I have been told I have to large of an A/C for the house I am in.

Has anyone had this issue?
Besides spending 10k to replace all the equipment... are there other solutions?

I assume this is a single stage system? If not, the oversizing may not be such a big issue.

Dialing back the fan speed dip switches may allow you to extend run time during cycle and effectively limit capacity, but that's not the ideal use of those settings.

It is a single stage condenser but a multi speed handler.

Handler is 5 ton, condenser is 4 ton, HVAC company says I need a 3 ton on both.

The main issue being it's not running enough to keep humidity levels down?

Add a dehumidifier?

YES, I have had this issue for 20 years, now solved w/new system

Not enough details, sorry
SF = ????
# stories = ????
Insulation walls/clg = ????
SF % of windows vs insul.wall = ????
West side shade = ????
Unit brand & SEER = ///?
Zip code = ???

No, it's always running and never drops temp. It stayed at 77 degrees from 6 until 11 PM last night. Just never drops temp.

GhostWipe15 said:

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It is a single stage condenser but a multi speed handler.

Handler is 5 ton, condenser is 4 ton, HVAC company says I need a 3 ton on both.

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Check your air handler models. Most of them come ready to accommodate many setups. My 3.5 system is also used on 4 and 4.5 ton setups. You just dial the air handler switches to whatever system it's mated too.

Are you sure yours is set up right?

Kenneth_2003 said:

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If the system is over sized then the obvious answer is a renovation and expansion. Time to close in that porch and add another room somewhere.

Generally oversized units cool but don't lower the humidity. Can't cool the house is some other issue at play. Get a 2nd opinion. What part of town?

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Haha this was going to be my exact follow up after reading the ops response.

Thank y'all. Will for sure be getting someone else out to look at it. It's never made a whole of sense to me, but I am a novice when it comes to these systems

You've got to be on your toes these days. So many bad contractors give the good ones a bad rep.

Really makes you wonder if these guys are being dishonest, or just completely inept. That seems like a big miss for an HVAC contractor.

Good thing there are online communities like this with really knowledgeable and helpful folks.

GhostWipe15 said:

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It is a single stage condenser but a multi speed handler.

Handler is 5 ton, condenser is 4 ton, HVAC company says I need a 3 ton on both.

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Sq ft of house ?

1 or 2 story ?

Rough location ? Houston ? San diego ? Mee york ?

SF = 2150
# stories = single
Insulation walls/clg = fully foam insulated
SF % of windows vs insul.wall = would need to count but if I'm taking a guess, maybe 10%
West side shade = NO SHADE
Unit brand & SEER = GOODMAN 14 SEER
Zip code = 78155

JP76 said:

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GhostWipe15 said:

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It is a single stage condenser but a multi speed handler.

Handler is 5 ton, condenser is 4 ton, HVAC company says I need a 3 ton on both.

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Sq ft of house ?

1 or 2 story ?

Rough location ? Houston ? San diego ? Mee york ?

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2150
Single story
San Antonio

San Antonio
IF your insulation package was ala 1980s then your system would be ideal using SF instead of a real Manual-J
as the 5 ton would be only 10% oversized for that era & 4 ton sized for humidity control. In that era, 3.5 tons would be recommend only by the power company, wanting all HVACs to run mostly full time = THEIR generators are making the most money by not cutting on-off so often. This was part of some Arch-Mech.Eng classes, in fact in-the-day.

WIth foam all about and such a LOW fenestration percentage, even a full setting sun West exposure can't explain your horrible performance. The last time I was involved in such was Building Committee of a church. The "C" rated contractor & low bidder ran off the job before connecting the main HVAC to the indoor return air ductwork = so I found the HVAC sucking attic air in to process as conditioned indoor air.

Ergo why I strongly suspect a duct leak, perhaps not so grand in size. Once fiexed, me think you can ride this system out to its 20yr life before investing more $$$$$ in something better designed.

Whatever the solution comes to be, please consider insulating your ducts ... even more so if attic not foamed
+
erect a lattic West shade until you can grow fast Ch.Pistache next to slow Live Oaks in October (not before).

tgivaughn said:

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San Antonio
IF your insulation package was ala 1980s then your system would be ideal using SF instead of a real Manual-J
as the 5 ton would be only 10% oversized for that era & 4 ton sized for humidity control. In that era, 3.5 tons would be recommend only by the power company, wanting all HVACs to run mostly full time = THEIR generators are making the most money by not cutting on-off so often. This was part of some Arch-Mech.Eng classes, in fact in-the-day.

WIth foam all about and such a LOW fenestration percentage, even a full setting sun West exposure can't explain your horrible performance. The last time I was involved in such was Building Committee of a church. The "C" rated contractor & low bidder ran off the job before connecting the main HVAC to the indoor return air ductwork = so I found the HVAC sucking attic air in to process as conditioned indoor air.

