As the weather begins to get hot here in Kansas City, it is clear our AC unit is not going to cut it another season. It failed to keep up during the hottest days last year. It hasn’t even reached 90 this year and it is already not able to maintain a comfortable temperature.
I know nothing about AC systems and advice is appreciated.
We’ve had the system serviced annually, so I have to believe it is properly charged. It is a Rheem and is about 15 years old. We have a big house… 3800 square feet without the basement. Unfortunately, the unit sits in the sun on the west side of the house.
I suppose I am wondering if I should get a new one… what it will cost installed… what size.. what brand…what else…
Thanks
Replies
Look at your last service invoice.
Did they add freon? Was there a leak? Did they fix it, or just charge the unit?
Did they clean the the condenser coil?
Lots of short cuts are taken durring the busy part of the cooling season. Some because they are in to much of a hurry, and some because they know they will be back agian.
If the unit was cooling properly for several years, there is no reason it should not continue to do so, barring a compressor failure.
One problem with rushed service work is not taking time to check the super heat on a unit, and or reading the charging tables incorrectly for the ambient temperature. Either of wich can lead to over charging the unit. Over charging is as bad as a low charge, except you don't get the iceing on the evaporator coil.
Did they clean the evaporator coil? That is another overlooked item on annual service. The unit may be doing what it is designed to do, but a dirty evaporator coil is not allowing the proper heat transfer.
Lots of little stuff can effect a units performance, but good service tech. will work down his check list to eliminate all of them. Not just the obviouse ones.
Maybe try a different service company. There are some good reasons to buy a new unit, but "not keeping up", if it gave good service for years, is not one of them.
Hope this helps a little.
Dave
Good responsed Dave.
NCL: Ask the service guy what the superheat on your unit was last year or what it is now. If you get a dumb look, you been screwed for years.
Go take a look at HVAC-talk.com and ask your question there, give your hometown, somebody there probably knows who screwed you ''cause there is always a bad apple.
A 15 YO Rheem that was serviced last year should be in good shape.
Dave and Junkhound: Thank you for your thoughtful advice.
The service guy was out this morning for the regular annual service call. His notes indicated they did not add freon last year and did not note the super heat value last year either. This year, however, he said it was "bad" and needed to add two pounds of freon (for which we paid an extra $22) to bring it to 10 degrees. He said the "record temperature drop" is 18. He wrote a bunch of other stats as well.
With the need to add two pounds of freon, is it safe to assume there is a leak in the system? The service guy said it would cost $190 to locate the leak and an additional cost of "up to $900" to fix it.
Again, advice is appreciated. Like the A/C in my last truck, I am happy to spend a few $ each year to charge it up, so long as it gets me through the season. But I can imagine I won't know if it is in need of a charge until I realize that we have been uncomfortable for a while. Is it worth finding and fixing the leak? Should I replace the unit the next time it fails to keep up?
Thanks again.
Adding freon indicates you do have a leak. Easiest method to locate a leak is look for an oil stain somewhere. Suspect point are around the filter drier, entry and exit lines at the compressor (outside condenser unit), condenser coil, and at the A-coil (inside the air handler).
The freon carries oil with though the refrigeration cycle, so a thorough inspection of the whole loop will generally get you in the neighborhood of the problem. Half hour at most, unless the system has really long line sets. Most leaks occure in the condenser coil, and rain may wash off the tell tell signs of oil. If you don't see the signs anywhere else go back to the condenser coil and compressor. Also stop at a HVAC supply house and purchase a small bottle of Big Blue leak detector, or whatever they sell. Put it in a spray bottle and liberally spray it on the compressor fitting, the filter drier, and the condenser coil. The leak will reveal itself in the form of bubbles, just like a leak in your car tires. Once you locate it, mark it with a crayon and call a couple of service companies for estimates.
$900.00 seems excessive for a leak repair. I could be wrong, but recovering the freon, repairing the leak, pulling another vacum, or charging with nitrogen,etc. should not take more than six hours, agian unless the system is large (over four tons).
Another warning is to read the label on the compressor/condenser unit. It will tell you the number of pounds of gas needed to properly charge the unit. Expect to see an additional amount charged to the unit when the recovered freon is put back in the unit, due to recovery and charging losses. Also look for a charge for adding some oil. If they don't add the oil, expect the compressor to burn up in the first week to month of operation.
You are doing your homework, so why not take it a step farther with a little investigative work. A lot of HVAC companies really don't care for knowegable home owners.
Good luck,
Dave
Dave -- Are you going to be in KC anytime this summer? I'll buy the beer.
Once again, thank you for your thoughtful, in depth, advice. .. but did I mention I don't know anything about air conditioners? : )
...filter drier, outside condenser unit, condenser coil, A-coil... huh?
I am of the industrious and frugal nature, so I'll certainly poke around in search of an oil stain. If it is sufficiently obvious, however, wouldn't the guys who just added freon have spotted it?
