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2 Ton vs 2.5 Ton

Posted by cjr76 (My Page) on
Mon, Aug 2, 10 at 18:45

I have a HVAC newbie question. I recently had an infinity furnace and performance heat pump installed with an infinity control. The system is not working up to par in my opinion. It runs constantly from about 1-3:30 til 11:00ish to maintain a temperature swing of less than 18 degrees from the outside and sometimes will also slip a degree or 2 during the hotter times of the day (I keep it at 75 and the worst day we had since install was 90). This is also causing very low humidity levels (29-35%) and I am sure a hefty electric bill. I am not sure exactly what is the issue since it is a 2 ton unit and it replaced a 2 ton unit. I do know that I am not getting the airflow I had before because the inifinity system only allows a max of 400 cfm/ton. My main question is, given these symptoms, would a 2.5 ton system be THAT much more of an increase in size? The dealer said he would install a larger condenser if needed, and I feel that this may be where we end up but I wanted to make sure that half ton is not an excessive increase.


Follow-Up Postings:

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RE: 2 Ton vs 2.5 Ton

What part of the country do you live in?
Did they install a new Evaporator Coil with the Condenser?
What is your sq footage? How well is the insulation?
Was the duct work inspected?
You cannot increase the size of the Condenser without replacing the Evaporator Coil.


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RE: 2 Ton vs 2.5 Ton

I live in NE Ohio. The whole system is brand new. The coil is a 2.5 ton coil, so they should not have to replace it. The home is around 1300 sq ft and the insulation is average. Brick build, insulated windows, and about 3 inch of insulation in walls and attic. I am not sure what they checked with the ductwork, but I know they have checked it out on more than one occasion.

My main concern is going too big and I wanted to see if people felt that a 6000 BTU increase is alot or maybe not enough? Right now my issue is not de-humidification, its cooling and airflow.


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RE: 2 Ton vs 2.5 Ton

You do know that long run times are more efficient. That being said - it seems like it shouldn't run longer than the prior system. Maybe something is wrong with the install? Inadequate charge might be the problem - what does the installer say?

And if you are at all concerned with bills - I'd be adding to that attic insulation but more for the winter than the summer. I know I live in a new house but I have 20 inches in the attic in a far milder climate that anywhere in Ohio. The 30% tax credit makes it a no brainer if you only have 3 inches in your attic. Payback could be less than a year.


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RE: 2 Ton vs 2.5 Ton

The longer run can be, I know that, but it definitely does run longer than my old system and at times when it should be cycling, which means that in the end, it's going to cost more to run. And, my larger concern is the desert dryness it's causing because of the excessively long run times. I shouldn't have to need a humidifier in the summer. An example was last night, where I had the set point at 75 and it ran for at least over 6 hours to go from 76 to 75 in the house. In the meantime, my humidity was down to 32% and the system was still running and I had to turn it up before I want to bed because its wreaking havoc on my sinuses.

I know additional insulation will help, and its in the plan, but I have to pay for what I just bought first. They did check the charge, and about 50 others things (it was a bit low at first), but everything is running fine now as far they can tell. They have already made 4 trips out here to check things, so we are at a breaking point.

Bottom line is that I know something is wrong and I wanted to get an opinion on the sizing up from 2 to 2.5.


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RE: 2 Ton vs 2.5 Ton

Without being on-site its impossible to know for sure but it sounds like your system is properly sized; 400-cfm per ton is correct. You said they checked your ductwork on more than one occasion. Installing a larger condenser may cause other problems if your ductwork cant handle it.

Keep in mind that the Carrier Infinity system has a 2-stage compressor; the air handler is multi-stage and may run continuously, at lower speeds. This may be more than your older system but may consume less energy overall as well.

You should be able to adjust your comfort level with the Infinity T-stat. Set it and let it do its thing for a while. This T-stat learns from previous cycles as it goes, give it some time.

SR


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RE: 2 Ton vs 2.5 Ton

Your Infinity unit is a 2 stage unit. If it is running (mostly?)in first stage, it is operating at 1 ton capacity. This in itself, would cause the unit to operate for prolonged periods. The Infinity stat should indicate stage of operation.

