Day 4 Update: I'm well into phase 2 which is the heat pump portion of the install. Yesterday I removed the old HP and brought the new HP to the site and set it on a new condenser pad. Today's fun project was crawling thru my crawlspace removing old refrigerant line and installing a new 50' lineset. My wife fed me the tubing thru a conduit feedthru I made thru the foundation of my garage right next to the air handler. Surprise #1 The lineset went thru the conduit just fine but hit a stub of a 2X4 hanging below a beam in the crawlspace. It was just a spacer for a water pipe but as luck would have it it was perfectly in line with the conduit feedthru. That was fun cutting off the stub laying on my back. Threading the lineset was slow going because the route was S shaped instead of a straight shot. I had to gradually bend the shape after every 4-5' was fed thru. It's now hung and tie wrapped with nice gradual bends. This time I got lucky since I have about 1-2' extra from a 50' spool. Surprise #2 It was really nice of Mueller to provide a 90 degree ell in the end of the lineset. However it now points 180 degrees from where it needs to to connect to the air handler. Trying to turn 50' of installed lineset 180 degrees just won't happen. I'll guess I'll just have to use a street elbow fitting. Next weekends fun project with be brazing all connections and doing leak testing, evacuation, final charge and checkout. Doing a project like this gives me newfound respect for the pros that do this type of work day in day out.

The connection between the evaporator & the AH should be sealed, however, a lot of them will have a little air leakage. More important is to test the ESP static pressure before the blower & between the AH & the E-Coil. Also, the CFM to each room should be checked & added for the total CFM. - udarrell Here is a link that might be useful: Air Side of Air Conditioning

Thanks tigerdunes, The house is a split level built in the 70s with about 2000 sq ft. The current furnace is the original and has 4 x 5 KW heat strips. It struggled to keep the house warm but I think that is more from it's age and upkeep than anything else. It's an old Westinghouse, I think it says the model number is ele068bh. Nov avg low 40 high 53, Dec avg low 36 avg high 47, Jan avg low 37 avg high 48. Last year we had 22 days during the summer with the temp over 80. Summer months avg in the high 70s

I guess I would say that the only way a 2-stage variable speed system would work is it is properly designed and installed AND if it paired with a zoning control system <That is properly installed and designed. What is 'properly'? The definition of whomever you choose is likely not the same. 1 stage, 2 stages, 5 stages paired to one control will never make up the difference to a system 'with more control' of the system. The more control of a system you have the more it will cost upfront. If you don't approach it from elegance it probably won't amount to much after about 5.5 years, maybe less. (I work on junk zone systems every summer.) 25% of this HVAC job is knowing what to do, the other 75% of this job is knowing WHAT NOT TO DO. If a thermostat is on lower level it doesn't know how hot or cool it is on upper level. If a thermostat is on upper level it doesn't know how hot or cool it is on lower level. For HVAC to work: it has to work in 80 degree weather and 50 degree weather, just as much as 100+ degree weather and 0 degree weather. I service the Katy, Texas area.