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Posted by Elle on December 24, 2007, 10:45 am
My house has a Rheem heat pump, installed in 1991 Model
#RPND-042C, with "Heater Kit RXPJ," according to its
nameplate. Temperatures are about 35-40 degrees F this time
of year where I am.
Often in the morning the heat pump blows cold air for a
half-hour (or more?). I had an HVAC service tech out here a
week ago. He could not find anything wrong.
Does it simply take a while for the refrigerant to get to
suitable temperatures for evaporation/condensation operation
when in "heating" mode?
What symptoms might I observe that indicate the unit needs a
charge of refrigerant?
Also, I would like an operating manual, hopefully with a
layperson's troubleshooting guide. Although I am pretty
handy and I would prefer to do electrical side
troubleshooting myself. Anyone know where I can get such a
manual for this unit? I tried both the Rheem and Ruud sites;
no luck.
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Posted by Bubba on December 24, 2007, 3:28 pm
On Mon, 24 Dec 2007 08:45:01 -0700, "Elle"
>My house has a Rheem heat pump, installed in 1991 Model
>#RPND-042C, with "Heater Kit RXPJ," according to its
>nameplate. Temperatures are about 35-40 degrees F this time
>of year where I am.
>
>Often in the morning the heat pump blows cold air for a
>half-hour (or more?). I had an HVAC service tech out here a
>week ago. He could not find anything wrong.
>
>Does it simply take a while for the refrigerant to get to
>suitable temperatures for evaporation/condensation operation
>when in "heating" mode?
>
>What symptoms might I observe that indicate the unit needs a
>charge of refrigerant?
>
>Also, I would like an operating manual, hopefully with a
>layperson's troubleshooting guide. Although I am pretty
>handy and I would prefer to do electrical side
>troubleshooting myself. Anyone know where I can get such a
>manual for this unit? I tried both the Rheem and Ruud sites;
>no luck.
Ellie,
Would you like fries with that?
Seriously, unless you do this stuff all day long, you WONT be able to
troubleshoot it. Lots of techs cant diagnose heat pumps properly. You
would need refrigerant gauges, digital thermometers, wet bulb readings
and the ability to understand superheat and/or subcooling readings
along with a good knowledge of a refrigeration circuit and airflow.
You might want to invest your time and money more wisely into finding
a good hvac company that can diagnose and repair your system
correctly.
Ask friends, neighbors, relatives and groups you belong to who they
use. You could also look up the local Rheem distributor and ask one of
them who they would use if their system broke and needed repair.
Bubba
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Posted by Ralph Mowery on December 24, 2007, 3:43 pm
> My house has a Rheem heat pump, installed in 1991 Model #RPND-042C, with
> "Heater Kit RXPJ," according to its nameplate. Temperatures are about
> 35-40 degrees F this time of year where I am.
>
> Often in the morning the heat pump blows cold air for a half-hour (or
> more?). I had an HVAC service tech out here a week ago. He could not find
> anything wrong.
>
> Does it simply take a while for the refrigerant to get to suitable
> temperatures for evaporation/condensation operation when in "heating"
> mode?
>
> What symptoms might I observe that indicate the unit needs a charge of
> refrigerant?
>
>
The refrigerant does not need time to 'warm up'. It should be ready to go
in a couple of minunits or less.
When you say cool air, what is that in degrees ? Most heatpumps will feel
cool to the touch for the air comming out as it is usually cooler than your
body temperature.
Are you cutting the temperature down at night and back up in the morning ?
That could be the problem.
One symptom of low refrigerant is the cooling coil will freeze up. That is
the outside unit in winter and the inside unit in the cooling mode. It will
also do that sometime on its own in the winter, but the unit should go into
a 'defrost' mode to get rid of the ice.
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Posted by Elle on December 24, 2007, 4:28 pm
> The refrigerant does not need time to 'warm up'. It
> should be ready to go in a couple of minunits or less.
>
> When you say cool air, what is that in degrees ?