Also, I believe there is a setting on the stat for 'comfort' or 'efficiency'. If it is set to efficiency, this could also be prolonging your cycles.

V


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RE: 2 Ton vs 2.5 Ton

The heat pump is not an infinity, it is a performance series single stage (the furnace is the ICS). This system has been installed for over 3 weeks and has not improved, even with the charge being properly set and the airflow set to maximum. I KNOW I got more airflow from old system, probably over the spec of 2 ton, because I could hear and see things like the blinds moving, much more than they are now. If I had to take a guess, the old system was moving around 1000 CFM. The only way to get the airflow up on an infinity controller is to get a larger condenser. I am guessing the size may be good if the airflow was out of spec, because sometimes I notice the floor is cooler. I am pretty sure the ductwork can handle the larger unit because it was handling more airflow before.

Something that I am not sure is an issue is that I have a little over 8 foot high ceilings, so I am thinking maybe the cubic footage wasn't considered? I think if I got the 2.5 ton, it would cure the issues because I would get more airflow, more cooling, and less dehumidification.


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RE: 2 Ton vs 2.5 Ton

Also FYI, the infinity controller is set for Maximum Airflow (400 cfm/ton) and all the de-humidification is turned off. Static Pressure is around .32 and blower RPM is ~650.


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RE: 2 Ton vs 2.5 Ton

I'm in NE ohio also. Last night was especially warm. I don't think the night time low was below 75.

Keep in mind, we are having a hot summer this year. That might explain why the AC runs more than before. This is a very hot summer. We've had many days over 90 daytime high.
Add some insulation to your attic. This will help.

You are definetly not oversized at 2 tons for 1300 sq feet. You sound like your sized perfectly to undersized slightly.

If you raise the fan speed it won't dehumidify as well if your trying to keep the house more humid.

At the beginning of the cooling season this summer my unit wasn't dehumidifying properly. Thats cause the fan speed was changed to the highest position when my heat pump was installed. Once I lowered the fan speed 1 setting it started dehumidifying properly.

I haven't heard to many people complain about having a dry house in the summer.


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RE: 2 Ton vs 2.5 Ton

Neo,

My house is bone dry, it's worse than winter. The problem with the infinity system is that you can't raise the fan speed because it knows exactly what equipment you have and won't allow it, so I am stuck with a max of 800 CFM which is obviously not enough for my home. So even if the unit is sized right for cooling, it is not adequate to circulate the air from what I am seeing, which is probably causing the cold air to not lift correctly.

I know we have been having a hot summer and I realize that I am not going to be able to cool from 80 to 75 in an hour, but I find it very hard to believe that a properly working and sized system cannot lower the temperature 1 degree in 5 hours and even slips a degree or 2 on days. According the contractor the units are sized for roughly a 17 to 18 degree temperature difference, which would mean that I should be able to hit 70 on an 85 degree day. My current system would never be able to do this, it's having a hard enough time keeping it 75 on a 82 deg day. We ran it from 7:30 AM to 11:00 PM one 87 degree day and it barely made it to 74 before it started to slip and eventually hit 77 before it started to cool for the night. I know many people who have AC and keep it at 72 and have no problem maintaining this on 90 degree days.


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RE: 2 Ton vs 2.5 Ton

I hope you are not confusing CFM with amount of BTUs for cooling. It shouldn't matter that you are only moving 800 CFMs - my system pushes that much on low stage and keeps 4000 sq feet at 76 in NC when it is 95 outside. Delta T has something to do with airflow but you don't need that much. I am exaggerating a bit but basically my downstairs system on low stage can maintain the temp.

Too dry. That is pretty amazing in an old leaky house.

My only point is to not blame airflow. Maybe you really had a different sized system before or maybe specs back then were way off or your system is not working properly - those are your 3 choices. 800 CFMs are not you problem.


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RE: 2 Ton vs 2.5 Ton

it sounds like your system is only having this problem during extreme heat days.

When the heat becomes not so extreme it should be better.

If you have the infinity system you should be able to control humidity from the thermostat I would think. It would raise the fan speed.

You must have a variable speed fan.

My house is 1730 sq. feet with 3-tons. Your equivelent would be 1950 sq. feet for 3 tons with the same size.

