High humidity in home

[TC215]

I’ve tried everything else except ask P-F, so….

A month or so ago, I walked upstairs at my house and found that the humidity was around 70%. The carpet and walls felt wet. Obviously, this is not normal. I figured something was wrong with the heat pump (I have two heat pumps, one for upstairs and one for downstairs— downstairs humidity is fine). I had a guy come out multiple times, and he could not find anything wrong. I thought maybe the coils were dirty in the indoor unit, but he said they looked fine. I bought a de-humidifier, and it’s working, but it has to run nearly all the time to keep the humidity at 50%. I thought maybe the thermostat was faulty, so I bought a new one, which did not help. I also had my roof inspected, even though there were no indications of a leak that I could see inside.

- The heat pump is the right size for my home.
- The refrigerant is not leaking.
- Windows are closed.
- Heat pump is not short-cycling.

Any ideas here? I keep hearing, “Well, it’s been really humid,” and that’s true, but it’s been really humid every summer for the last 8 years that I’ve lived here. Something had to have happened for this to be an issue so suddenly.

[Leroy Suggs]

Have you checked the ductworks?
For breaks or leaks?

[RoyGBiv]

Attic and soffit vents clear?
Whirlygigs on the roof spinning freely?

Anything change with the air flow to/through the evap coils inside the house?
When I was on a heat pump I could adjust the proportion of house air vs outside air being used across the coils.

[TC215]

Have you checked the ductworks?
For breaks or leaks?

I brought that up when the repairman first came. We checked all the vents and they were all blowing cold air. He said the ducts were good…don’t know if there’s anything more to do to check that’s more involved.

Attic and soffit vents clear?
Whirlygigs on the roof spinning freely?

Anything change with the air flow to/through the evap coils inside the house?
When I was on a heat pump I could adjust the proportion of house air vs outside air being used across the coils.

Everything in the attic looks clear.

I’ve not made any changes to the house that would change the airflow. I’m really stumped.

[LittleLebowski]

My Midea dehumidifier that pumps out the water collected vertically (I think up to 6’ vertical) is one of my best investments. I think it’s been continuously running since June. But yeah, figure out what’s wrong.

[UNK]

Im not a tech so of course I googled it. Found this over at fine homebuilding

What are the run times for the system? Does it rarely run even on hot days? It can't de-humidify if it isn't running. Too large of a system will mean short run times, cool temperature in the conditioned space and high RH.

What is the temperature drop across the evaporator (indoor) coil? It should be about 20*. Higher is caused by insufficient load, check your filter, fan speed, diffusers open, you get the idea. If the temperature is less than 18* then the charge is either too low or too high. Too low is not fully utilizing the coil to evaporate the refrigerant, Too much charge is using part of the coil to carry liquid refrigerant that is not evaporating. The contractor needs to check the delta T, the superheat and the sub-cooling to determine if the system is working to design.

[Welder]

Humidity is a constant fight for me since I live on the edge of the Nat'l Forest and have a stream flowing right by the house. The water table is so shallow that my wells are 15' deep with the water level at like 6' down; I have to run multiple dehumidifiers and the ones that aren't piped to permanent drains have to be dumped daily.

Do you have any propane or natural gas appliances that are vent-free and newly installed? Or if vented, that could have issues with their vents letting the exhaust gases get into the living space? The main ingredient of both of those fuels' exhaust is water vapor.

Have you had any work done on the house since the last time you could've had potentially high humidity? Say, since last summer? If so, that work area might be a decent starting point.

If it becomes a long-term issue, don't forget to clean the filters on your dehumidifier every couple of months to keep it's performance up.

[TDA]

Is the drain line for your condensate pump clear? You’d probably see water if it wasn’t, but every system is different. You might also want a slower fan speed across your AC coil, a lot of systems factory default settings are higher for energy efficiency but optimal dehumidification might be like 350 CFM across the coil.

[LittleLebowski]

Is the drain line for your condensate pump clear? You’d probably see water if it wasn’t, but every system is different. You might also want a slower fan speed across your AC coil, a lot of systems factory default settings are higher for energy efficiency but optimal dehumidification might be like 350 CFM across the coil.

WHAT HE SAID!

[scjbash]

My house got humid as hell out of nowhere. I'm now running two dehumidifiers and I found mold in the crawl space. I eventually found a clog in the condensate drain that was causing it to pour out the overflow then sweat on everything. I tried flushing it with baking soda and vinegar but it didn't help. The drain line runs under the plastic that's on the ground so I pulled it up and finally found the problem. One of the fittings wasn't glued and had popped apart just enough to leak and create mud which then flowed into the pipe until it clogged up the p trap. Now I get to deal with the clog, mold remediation, and hopefully not carpet replacement. All over someone not gluing a fitting.

Since your problem is on the second floor it would seem unlikely to have a lot of water go unnoticed but I would check the drain to be sure. If the unit has a large pan I guess it's possible that's the source of the moisture.