I estimate about 62 degrees F or lower. That's where the
thermostat's built-in thermometer was sitting this morning,
after I raised the thermostat setting from 67 to about 75 F.
The outside temperature this morning was about 40 degrees F.
> Most heatpumps will feel cool to the touch for the air
> comming out as it is usually cooler than your body
> temperature.
When it seems to be running correctly, the air coming out is
warm to my touch.
> Are you cutting the temperature down at night and back up
> in the morning ? That could be the problem.
Yes. Typically we set the thermostat to 67 F for nighttime
sleeping. Then we raise it to 75 F or higher upon rising.
What's going on?
I do see the warnings on the net about playing with the
thermostat too much. I presume the control system for the
heat pump has trouble catching up to a lot of changes.
> One symptom of low refrigerant is the cooling coil will
> freeze up. That is the outside unit in winter and the
> inside unit in the cooling mode. It will also do that
> sometime on its own in the winter, but the unit should go
> into a 'defrost' mode to get rid of the ice.
I will inspect the cooling coil sometime soon in the
morning.
Also, this morning I heard a pulsating noise coming from the
unit. Right now, with the ambient outside temperature at 59
degrees F, the heat pump is working fine, raising the
temperature from about 67 degrees F (setting while I was
running errands) to 71 F pronto. Nice warm air is coming
out. I hear no pulsating noise. I will inspect tomorrow and
see if it's the guts of the compressor making this noise or
what all. I am also of course open to suggestions.
J.A., I understand from reading that heat pumps differ from
furnaces in that the hot air they produce is not as hot as a
furnace set on high. But the things will get the house up to
the desired temperature, if all is in good working order.
Bubba, fair point. I work on my car a lot and consult the
Honda newsgroups for same, but one area that people tend to
stay away from advising DIYers on much is the air
conditioning unit.
I bear in mind that, from my reading, 16 years is very old
for a heat pump. I am keeping my eyes and ears peeled for
catastrophic failure of some parts.
Thanks for sharing your experiences, Bubba, Ralph, and J.A.
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Posted by Ralph Mowery on December 24, 2007, 5:04 pm
>> The refrigerant does not need time to 'warm up'. It should be ready to
>> go in a couple of minunits or less.
>>
>> When you say cool air, what is that in degrees ?
>
> I estimate about 62 degrees F or lower. That's where the thermostat's
> built-in thermometer was sitting this morning, after I raised the
> thermostat setting from 67 to about 75 F. The outside temperature this
> morning was about 40 degrees F.
>
>> Most heat pumps will feel cool to the touch for the air comming out as it
>> is usually cooler than your body temperature.
>
> When it seems to be running correctly, the air coming out is warm to my
> touch.
>
>> Are you cutting the temperature down at night and back up in the morning
>> ? That could be the problem.
>
> Yes. Typically we set the thermostat to 67 F for nighttime sleeping. Then
> we raise it to 75 F or higher upon rising.
>
> What's going on?
>
> I do see the warnings on the net about playing with the thermostat too
> much. I presume the control system for the heat pump has trouble catching
> up to a lot of changes.
>
The air output is going to be about 85 to 95 deg from the heatpump. If more
than this you may be using the heat strips (electrical heaters in the air
ducts, often called emergency heat).
The heat output will be a constant value and the setting of the thermostat
will not make the air comming out of the ducts any hotter no mater what you
set the thermostat at. Over a long period of time the room temperature will
go up. When raising the thermostat more than about 3 degrees some heat
pumps will activate the heat strips and your energy usage will go up.
As mentioned, set the thermostat at one temperature and let it go at that.
YOu may cut it about 3 degrees at night. If you are not in the house for a
long period of time (say 8 hours) and have a timer on it, you may want to
set it back 3 degrees while you are out.
If you have the thermostat set for 67 and the temperature is 62 on the
thermostat, then you do have problems. The heat pump is probably not
working and you are probably running on the heat strips when you go to 75
deg on the thermostat.
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