Your just a touch undersized if at all. On hot sunny days my system runs alot to keep the temp the same.

I have all brick. No wall insulation. New windows though. I also have about 9 inches of blown cellulose in the attic. I've sealed all leaks too. Good doors. Try sealing some leaks and adding some attic insulation.

It sounds like the main problem isn't the cooling. Its just the humidity level. Too bad you can't raise the fan speed some. I know that would cut back on the de-humidifying.


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RE: 2 Ton vs 2.5 Ton

David,

No, I am not confusing CFM's with BTU's. I am just trying to make sense of this all. My old system was 2 ton according to not only the dealers I had give me quotes, but also on the receipt from the installation of it which was left with the house. Assuming the systems have equal BTU's (I know my current system is rated at 22,800 according to AHRI), the only difference is the airflow, which I know was higher with what I had before. The old system did cycle on most days in 75-88 degree range outside, even if just for 20 minutes off at a time. 90 degree weather would keep the old system running most of the day also, which I can live with. I am at a bit of advantage here because I was able to see how my old system ran in all levels of heat vs the new system due to the time I had it installed.

My house is actually not leaky from what I can tell, the windows are pretty new and I have yet to feel a draft from any of the doors. It was built in 65, but seems to have had improvements made to it over the last 10 years. But yes, dryness is a real concern and it has to be tied to run time. I have been tolerating it while the dealer troubleshoots, but its wearing on me.

Neo,

I have been tracking the system since last monday to give the dealer data and its not just the extreme days. The only days it ever cycles are ones that are under 80 and overcast. I dont consider an 82-85 degree day extreme in that an AC unit would be slipping degrees, especially set to 75. Maybe if its 93, but not anywhere in the 80's. But yet I am still seeing it go from 75 to 76 and fighting to keep it there. For a system that is supposed to be sized to maintain a 17-18 degree swing, I would think a 10 degree swing would be a cakewalk, right?

It does have a variable speed fan, but according to the manual, the fan only runs variably in Comfort mode, which locks the airflow to 350 CFM and then can cut the speed lower if needed to de-humidify. According to everything I read, the infinity control is locked to a max of 400cfm/ton, but to get this speed, you lose the variable speed of the blower. So that is why I am considering pushing for 2.5 ton, because it would increase my airflow to 1000 CFM max and increase the cooling, which should also decrease the de-humidification, however, I dont want to go too high because I want to massively oversize. The nice thing about the infinity though is that you can set it reach a desired humidity level and it will continue to run until it is met, even after the desired temperature is met.

I know i do need to increase the attic insulation, but like I told the dealer, I offered to let them see anything they needed to in the house to make a sizing estimate and if this was not considered, then it is not my problem.

I don't know, but I don't feel I am crazy here. Even though I feel bad being a pain in the ass to the dealer during their busy time, I still feel like the system is underperforming and I have alot wrapped into this that will need to work for the next 15 years or so.


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RE: 2 Ton vs 2.5 Ton

Has a Manual J heat gain/loss analysis been done on your home?

If all else has been tried, maybe you are right and you do need (at least) the 2-1/2-ton condenser. That may entail adding additional supply & returns though.

SR


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RE: 2 Ton vs 2.5 Ton

I'm curious - have they checked the output temps on the registers? Does the dealer have an explanation for any of this? I mean you should have the same run times as before - unless they messed something up.

I mean a big leak would explain things. Lots of other install mistakes would explain things.

I'm going to guess that 2 tons today is not the same as two tons 10 (or whatever) years ago. Anyone who knows cars, knows that published HP numbers are sometimes whatever the manufacturer wants them to be. Perhaps a/c units were oversized by default back then. Now - with greater interest in efficiency (and ES standards), maybe they are more accurate. So then I guess you would need 2.5 tons.

I don't think 2.5 tons is going to be a problem for you. Anytime you go higher, you make the humidity in the shoulder seasons more of an issue. But it sounds like that is hardly a problem and might be a reasonable trade off for you.

I'd think a 1965 house would leak like a sieve, even with the latest doors and windows. The leaks would be in other places. I am always surprised by holes that you find in older homes - like they had no desire back then to keep vermin out. To see what I mean - look under insulation in the attic at a light fixture or around a register or return. But maybe I'm wrong.


