New HVAC 18 Seer2 Humidity???

[dieselscout80]

Our old American Standard system didn’t show the humidity, but our thermometer has it, and I think it was in the 55% to 60% range, but I didn’t think to document it.

 

[Chewwy]

We just got a new HVAC system American Standard variable speed split system rated at 18 Seer2 and we live in South Carolina.

What should it bring the inside humidity down to?

We aren’t seeing the humidity get below say 48% at the lowest and typically its around 50% or above. The humidity menu is set at 45%.

We also live is SC. We have had dehumidifiers in our basement for well over 20 years. Initially, they were stand alone units. We replaced the stand alone units with an in-duct-work dehumidification unit about 12 years ago when we ureplaced the hvac for the basement.

Our dehumidifier is set a 50% rh and the unit runs quite often this time of year, but hardly ever in the cooler months. The a/c also removes the humidity quite well but dos not run enough even with the themostat set at 70 deg F. Our system can bring the humidity down to well below 45% rh but it then runs even more.

One thing we have learned is to have a backup dehumidifier unit readily available. The dehumidifiers do not last forever, are generally not repairable, and the in-duct-work units take days or even weeks to get replaced.

 

[Torvy]

Man you got a new tractor and a new house within a year of each other.

Was the new house part of the buying the tractor deal with the wife .

If so, wasn't that quite an expensive tractor?

Old house in the city is just 1/3 acre. No room for a tractor.

We bought the land a couple of years ago. House is paid off thanks to equity in old house. Paid cash for the tractor because boss, er, wife, doesn't like to pay interest.

Needed to get the shop built to store the tractor or we would have bought the tractor sooner. Now I just need to get 1 or 2 more pickup loads moved.

 

[Dftodd]

We live in a 2500 sqft 4-story townhome in Chicago with 2 separate HVAC units (on top and bottom floors, specs below). During first week of hot temps, we have a few issues, some seemingly related, with a brand new HVAC system running a/c:

* 16 x 22 top floor has musty smell, is humid, never gets to thermostat temp (5 degrees hotter than floor just below)
* chalky, dusty, sort of industrial smell in other rooms on other floors since new system installed (not new construction)
* high efficiency and possibly too big a/c units (?) are causing rooms near thermostats to cool quickly without dehumidifying enough (short cycles); humidity makes house uncomfortable and only thing that helps is turning a/c set point temp way down (66-68).
* top floor HVAC closet ducts needs sealing (some water drops running down outside of ductwork, existing sealant at top of ducts leading to ceiling/roof now unsealing and falling off in chunks)

In doing some research on just the humidity issue, what we've found is one possible idea: slow blower down to 350 CFM per ton and enable comfort R? Not sure what the settings are currently.

Installer has come once to diagnose, adjusted the charge on a/c compressors, recommended setting fan to on (vs. auto). This increased humidity and smells and dripping persist. Any other ideas? This is driving us crazy given the expense and time put into all-new system.

Top floor furnace:
American Standard Furnace, DOWNFLOW MODEL #: S9V2B060D3PSBA,95% 2 Stage Variable Speed 60K BTU 17.5" Wide

Bottom floor furnace:
American Standard Furnace, MODEL #: S9V2B060U3PSAA, 95% 2 Stage Variable Speed 60K BTU 17.5" Wide

Air conditioning compressors:
American Standard - 18 SEER - 3 Ton - Air Conditioner MODEL #: 4A7V8036A1000A, ADP Cased Coil - 17" wide
American Standard - 18 SEER - 2 Ton - Air Conditioner MODEL #: 4A7V8024A1000A, ADP Cased Coil - 17" wide

I think part of your issue is the vents need to be adjusted to allow for more cooling further away.

I've had to do that in a couple different places I've lived.

The current house, master bed, bath, closet, as well as laundry room would freeze you out.

The other end of the house was boiling.

Took a few tries, but I finally got it to where it's pretty even across the house.

