This is the first part (from my other recent thread):
So, I called the company back up last night, and they sent two more techs out to the house today (I believe one of them was an apprentice). I talked to him about the high static at the blower, and he measure 0.8" W.C. I mentioned that with the small return drop (20"x12") the face velocity at the filter was over 900 FPM. He said that's fine, and actually looked at his "duct-u-lator" chart and told me that 10"x18" was fine for a 3.5-ton system, so my drop was plenty big. He also measured 0.35" pressure drop across the filter. He said that had nothing to do with size of the return drop.I had posted an earlier thread about what to expect with a service call for the A/C not cooling properly. I had a tech come out and look at the system a little while ago, and here is what he said:
- I asked him about static pressure, and told him the numbers I had gotten from an energy audit: He said
* 0.35" W.C. across a clean blue fiberglass filter was fine (shouldn't it be more like 0.05" - 0.10" if the system is designed properly?).
* static depended on the system and house, not the 0.5" W.C. allowable on the name plate
* said high static was common
* he didn't have the tool with him to measure static pressure, and he said that they don't do that for residential, only commercial.
- I told him about lowering the fan from High to Med/Hi (see other thread). He said he never would have checked if I hadn't mentioned it
- I asked about face velocities and asked him if the return drop might be too small. He said that that's way over his head (exactly what the last tech said).
- He originally set the blower speed for heat to medium low, which is definitely not enough air flow for the 80K output furnace. I asked him why, and he said you couldn't have the heat and cool on the same blower tap (I don't see why, because you would just splice the wires). I asked him about the heat exchanger cracking, and he said that there were plenty of "safeties" in place to prevent that from happening. I said I didn't want it tripping on the high limit, and he just said yeah. He just left the blower lead for heat unplugged.
- He said the system was a little low on freon, and he said he added a little under a pound. He said there was a 21 degree difference at the outside unit, and super heat was 12 degrees. I have no clue if that's good or bad, but he sounded like it was good.
- I asked him about it taking longer to cool the house down with the much reduced airflow. He said that would cool the house down faster.
It's been over 45 minutes since he left, and the temperature hasn't even cooled down 0.1 *F inside (it's 75.3 inside currently) - it's only 82 *F outside. What should I be doing now? I'm afraid you all are going to say get another tech.
He said that my system was undersized. He was using his "rule of thumb" and said I should have a 5-ton for 2200 sq. ft. He said I should get a load calc done, and I should, but the price he quoted me was astronomical. He also said that when contractors size duct work, they do it for the size of the A/C system. Because of this, without doing any research or measuring of anything, he said the duct work was too small.
Anyways, I feel like I'm really screwed at this point, because the system is now operating worse than it was when I called them out. Before, I was getting a 23 *F temperature split at the air handler with the blower on Med/Hi (1592 CFM). However, yesterday, the tech said that the system was just under a lb. low and supposedly charged it with some more R-22. He set the blower at Med (1376 CFM), and I'm seeing a drop of around 23 *F. With the drops being the same, I would have been removing more heat from the air before the charge and with it set on Med/Hi. Now that he's added more freon, I'm guessing I won't be able to achieve that 23 *F drop at Med/Hi, will I?
I really don't know what to do at this point, as I've got a bill for 2.5 hours and 1 lb. R-22 from 2 visits, and my system is performing even more poorly than it was before. I feel like I was better off before calling them out. It may be undersized, but for now, I at least want it running the way it was before I called them.
I really appreciate the help you guys have given on other threads. What should I do now?