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RE: 2 Ton vs 2.5 Ton

fsq4cw,

I know a full manual J was not done. I discovered it after the fact, but I know this was one of the few dealers who took the time to go around and count registers, windows, doors, measure ducts, etc..

Just out of curiosity, why would I need more ductwork if the old system was moving probably at least 2.5 tons worth of air and doing fine?

David,

The did not check the registers, however they did check the temp at the intake and output at the furnace and it was definitely low (around a 15 deg drop), but since then they leveled out the charge, however, they have not re-tested.

The initial screw up was the under charge and not setting the airflow to Maximum according to them. I have a feeling they think this is a normal operation now and that I am being overzealous because of the higher temps we have been seeing in the area, although they haven't come out and said it. I know for a fact the system does not cool as well as the old one, its close, but its just not cutting it. They seem reluctantly intent on making me happy though. Why have AC if its going to under-perform on the days you need it most? Thats why I am here looking for opinions that are not my own, to help re-enforce that there is an issue.

Honestly, I may be delusional, but I think this house is sealed up pretty tight for its age. I am sure it has leaks, but you can tell from the build, if nothing else, they were trying to keep the place secure. After I pay this venture off, sealing and insulation is my next avenue of attack.


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RE: 2 Ton vs 2.5 Ton

if your vents are accessible in the basement, try to find leaks while the system is running. Seal the leaks in the vents with silicon or tape. It may help a little. Better to have what your furnace is pumping circulating thru the vents and not seeping into your floor from leaks in the vents.


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RE: 2 Ton vs 2.5 Ton

cjr

what size did you replace?

was a load calc performed? if so, at what design temperatures? what has outside temps been recently? above average?

any reasonable opportunity to reduce the load by adding insulation? I know this for certain;you are not going to save any money with that system running constantly for long periods and if system is losing ground, then it is reasonable to think you may be undersized. there is a difference between having long run cycles and running constantly for 8-10 hrs.

sorry for your trouble.

IMO


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RE: 2 Ton vs 2.5 Ton

Tigerdunes,

Old unit was a 2-Ton, 11 year-old Lennox Unit.

As far as I know, a full Manual J was not done, although I know certain things were inspected like windows(but maybe not considered?). Not sure exactly about the design temps other than 17-18 degrees below outside temp.

Temperatures for the past month have been a bit on the hot side, although considering I like to have my house at 75, they fall well within a 17-18 degree swing. Usually mid to high 80's, with a couple days in the low 90's at worst. Like I said before, I have had the advantage of having both the old and new system in the house during both the 90 degree and more moderate temperatures, so I can honestly compare run times between the two system.

Right now, insulation is not in the financial cards right at the moment because all my $$ is tied up in this new system until next year.

Just for my reference, what would be considered a "normal" long run time between cycles?

Because yes, right now, I am looking at 6-8 hour run times unless a day is below 80 and overcast.


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RE: 2 Ton vs 2.5 Ton

You may need additional supply & returns if the static pressure level of the system is raised too high by the additional cfm. Noisy registers or freezing of the heat exchanger in the air handler may be a side effect of more cfm, but freezing is not likely with an Infinity air handler.

SR


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RE: 2 Ton vs 2.5 Ton

cjr

any idea of supply temps from your supply register? I would want several readings at different registers over the course of the day-morning, afternoon, evening and note outdoor temperature at the times taken.

you will get different opinions of normal run times but mine is anywhere from 15 minutes to 30 minutes-definitely not 6-8 hours running continuously and losing steam as the day heats up.

IMO


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RE: 2 Ton vs 2.5 Ton

Tigerdunes,

No readings have been taken at the registers. I do not have tools to do this myself.

Here is an example of my reading from the thermostat over last week. Thermostat set to 75 for all week:

Mon:
5:00 Out = 83 In = 77 Hum = 41%
8:00 Out = 77 In = 76 Hum = 36%
11:00 Out = 68 In = 75 Hum = 32%

The system did not cycle from 5 to 11 and may have been on longer because I did not get home from work til 5. I had to turn it up to 76 at 11 before bed because it was so dry in the house

Wed:
3:30 Out = 89 In = 75 Hum = 40%
5:00 Out = 89 In = 76 Hum = 40%
8:00 Out = 84 In = 76 Hum = 36%
9:00 Out = 80 In = 77 Hum = 35%
11:00 Out = 73 In = 76 Hum = 31%

This was the hottest day of the week and again it did not cycle once all day. It also slipped 2 deg for the day.