Ergo why I strongly suspect a duct leak, perhaps not so grand in size. Once fiexed, me think you can ride this system out to its 20yr life before investing more $$$$$ in something better designed.

Whatever the solution comes to be, please consider insulating your ducts ... even more so if attic not foamed
+
erect a lattic West shade until you can grow fast Ch.Pistache next to slow Live Oaks in October (not before).

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We actually did have some substantial leaking in duct work, that is really what kicked this whole saga off. We had all of the ducting completely re-done and I have inspected it back and forth looking for a leak since it was redone. Strangely enough, the system worked better before we had the duct work fixed (except one room that was getting virtually no flow)

The attic is also foamed, and most of the duct work is suspended, so I am not sure I would be able to insulate it.

htxag09 said:

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The main issue being it's not running enough to keep humidity levels down?

Add a dehumidifier?

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That's what I first thought when I read the title.

In very broad and general terms:

An oversized system will cool the house down relatively quickly. The temperature will be what you set on your thermostat. You feel uncomfortable because the humidity may be high.

The quick band aid fix for this would be to buy a de-humidifier. Look at something that's 100 pints or more. That measurement is how much water per day it can remove from the air. Units will cost between $200 - $300 depending on actual size, brand, extra features and so on.

Not cooling the house is the exact opposite issue. The system is undersized; assuming nothing is broken, and it was installed correctly. (again very broad terms).

If everything is functioning correctly, the fix would be replacement or adding some kind of auxiliary system and reconfiguring. Such as adding a mini split to a couple of rooms and removing the ducts from the original system. That way the original system is responsible for less volume to cool. Having a system too small is not where you want to be.

I feel for you. These kinds of things always seem to happen at the worst possible times. I would definitely get a few different opinions. Many companies just want to sell you a new system and will push that hard.

Have your shortlist of who to call. If someone says you need a replacement, get their bid and wait for the next one. If they say its repairable like being low on refrigerant some other thing and says it going to be a few hundred bucks, pay the man and enjoy your AC.

If you need a new system and can hold out until February, you will save a good chunk of money.
Add 'Dileo AC & Refrigeration' to the list of people you call.

Good Luck

After ductwork is jostle about, some might find leaks at duct sources, so bring some smoke (or better) if DIY.
Aside from a blower door test (sometimes free via your utiltiy co. but often a long wait to schedule), I would of course call them back out with goal to actually IMPROVE the performance this time. Failure again = new HVAC company, 5-star rated & not so eager to sell NEW (unless yours is 15-20yo).

Until the hi-IQ HVAC minds chime in here, I am stuck on blockage or leak
and of course blind to all other conditions thus far.

We just went through something similar with our new 2-stage unit. Even though it seemed oversized it struggled to cool the house in the afternoon, and constant humidity.

After we found a reputable tech, he found that there was a short in one of the wires between the air handler and condenser. Rather than replace the wiring, our original installer had just rigged the wiring to have the fan run at Stage 1 speed no matter what stage the thermostat was trying to run. The first stage just couldn't keep up with the summer afternoon heat.

After the wiring was replaced, they also reduced the blower speed to optimize the temp drop across the coils. We went from a 14 degree drop to a 20 degree drop which seems to have helped with the moisture in the house.

I've also heard some smart thermostats have difficulty with multi stage systems. We were initially blaming our Nest until we realized it was actually wired wrong.

TLDR: find a reputable tech and have them check your wiring. Make sure the wiring matches the system diagrams. Also have them check the temp drop across the coils.

BenTheGoodAg said:

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You've got to be on your toes these days. So many bad contractors give the good ones a bad rep.

Really makes you wonder if these guys are being dishonest, or just completely inept. That seems like a big miss for an HVAC contractor.

Good thing there are online communities like this with really knowledgeable and helpful folks.

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The real issue is that many are not honest about how inept / inexperienced they are.

There are many contractors that want a job and build their business and will overstate their knowledge and experience, which then begets trouble, which then begets more dishonesty and more trouble.

To your point, educate yourself as much as possible whenever and wherever possible particularly when spending serious money.,

fka ftc said:

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BenTheGoodAg said:

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You've got to be on your toes these days. So many bad contractors give the good ones a bad rep.

Really makes you wonder if these guys are being dishonest, or just completely inept. That seems like a big miss for an HVAC contractor.

Good thing there are online communities like this with really knowledgeable and helpful folks.

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The real issue is that many are not honest about how inept / inexperienced they are.

There are many contractors that want a job and build their business and will overstate their knowledge and experience, which then begets trouble, which then begets more dishonesty and more trouble.

