Humidifiers and Dehumidifiers - FL lake house with humidty probem

I have a duplex lake cottage in north central Florida (Melrose, FL Lake Santa Fe) that I use only once every 3 months or so. One side is about 1200 sq ft and the other is 800 sq ft. Each side has its own heat pump. The structure is frame construction (started out in 1945 as a surplus barracks from a nearby army base), and sits on pier and beams supports. The space underneath the floor is open to the outside but airflow under the house is fairly restricted.

Just as another post stated, when I'm not there I leave the thermostat set so that the AC doesn't come on until the temp is over 85, and in winter change to "heat' with a setting such that the unit would not run until the temp gets below 60 (yep in that part of Florda there are freezing days in every winter season).

Below is the quoted solution from the post I found on this site. First, I didn't understand exactly how this solution worked (because I don't know what the "humidistat" does or how it operates), and second I don't know if there would be a problem applying this technique to a heat pump (I know thermostats for split AC with heat strips are different from thermostats for heat pumps). Could someone provide a more detailed explaination of what occurs when this solution is applied?

"You could try what we do down here in FL for when they are away for a time. Put a humidistat on the wall by the tstat. Now put it in the R wire to the tstat. When you are there turn it up and the tstat will work the AC for cool. When you are gone turn the tstat all the way down for cool then set the humidistat for what you want the humidity in the home to be. Works fine here."

Is there someone who builds a thermostat / humidistat in one (for a heat pump) that would take care of the humidity problem using my heat pump (both winter and summer)? Any other suggestions?

Thanks,
Jim :wall:

Is there someone who builds a thermostat / humidistat in one (for a heat pump) that would take care of the humidity problem using my heat pump (both winter and summer)? Any other suggestions?
Yes but how much do you want to spend Carrier has one and others also that has a Dhum and a hum control on it.

"You could try what we do down here in FL for when they are away for a time. Put a humidistat on the wall by the tstat. Now put it in the R wire to the tstat. When you are there turn it up and the tstat will work the AC for cool. When you are gone turn the tstat all the way down for cool then set the humidistat for what you want the humidity in the home to be. Works fine here."
I think I said that here in a post and it works on a heatpump or just a AC what every.
But first
sits on pier and beams supports. The space underneath the floor is open to the outside but airflow under the house is fairly restricted.
Why------ Open it up all around. Put a 6 mil poly on the ground down there also.
Now a heat pump is only an AC unit is all. We make it put out heat with just some valves in it is all. So in the summer its just and AC like all the rest and its main job is to get the humidity out of the home. Now when you turn the AC on it works off the tstat on temp. Now if you push it down all the way it will just run and run trying to pull the temp down. But if you put a humidistat on the wall their and run the R wire to it then to the tstat it will turn the AC on and off by what the humidity is in the home. I dont think you need it in the winter. So you turn the humidistat all the way for calling and let the temp take over on the tstat. You see if you put a humidistat up thereyou can set it anytime for it to control the the unit or the tstat to control.
If any more ??? post back here in the same post and will try and answer them.

ED ;)

Thanks Ed,

Yes, the part I quoted was from your reply in someone elses post.

I am starting to feel that the ventilation under the floor "is" a big part
of my problem (the generations that preceeded me in this house never
seemed to have this probelm). I'm going to visit this weekend and see
how I can restore the air flow that used to be there.

Now a specific question; You said "put a humidistat on the wall their and run the R wire to it then to the tstat". By "R wire" is this a specific connection from the humidistat (I know, I'm totally ignorant of humidistats, please bear with me). Which point within the thermostat would you connect this wire to? Do humidistats come with installation instructions that mght diagram this cross connection to a thermostat?

Thanks again,
Jim

Have put up rooms like for add on of a home. Like pier it up off the ground like you say yours is. Not a crawl space all the air can get under it. So its like a outside wall to us we put like a R 19 insulation In the joist, paper to the room side then a 6 mil poly over it them the sub floor
. On the under side a cheap siding of some kind . This is not a crawl space in any way its the same as an outside wall. Have a friend down in the Keys his is the same way only its 13' up for code. No humidity in the home with the AC on. Now a true crawl space we seal up and put registers in the duct there to dry and heat it . Insulation on the walls and around the belt board but none up in the joist a6 mil poly on the ground .
Now that R wire The R wire to any tstat is power its the + R is what makes everything work. So if you just put a humidistat with the R wire to it and out from it to the R on the tstat. You can set the tstat say for the AC to run push it all the way down. Now it cant run till the humiditistat said it can. Does this help? Draw it out on paper helps a lot
You are going to cut the R wire to the tstat and just put the humidistat in there.

ED ;)

Thanks,

I think I understand now; (how I think about what's going on) the humidistat is in front of the thermostat (via the R wire) hence overrides anything the thermistat does. So set thermostat low and humidistat to desired setting. Thermostat always wants to send "run" but can't until humidistat also wants to send "run".

I like your thinking about the floor like its an outside wall. I can get insulation
between the joists, but obviously with a retro fit can't get plastic under
the subfloor. Would it be worthwhile to cut plastic to fit between the
joists first then put the insulation in next? There is a good slope to the
property running down to the lake, and I have seen in the past evidence
that in torrential rains water runs off from front to back under the house
(never stands). So I don't think putting poly on the ground would do much
in this case.

Thanks again,
Jim

Just put the paper side to the floor for the insulation in the joist. For get the poly there. Have some 2 ' above cement floor like. Just let it open under there. In fact have 2 up inMissouri that the whole home is over the lake. In one held off with the duct work under it till the lake froze over .So we could walk on it and set ladders up. Put the duct work up then closed it all up. Its just another outside wall

ED :D