New Carrier 3 ton, 16 SEER HVAC and air handler issues
Hey all...I was out here in June and early July investigating options for replacing my older Carrier, 3 ton, 13 SEER HVAC system (outside unit was very noisy and had a hard start added to it, but we felt we were on borrowed time)...Long story short, we went with installing a new air handler (same variable speed, etc) and a new outside unit (Carrier, 3 ton 16 SEER upgraded outside "cage")...When they installed the system, the old system didn't seem to have the appropriate "plenums", so they added new plenums (at no charge to me). Ever since we had this new system, electric bills were higher and we checked out our usage and it seemed to be in line with our usage the year before, so we didn't dwell on that at the time...Our issue is that although the thermostat states 72 (we set it there and never change it - set on cool)...It seems to be hotter than 72....Our remote control for our fireplace has a temp reading on it, so we moved it from room to room and it was pretty consistent with saying it was really 74-75 degrees in each room. We contacted the company that installed the unit and they came out to do their check up (post install checks and balances, I guess)...They found that there were a couple of places that were not sealed all that well on the air handler, so they rectified that, but didn't feel it would create the issues we felt we were dealing with. They started talking about humidity and that made sense...It was a humid 72 versus the 72 we were used to...At any rate, they tested the defrost board (not sure that is the right term) and decided that it needed to be replaced. Keep in mind, this is supposed to be a brand new unit right out of the box! We weren't happy that a part needed to be replaced right off the bat, but it wasn't costing us, so we accepted that as a potential fix.
We still experienced the same issues over the next 30 days and had the company sales rep come back out. He used some commercial readers (sticks that read temp, humidity and some other stuff) and left them in two different rooms over a period of 10 or so days. They just sent us a copy of one of the data results and the temp only varied by 3 degrees, but the humidity varied considerably (up to 61.1% - varied a lot)...
Does anyone have any suggestions as to what could be causing this new system to feel like it isn't doing as good of a job as my old failing 13 SEER Carrier system???JamesRiverAir_HVAC_MonitoringReport.pdf
Did they leave you any service tickets with technical data such as pressures and temperatures etc.?
Originally Posted by CoastalWGSD
Rather unusual for the defrost board to be replaced when insufficient cooling is the problem. Is this in southern Va.?
The general question that everyone asks is did you get a load calculation done? Humidity problems are usually due to oversized units. Higher electricity bills may also mean shorter on cycles because of oversized units. Your older Carrier might be the same tonnage but it had to deal with an improper plenum.
Looking at your attachment... the humidity is ranging around 50-60% which isn't uncommon. How long does your AC stay on before it cycles off?
You can call me Sam
It should be a crime to be a mechanical engineer in San Diego
Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7
10 days plotted (squeezed) on that graphic is horrible. How can one read and interpret that graphic?
We are NOT at your house. So without data of the unit performance, we cannot give you advice. Besides, call the contractor back since you are not 100% satisfy.
Relative humidty at 51+/- 3% at 72'F seems near constant and close to meat locker conditions.
Originally Posted by CoastalWGSD
My 78'F at 42% R.H. is very comfortable.
Ultra-Aire dehumidifier unit is needed if you wish to operate at the lower 70's 'F.
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LOL, you wouldn't like how cool I keep my place then.
and close to meat locker conditions.
72°F and 48%RH.
OP, do you have a VS blower.
Same here, I should probably live up North for as cold as I like in the house
Originally Posted by beenthere
Originally Posted by hcong
I am no pro...I learned most of what I think I know from this site! I KNOW that my old unit that was limping with a hard start kit kept my house nice and cool and an even 72 degrees year round. I KNOW that this new unit doesn't seem to do that. I was told that the humidity can make the 72 degrees showing on the thermostat feel warmer than 72 (which makes some sense, but my other thermostat on my fireplace remote says otherwise. It states that it is 74 to 75 degrees when the thermostat for the HVAC says 72...The only differences in the old unit and the new unit is that the old one was 13 SEER and the new one is 16 SEER...They both had/have a variable speed air handler (same model, but new one with new system)...The Plenums that were added are about 18" x 18" I think, haven't measured them, but that is what I am guessing with what I saw. The old system didn't really have a true plenum, but had a 90 turn on the return side...I think it had a regular plenum on the supply side...
As far as cycling...Havent really sat here and waited for it to turn on and off and am not sure I would know when it is cycling...
I agree on trying to read the data squeezed in like that...I am in touch with the sales rep and the company has been very cooperative about coming out and checking out the system the first call...My concern is that they had to replace the defrost board (motherboard) on a brand new unit...I wonder if that part is still not working correctly...
meat locker conditions? Guess it depends on how thin your skin is! LOL! I have always had it at 72 degrees...What the relative humidity has never come into play until they put the readers in the house to determine system variation...
I do have tickets from them...We are in central VA, what info would I be looking for?
This is what I have from their QC checklist visit
Line Set Size 7/8-3/8
Method of Charging Subcool
Evacuated to Microns 176
Amount Ref +/- 10 oz
Temp Split In 76 Temp Split Out 57
Ref Pressure (lbs) Suction 140 Dischard 275
Static Pressure Supply .20 Return .40
I had the sales rep come out again with their lead tech on 8/13 and that is when they decided the defrost board needed to be replaced. I have no numbers from that visit or the visit after they replaced the boards except the diagram of readings from the inside monitors they left here for 10 days...
72 and shuts off, or 72 and never shuts off? If it hits 72, shuts off, and you arent comfortable then set it to 70! Some people require thermostats to tell them they are comfortable, and obsess when the number doesn't rigidly conform to their preconceptions. (when I run into one of them, I game the stat. Good stats let you tell ho what they want to see.)
Size of this house?
By the chart it appears there are a lot of cycles. Hcong said it first, grossly oversized.
Which makes more sense to you?
- turning your thermostat back and being uncomfortable. Maybe saving 5-10%
- leaving your thermostat where everyone is comfortable. Saving 30-70%
DO THE NUMBERS! Step on a HOMESCALE.
What is comfort? Well, it AIN'T just TEMPERATURE!
Energy Obese? An audit is the next step - go to BPI.org
, or RESNET
, and find an auditor near you.
What are the model numbers of the indoor and outdoor unit, what thermostat do you have? If its the variable speed airhandler I think it is, there are some adjustments to it.
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