New house near Dallas - high humidity?

[shepx2]

Hey HVAC R US, can you give me more specifics on that? The guy who owns this company is apparantly a major @ss, and I want to have whatever info I can to back myself up on this if I need to.

[hvac r us 2]

Originally posted by topdog
Thanks hvac r us 2,I was suspicious about the indoor unit when I saw the model# but did not want to commit.

I know what you mean Dog, I voiced my opinion when I wasn't 100% sure and got my butt handed to me on silver plater by about 12 people! LOL There is always going to be people who never have anything to say, except to point out when you are wrong. Such as life I guess...

Anyhow, in regards to the above mentioned units the big problem is in the metering device. The fan coil is okay ( not the best choice) but it is only rated with a TXV for Puron. You must have a TXV or the operation will never be correct.
As I mentioned the charge affecting the refrigerant flow will always be off. Without proper flow you will not be able to cool or dehumidify properly. This would be the first thing I would check followed by airflow. And if the unit is in the attic be sure ductwork is sealed and insulated properly.

Good luck

[topdog]

hvac r us 2 you did say that this was an add on and it is an external txv,outside of the cabinet? Which means customer should be able to see it without openning the cabinet.

[hvac r us 2]

Good point, yes all TXV kits are external mounted. As you pointed out this can easily be identified. By the way for the homeowner if you do see the TXV it better have a rose color sticker on it, not green!

[Short Circuit]

The "Kits" are externally mounted. However, some coils have factory TXV's installed, and they are installed internally to the case, such as the carrier CK5Px. So, visual inspection is not necessarily 100% proof of a TXV or not. You still need to know which manufacturers install TXV's internally to their packaged coils...

[hvac r us 2]

Originally posted by Short Circuit
The "Kits" are externally mounted. However, some coils have factory TXV's installed, and they are installed internally to the case, such as the carrier CK5Px. So, visual inspection is not necessarily 100% proof of a TXV or not. You still need to know which manufacturers install TXV's internally to their packaged coils...

You are right, however his model fan coil is designed with a piston from the factory.

[dash]

hvac r,

My book (2003)doesn't show an FA048 as an approved match,just the 060.What do you have?

[hvac r us 2]

Originally posted by dash
hvac r,

My book (2003)doesn't show an FA048 as an approved match,just the 060.What do you have?

Oh boy, how did I know you were not going to miss that Dash? LOL

I wasn't going to open a whole can of worms here as unapproved matches happen all the time (again not a good choice) but since you pointed it out, here we go...

A 38EYG048 is not an approved match with the FA048. This is due to the coil circuit flow not being enough with Puron as opposed to R-22. You need a larger surface area. This can become a greater problem in the heating mode.

You can locate the facts in the Product Data for the 38EYG, page 29, 2004 catalog, form# 38EYG-3PD.

Not sure about in the Dallas area, but I would think a Carrier dealer or distributor could get you a copy of this.

Good Luck

[shepx2]

Thanks for the info guys, you always seem to impress me.

Ok, here's an update. I called the dealer here on Friday, and he said that they DID replace the metering device, and add the TXV. He's going to send someone over next week to take another look at the system.

When you say it's "not an approved match", you are saying from Carrier itself, right? Could this be the cause of my humidity problem? If so, I may be able to request he change the air handler for me.
Here's the situation: the home we bought is in a brand new subdivision of 420+ homes when it is completed. There are 2 builders, splitting the homes. The same HVAC company is doing ALL the heating/cooling for the builder I used. The builder is a no-nonsense guy, and if they shouldn't be putting these systems together like this, I'd bet he'll put pressure on the HVAC company to set things right. Considering the $$$ involved, I'd bet it would be taken care of quick.