For the sake of getting an idea what I might be in for if I needed to replace it, I let the A.B. May folks pushing Trane at the Home Depot stop over. The guy was nice enough and told me I currently have a 10 seer 4 ton unit. For my 3800 square foot house, he recommended 5 tons. He also suggested a heat pump with a gas furnace back-up. I realize they are trying to sell both the ac and furnace at the same time, but he's got me thinking. I am familiar with the efficiency of heat pumps, but have had a negative impression of them for areas that get real cold. I have always thought of an electric coil heat backup, which I associate with high operating cost. Using gas back-up, however, seems appealing.
Since I would use the heat pump most of the time, he suggested just a 80% efficient furnace with a variable blower. I like the variable blower idea because I have an electrostatic filter and like to leave the fan run 24/7. I think the lower spread option would same $ and noise. My furnace is also 15 years old. Ribbon burners. He said it was a 50%. Keeps us warm ok.
Combine the 80% furnace with a 16 seer heat pump for just over $10K installed. Certainly not chump change, but worth considering. We'll be in the house for a while.
Any thoughts? Thanks again.
my first thought is don't spend 900.00 for a repair on a 15 yr old unit!!! thought 2 and this is just my opinon [by the way i live in wichita] i have a heat pump w gas back up,when it's time to turn on the heat i flick the gas furnace on and give my condenseing unit a 6 month rest, plus i like the heat "feel" of the gas furnace. were in the process of building a new house and i bought a 5 ton ac with a 125k 2 speed 92% furnace from a guy on the internet for 2000.00. that tells you what i think of heat pumps.i have bought sveral units from this guy and he is absoulutly stand up type of guy,if your interested in getting a hold of him let me know. 3rd thought! get some other bids i would think around here in wichita you should be able to do that job in the range of 5500- 7000. with no problem. good luck stay cool larry
Heat Pumps are getting "common" in the KC area.
I know that many of the utility companies have "programs" for pushing heat pumps.
I am thinking about going that route (HP with gas pack) when I replace mine. Actually I am thinking of using a hot-air system fueled by a high output water heater. But I have an unusally application with 2 heating zones, but only one cooling zone.
"The guy was nice enough and told me I currently have a 10 seer 4 ton unit. For my 3800 square foot house, he recommended 5 tons. "
Based on WHAT?
Only way to go is to have then do a manual J calculation. If they won't do that show them the door.
Yes, as I understand it, KCP&L has had a program for 10 years which essentially cuts your power rate in half for about 9 months out of the year if you install a heat pump. I'll take it, but I must admit that I do not understand the business sense behind such a program..."We'll make it more attractive for you to use less of our product." Unless the power company is subsequently reimbursed by the government or something...
I am afraid I do not know what a manual J calculation is. Can you explain? I believe he based his recommendation of a 5 ton unit based solely on the square footage.
Thanks
I am on MoPub.
Here the rate are the same for the first increment of usage, Need to find an old bill to give the details, summer an winter.
Then for 9 months the rates go down for higher usage factors. In the summer they go up.
This is for ALL customers.
Also there is a reducing of about 10% during the winter months if the primary source of heat is electric.
"I'll take it, but I must admit that I do not understand the business sense behind such a program..."We'll make it more attractive for you to use less of our product." "
What they really want is to sell the same amount of power 24/7/365. Lots of capital equipment not in use this time of year. And at 4 pm Aug 21 they are throwing everything on line that they can find and spending gobs of money to get power out of the less efficient units that they have.
Manual J is a manual from the aircondition association (American Society of Air conduiting and Heating engineries or something like that) that gives all of the details of the steps needed to calculation heating and aircondition loads. Takes in account things like size, type, and orientation of windows and amount of insulation.
Often done by software such as http://www.havac-calc.com
"We'll make it more attractive for you to use less of our product."
It saves them having to build new power plants, which are fabulously expensive and entail huge regulatory hassles.
"The guy was nice enough and told me I currently have a 10 seer 4 ton unit. For my 3800 square foot house, he recommended 5 tons. "
Based on WHAT?
Yeah, I got that too. The "rule of thumb" is 1 ton per 500sf, so that would give a 7 ton load. A two-story house with a near 50/50 split might could get by on 5 tons--but I'd run a complete calculation before I told a potential customer. It could be that the best equipment answer is a 7.5 ton compressor and two airhandlers with 3 ton A coils--or it might not.
The only "gotcha" for the original poster is the age of the system. For the cost, the consumer wants 20-25 years out of the equipment. The people making the equipment want you to believe that the technology improves on about a 5 year cycle (and the sales staff thinks conumers will believe ten years). The Ruud system that was in my house when I bought it had run for 18 years, and I got another 2 out of it before a cracked heat exchanger forced my hand.
Is the new system better? Yes and no. Puron is less efficient than freon--but instead of 18° delta T under 95° ambient and maybe 13-14° over that, I get a solid 19-20° delta T whenever I want. The piezo "hot plate" igniter for the gas heat means not running a pilot light, so the cost goes down. The efficiency of the furnace is not much different though, went from the .77 Ruud to a .79 Carrier.Occupational hazard of my occupation not being around (sorry Bubba)
Others have given several suggestions, but something else to check is the air filters and blower speed. Clogged air filters or a variable speed fan that isn't kicking up to high when it should will greatly reduce unit output.