350

5.0 ton - $2883

So while there is not a big price difference, it would have been better to size the unit correctly for the returns.

As a stop gap, we borrowed room air conditioners from a neighbor.  These worked remarkably well and we were tempted to purchase (4) of them from Costco for around $500 each.  It is a similar solution to getting space heaters rather than trying to heat the whole house in the winter.  This was working fine.  One potential issue was having to drain the condenser reservoir periodically.

Ultimately we opted to get a second air conditioning unit.  Rather than get a second furnace, we went with an air handler and a 2.5 ton unit.  The upstairs (4) bedrooms each have (2) registers/vents and there is a central return in the hallway.  So far it has made an incredible difference and will hopefully be more energy efficient to cool the upstairs at night and the downstairs during the daytime rather than trying to cool the whole house.