Am I wrong that this is abnormal?


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RE: 2 Ton vs 2.5 Ton

Go to Bed Bath & Beyond and buy an instant read cooking thermometer. They cost around $12 and usually have a range from 0* to over 200*. Use this to measure the air temp of the inlet and outlet air at furnace.

For me, 2.5ton Trane, inside 74, outside 90, humidity of 40%. Unit cycles occasionally for about 10 minutes duration. At night, my unit can lower the temp from 74 to 70 in about an hour, same humidity, with the outside temps in the mid 80s.


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RE: 2 Ton vs 2.5 Ton

Weedmeister,

What is the sq footage of your home? Is it insulated well?


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RE: 2 Ton vs 2.5 Ton

Have you tried changing your fan from auto to on all the time? That should reduced dehumidification some. Does seem strange that it dehumidifies that much though. My house usually sits at 45-48% and the infinity controller has worked superbly.

Good luck in resolving this issue.


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RE: 2 Ton vs 2.5 Ton

emarston,

Yes, I have my fan on low when the cooling is not running and it definitely does raise it a small amount. The problem is that the cooling cycle is so long (it basically never stops running from the first time it starts til it is done running for the day), that it only stops running from late night to early afternoon, so the humidity never has a chance to "catch up".


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RE: 2 Ton vs 2.5 Ton

Around 2000 sqft, and not insulated that well at all. Probably R11-19 in the walls, R25 in the attic. Lousy windows and big sliding doors.


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RE: 2 Ton vs 2.5 Ton

Sorry to hear that. Sounds like the contractor is going to have to do some work to resolve the issue. Hopefully, they will take care of you fairly as you spent a lot of hard earned dollars to purchase a properly functioning system.


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RE: 2 Ton vs 2.5 Ton

You have a contractor problem! Here is my suggestion.

First, change your approach. Stop playing HVAC contractor. I understand feeling the need to based on how your contractor is responding, but stop, now.

Escalate the problem to the local Carrier distributor. They have at least one dedicated technical advisor on staff to help a contractor who is struggling, and your contractor is clearly struggling.

(Sidenote: You distributor will be either independant or factory owned.)

Monday morning call the distributor. Calmly tell them you bought a brand new Carrier system x weeks ago from x contractor. It has never worked correctly. They have been out x times since the installation and they don't seem to know what to do.

A good distibutor will jump right on it. First, he will talk with the contractor to review what has been done so far. He may suggest a course of action for the contractor to take or decide he needs to see the installation first hand. Push to have him see the installation. Also, confirm this is the distributor's dedicated technical guru you are dealing with and not the distributor's sales person who sometimes is dispatched to go out and smooth things over, ultimately hoping to explain away the problem.

Be nice, but firm. Good luck.

If you get any push back, and hopefully you won't, point them to the link below.

Here is a link that might be useful: 100% Satisfaction Guarantee


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RE: 2 Ton vs 2.5 Ton

oneuglymother,

How do I go about contacting the distributor? My plan was to give them til the end of monday to get back to me and then email carrier directly to ask their opinion of the situation. I know the contractor said they asked a Carrier tech (not sure if it was the distributor tech or not) about my problem and got an answer to try something else (something about getting more humidity reading from another device), but I guess they kinda of made a comment like "he has air conditioning?" meaning that they didnt seem to be too interested in helping because they have so much other work to deal with or something. This is coming from the contractor though. I am just starting to get the feeling that they are getting less willing to work with me, even though I am being VERY patient with them because I understand this is a busy time. I want to try to avoid throwing someone under the bus prematurely, but I need to get what I paid for.


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RE: 2 Ton vs 2.5 Ton

Try the link below. If they are not the right people ask who is. Good luck.

Here is a link that might be useful: Carrier Distributor Ohio


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RE: 2 Ton vs 2.5 Ton

Thanks, I will see what kind of response I get.


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