Whole house dehumidifier in spray foam house - Installed correctly?

[clent724]

I will start by saying that I am just a homeowner. I have a 55' 4" x 28' house. The walls were all spray foamed and R38 batt insulation in the ceilings. I do have 3 bathroom exhaust fans and probably 15 recessed lights throughout the house. I was having a high humidity issue. I had a HVAC guy come and check it out and he suggested a Lennox HCWH-090 whole home dehumidifier. I have pictures that I will attach that I labeled for easy viewing. Now the dehumidifier has a knob on it that goes from 1 to 7. The higher the number the more moisture removed I was told. He also said that it is more effective if I leave the furnace fan set to the ON position instead of Auto. Leaving the fan set to ON makes my electric bill insane (I believe because of all the hot or cold air inside is lost not just because the furnace fan is running). The install seems kind of weird to me especially since all the ducts go into the return and none to the supply.

There is no humidistat installed anywhere, just my basic thermostat on the wall. I know the % humidity by a hygrometer I bought at the store.

With the fan in auto mode, on a summer day humidity will get up to about 52-54% and with it in the on position it stays around 46-48% but seems to make my a/c run constantly due to sucking in fresh hot air from outside.

Last winter I basically ran the fan the entire winter and it stayed around 42% humidity. I am not sure the % without running it. And again it seemed to make my heat run a lot.

So my questions are,

Do you think possibly it is sucking in too much fresh air and defeating the purpose of a tightly sealed house?

Should I make any changes?

And does this installation seem correct?

[lkapigian]

Teddy Bear is the man on this and I am sure will chime in, but I don't think all the outside air goes through the dehumidifier that should be ducted to the home fresh air separate or I am seeing this picture wong ( I am in a dry climate so I don't see this )...........but that is some bad ducting

[clent724]

It is pretty ugly! I just want it to work properly with minimal heat & a/c loss. The house was built in 2012 so I surely don't want mold issues either. Also, from time to time around this time of year mostly, when it is around 70 or so outside and I keep it on Auto it gets a weird smell inside the house so I try to keep it to the ON position when it's like that.

[teddy bear]

There are a lot little things to pick on here. But all things considered, fan "on", fresh air ventilation and <50%RH are pretty good. In fact better than most homes. Tere are ways to install a whole house dehu in a way to avoid running the furnace blower all the time. If you have a vs blower in the fan "on", the cost is low.
Fresh air is suggesedt when the home is occupied at a minimum. The amount of fresh air is an air change in 405 hours. To determine how much fresh air the home is getting tougher to estimate. I suggest a CO2 meter if you want to track on a on going basis. co2 meter.com has a good CO2 meter for $100. CO2 levels of 700-800 ppm with 2 occupants indicates 30-40 cfm of fresh air per occupant. This will purge indoor pollutants and renew oxygen.
Another indication is the indoor dew point of the air verses the outdoor outdoor dew point. When the home is <40%RH with a couple occupants, slow/stop fresh air ventilation. So if you live in a cold green grass climate, you may not need mechanical fresh during cold windy weather. Yet in the warm seasons and calm winds, fresh air ventilation is a must when the home is occupied.
Keep us posted on your results.
Regards TB

[clent724]

There are a lot little things to pick on here. But all things considered, fan "on", fresh air ventilation and <50%RH are pretty good. In fact better than most homes. Tere are ways to install a whole house dehu in a way to avoid running the furnace blower all the time. If you have a vs blower in the fan "on", the cost is low.
Fresh air is suggesedt when the home is occupied at a minimum. The amount of fresh air is an air change in 405 hours. To determine how much fresh air the home is getting tougher to estimate. I suggest a CO2 meter if you want to track on a on going basis. co2 meter.com has a good CO2 meter for $100. CO2 levels of 700-800 ppm with 2 occupants indicates 30-40 cfm of fresh air per occupant. This will purge indoor pollutants and renew oxygen.
Another indication is the indoor dew point of the air verses the outdoor outdoor dew point. When the home is <40%RH with a couple occupants, slow/stop fresh air ventilation. So if you live in a cold green grass climate, you may not need mechanical fresh during cold windy weather. Yet in the warm seasons and calm winds, fresh air ventilation is a must when the home is occupied.
Keep us posted on your results.
Regards TB

I will order one of the meters now. My wife, 1 dog, 1 cat and myself live in the house. We always run the bathroom fans on a 1 hour timer after a shower. I will definitely post results once I receive the meter. I live near Pittsburgh so the winters can be brutal at times. Last year at one point it was near 0 degrees for about a week and in the ON position it went as low as 32% humidity. I try to turn it to Auto or ON as I think it's needed.

As far as the piping the HVAC guy did, do you think I should change or re-route anything? I know it may be hard to see in the pictures. I did my best to label everything.

[teddy bear]

I will order one of the meters now. My wife, 1 dog, 1 cat and myself live in the house. We always run the bathroom fans on a 1 hour timer after a shower. I will definitely post results once I receive the meter. I live near Pittsburgh so the winters can be brutal at times. Last year at one point it was near 0 degrees for about a week and in the ON position it went as low as 32% humidity. I try to turn it to Auto or ON as I think it's needed.

As far as the piping the HVAC guy did, do you think I should change or re-route anything? I know it may be hard to see in the pictures. I did my best to label everything.

When your indoor %RH is >35%RH, turn off the fresh air ventilation.
Keep us posted on the CO2 PPM.
Regards TB

I live near Lincoln Hill 1 mile from Washington, Pa 1968. Great people.