Posted by JohnW on January 23, 2005, 2:37 pm
I have a lot to ask her but thought it's worth a shot. It has to do with
the house not heating well.
Last August we moved into a single family home (2 years old), which has a
number of heating/cooling systems.
The upper floor has a heat pump, presumably in the attic. When we had the
home inspected I followed the guy into the attic where he pointed out the
unit. My assumption is that this unit handles the heating/cooling of the
2nd story. It has a thermostat in the master bedroom and appears to work
fine when the outside temp is above 20 degrees or so. I'm not worried about
this system.
The main floor and basement are handled by several systems, and it's here I
have questions. There are two units outside, one of which appears to be a
dedicated air conditioner and a second unit that's a heat pump. We also
have propane furnace/air handler. These units were controlled by a
mercury-based manual thermostat, but I replaced it with a Honeywell RTH7400D
programmable thermostat using the same wires (4 wires: g,w,y,r). For what
it's worth, the propane also provides the heated water and a gas fireplace.
Here are the questions:
1. Is the heat pump the primary heat source and the propane secondary, or
the opposite? The inspection report calls the propane the primary source,
but that doesn't seem right, and the seasonal contractor we had inspect the
unit recently said the propane "appeared" to be the secondary. If it's not
all that cold outside, the heat pump is on, but not the propane, for
example. Today, at 16 degrees, both units run. And struggles to maintain
70.
2. The thermostat required a setup before programming the 7 days of the
week. One of the steps was choosing the heating/cooling system. There are
10 choices:
- heating and cooling (conventional)
- single stage heat pump with no backup or auxilliary heat
- heat only with no fan (conventional)
- heat only with fan (conventional)
- hot water heat only (conventional)
- Cool only (conventional)
- multistage heat pumps
- multistage conventional heating and cooling (2 stages heat and 2 stages
cool: requires w/w2 and y/y2 wires)
- multistage conventional heating and cooling (2 stages of heat and 1 stage
cool)
- multistage conventional heating and cooling (1 stage heat and 2 stages of
cool)
Right now I have it on the first setting.
3. What are the "stages" regarding heating systems as referred to above? My
assumption is that a heat pump with emergency/auxilliary heat is a
multistage heat pump (like the one in our attic for the second floor) but
does it also refer to a secondary heating source like natural gas, oil or
propane? If I had a W2 wire I suspect the 9th choice would be the most
appropriate but I just had the 4 wires mentioned above. After calling
Honeywell, the person agreed that the first choice seemed the most
appropriate.
4. I have heard twice now that heat pump/propane heat systems work just fine
if you leave the temperature constant throughout the day/week, but have
trouble with "recovery" when you let it dip in the evening and try to reheat
in the morning when everyone rises. This seems to be the problem with these
systems and programmable thermostats. Today I programmed every day and
every "event" to the same temp to see if this pans out over the next few
days.
I AM going to get the HVAC contractor out here again, at my expense, to pick
his brain in person, since I wasn't at home when he did the initial
inspection for us. However, any insight to the above beforehand would be of
great help. Thanks in advance.
John
Posted by Travis Jordan on January 23, 2005, 2:56 pm
> The upper floor has a heat pump, presumably in the attic. When we had the
> home inspected I followed the guy into the attic where he pointed out the
> unit. My assumption is that this unit handles the heating/cooling of the
> 2nd story. It has a thermostat in the master bedroom and appears to work
> fine when the outside temp is above 20 degrees or so. I'm not worried
about
> this system.
A heat pump is just a reverse-cycle air conditioner. In your case it the
air handler is in the attic - but the compressor for the AC / heat pump is
outside.
> There are two units outside, one of which appears to be a
> dedicated air conditioner and a second unit that's a heat pump.
Nope, they are both condensers, used in conjunction with your inside air
handlers. Likely one or both are also capable of reverse cycle (a heat
pump).
> We also
> have propane furnace/air handler. These units were controlled by a
> mercury-based manual thermostat, but I replaced it with a Honeywell
RTH7400D
> programmable thermostat using the same wires (4 wires: g,w,y,r). For what
> it's worth, the propane also provides the heated water and a gas
fireplace.
G - Fan
W - Heat (1st stage)
Y - Cool (1st stage)
R - Power
> Here are the questions:
> 1. Is the heat pump the primary heat source and the propane secondary, or
> the opposite? The inspection report calls the propane the primary source,
> but that doesn't seem right, and the seasonal contractor we had inspect
the
> unit recently said the propane "appeared" to be the secondary. If it's
not
> all that cold outside, the heat pump is on, but not the propane, for
> example. Today, at 16 degrees, both units run. And struggles to maintain
> 70.
Most commonly the heat pump is primary (1st stage) and the propane would be
secondary (2nd stage). Are you sure the old thermostat didn't have another
wire for second stage heat? It could be that the furnance controller
handles calling for the 2nd stage, but that is unusual.
