High Humidity after new systems installed

[dcpen]

Thanks for help/advice in advance.

I had two new systems installed a little over a month ago, and the humidity has dramatically increased in my house following the installs. My installer has not been able to remediate after several visits, so I want to make sure I am thinking about the right things that should be done to resolve the issue.

I have a ~3700 sq ft house in the Dallas, TX area. Prior to the installation of the new systems, I had 5 ton (downstairs) and 3 ton (upstairs) Goodman builder grade systems. The contractor did a load calc and determined proper sizes were 4.3 tons and 3 tons, respectively, and installed a 5 ton and 3 ton Lennox XC21 systems with the 80 furnaces (forget exact model #) and Pure Air filtration systems. The old systems were replaced because the upstairs unit had a R-22 freon leak that was going to be more to fix than it was worth - and I decided to go ahead and replace both systems.

Prior to the new systems, RH in the house was typically in the low to mid 40% range, measured over multiple seasons (I have screen shots from a monitor system with a hygrometer to document this). After the install, they are in the upper 50's and even low 60's range. Even worse, the S30 thermostats they installed never show below 60%, and often are near 70% (they have replaced the thermostats - the originally installed ones were even worse - high 60%'s to low 80%'s). I have a couple of hygrometers that have been calibrated that always read at least 4% below the thermostats, and often closer to 10%. The installer has also verified the thermostats are not accurate using their own hygrometer.

In the install, they replaced a fair amount of duct work, including replacing duct-board junction boxes with "Y" junctions, and and added second return duct for each system. They say they have rechecked those items for leaks, but I don't know how thoroughly they have actually checked them.

One other thing I have noticed is that the coil on the larger system sweats - not enough to drip into the drain significantly into the pan below it, but the sweat on the outside of the coil box is readily visible. The installer said this normal, but I find it strange the smaller system doesn't exhibit the same then.

What I know my installer has tried:
1) Installing a second return for upstairs system (originally they only added one for the downstairs system);
2) Resealing behind the thermostats;
3) Some sealing around the units (he said he felt a cold air leak around the coil on the upstairs unit);
4) adjusting blower speed;
5) adjusting coolant pressure; and
6) running air really cold (66 degrees) for 48 hours to see if that pulled humidity down (it did some according to separate hygrometers (mid 50%), but thermostats were still showing high 60% to 85%+ range (this was before they changed thermostats);
7) replacing both thermostats.
8) their next proposed step is to have a Lennox rep come out and diagnose the systems later this week

My thinking is that, because the humidity was well below these levels before the install, it points to a problem with the install, rather than an existing problem with the house (e.g. it being too leaky). Maybe the systems are oversized, maybe their ductwork has leaks, maybe something is just wrong with the systems themselves or they are not set up correctly? Does this seem to be a reasonable conclusion?

Second, the high humidity readings on the thermostats seems to be a gating problem - if they aren't properly reading humidity then I don't think I can expect the system to function correctly. However, because the systems are almost always running a dehumidifying cycle, and the house is not getting to appropriate humidity levels, it seems that there must be a bigger problem than just the thermostats.

What should be my approach with the installer at this point? It has been over a month and I don't have properly working systems - how much longer, how many more visits is it reasonable to give the installer a chance to fix the issue? Is there something else I should be doing (like reaching out to Lennox directly, having their work double checked by another company, etc)? I'm halfway ready to tell them to take their systems back and have something else installed.

[Advanced Response]

It sounds like the units may be oversized.

However, one question is;
Xc21 units should be two stage units with matching two stage variable speed furnaces, do you notice the unit starting in low stage and then only sometimes going to high stage?

It would help to know the actual model #s of the indoor and outdoor units to know if they properly matched them for proper operation.

[dcpen]

Thanks for the quick reply. I actually mistyped system info - they are variable speed XC20s instead of XC21s. I do clearly notice them start faster and then blow less when maintaining temp.

Complete model list is:

Downstairs
Air Conditioner - XC20-060-230
Coil - CHX35-51/61
Furnace - SHL280UH090V60C
Thermostat - Icomfort S-30
Air Quality Device - PC03-20-16

Upstairs
Air Conditioner - XC20-036-230
Coil - CHX35-48B-6F-1
Furnace - SHL280UH090V36B
Thermostat - Icomfort S-30
Air Quality Device - PC03-20-16

[Advanced Response]

That is an variable inverter system.

I am not familiar with Lennox units enough but looking thru the manual, there are a multitude of setting in the control that will create greater comfort and increase humidity removal by lowering air flows.

You need to get ahold of the best technician that is well versed in setting the thermostat control for the maximum humidity removal and lowest airflow. Like I said it looks like there are tons of settings that if not set properly could cause less dehumidification.

Again you need a tech that is well versed in the control and understands how to maximize dehumidification. If it is already maximized and airflow is already reduced to the minimum, then your systems have to be grossly oversized.

[dan sw fl]

WHAT IS YOUR ACTUAL RUNTIME when it is > 87'F outside?

Presume THERMOSTAT setpoint is ~ 76'F.

[dan sw fl]

Thanks for the quick reply. I actually mistyped system info - they are variable speed XC20s instead of XC21s. I do clearly notice them start faster and then blow less when maintaining temp.

Complete model list is:

Downstairs
Air Conditioner - XC20-060-230
Coil - CHX35-51/61
Furnace - SHL280UH090V60C
Thermostat - Icomfort S-30
Air Quality Device - PC03-20-16

Upstairs
Air Conditioner - XC20-036-230
Coil - CHX35-48B-6F-1
Furnace - SHL280UH090V36B
Thermostat - Icomfort S-30
Air Quality Device - PC03-20-16

HEAT 180,000 BTU/HR ___ that's overwhelming

Residence built: 19 _ _ OR 20 _ _
3,700 SQ FEET. 2 story
Maybe ~ 550 sq feet total glass area

Perimeter of house: _____ feet

Is DALLAS a Very opportunistic locale for heat pumps?

Heating Degree Days
( Basis 65'F) = 2,161 __ ASHRAE FUNDAMENTALS, 2017

[Advanced Response]

Dan I did not even look at that.

Wow that is a lot of heat even for a 3700sqft house in Ohio.

Also at 8tons of cooling, that is 462 sqft per ton. Might be grossly oversized on both but I am sure the heat is way grossly oversized for sure.

[dcpen]

HEAT 180,000 BTU/HR ___ that's overwhelming

Residence built: 19 _ _ OR 20 _ _
3,700 SQ FEET. 2 story
Maybe ~ 550 sq feet total glass area

Perimeter of house: _____ feet

Is DALLAS a Very opportunistic locale for heat pumps?

Heating Degree Days
( Basis 65'F) = 2,161 __ ASHRAE FUNDAMENTALS, 2017

Thanks for replies all.

House was built in 2007. the outside perimeter of the house is about 235 feet if that is what you are asking.

I don't know how long the system runs when it is 87 degrees outside because, thus far, it has only gotten down to 87 degrees late at night when I am asleep. Since the install, daytime temps have typically been 100+ or high 90s over the last week. Next week is supposed to get down in that range during the day. The thermostat is typically at 72-73 degrees, but allows overcooling of 3 degrees to dehumidify.

Hopefully the Lennox rep they are bringing in is the well versed tech that is recommended, but we'll see. I don't know if he would tell me if the system is grossly oversized given relationship with the installer. The only point of reference I really have on size is that other houses in our neighborhood have similarly sized systems, but most of those are still the builder installed systems, so who knows.

My understanding is that heat pumps are not popular in the Dallas area because the cost of electricity is significantly higher than natural gas.