Where are you measuring inside humidity?

Basements below grade are a chronic source of excessive humidity.

On furnace, do you run your AC blower in "on" or "auto mode"?

What is the CFM/ton setting on control board? Should be no more than 400, even perhaps 350. The lower setting allows for improved dehumidification.

Pst back.

IMO

I'm measuring humidity at the thermostat, not in the basement.

How do I figure out the CFM/ton setting on control board? It's set to default, which I the manual states as 1000 CFM, but it doesn't say "per ton".

The humidity in the basement is actually lower at 45%, since I have dedicated dehumidier there.

Thanks!

If you are concerned about humidity in your home, I would purchase a digital temperature/humidity gauge at one of the big box stores. Take the reading at different locations in your home both on main floor and upper floor.

Again, do you run your blower motor in "on" or "auto" mode? I would change to "auto" if not already in that setting.

There should be a chart inside the furnace control cabinet with setting instruction. I am not familiar with the Rudd furnace. However for a 3 ton AC, the lowest setting proably is 350 CFMs/ton. I don't recommend you changing setup unless you are comfortable doing such. You might ask installing dealer for instructions. I would think getting dehumidify on demand feature setup would be helpful.

IMO

I'm running in 'prog' -- which will run fan periodically, even if call for heat/cool doesn't happen. I have installer instructions and it talks about changing CFM settings, but no reference to 'per ton' settings. I have 3 ton unit and it's set to 1000CFM, so perhaps that's about right on to what you're saying.

The thermostat says current humidity 55%, set point 45%, when it sends call for cool, thermostat says "cool on, dehum on", but it never runs "dehum on" without call for cool as well.

My understanding of on demand dehumidifcation with ruud would be that thermostat would call for dehumidifcation even in absence of call for cooling, and furnace would run in a low CFM dehumidification only mode. Anyone know if that's a correct understanding of how it's supposed to work? Can't seem to find info on ruud site or instruction manual, and installer doesn't seem to be very familiar with this particular setup.

Many thanks for help/suggestions.

I am not familiar with the Rudd system, but I highly doubt it can dehumidify without cooling. Dehumidify on demand generally means running the blower at a slower speed and cooling up to 3 degrees below the set point in order to achieve the desired humidity.

We have had a tremendous amount of rain the past several days in NJ with mild temperatures. This may explain why your humidity is so high. What temperature do you set the thermostat? You should be able to get down to 45%. Your system may not have been set up properly. Are you still within the warranty period?

Thanks. I'm setting thermostat to 71 upstairs and 73 downstairs. Still within warranty period.

I did read up some and ODD does indeed just slow down the blower. How do I verify that the blower is indeed running at a lower speed, any ideas?

Some communicating thermostat will display the blower speed. I don't know if yours has that capability. You may feel less air coming out of the vents at the lower speed, but it is hard to detect.

I am a little concerned your thermostats are down to 71 and 73 degrees and the humidity is still in the mid 50s. Yet your basement is down to 45% humidity. I would be disappointed with this humidity control.

Have the HVAC company check everything out and verify it the dehumidify on demand is actually working properly.