New A/C not cooling enough (73+)

[cernicky]

Funny, I typed my zip code (15068) into the trane link someone mentioned and the two places it mentions on the top are the two I have had my experiences with!

[alinnova]

Originally posted by cernicky
The system is clearly putting out more air and is much cooler than it has been to date after the recent changes. It was 74 in the house today (80 with 55% humid outside) but "felt" much cooler. I would have set the level lower than that but my wife was actually complaining about it being too cold (for once). My area is due to have near 90 (and likely very high humidity) in the next week so that will be a decent test.

A fellow homeowner here again. Please list the dip switch settings are they are now for the pros here to look at. It appears from what you say that the settings do not match what Mark Beiser said to do.

Is the system really putting out "more air"? Your first list of settings had 3=on and 4=off calling for 450 CFM/TON. Mark's list is for 3=off and 4=on to give you 350 CFM/TON. With 1=off 2=on for 2.5 ton setting, this gives you 875 CFM total which is still a bit higher than what you should have for a 2 ton system. In a system that is correctly sized for the humid climate, the cooling demand, and the duct system of the house, you should get better dehumidification when the air over the evaporator coil moves at the correct speed, giving you better comfort at a given or higher thermostat setting. Faster flow over the coil does not let the coil draw as much moisture out of the air, making the air feel more clammy.

Is Comfort-R set? If so, you will notice the speed of the furnace fan changing as it works through the cycle for better dehumidification.

Originally posted by cernicky

Besides the dip switch thing, I closed the vents downstairs. I had not previously had to do that with the old system.

I do that in my split foyer house with this new Trane system.

Originally posted by cernicky

My old system had a 100K BTU furnace and a 2 ton A/C. I used to set the A/C at 70 and it would go to 69 for some reason before kicking off. Both older units were at least a dozen years old.

Now you have an 80K BTU furnace. That is good if the old furnace was oversized and not running efficiently, giving you short and frequent blasts of too much heat.


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Originally posted by cernicky


Is it worth me spending the $50 to do a Manual-J software setup of my house to see what I really should have?

Would there be a fee to have a Trane tech come out?

With all the attention you've already given to this, and with the questions about the sizing of both the A/C and the furnace, you'll probably be happier doing the Manual-J yourself. I assume the contractor did not do one.

There should be no fee for a Trane regional or factory rep to come out.

Originally posted by cernicky


Thanks for all the comments. I don't believe I need to take any action on contacting Trane or ask for reimbursement or newer system just yet, but I do want to ensure that by pushing more air and the system thinking it has a 3 ton system is not going to hurt the system or void some type of warranty. I have no written record that they switched the dip switches so I can imagine their response in five years if it were to break down and they would indicate that I did the changes.

1) Is setting the furnace for 3 ton on a 2 ton system
something to be cause for alarm as far as warranty or life of the system?

2) Is setting the furnace for 3 ton on a 2 ton system something to be cause for alarm for added cooling bills?

3) Someone mentioned having them install a furnace that would properly handle my 2 ton unit. Would that not be a smaller one and thus provide less heat?

Back to the possible settings of dip switches 1 and 2. The best you can do is to make the furnace think you have a 2 1/2 ton A/C, as Mark Beiser recommended. If it remains set for a 3 ton system, as I understand the theory, your blower fan will get more revs over time, and you will not get as much dehumidification as you should. But I leave it for the pros to say whether there is any bad effect on the operation of the TXV and the condensing unit.

As for the bills, the harder the system works at dehumidification, that is, dealing with latent heat, theoretically if nothing else changes, the more electricity you are using. But if you end up raising the thermostat like your wife wants, you should end up saving on the electric bill.

Looking at your dip switch link, note the dip switches 1 and 2.
http://home.comcast.net/~brandon.cer...ac/xv80dip.jpg

It seems that the XV-80 series furnace has two ton settings on their 60K BTU furnace and one of their 100K BTU units. Go figure. Maybe the Manual J drill will help you work this out. And maybe the 80K furnace you have is the best option.

Good Luck
Al

[alinnova]

Originally posted by cernicky
Funny, I typed my zip code (15068) into the trane link someone mentioned and the two places it mentions on the top are the two I have had my experiences with!

Looks like those guys really need some refresher training.

Al

[dave_slo]

Originally posted by alinnova

Originally posted by cernicky
Funny, I typed my zip code (15068) into the trane link someone mentioned and the two places it mentions on the top are the two I have had my experiences with!

Looks like those guys really need some refresher training.

Al

Told ya so...

[rcp]

I prefer the temperature in the house to be between 70 and 72 in the summer depending on the humidity.

The humidity would have to be awfully low(out West maybe) for 75+ to feel comfortable to me.