> 2. The thermostat required a setup before programming the 7 days of the
> week. One of the steps was choosing the heating/cooling system. There
are
> 10 choices:
> - heating and cooling (conventional)
> - single stage heat pump with no backup or auxilliary heat
> - heat only with no fan (conventional)
> - heat only with fan (conventional)
> - hot water heat only (conventional)
> - Cool only (conventional)
> - multistage heat pumps
> - multistage conventional heating and cooling (2 stages heat and 2 stages
> cool: requires w/w2 and y/y2 wires)
> - multistage conventional heating and cooling (2 stages of heat and 1
stage
> cool)
> - multistage conventional heating and cooling (1 stage heat and 2 stages
of
> cool)
> Right now I have it on the first setting.
Makes sense with only four wires. Are you SURE there wasn't a fifth wire?
> 3. What are the "stages" regarding heating systems as referred to above?
My
> assumption is that a heat pump with emergency/auxilliary heat is a
> multistage heat pump (like the one in our attic for the second floor) but
> does it also refer to a secondary heating source like natural gas, oil or
> propane? If I had a W2 wire I suspect the 9th choice would be the most
> appropriate but I just had the 4 wires mentioned above. After calling
> Honeywell, the person agreed that the first choice seemed the most
> appropriate.
If you have aux / emergency heat strips then it is a 2-stage heat system
(NOT a multistage heat pump, which is a different animal). Of course you
COULD have both a multistage heat pump AND aux / emergency heat, but that is
uncommon.
> 4. I have heard twice now that heat pump/propane heat systems work just
fine
> if you leave the temperature constant throughout the day/week, but have
> trouble with "recovery" when you let it dip in the evening and try to
reheat
> in the morning when everyone rises. This seems to be the problem with
these
> systems and programmable thermostats. Today I programmed every day and
> every "event" to the same temp to see if this pans out over the next few
> days.
Ignore what you are hearing. ANY setback saves energy. Google for more
information on this widely misunderstood topic.
> I AM going to get the HVAC contractor out here again, at my expense, to
pick
> his brain in person, since I wasn't at home when he did the initial
> inspection for us. However, any insight to the above beforehand would be
of
> great help. Thanks in advance.
Good idea.
Posted by Travis Jordan on January 23, 2005, 6:04 pm
> I take it back. On setting 7, the heat pump comes on but nothing will
> trigger the propane. Interestingly, I replaced the OLD thermostat, and the
> propane comes on, but NOT the heat pump. What the hell...
What is the current outdoor temperature, and what was it when the HP was
running? Most likely you have an outdoor temperature sensor that 'locks out'
the HP when the OD temperature is below (fill in the blank) degrees..
Posted by Travis Jordan on January 23, 2005, 6:16 pm
As an experiment, I put the face plate back on and pulled up the
> thermostat's setup menu where the heating/cooling system is to be selected
> and again browsed through the choices (note I've added details for the 7th
> item in parenthesis as written in the manual):
> 1 heating and cooling (conventional)
> 2 single stage heat pump with no backup or auxilliary heat
> 3 heat only with no fan (conventional)
> 4 heat only with fan (conventional)
> 5 hot water heat only (conventional)
> 6 Cool only (conventional)
> 7 multistage heat pumps (heat pump with auxilliary or backup heat)
> 8 multistage conventional heating and cooling (2 stages heat and 2 stages
> cool: requires w/w2 and y/y2 wires)
> 9 multistage conventional heating and cooling (2 stages of heat and 1
> stage cool)
> 10 multistage conventional heating and cooling (1 stage heat and 2 stages of
> cool)
> I changed the setting from 1 to 7 and the other heat pump can on
> immediately! It cycles off and on periodically as it maintains 70 degrees.
> However, now the propane shut off, which always seemed to be running before.
What is the make / model of the furnace to which you have the RTH7400
connected?
Also, do you have the wires connected to the "conventional" or "heat pump"
terminals on the new thermostat?
Posted by Travis Jordan on January 24, 2005, 10:20 am
JohnW wrote:
> The furnace appears to be made by International Comfort Products
> Corporation and is the NTG3/FBF model (at least the serial number
> have NTG3 as a prefix). The manuals says Installation 80+ Single
> Stage.
Just as a matter of historical interest, Carrier (United Technologies) bought
ICP in 1999.
> The programmable thermostat has only one set of terminals, but the
> inside of the terminals are coded for conventional lettering, and the
> outside are coded for heat pumps, but share the same hole for the
> wire:
> Heat Pump Conventional
> C C
> G G*
> Y Y*
> O/B W*
> RC RC
> R R*
> The asterisks indicate which wires I've connected. Also, the RC and
> R are jumpered per instructions.
> A second post has:
> Conv. Heat Pump
> W2 Aux
> Y2 E
> L
> but nothing is connected there.
W2/Aux is where you'd connect the 2nd stage heat (if you had a wire for it).
> I'll just see how fast I can get service in here to explain exactly
> what we have, what to expect, and confirm the programmable is set up
> correctly.
It sounds like you are set up OK and that the outdoor thermostat is
determining whether the HP or propane funance is used when the thermostat
calls for heat. How is the system working today?
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> home inspected I followed the guy into the attic where he pointed out the
> unit. My assumption is that this unit handles the heating/cooling of the
> 2nd story. It has a thermostat in the master bedroom and appears to work
> fine when the outside temp is above 20 degrees or so. I'm not worried
about
> this system.