 

[Sigarms]

We live in a 2500 sqft 4-story townhome in Chicago with 2 separate HVAC units (on top and bottom floors, specs below). During first week of hot temps, we have a few issues, some seemingly related, with a brand new HVAC system running a/c:

* 16 x 22 top floor has musty smell, is humid, never gets to thermostat temp (5 degrees hotter than floor just below)
* chalky, dusty, sort of industrial smell in other rooms on other floors since new system installed (not new construction)
* high efficiency and possibly too big a/c units (?) are causing rooms near thermostats to cool quickly without dehumidifying enough (short cycles); humidity makes house uncomfortable and only thing that helps is turning a/c set point temp way down (66-68).
* top floor HVAC closet ducts needs sealing (some water drops running down outside of ductwork, existing sealant at top of ducts leading to ceiling/roof now unsealing and falling off in chunks)

In doing some research on just the humidity issue, what we've found is one possible idea: slow blower down to 350 CFM per ton and enable comfort R? Not sure what the settings are currently.

Installer has come once to diagnose, adjusted the charge on a/c compressors, recommended setting fan to on (vs. auto). This increased humidity and smells and dripping persist. Any other ideas? This is driving us crazy given the expense and time put into all-new system.

Top floor furnace:
American Standard Furnace, DOWNFLOW MODEL #: S9V2B060D3PSBA,95% 2 Stage Variable Speed 60K BTU 17.5" Wide

Bottom floor furnace:
American Standard Furnace, MODEL #: S9V2B060U3PSAA, 95% 2 Stage Variable Speed 60K BTU 17.5" Wide

Air conditioning compressors:
American Standard - 18 SEER - 3 Ton - Air Conditioner MODEL #: 4A7V8036A1000A, ADP Cased Coil - 17" wide
American Standard - 18 SEER - 2 Ton - Air Conditioner MODEL #: 4A7V8024A1000A, ADP Cased Coil - 17" wide

Part of my experimentation when I installed my original whole house dehumidifier about 15 years ago (which the manufacturer could not give me with any certainity) is how would it affect our 3 story house (3 independent systems with duct).

First floor (where the dehumidifier was tied into) brought it down 10%. The upstairs and basement was around 5%. More than happy.

When I was at manufcaturer's in the lab and testing facility, I asked a pretty smart engineer who spent 20 years with the brand you mentioned (Trane makes AS) about multi stage variable speed constant air flow blower motors about the effect these types of systems will actually work with humidity issues. His response basically confirmed my own findings.

Keep in mind, HVAC equipment is not installed in a lab, but they do run units in "real life" conditions as well.

As mentioned by somewhere else here or in Torvey's thread, and from talking to a bunch of guys in the trade out of my own curiosity about actually measuring the data, on average even with a multi stage compressor variable speed constant airflow blower motor, you're going to average about 50% RH. Every house is different though per build and layout, so you will always have abnormalities from time to time.

 

[dieselscout80]

We have the temperature feeling warm in the house during the afternoon even though it shows normal inside temps (door opened quite often).

Yesterday it was 74 degrees it seemed hot inside as the humidity was up to 60%. The system seemed to be running really low.

I wonder if setting lower would help with this feeling as the system is running fine otherwise?

A friend who worked in HVAC field said if we’re getting 50% humidity that’s good.

 

[Sigarms]

A friend who worked in HVAC field said if we’re getting 50% humidity that’s good.

It is.

When 16 SEER 2 stage variable speed blower motor systems first came out over 20 years ago, the sales pitch has always been you're buying comfort, not return on investment.

When I replaced my first system back around 2006, I couldn't justify the price difference for a two stage variable speed system vs a single stage X-13 blower (on a side note, now the sales pitch on the X-13 motor is it's multi stage! LOL).

The question I've always asked is given identical houses, same load, same everything, exactly how much will a multi stage compressor variable speed constant airflow blower actually acheive vs a single stage compressor X-13 (AKA variable speed constant torque motor), and for whatever reason, no one who I considered pretty smart couldn't give me a straight answer.

The nice advantage however for a 2,3, 5 stage or inverter compressor is the wide operating range of the compressor for loads. If you have the money, go with a basic 16 SEER 2 stage with variable speed constant airflow blower motor and install a whole house dehumidifier. If you don't have the money but still want the best comfort available, go with a 14.3 SEER system with X-13 blower and install a whole house dehumidifier.

At least for all the variables in my own home, I'm absolutely sold on the comfort level of a whole house dehumidifier because last year I finally replaced the system I installed in 2006 with a 2 stage compressor variable speed air handler, and it still only pushes 50% RH without the dehumidifier running.

I would however also always reccomend to NEVER get a brand speciffic communication HVAC system that REQUIRES the same brand proprietary thermostat. Believe me, you may never have a problem with it, but if you do, you're chances of being screwed over greatly increase.