New Central System for old home

[JJ57]

Hello,

Have a question on a new Central system that may get installed into an older home.

A family member decided to do some home improvements, and adding central air may be one of them.

The house currently has a wall unit (24K BTU) and a Window Unit (7.5 BTU) and both are from the 1970's.

After some of the window and door upgrades a load calculation was done for cooling requirements and it came out to around 26,500 BTU.

Now he is older, and in the summer, he likes to keep the house cold, around 68* inside on a 95 Degree day is common. Hey, it's not me, but to each is own.

The installer quoted him for a 2.5 ton system single stage, or a 3 ton system 2 stage/variable speed. These are units that he has several of in stock and giving him a price break.

Now both units appear to be slightly oversized, but like I said, he likes it cold in there, and it's been that way for the past 20 years, so that can't change.

Which system would do the better job for what he likes. Price is not a concern, rather comfort.

Thanks Again.

[tigerdunes]

JJ

Without knowing more info, I would say either will be fine just change from AC to a Heat pump with var speed blower. New ductwork system to be installed? Pa has reasonable electric rates-correct?

TD
:)

[beenthere]

Was the load calc done using 68*F as the indoor design temp, or some other indoor temp. It makes a big difference in the equipment size selection.
The break down of how much of that load is sensible heat is important also for equipment selection.

A 2.5 ton may not be able to handle that load, do to capacity loss the colder you try to keep it.
A 3 ton 2 stage may be needed if he insists on being able to drop the indoor temp to 68*F, and wants the humidity to be < 55&#37;.
You east of me a bit. But your still going to want a coil match up the has a reasonably low SHR. To keep the humidity low during our mild temp days. So just because he has these units in stock, don't just match to one of those coils, without him checking if its one of the lowe SHR coils. (The lower the SHR, the better it removes humidity ).

Did the installer give any model numbers. If so can you post them please.

[beenthere]

Was the load calc done using 68*F as the indoor design temp, or some other indoor temp. It makes a big difference in the equipment size selection.
The break down of how much of that load is sensible heat is important also for equipment selection.

A 2.5 ton may not be able to handle that load, do to capacity loss the colder you try to keep it.
A 3 ton 2 stage may be needed if he insists on being able to drop the indoor temp to 68*F, and wants the humidity to be < 55%.
You east of me a bit. But your still going to want a coil match up the has a reasonably low SHR. To keep the humidity low during our mild temp days. So just because he has these units in stock, don't just match to one of those coils, without him checking if its one of the lowe SHR coils. (The lower the SHR, the better it removes humidity ).

Did the installer give any model numbers. If so can you post them please.

[JJ57]

I Don't have the numbers in front of me. And I think they are Tranes, but don't quote me on that one. I will not be seeing him until next week.

Basically he told the installer what he wanted, as a friend of his installed a system last year, and had it build to what he wanted.

There will be all new duct work, and what not, so that will probably help.

He told the installer that when it's 95 and humid, he wants the unit to be able to keep the house at 68 Degrees inside. The installer did the load Calc, and then came up with those 2 choices.

He did mention, as did I about the humidity control issue, and that the 3 ton may be slightly larger, but being a 2 stage system, will offer better humidity control.

Reasonable Electric Rates where we're at.

I will check on the coils. I will also check if it's R22 or R410a

I know it will be a matched system, and the price difference is not that great, and the 3 ton will also include a programable thermostat.

But like I said before, $$$ is not the problem, it comfort.

The old wall and window units from the 70's are a bit noisey, but that place is freezing in the summer, no problem. :D

Old people and cold in the summer, go figure. :rolleyes:

[beenthere]

Please remove the price reference. Prices aren't allowed on this site. Thank You.

Depending which trane 2 stage he gets, the one removes humidity better then the other.
The one uses R22, the other R410A.

With proper humidity control, 72*F can feel like 68*F.

[JJ57]

Ok, I called and checked.

They are Tranes here are the models:

2.5 Ton XL14i 2TTX4030B R-22 Single Stage

3.0 Ton XL16I 4TTX6036B R410a Two Stage

There is about a 15-20% cost difference. However, comfort and performance will need to be the deciding factor.

The other issue is a rather silly one. He is a old timer, and likes things the old way. The 2.5 ton unit is R-22, and he has about 140 pounds in the Garage. He even still has about 70 pounds of R-12 left, I just did his car last year and replaced the compressor, Accumulator, and O-tube, aong with the hoses. Filled it back up with R-12 from a R-134a converstion. Needless to say he is happier.

I told him that 410a will be the future, and when installed and maintained correctly, that it will provide the same level of comfort as an R-22 system.

And he is buying the service contract and extended warranty on this, correct me if I am wrong, but most service contracts that are "Full" contracts (Parts and labor) cover Referiferant, is this correct?

Heck, if it's something small or what not, I can even give a shot of Whatever to hold him over until a service Tech can get there. (Yes, I'm certified)

I'm thinking that the 3 ton 2 stage 410a system will be the better choice, anybody else have any thoughts?

[beenthere]

If he's partial to R22, then get him a quote on a Trane Xl19i, its uses R22, and has a better capacity reduction in first stage. (It will be a bit taller then his house. :) )
Nothing wrong with the 16i.

If he wants to keep it at 68 in the house, the 2 stage units are a better choice.

[teddy bear]

Maintaining <55%RH with a/c at 68^F will require a dehumidifier for the wet cool weather that you have in green grass climates. 65^F-75^F +rain and evenings does not have enough cooling load to remove the 60-80 lbs. of moisture everyday. I suggest a simpler a/c with a 90 pint/day whole house dehumidifier as more cost effective method of providing ideal temp/%RH. Cooling below the outdoor dew point dramatically increases the dehumidification load. Moisture may condense on any of the interior clading of the outside walls. The moisture moves through the wall into the home.

Providing 72^F, 45%RH freezes most people. Check out the multitude of whole house dehus that becoming available. Lower investment, lower cost of operation, and better humidity control is a result of incorporating the whole house dehumidifier. Regards Dehu TB

[JJ57]

Thanks for all your help.

I didi see the Trane XL19I, if I am correct, this has 2 compressors on it, not just 2 stage.

And they do offer it it R22, so that may be something to consider.

But the 3 ton 2 stage system will seem like the better bet.

I don't know if he is part snake, bu he just loves it cold.

I remember when he had his car (RWD V8) converted over to R-134a at a local shop. He Flipped when he found out that the vent temps were at 48*

Evenutally I put a new compressor, Accumulator, O-tube, and FLushed the system.

Since he had around 75 pounds of R-12 around, we used that.

Now it blows 36* on the highway, I'm not kidding. :cool:

Looking at one of thise Weather station things that he has in the home in the summer, the RH is showing about 48&#37; and the Temp is about 68-69*

He loves it cold. :D

So I'm thinking in any way he goes, that a 2 stage or a 2 compressor system will do the job.

And if he gets a R-410 system, you can bet that we will have to go and "Stock Up" on Referigerant. :rolleyes: