Communicating amana not removing much humidity

[joe2012]

I am an HVAC technician and I recently purchased a new home which was under construction. When I found the house, the heat pump and air handler were not installed but the duct work was completed. I asked the builder if I could install the heat pump and air handler myself if he would remove some of the price from the house he planned on paying for the equipment and installation. He agreed. I installed a 16 SEER 3 ton amana heat pump and air handler with communicating thermostat. I really like the thermostat and the communicating features it offers. Everything except the heat strip kW can be set on the thermostat. The problem I am having that is making me very upset with the system is it will not remove hardly any humidity from the air in my house. Here are all the things I've checked and done...

Turned the dehumidification feature "on" in the thermostat settings and lowered the humidity set point to 49%RH. Even when running more from a hot day the humidity only gets down to about 56%. On a mild day when it doesn't run much it can get up to 70%.

Verified that the humidity reading the thermostat shows is correct with a psychrometer.

Installed a vapor barrier in the crawl space.

Checked the Freon charge to make sure the system was not over or under charged.

Verified that the CFM the blower was running at was less than 1200CFM when system was running. Meaning it was lowering the fan speed to try and pull more humidity from the air. When it was in second stage cool it was running at 1000CFM and is first stage cooling I believe was 700 CFM.

When I check the condensate drain pan there is water in it, but not much. Even on a hot day I can go to the condensate drain line outside and put my finger in the drain and there is barely any water in the line.

Before installing the system I had my service manager do an heat load calculation to size it correctly.

When I call goodman technical they are pretty rude. And now that I'm working so much since the summer is busy for us techs, I never get home to call them before they close. Any ideas on what to do?

Thanks in advance,
Joe

[qwerty hvac]

Did you verify that the preinstalled ductwork was sized correctly? Is it all air sealed? Is their the proper amount of return air? What is your indoor dry bulb and wet bulb temps? SH and SC readings?


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[SBKold]

Lets have a look at the sat evap temp. And what air handler did you use? Avptc3137?

[joe2012]

air handler model: AVPTC313714

I don't remember the exact numbers but they were very close to spec. I think the SH was probably 3 degrees and SC was 3 degrees in first stage. I couldn't really do anything about these numbers beside add or remove 410 because the TXV cannot be adjusted. Instructions say adjust the TXV to 5 degrees SH but there is nothing to adjust. bulb is mounted horizontally and insulated, 10 o'clock.

After writing the first post I switched the fan from "on" (low), to "auto" and the humidity has already dropped a couple %. down to 52% last I checked. maybe the water on the coil was being evaporated off while the fan only was running when in off cycle.

I believe the duct work was installed for a 2.5 ton system so I added a 10inch return and another run of 10inch supply directly off the plenums.

[Southern Mech]

Fan on. on is not good.

[SBKold]

That pan holds a lot of water. I used to put a pretty aggressive slope to those units before they resigned the coil/ pan on there smartframe units.

[beenthere]

air handler model: AVPTC313714

I don't remember the exact numbers but they were very close to spec. I think the SH was probably 3 degrees and SC was 3 degrees in first stage. I couldn't really do anything about these numbers beside add or remove 410 because the TXV cannot be adjusted. Instructions say adjust the TXV to 5 degrees SH but there is nothing to adjust. bulb is mounted horizontally and insulated, 10 o'clock.

After writing the first post I switched the fan from "on" (low), to "auto" and the humidity has already dropped a couple %. down to 52% last I checked. maybe the water on the coil was being evaporated off while the fan only was running when in off cycle.

I believe the duct work was installed for a 2.5 ton system so I added a 10inch return and another run of 10inch supply directly off the plenums.

New house, 3 tons. Sounds like a large house. 3000 sq ft or so.

[joe2012]

New house, 3 tons. Sounds like a large house. 3000 sq ft or so.

How could you know that after the very minute amount of information I've said over a post on the internet?

Every new house that's about 3000 sq ft would have a 3 ton ac?? I haven't said what part of the country I'm in or anything about my house. I could only imagine the amount of different sizes that could be needed to adequately cool a house of this size with so many variables unknown....

One of the best things I've heard people say in various forums online is don't give an answer if you can't.

[ReferYankee]

How can you ask for an answer... If i can quote you... " with the very minute " amount of information you have given?

[joe2012]

When questions were asked I answered them. Implying the unit is over sized in a way like that shows ignorance. The house could be 1000 sq ft or it could be 5000sq ft. Installing the correctly sized system isn't dependent on square footage alone or much at all. A heat load calculation on the house was done by a professional to properly size the unit. If you know a better way to size an ac for a house then please tell the industry they've been doing it wrong.

[jpsmith1cm]

How can you ask for an answer... If i can quote you... " with the very minute " amount of information you have given?

ReferYankee

Please review the AOP Forum rules.

Thanks,

AOPC

[SBKold]

When questions were asked I answered them. Implying the unit is over sized in a way like that shows ignorance. The house could be 1000 sq ft or it could be 5000sq ft. Installing the correctly sized system isn't dependent on square footage alone or much at all. A heat load calculation on the house was done by a professional to properly size the unit. If you know a better way to size an ac for a house then please tell the industry they've been doing it wrong.

The guy you are calling ignorant was just being nice and commenting on your thread. You really screwed up by overreacting ....you might want his help or comments down the road.

[motoguy128]

IF your airflows are correct, the system is charged properly, if you're having humidity problems one can reasonable conclude you have 1 of 2 issues...

1) The system is oversized. What is your location, what are hte indoor and outdoor conditions when the humidity is high. Please describe the house a little.

