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Message
New AC running much longer than old one
Posted on 7/9/24 at 9:00 pm
Posted on 7/9/24 at 9:00 pm
Old unit was a 13 SEER and this one is a 14 SEER. Old unit ran for a max of 10 hours on 100° days set at 72° during the day. Now this new one runs 12 hours a day set on 75° during the day on 93°-95° days.
I called the installer and he came out to take a look. He swears nothing is wrong. I call bullshite. He says these new systems will run longer but are more energy efficient. Well, my first month with it is $85 MORE than normal.
Is this normal? No way this is normal.
I called the installer and he came out to take a look. He swears nothing is wrong. I call bullshite. He says these new systems will run longer but are more energy efficient. Well, my first month with it is $85 MORE than normal.
Is this normal? No way this is normal.
This post was edited on 7/9/24 at 9:00 pm
8
Posted on 7/9/24 at 9:09 pm to TDsngumbo
Are they the same tonnage? Both single stage, 2 stage, or variable speed? Did you replace the whole unit (inside and out)?
Posted on 7/9/24 at 9:13 pm to TDsngumbo
$85 more than this time last year or $85 more than last month? Mine runs all day on low but it's variable speed. It's more comfortable for it to run longer and not cool as fast.
Posted on 7/9/24 at 9:15 pm to mdomingue
Yes same tonnage, both single stage, and the outside unit was replaced also.
Posted on 7/9/24 at 9:16 pm to LEASTBAY
quote:
$85 more than this time last year or $85 more than last month?
$85 more than the second highest bill ever.
Posted on 7/9/24 at 9:19 pm to TDsngumbo
Then you are right, something is wrong with the picture you painted. A more efficient unit should not cost you more to run in the same conditions.
Posted on 7/9/24 at 9:32 pm to TDsngumbo
Something is wrong. I replaced ours with a variable speed. It pretty much runs 14 hours a day but my bill is way lower than it used to be.
Posted on 7/9/24 at 9:46 pm to TDsngumbo
Go find the supply grill closest to the return grill and shoot the temperature of the air coming out after 15 mins of running. Then take the temperature of the air entering the return air grill. Report back.
Posted on 7/9/24 at 10:01 pm to JusTrollin
69° going into the return air and 55° out the nearest vent.
Posted on 7/9/24 at 10:05 pm to TDsngumbo
Are you timing it?
Posted on 7/9/24 at 10:08 pm to OysterPoBoy
I’m not, but just estimating it’s on for 10-15 minutes then off for 10-15 minutes.
Posted on 7/9/24 at 10:23 pm to TDsngumbo
They do any duct replacement? Some considerable leakage in the attic could really make it hard on the new system.
Posted on 7/9/24 at 10:26 pm to Turnblad85
They did and he went up there then came back and said there’s very minimal leakage, not enough to make a difference. They used splitters, so to speak, with the ductwork. I didn’t have that before, when it was one line to each register. Well, these splitter type devices have air coming out of them in some places. Granted, even I agree it’s minimal leakage but I’m not an expert.
Posted on 7/10/24 at 12:40 am to TDsngumbo
quote:
69° going into the return air and 55° out the nearest vent.
14 F split, is not great, normally would looking at 18-20 F split, but it’s hot and high temps in the attic the ducts could be picking up a lot of heat - that why you measure the nearest vent to the supply plenum (shortess duct run). Ideally the temperature split should be measured by taking temp in inside the return plenum and inside the supply plenum, right after the evap coil, before it enters the ductwork. If you have a 14 F split there, then there is an issue.
Ideally a new install should be commissioned, meaning all the appropriate measurements are taken (refrigerant pressures, superheat, subcool, static pressure, temperature splits, etc,), written on a commissioning sheet, and verified that everything is operating according to manufacturers specs. That info should be given to you for your files - like taking a blood panel. Unfortunately few installers commission their installs - only the best installers do so.
Posted on 7/10/24 at 6:40 am to CrawDude
So what could the problem be to cause this?
Posted on 7/10/24 at 7:21 am to TDsngumbo
quote:
Well, these splitter type devices have air coming out of them in some places.
Where is it coming out? I understand that it is difficult to completely seal a system but if you can feel cold air exiting then I would think that should be sealable. If it is at connection points, duct tape should be able to reduce or even stop the leakage. The ducts should be insulated as well. You may want to check for leaks in the return air plenum if it is all or partially in your attic. If you are pulling attic temp air into your return air plenum, that will have an impact, significant if enough is coming in.
Not sure that helps. If this was not a new install, I would suggest you get another person in to look at it.
I'm curious why they replaced your old ductwork and if they went in with hard ducts (sheet metal) or flexible ducts. What type of ducts were the old ones?
Posted on 7/10/24 at 7:46 am to TDsngumbo
quote:
So what could the problem be to cause this?
My uneducated guess would be low on freon. Last AC I had replaced it was a fine balancing act between under charging and over charging.
I'd get the duct leaks sealed up in your attic. I don't think they're going to cause the problem you explain, but it's still nickels and dimes leaking into your attic.
Posted on 7/10/24 at 7:50 am to TDsngumbo
A couple things, you need to compare the size of you old unit to the size of the new unit. If you are on the border of sizes, it’s very possible you had say a 5 ton 13 seer and the new unit is a 4 ton 14 seer. That’s not unheard of.
2ndly, you need to look at your electrical bill costs they all are comparable to the prior month and prior year. It’s very possible your energy cost per KWh has gone up and not just your usage.
Most newer systems especially but really all systems are designed in the middle of summer to run longer. The idea is you want a smaller more energy efficient unit running longer, then a larger unit running less.
Given that, sounds like you do have an issue.
2ndly, you need to look at your electrical bill costs they all are comparable to the prior month and prior year. It’s very possible your energy cost per KWh has gone up and not just your usage.
Most newer systems especially but really all systems are designed in the middle of summer to run longer. The idea is you want a smaller more energy efficient unit running longer, then a larger unit running less.
Given that, sounds like you do have an issue.
This post was edited on 7/10/24 at 7:51 am
Posted on 7/10/24 at 8:13 am to TDsngumbo
Your original post is misleading, as it says you set your air on 75 but you later said the return air was measuring 69?
Of course it will run longer if you are trying to pull the temperature down lower....
Also you should have no leakage in your duct work. Use hvac foil tape to seal it up. Thats very easily and indicative of a lazy install.
Of course it will run longer if you are trying to pull the temperature down lower....
Also you should have no leakage in your duct work. Use hvac foil tape to seal it up. Thats very easily and indicative of a lazy install.
Posted on 7/10/24 at 8:19 am to JusTrollin
quote:
Your original post is misleading, as it says you set your air on 75 but you later said the return air was measuring 69?
I set it on 75 during the day but by the time I posted about it being 69° going into the air handler, it was evening and the house had cooled a bit.
I do plan on buying some air duct sealant and sealing it all soon, though. The installer said it is only leaking around 3% which according to him up to 12% is acceptable but I disagree, as any leakage is unacceptable to me.
This post was edited on 7/10/24 at 8:20 am
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