Well rules of thumb are not going to do much for you and most of us frown on them. A properly sized system is designed to maintaint comfort. In the hottest conditions, recovery may be dealyed until it cools off in the evening. Initially, the load may be high but for the most part, day two ought to be pretty much on target.
If the thermostat is on the 1st floor and it satisfies, there is no more cooling to the second floor. This is where system balancing comes in and frankly that has absolutely nothing to do with the brand selected. You have two different loads, seperated by a floor and ceiling. They need to be treated differently.
You're system may be undersized, it may also not be balanced. Cant tell from here. The new system was not designed to operate like your old one and blast air or sound like a rocket. Many folks consider noise to be part of comfort levles. The problem is rarely will the duct system be changed when the equipment is and yet the expectation is that the system act as a complete new system would. Hard to do when you start off handicapped with who knows what for ductwork. Sort of like buying a new car and having the old car's tires and transmission be used and then expecting it to meet the fuel economy on the window sticker.
The service tech came out one week ago and made some minor adjustments... added a bit more puron and set the stat so the fan would come on high anytime the o/s temp is >80. Told me to leave the fan on auto. He also said he has heard many complaints lately about the infinity sytem not cooling fast enough. Said my ductwork was fine and that the system could not be fine-tuned any further. "It is doing what it was designed to do." Would not comment on any sizing issues...said their salesmen all use laptops and have software to calculate sizing. Said the salesman gave me what he thought was best. He left however, saying he did not think I was being unreasonable in complaining about the lack luster performance.
The salesman called me the next day to propose a fix, said they would replace my 2 ton with a 3 ton. Still claimed his calculations called for a 2 ton, but said sometimes calcs vs. real life can be different. Also had me measure the o/s of the house (while on the phone) and said he would redo the calcs just to be sure. He was going on vacation the next day and is to call me back later this week.
His initial proposal is to rip out the 2 ton and replace it with 3 ton...he said he would absorb all the intallation costs (including retrofiting and a new coil if necessary)and 1/2 the diff btw 2 & 3 ton cost. Wants me to pay an additional $250. I will probably do it, but I am not so sure it will solve the problem.
I have been taking temps the last few days and notice that the system can only drop 2-3 degrees after 6-7 hours on high during the afternoon hours. Even with o/s temps of 78, it took the system from 2:00 pm until 7:00 pm to drop from 78 to 76. While it was rather hot today (80-90), it took from 2:00 pm to 12 midnight to drop from 80 to 77.
It still seems imo that the blower is not strong enough (Infinity 58MVP 060-14). The 2nd floor still wont get under 80 and the air velocity is weak out of all but the one supply just above the furnace.
BOTTOM LINE QUESTION:
WILL A BIGGER A/C SOLVE THE PROBLEM, ALONE, OR DO I NEED A BIGGER FURNACE TOO?
By doing the load calculation (J-manual or Carrier Rezcal) see if the equipment was sized right. It might be too small. If the unit has a long lineset(copper tubing between outside condenser and evaporator coil after furnace, the PURON(r410a) charge has to be checked by sub cooling. Have the technician check the Freon charge. If there is a leak he should find it and repair it. Make sure it is going up to high speed. When you turn the stat down below room temp more than 2 deg it should go to a faster furnace speed and outside condenser speed. Have the technician check that it is running on high. The low speed is 1/2 the high speed (compressor drops out a cylinder by the direction the compressor runs).The tech needs to make sure the control is changing the operation on the equipment, could be a board problem (furnace, motor, condenser and the infinity control.
The Carrier distributor (who your dealer buys from) in my area (Chicago) has a specialist on this system and they offer to help the dealers set up the infinity if there is a problem with it. Ask it might be a service they provide in your area.
If it has a leak and is low on PURON (410a)the outside unit may be going on and off on the pressure switch, I would recommend a delay timer the compressor contactor, Carrier forgot to protect against short cycling on the infinity, low pressure control. Otherwise is a very nice system.
Originally posted by dhvac
just wondering where you are in pa I am in New Stanton
I live in Pittsburgh
Originally posted by furnace doctor
If the unit has a long lineset(copper tubing between outside condenser and evaporator coil after furnace, the PURON(r410a) charge has to be checked by sub cooling.
The lineset is approx. 45 feet. Goes all the way through the basement, into the garage and out the back of the garage (below grade) to the back yard (above garage). They could have placed the new a/c above the basement wall where the furnace is (10' lineset max), but I guess they wanted to use the existing electrical connections to the old unit.