OK, went with completely new 13 SEER York A/C

[seekr]

...instead of simply replacing the condenser units with 10 SEER units and using the existing 30 year old York 3 and 4 ton evap coils, based on your unanimous recommendations. Purchased York Affinity 3S units. A 5-ton rated coil was installed with the 4 ton unit.

Ran the units for the first time yesterday. Large solar gain had brought house temp to about 81. Set the thermostats (two separate furnaces, two separate A/C units)to 76 degrees. Took about 3 hours to bring temp down to 76 degrees. By this time, it was night, and the outside temp had dropped to about 76 degrees or less. The old, same tonnnage units, with capillary valves would have done it in much less time - I'd guess perhaps 45 minutes. Then, as the temperature almost reached 76 degrees, I felt the air being blown out of the condensers, and it was cold, not warm, and ran that way for about a half hour until the inside thermostat said 76 was reached.

Is something wrong? The installer said that with the TXV valves, the units would run longer, but I'd be saving money because the compressor would not be under as much load. Doesn't seem right to me. He did have some problem with the installation, and had to come back and replace the original TXV valve which apparently failed during the initial startup. I'm not sure he had a lot of experience with 410A. The plenum feels very cold, I think colder than the old units ever got it. Could the new larger evap coils be restricting air flow?

Any thoughts would be appreciated.

[ambarton]

what is the model numbers on your units

[BaldLoonie]

I'd find it hard to believe that a unit would be able to drop the temp 5° after you've allowed the temp to build up. The A/C is not only cooling the air but everything in the house. If humid, it has to remove the humidity first. To me, the 3 hours doesn't sound that bad.

060 TXV coil is right for the 4 ton Affinity unit. It could be possible that he doesn't have the refrigerant level correct. You can't go by the temp coming out of the condenser, high SEER stuff moves more air and the temp may not be that hot, especially in mild weather, compared to lower SEER.

[seekr]

Thanks for your responses. Ambarton, the models are CZB04811A and CZB03611B.

BaldLoonie, do you mean that if there isn't a great difference between the inside temperature and what I want to lower it to, the higher SEER units will cool more slowly than the older low efficiency models?

And still, why would the air being blown out by the condensers be cool instead of warm? Seems like that means they are not providing any cooling, even though the A/C unit doesn't "know" its close to reaching the thermostat's shutoff point.

[BaldLoonie]

Cooling capability between 2 units is a function of the BTU capacity, not age. Replacing a 4 ton with a 4 ton should have similar cooling.

As for the temp leaving the unit, new stuff moves much more air so it doesn't have the temp rise of the old. Also, condensing temp is lower so the air won't be as hot. The air coming off my 13 SEER is much cooler than the air coming off my neighbor's 10 SEER 20' away. Even though mine is 2 ton and theirs is 2.5 ton there is more air coming out of my unit and it has about twice the coil surface area with a much bigger fan blade.

Unless there is an issue with refrigerant level, I can't see why your new units don't cool similarly to the old ones of the same capacity.

[RoBoTeq]

Longer running cooling systems operate a much higher efficiency. Set it and forget it and you will appreciate that new system much more then the previous one.

[beenthere]

What are the model numbers of the furnaces.

[udarrell]

I would say the techs are not getting enough of an airflow heatload through the Evaporator coil. (Condenser discharge temp comparisons to another 13-SEER system below)

Are the Return Air registers at the ceiling?
They need to check static pressures & CFM airflow.

I am going to do some comparisons to a Goodman 13-SEER 4-ton condenser & 5-ton E-Coil with R-22 refrigerant. The amount of heat & pressures should cross-reference to each other to get the same BTUH operating capacities & temperatures.

We do not know how the coil & fin areas compare or how the condense CFM compares.

Concerning the condenser discharge temperature splits:
If the coil area & cfm are close, your initial heatload "may not be that far off, who knows," from the rated load at 95 ambient 80-IDB, 67-IWB, & 1500-CFM or 375-cfm/ton of cooling indoor airflow through the 5-ton coil of your system.

The Expanded Performance Data shows 228-psig or 114-F SCT minus 95 ambient equals 19-F condenser discharge air temperature rise.

Second data, may be somewhere near your last conditions when condenser air felt cold:
85 ambient 75-IDB 63-IWB, & 1500-CFM or 375-cfm/ton, gets 226-psig or 103-SCT
Minus 85 ambient equals 18-F temperature rise split.

Get your good mercury thermometer out & check temps at condenser & indoors.
IMO only with virtually no critical test data, I would say, they are NOT getting an adequate heatload on the evaporator & therefore on the condenser, unless there is a refrigerant system problem. The system appears to have problems!
http://www.udarrell.com/ac-trouble-shooting-chart.html

We are only guessing from here & are NOT liable for what you & your techs do - based on anything we say herein! – udarrell


[Edited by udarrell on 09-10-2006 at 09:39 PM]

[ambarton]

yes you are the proud new owner of in my opinion the quietest running outdoor units on the market. for the installer changing the txv valves, the york brand currently does not install 410a valves into there coils (some) so you have to order and replace prior to installation. im assuming that is what he did. no big porblem, just wont work and shows in-experience with the equipment. this ,i feel in turn, lead you to examine your setup more closely and may have never noticed how long it takes from a dead start to actually cool your home. if he was good enough to leave you the installation instructions instead of using them as a knee pad, you will find two important numbers; one the sensable cooling capacity of that unit and second the latent cooling capacity. in a nutshell that means that you may have too little air flow to produce "sensible" cooling, but doing a great job removing the latent (humidity) heat from the supply air. make sure your filters are clean and ask the installer to measure your air flow to make sure you have a minimum (york specs) 325cfm per ton. and by this i dont mean the gifted waving hand over the grill meathod. find somebody who knows how to properly measure air flow and im sure your problems will be resolved.