Heat Pump or Not

[barberbunch]

Good day. I have a 2002 Carriage Cameo fifth wheel camper. My single rooftop AC stopped working, so I took it in for service. The unit needed replacement. The service manager called me and informed me that after a replacement unit was installed, his service guy realized it was supposed to be a heat pump unit. Can anyone tell me if that sounds right? The reason I ask is because whenever I've used the electric heat option on the existing thermostat, I hear no activity with the rooftop unit, and the heat comes from the floor vents the same as with the propane furnace. Do I have a different type of electric heat? Since Carriage is no longer in business, I'm having trouble researching. Thanks.

Al Barber

[TXiceman]

With an electric strip heater and 12.5 amps at 120 volts you will get 1500 Watts of heat which is 5,118 BTUH. If you run that same 12.5 amps and 120 volts on a heat pump, it will produce 10,000 to 12,000 BTUH. A bit over twice the heat output than an electric strip heater.

Ken

[valhalla360]

dougrainer wrote:

The Heat Pump is an electric source for heat. It will supply and maintain heat assuming the
outside (ambient) temperature is above 40 degrees.

Just a slight clarification: Both use electric for power but in very different ways.
- A heat strip converts electrical power to heat power. It's basically like a toaster with a fan blowing across the coils. The total electrical power that goes in will roughly equal the heat power out. Very similar to a small electric space heater but built into the air/con unit. It will put out the same amount of heat energy regardless of the interior or exterior temperature.
- A heat pump, uses electricity to run a "pump" to push heat from outside to inside (or vice versa when cooling). As a result it tends to be more efficient than a heat strip at moderate temps but as it gets colder outside, it takes more electrical power to push across the larger temperature difference (similar to pumping water to a greater height). (A traditional roof air/con unit is basically a one way heat pump that can only pump heat from inside to outside).

An analogy: Moving a wheeled cart.
- Heat Strip is like lifting cart off the ground. You might be able to lift a 200lb cart by yourself but quickly you will reach your limit. (this is also equivalent to a propane furnace where chemical energy stored in the propane is converted to heat energy). If it's within your lifting ability, the slope of the hill you are standing on doesn't make much difference so long as you can stand securely.
- Heat pump is like pushing the cart forward on the wheels. I can push a 3000lb compact car on level pavement by myself. I can push a 500-600lb cart up a 2-4% slope (far more than I could lift). But as you increase the slope, it gets harder and harder and the cart moves slower and slower. A steep hill is equivalent to heating in cold weather...eventually, the pump simply can't overcome the temperature difference.

[BarneyS]

Yes Al, there is another retired USAF (He may have been Navy) Al Barber out there! He was a regular snowbird at the MacDill AFB Famcamp for many years - as were we. I don't know if he is still RVing or not or even if he is still alive. A lot of us are really getting up there in years!:E
Thanks for answering my question.
Barney

[Bob_Vaughn]

Do not go with the Atwood Heat Pump it is useless...

[barberbunch]

No, not the same one, but it may still be a small world. I am retired USAF, and in my travels, I discovered that there was another Al Barber out there, possibly a military retiree as well. I hope I responded the correct way. I wasn’t sure if I could answer you directly.

Al Barber

[TXiceman]

dougrainer wrote:
How does the Heat Pump Thermostat Work
The RvComfort.HP, the RvComfort.PHP, the Coleman True-Air, and the RvComfort.ZC
thermostats by RvProducts Inc. are all capable of running not only an Air Conditioning unit, but
also an Electric Heat Pump. Frequently we receive calls from customers who do not
understand the functions of the Heat Pump Thermostats. This guide is a quick run through of
the information already provided in the Thermostat Operation Manual, included with each
thermostat.
.

Doug, thanks for the explanation for those that refuse to read the instructions for the thermostat. It is all there in plain print.

Anytime we are where it will be dropping to near 40 degF ambient during the night, I shut down the heat pump and plan to use my small space heaters and/or propane heat. No sense in torturing the poor unit.

Ken

Ken

[BarneyS]

Al,
Welcome to the forums! We are glad you are here and hope you find all the information you need. You will find our members to be very knowledgeable and helpful for the most part.

Are you by chance the same Al Barber I knew from the FamCamp down at MacDill AFB in the winter months?
Barney

[vidotchis]

After opening the camper for the first time, Zone 2 unit wasn't working, initially, there was an error code E1. The problem was with the power to the air conditioner unit. Is the issue with the air source heat pump? Is it ok to replace the circuit board in Zone 1 and Zone 2.