[obi-wan]

Check out http://www.centralcityair.com look in the library on undersizing coils. Contact them if you have to (out of Houston)

[airman1]

you will NEVER NEVER NEVER did i say NEVER be happy with a heat pump where you are in that set up...look at the heat pump coil specs...twice the surface area and square ft of a slab coil of the same ton...you bought a heater that cools not a cooler that heats...it is over ..buy a thermastor central dehumidifier...to say a heat pump cools just as good as a non heat pump?...well i am waiting to see it...havent yet in 35 years...but!!

[shepx2]

Well Airman, I didn't have much choice, since this development does not have gas.

[airman1]

sorry not trying to rub it in just stating the facts as i see it...you will probably be better of changing the cooling coil to a smaller one and dont use a heat punp to heat..

[thorton]

Originally posted by topdog
The board for blower operation is inside this unit and it is a VS. Make sure board is set up properly.As Short Circuit and justwarmingup has already posted.You will see better results,probably wasn't done and left at factory default. Puron??? Not so sure if it is a VS motor in the air handler maybe dash or hvac r us 2 or jrbenny will come in. They'll know.

[Edited by topdog on 05-19-2004 at 09:41 PM]

I don't think it's a variable speed motor in air handler g]either. Carrier's variable's have a V in the model # I believe.

Thorton

[mark beiser]

Even if everything about the equipment was perfect, wich is sounds like it is not, you will have high humidity with a single stage system with the kind of weather we have been having for the last few weeks here in the DFW area.

Systems are generally sized in this area to keep it 75º with 50% RH inside the house with 100º oudoor temperature and ~25 grains difference of moisture.

Even if it isn't oversized at all, it is big enough that it won't run enough in this 70-78º humid weather to keep the humidity levels down.

[teddy bear]

Originally posted by shepx2
Well Airman, I didn't have much choice, since this development does not have gas.

With moisture from the occupants, normal air & moisture infiltration, up to 100 pints/day of moisture must be removed during 60-70^F outdoor dewpoints. The simplest fix is adding a 100 pint/day dehumidifier to the air handler. The dehumidifier will remove enough moisture to provide 50%RH even without any a/c load or operation. Using a high efficiency unit like the Ultra-Aire 100V and being able to set the t-stat higher keeps the operating cost inline with the a/c only. I maintain that the ideal sized a/c is unable to maintain <50%RH during the 65^F-75^F "rainy spell" of weather without supplemental dehumidification. I will supply a set of inside/outside data loggers to prove over cooling is not a practical solution to this problem. Removing 100 pints of moisture per day to maintain <50%RH by overcooling requires 1.5 ton of constant a/c. This will not be a comfortable home. The home is a flywheel and the lenght of the wet/cool weather is load. Without supplemental dehumidification, over-dry the home during hot weather, avoid fresh air ventilation, and lengthly wet, cool weather.

[pstu]

Teddy Bear tends to advocate getting a Thermastor dehumidifier system and I tend to agree with him. Airman has really studied what it takes to dehumidify using the AC system and if he says you are way out of whack, I would believe him.

I bought a floor-standing Thermastor model and have observed about a 10 point drop in relative humidity using it, near Houston TX. If you want to "test" the idea by buying a cheaper dehumidifier and running it first, you can do that for a couple hundred dollars -- with reduced capacity and you will soon tire of manually emptying a water bucket<g>.

Your Dallas location will soon get into cooling season and you *might* see things getting better. But your Mississippi reading of 52% indoor RH is awfully good, I would not expect your new house to do anything like that.

By all means, if you have ducts in the attic and a supply leak, the result will be negative indoor pressure and outside hot humid air will be pulled in. If this turns out to be the case, fixing the leaks will tend to solve your problem. It will cost a few bucks to investigate but in my opinion will be money well invested.

Best of luck -- P.Student

[dan sw fl]

Originally posted by shepx2
Ok, I got up in the attic. The model of the Air Handler is FA4BNF048.

FA is a CONSTANT Speed.
Plus, 4-ton unit seems to be a bit oversized for 1,900 Sq. Feet.

You may wish to investigate the use of AprilAire model 1700 or Therma-Stor UA_135H dehumidifiers.