Does a Rheem RHBK-21-J00NHB variable speed air handler need a 2 stage thermostat in order to function properly? Mine was installed using a single stage thermostat, and it only runs at one speed. Was the extra cost of the variable speed unit wasted?
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I am not that familiar with Rheem/Huud air handlers. We deal mostly with Trane, Carrier and Amana and sell a lot of them with VS. They do not require a special thermostat. They can be set up to run at about 50% for about a minute, then ramp up to around 70% for approx 7-8 minutes, then go to full speed if the unit still has not satisfied the tstat. A humidistat will actually do more than anything else. It can be set to drop the blower to 70-80% when the humidity is above whatever the humidistat is set at. See if yours performs as described, and I will try to find out if Rheem VS can be set up that way-- Trane calls it "enhanced mode", or at least they used to. Think maybe they call it something else now, but not positive. Good luck. Larry
All the manual says is it give a "soft start and stop". Nothing about setting up involving minutes. It does say "When the Y or R thermostat circuit is opened a 60 second delay will occur before the blower motor motor will cycle off." This happens, but it don't sound like that is doing much in the way of dehumidifying. The brochure for the Air Handler says "It automatically adjusts the airflow for the greatest comfort." Could that mean that it simply turns it on or off? In another place it says it "..can automatically adjust airflow to remove humidity from the air..."
Rheem calls it ODD for On Demand Dehumidification. According to the manual, that requires either a 2-stage thermostat or a Humidistat. The wire from either goes to "Y2". I just wonder why the installer never mentioned that it needed one of these devices. He did correctly say that all the variable speed unit did was ramp up slowly. But the brochure promises more than that.
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It's kinda funny here--I usually check alt.hvac first and then here as soon as I get home, but today I came here first and replied, then saw your post in hvac. You were lucky as homeowners' questions are not always answered as your was. Actually, I was going to EMail NoonAir to get in contact with you before I saw the hvac post. He is a Rheem dealer and is very knowledgeable on their equipment, as well as being a pretty nice guy. I personally would recommend a humidistat on that unit. They are not very expensive at all and usually can be installed right in the return air compartment in a few minutes. One other advantage to VS is that the motors are more efficient than a standard motor=less electricity used. However, in your situation--a/c only, and in a Northern climate, the savings will probably be minimal. Larry
I posted first in hvac, but noticed a very high level of spam/trolls/wiseguys. For whatever reason they waste their time and everyone elses. It has ruined many otherwise useful newsgroups.
Thanks for your suggestion that I get a humidistat instead of a 2 stage thermostat. Up until recently I had never heard of a 2 stage thermostat. I assumed (without any real knowlege) that it is like 2 thermostats, set about 1 or 2 degrees apart. If the first call for cooling doesn't bring the temperature down, the 2nd one would call for more cooling. You say it is mounted in the return air compartment? I would have guessed it would go on the wall next to the thermostat.
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Actually, when I mentioned putting a humidistat in the return air compartment I was thinking of a gas furnace where there is always access by removing the blower door. Air handlers are a different story. It just depends on the installation as to accessability to the R/A area.In some cases it would be real easy to put one there and in others it may indeed be easier to put it on the wall at the thermostat location.Once it is installed and set, it should just be left alone, but it would be good to have it where it could be accessed without any major work, just in case. Good luck Larry
Actually, when I mentioned putting a humidistat in the return air compartment I was thinking of a gas furnace where there is always access by removing the blower door. Air handlers are a different story. It just depends on the installation as to accessability to the R/A area.In some cases it would be real easy to put one there and in others it may indeed be easier to put it on the wall at the thermostat location.Once it is installed and set, it should just be left alone, but it would be good to have it where it could be accessed without any major work, just in case. Good luck Larry
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