[barberbunch]

Doug, again thank you. I like to know how things work and why they are designed the way they are. This information is priceless. I had not been able to find anything this thorough and clear to understand during my research. After a career in the Air Force and just the business of life, we are just now getting to the place where we can start to use our RV. It's older, so there have been a few kinks to work out. This information is very helpful. You should write a book (if you haven't already). I'm new to the forum, but I will try to figure out how to follow your posts specifically. Thanks again.

Al Barber

[dougrainer]

How does the Heat Pump Thermostat Work
The RvComfort.HP, the RvComfort.PHP, the Coleman True-Air, and the RvComfort.ZC
thermostats by RvProducts Inc. are all capable of running not only an Air Conditioning unit, but
also an Electric Heat Pump. Frequently we receive calls from customers who do not
understand the functions of the Heat Pump Thermostats. This guide is a quick run through of
the information already provided in the Thermostat Operation Manual, included with each
thermostat.
The Heat Pump is an electric source for heat. It will supply and maintain heat assuming the
outside (ambient) temperature is above 40 degrees. This number of course can be slightly
higher or lower depending on the humidity. Higher humidity can cause a heat pump to lose
efficiency at a slightly higher ambient temperature, while lower humidity can cause a heat
pump to lose efficiency at a lower ambient temperature.
Since no one wants to wake up to find that the outside temperature dropped below forty
degrees and it is now 50 degrees inside the coach, the Heat Pump thermostats are programmed
internally to recognize when the temperature drops five degrees or more from the set
temperature to the actual inside room temperature. When the temperature exceeds five
degrees or more between the two, the thermostat will default to the next available heat
source.
The thermostat, upon sensing a temperature split of five degrees or more in the electric heat
mode will bring the gas heat on to assist the electric heat. This is the first strike. A strike is
created by the thermostat having to change modes (or run dual modes to sustain a
temperature split). The electric heat and the gas heat will continue to run together until the
thermostat reaches the set temperature and satisfies. When the electric heat comes back on, it
will be in electric heat only at that point. If the temperature again drops five degrees or more
from the set point, the thermostat will again bring the gas heat on to assist. This is strike two.
The system will then go through the above stated procedures. If the temp should drop five
degrees from set point for a third time, the thermostat will give up on the electric heat, lock the
electric heat out for two hours (showing either DIFF on the display or FLASHING GAS HEAT on
the display) and default to Gas heat only. You WILL NOT be able to run any Electric heat
during this two hour lockout.

[joelc]

I have a 2012 Carriage Cameo. I have a heat pump at one end and an air conditioner at the other. GET THE HEAT PUMP. It is the way to go. 5000 BTU

[barberbunch]

Doug, thank you, thank you, thank you. That's exactly the expertise I was looking for. NOW, it all makes sense why I had it set for electric heat and the furnace kicked on. I just knew that no heat ever came from the rooftop unit. I guess I was being thick-headed. You gave me clarity. Thanks again

Al

[dougrainer]

2002 Carriage came with RVP/Coleman roof top units. Doug

[dougrainer]

barberbunch wrote:
Does anyone know if any RVs with an electric heat option ever had a different set-up than a heat pump?

RV Heat Pumps started in 1999. Before that NO HP on a RV roof top unit. Prior and NOW, roof AC's have always had a HEAT STRIP option. What this is, is, a 5600 BTU 120 volt electric heat coil on top in front of the AC evaporator.
REGARDLESS, if you have a roof top HP or a roof top Heat Strip, the roof AC fan MUST run for either system to work.
The difference between a Heat Strip(5600 btu) and a HEAT PUMP is, the HEAT PUMP will have the BTU rating of the roof AC (13500 btu or 15000 btu). MORE heat capacity. BUT, HP's will NOT work below 36 to 38 degrees outside ambient temp. HEAT STRIPS will work, but they only put out warm air to take the chill off, they will NOT heat an RV.
Now, from your previous response about you NEVER had roof top air flow on your "heat" option only thru the floor vents. Carriage did not install a hybrid system. IF you had a TRUE HP before, it all depends on the BRAND of the HP. Coleman(RVP) or Dometic. Coleman roof HP's have a design quirk built into the logic. When in HP heat mode, IF you set the wall tstat MORE than 5 degrees from the inside temp of the RV, the Coleman system will activate the LP furnace and the furnace will heat the RV. Once the interior temp is LESS than 5 dgrees of that set temp of the tstat, the furnace kicks out and the roof HP comes on and heats the unit up to preset temp. Dometics do not have this design. SO, if you indeed had a HP originally and your only heat came from the LP furnace, your system has never functioned as designed.
There IS a COST difference between a HP and a COOL only roof top AC unit. HP's cost more. Doug