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

On Wed, 7 Jun 2006 19:39:35 -0500, (lp13-30) wrote:

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.

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..."

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

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

On Thu, 8 Jun 2006 00:19:02 -0500, (lp13-30) wrote:

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.
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.

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

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