[hackmaster]

Cernicky a word of advice. Whenever purchasing services in the trade industry a good rule of thumb is if the guy coming to give your estimate has khaki pants on and a golf shirt toting a brief case with a bunch of brochures...then send him on his way. You want to buy from the person who is doing the install and that can service the unit or with the owner of the actual company. When you purchase from a company with a payed salesman you simply will pay more for the same equipment you may pay less for somewhere else. Imho professional salespeople have no place in our particular industry as far as homeowners go. Secondly never go by the fact that youve "heard" they are a reputable company. The only way to know for sure is to get 3 good references on installs that company has done that are at "least" 5 years old. Reason being is you will find out better how they have provided service over the long haul and a better idea of how that companies particular brand has performed. I know you say it is cooling better but I personally would get a second oppinion from another company on whether that unit is charged properly...my gut instint tells me you still have problems in that regard even though you are getting better cooling now with the fan changes. Spend the money for a service call from another company just for your own piece of mind. Something tells me your unit is running continuously when it should not.

[daverubin]

Personally, I invested $50 in HVAC-Calc, did my own Manual-J, then turned away all the contractors who either (a) did not want to do their own Manual-J, (b) told me I needed a bigger unit despite my calculations, "just in case."

The contractor I chose actually recommended the smaller system, and guaranteed it would meet my expectations or they would install a bigger one. He measured my ducts and told me that they simply were not built to handle more airflow.

Long story short, I got a 2.5 ton system in a 1,800 sq. ft house with high ceilings. On very hot days the system runs continuously and cools to about 74 degrees, but taking all the humidity out. It actually feels chilly and we usually turn it up to 76 or even 78.

I was amazed at the number of contractors who showed up, asked me the square footage of my house, and without doing any measurements or calculcations said I needed a 3.5 ton system. I showed them the door immediately.

[hackmaster]

Just remember dave...one mans chilly is another mans hot. Each customer has their own comfort level. I have some customers that no matter how comfortable it may feel in the house that if they looked at the t stat and it read 74 at its best then they would go bonkers. Your unit should still be able to lower that temp lower than 74 if its running continuously on really hot days.

[daverubin]

By "very hot days" I mean maybe 5 days out of the entire summer, when it is over 90 and very humid. On most days, even those in the high 80's, I can get the temp down to 72 if I want.

Nobody has ever come to my house with the temp at 76 and complained it was too warm. But even if they did, I would just show them my electric bill and tell them to have a cold drink

[hackmaster]

Im sure it is fine and the only reason I bring it up is I have run into this situation in the past. Lets say you decide to sell your house and it just happens to be in a hotter than normal summer and the home inspector is out there this could then become an issue for the new home buyer. You may have 1 company come out and say its fine while another company says its not which could in the end run be a negative to selling your house. Now if you plan to stay there forever mute point obviously.

[daverubin]

Oh yes, that is a good point. The problem is that the homes here were not designed for A/C. Some contractors wanted to put in a totally new duct system and attic-based unit instead of piggy-backing on the furnace, but that was a huge expense.

I can definitely understand how some people might not be comfortable with a system that won't make the house 68 degrees if they want.

I'll be sure not to sell my house in July or August ;-)

[alinnova]

Originally posted by hackmaster
Cernicky a word of advice. Whenever purchasing services in the trade industry a good rule of thumb is if the guy coming to give your estimate has khaki pants on and a golf shirt toting a brief case with a bunch of brochures...then send him on his way. You want to buy from the person who is doing the install and that can service the unit or with the owner of the actual company.

As of now, after buying two systems in 10 years and having about seven or eight visits each time, I had the best experience with the owner. In my last round, the owner of a small company with maybe five service vehicles answered my questions, outlined several good options up and down the price range for Carrier and Trane, and quoted a reasonable price for a Trane XL 19i A/C and XV 80 furnace. Then as a good supervisor should do, he highlighted in yellow marker the specific parts of the installation instructions for the crew to follow, dip switch settings, etc.

Originally posted by hackmaster

Secondly never go by the fact that youve "heard" they are a reputable company. The only way to know for sure is to get 3 good references on installs that company has done that are at "least" 5 years old. Reason being is you will find out better how they have provided service over the long haul and a better idea of how that companies particular brand has performed.

To do a complete job on checking reputation of your short list of contractors, check them out with the Better Business Bureau and with the consumer affairs office of your city or county. That way, I learned that a family owned company with maybe 8 or 10 service vehicles that I had done business with for service calls and parts and I liked had gone bad. They were conveniently located on a major highway nearby and always seemed to be working about the neighborhood. They now had changed ownership and had several cases of complaints summarized as marketing practices.

By the way, I also like to visit the shops and showrooms at their business addresses. That helps give me a feel of what the whole staff is like and whether they have expensive overhead.

Al