2) The house is a leaky and/or lacks a proper vapor barrier.


THe guy you berated is one of the most experienced and knowledgeable on this message board. He's jumping to conclusion based on his experience and the limited info given.

[motoguy128]

IMO - any new construction in any climate that needs more than 2 tons for normal occupancy that's under 3000sqft is a poorly designed and is not using good building science principles and strategies. I have a 88 y/o house that out performs most similarly sized new construction because it has several simple design features that have a very large impact. It's 3200sqft and can be cooled with 3 tons @95F and heating with 60k BTU's. @ 0F. Since it has 2 systems, there is 4 tons and 120k BTU's combined installed.

[Shophound]

I am an HVAC technician and I recently purchased a new home which was under construction. When I found the house, the heat pump and air handler were not installed but the duct work was completed. I asked the builder if I could install the heat pump and air handler myself if he would remove some of the price from the house he planned on paying for the equipment and installation. He agreed. I installed a 16 SEER 3 ton amana heat pump and air handler with communicating thermostat. I really like the thermostat and the communicating features it offers. Everything except the heat strip kW can be set on the thermostat. The problem I am having that is making me very upset with the system is it will not remove hardly any humidity from the air in my house. Here are all the things I've checked and done...

Turned the dehumidification feature "on" in the thermostat settings and lowered the humidity set point to 49%RH. Even when running more from a hot day the humidity only gets down to about 56%. On a mild day when it doesn't run much it can get up to 70%.

Verified that the humidity reading the thermostat shows is correct with a psychrometer.

Installed a vapor barrier in the crawl space.

Checked the Freon charge to make sure the system was not over or under charged.

Verified that the CFM the blower was running at was less than 1200CFM when system was running. Meaning it was lowering the fan speed to try and pull more humidity from the air. When it was in second stage cool it was running at 1000CFM and is first stage cooling I believe was 700 CFM.

When I check the condensate drain pan there is water in it, but not much. Even on a hot day I can go to the condensate drain line outside and put my finger in the drain and there is barely any water in the line.

Before installing the system I had my service manager do an heat load calculation to size it correctly.

When I call goodman technical they are pretty rude. And now that I'm working so much since the summer is busy for us techs, I never get home to call them before they close. Any ideas on what to do?

Thanks in advance,
Joe

You're a service tech. It's time to ratchet up your HVAC performance analysis efforts a few notches. Write down everything you find from the following steps, and post it here to amp up the amount and quality of help you can get from us:

• Start the system and let it run awhile to stabilize.
• Measure and record return air dry and wet bulb temperatures.
• Measure and record supply air dry and wet bulb temperatures.
• Measure and record total external static pressure (TESP) at the air handler.
• Verify airflow independent of the communicating thermostat's readout.
• Measure and record superheat at the condenser suction line upstream from the service valve.
• Measure and record subcooling at the condenser liquid line downstream from the service valve.
• Measure and record saturated vapor temperature.
• Measure and record saturated condensing temperature.
• Measure air temperature rise over condenser coils (discharge air vs. ambient air).

Once you have all this data in hand, post it here and watch what happens. I'm betting you will get some very helpful responses.

[motoguy128]

Also post the model numbers of the indoor and outdoor unit.

Also, is this unit located in an attic? or have returns in the wall cavities? Ductwork sealed? You sure?

Of course taking the wet bulb and dry bulb of the return air will tell you if it's an air leak problem.

If you open a downstairs window on a calm day, does air rush in? In a 2 story home it should actually go out of the downstairs.... unless the house is negative.

[teddy bear]

Plastic on the earth, fan "auto", shophound's post, and your post to our forum are the positive things that have happen so far.
The equipment has been installed, so the comments that the system must be oversized are not constructive.
You are making progress. Close the vents on the crawlspace to stop high dew point outside air from infiltrating. This a big moisture source to the home.
Comfirm the a/c coil temperature, should be <20^F lower than the desired dew point. 75^F,50%RH is 55^F dew point, so a 45^F cooling coil temp is ideal. By checking suction pressure confirm a <45^ coil temp. Also measuring the supply temp/%RH to confirm 48-50^F dew point supply air. Slow the air flow to get a colder coil if needed.
During moderate to high cooling loads, your a/c should maintain <50%RH.
When there is low/no cooling load, the a/c will not maintain 50%RH in the home. A small amount of supplemental dehumidification will maintain <50%RH without any cooling load.
Techs get cranky when over worked. Keep us posted. We are here help and push our agenda.
Regards TB

[comfortdoc]

Is there published data for SH / SC in low speed? If not you need to check in high speed to verify operation. Do you have that info?

[comfortdoc]

How could you know that after the very minute amount of information I've said over a post on the internet?

Every new house that's about 3000 sq ft would have a 3 ton ac?? I haven't said what part of the country I'm in or anything about my house. I could only imagine the amount of different sizes that could be needed to adequately cool a house of this size with so many variables unknown....

One of the best things I've heard people say in various forums online is don't give an answer if you can't.

I'm just guessing here, but I think Beenthere was leaning towards bigger NEWLY constructed houses typically have more moisture that must be removed before it comes to equilibrium. But since you decided he doesn't know what he is talking about, I would not expect him to return to explain.

[beenthere]

How could you know that after the very minute amount of information I've said over a post on the internet?

Every new house that's about 3000 sq ft would have a 3 ton ac?? I haven't said what part of the country I'm in or anything about my house. I could only imagine the amount of different sizes that could be needed to adequately cool a house of this size with so many variables unknown....

One of the best things I've heard people say in various forums online is don't give an answer if you can't.

I thought you lived near or around Springfield, Missouri.