To your point, educate yourself as much as possible whenever and wherever possible particularly when spending serious money.,

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The unit may indeed be oversized, and I think you're correct to your other point. They don't have a clue why it's not cooling the house. They're hoping that by going to a completely new system they'll magicly fix what else is wrong.

OR they found the problem, recognize it's a cheap and quick fix but know that when they fix it you'll have the humidity issue and don't want to either 1) explain the need for a dehumidifier up front or 2) you come back and say now i've got a "new" humidity problem because they never warned you in the first place... And the whole new system is crazy good $$$ for them.

UPDATE:

I have talked to another tech on the phone and described as much as I can. He thinks the problem is that my return is to small. I have a single 20 x 20 return for this entire system. He thinks I need to double or even triple that.

Also, he is not local, he is someone who I had worked with in the past when I lived somewhere else, so he isnt trying to get my business.

If anyone knows someone reputable in the SA/Seguin area, let me know because I would like some good eyes on this.

20x20 is without a doubt too small!!! Can't help you with who to use, I have a Houston area and CS area guy but I don't think he'll go that far.

GhostWipe15 said:

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UPDATE:

I have talked to another tech on the phone and described as much as I can. He thinks the problem is that my return is to small. I have a single 20 x 20 return for this entire system. He thinks I need to double or even triple that.

Also, he is not local, he is someone who I had worked with in the past when I lived somewhere else, so he isnt trying to get my business.

If anyone knows someone reputable in the SA/Seguin area, let me know because I would like some good eyes on this.

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You need roughly 1000sq in of return filter grille to get 2000CFM for your 5 ton system. You have 40% of that currently. Make sure the return air duct is sized right. What diameter is it?

You should reach out to Tri County AC & Heating. Bubba is an Ag and they do solid work.
https://www.tricountyac.com/

VERY helpful, thanks!

Always we design min. 1sf of return air chase per ton
(we leave filter sizing to others)
or
Google
How many square inches of return air filter per a ton?
144 sq.in.

Ergo, 5 tons = 26x26in
Your 20x20 = 2.77 ton system
Your air handler indoor condenser is 4 tons = 24x24 inch filter
Mine air/condenser attic 3.5tons = 25x25 Honeywell electronic filter
but that has also worked for 5-ton & 4-tons in these 40 years ...
BUT
that alone cannot create your big problems, me thinks
Change to a 5-star Google/BBB HVAC service, please
and inquiring minds need to know
The Answer later

I have a 4 ton system. The air handler is a vertical install and the cutout on the bottom of the unit is not 4 sq ft? If my filter grille is the same size as the cutout in the metal bottom am I good? or should I add more filter grill to equal 4 sq ft?

Is 1 sq ft per ton an old school rule ?

On 4 tons I usually see 20x25 and 20x30 on 5 tons

This is kinda like saying 500sqft to a ton is good enough. A chase and a return grill are two separate animals. A chase 26x26 for a 4 ton is fine but a 26x26 return grill is not. To break my own rule and use a rule of thumb, a poster above got it right…..you plan for 2cfm/sq inch for sizing your filter grill. A lot of guys get this very wrong. A five ton unit should have a 12x12 in every bedroom and two 20x25s in the main areas or corridors with properly sized supporting duct. The correct way to do it is to calculate the actual pressure drop across the grill, filter, plenum and duct work but who has time for that when Chuck in a truck will do it "real good" for $7,500?

tgivaughn said:

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Always we design 1sf of return air chase or filter per ton
or
How many square inches of return air filter per a ton?
144 sq.in.

Ergo, 5 tons = 26x26in
Your 20x20 = 2.77 ton system
Your air handler indoor condenser is 4 tons = 24x24 inch filter
but
that alone cannot create your big problems, me thinks

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Had the HVAC company owner out today to work on it while on the phone with the manufacture.

Two things happened.

First they decided to slow the blower speed down to try and maximize the time spent on the coils rather than blowing right past them, they also adjusted the charge after this.

Second thing is they rolled the txv bulb to the 2:00 position on the line. It was at the 6:00.

Guess I will see.


I know I have already said this, but I really do appreciate everyone's input on this.

So far this has dropped the humidity in the house from 56% down to 50% but hasn't really effect the temperature. Verrrry slowly gone from 74.9 to 74.1 (over a three hour period) but maybes that's the heat outside… 102 right now.

So no discussion of return air sizing?

We discussed it, he thinks I am slightly undersized - which i dont agree with. I think its more than slightly.

He told me that if I really want to, they can install another return, there is no such thing as to much return right, but wanted to try this first. He suggested a 12 x12 in addition to the 20 x 20 that I already have. I would think I want either large than 12 x 12 or more than one added.