Heat pump doesn't put out heat when temperature is below 30. when i put the thermostat in EM Heat it is warmer but still not very hot.

If you have an air to air heat pump, in colder temperatures, the heat pump will not heat as well as it would in warmer outdoor temperatures making it run longer. the digital thermostats work off of a built in algorithm that kicks on the auxiliary heat when the heat pump runs to long so that it will satisfy the thermostat quicker. This can be tied to the Emergency heat @ the thermostat energizing a few heating elements, or just energizing a separate element from the emergency heat. I always recommend on an air to air heat pump to run the emergency heat when you have consistent Outdoor temperatures below 20 degrees F because you will cycle the heat less by getting hotter heat making life more comfortable, and it costs about the same as running the heat pump since @ those temperatures, it will run all the time.

You have a heat pump.
Once the outdoor temperature falls below 36 degrees, heat pumps will sharply lose their ability to heat.
If you are getting a 72 degree indoor temperature when the outdoor temperature is 28-30 degrees, the heat pump is performing up to spec.
On heat pumps, the air coming out of the nearest air vent to the unit should be heated approximately 40 degrees warmer than the air entering the unit.
If you have a 70 degree indoor air temperature, the heat pump should be supplying 110 degree air at the closest air vent to the indoor unit.
Gas heat is a much better heating source where outside temperatures are commonly below 36 degrees.
Even electric furnaces perform better than heat pumps under these conditions.

It's likely a bad tstat. Turn the power off to your air handler. Remove red , green, yellow and orange wires inside the tstat and wire nut them together. Not sure if your reversing valve energizes in heating or cooling but, turn the power back on. If the unit is heating turn the power off and remove just the orange wire and turn power back on. Let this run and see if it you are ONLY getting cool air ALL the time. If so you have a bad stat. If still getting heat possibly you have a bad control board in the air handler. Good Luck!!

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If your thermostat has an emergency heat setting this means you have a heat pump system.
Yes you need to set the thermostat to heat for heating the house.
The emergency heat setting should never be used unless your outside unit is not functioning.
The emergency heat setting overides the heat pump (the outside unit will not be energized).
The emergency heat setting will run the auxillary heat (heat strips) only.
When the thermostat is set in the heat position the heat pump will run to heat your house.
If the heat pump can't keep up (extreme cold) then then the auxillary heat will kick in to augment the heat pump until it satisfies the thermostat settings. If your room temperature gets 2 degrees below your thermostat setpoint, your auxillary heat will kick on. Example, say you are going to be gone a couple of days and you turn your heat down to 60 degrees. When you return and it is 60 degrees in your house, you turn the thermostat up to 70 degrees. Since you are turning the temperature up 2 degrees or more (10 degrees in this case) from the 60 degree room temperature then the heat pump will come on and the auxillary heat strips. The unit will continue heating like this until the temperature in the house gets to 69 degrees and the heat strips will turn off and the heat pump will continue to run until the 70 degree setpoint is reached.
Hope this helps.
SeagullAC

anytime your below the workable temp of your heat pump, so say your heat pump is putting out 70 degree air at the vent its time to switch. no sence in over working your heat pump

A basic model heat pump with an air handler with electric strip heat generally will continue to run with a call for heat regardless of the outdoor air temperature unless there was an outdoor thermostat (an accessory) installed. There is still heat in the outdoor even at temperatures of zero and below. Generally, there is a balance point of approx 30-35degF that allows the heat pump to heat your house to 68degF without the need for the electric heaters. Below that, the heat pump can still extract heat from outside and "pump" it into your house; however, it will need help from the electric heaters. In temperatures below the balance point, the heat pump will run non-stop. As the temperature in the house falls approx 1 - 2 degF below the setpoint, the electric heaters will energize. So it is not uncommon for the system to run non-stop with the temperature falling a few degrees below setpoint. The colder the outside temperature, the more often the strip heaters will cycle on/off. If your system is well-maintained and operating at proper performance, it is still cheaper to run your heat pump than it is to run on straight electric heat. If you live in a climate where below zero temperatures are normal during the winter months, you might want to research heat pump options that offer higher COP's and increased performance in colder temperature than the basic contractor's model. Start with initiating communication with a local contractor. You will need to consider initial cost and the pay-back period based on your local energy costs and your specific demands you want your system to meet.

Hope this helps!

Economy Mode = EM
Auxelary Mode = AUX
in em mode heat pump does most of the work in aux either an electric heating element is used or gas depending on if it is gas or all electric

Sorry, neither of these answers are completely correct.
You have a heat pump (or the wrong thermostat). Let's assume you have a heat pump.

In air conditioning mode, it works like every air conditioner you have ever had, but...

In heat mode, it reverses its operation. Have you ever felt the air coming out of the outdoor unit of your A/C unit? It's hot, isn't it. And the air coming out of the indoor unit (out of the registers) is cold. Now for a heat pump to produce heat it simply runs the air conditioner in reverse and the heat comes out in the house and the cold is released outside. Neat, huh!

Here's the problem with heat pumps...when it is really cold outside the heat pump can't produce enough heat to heat your home. So it has an additional heat source called "Auxiliary Heat". This heat comes on automatically when the house doesn't get warm enough. The source of this heat is based on the region of the country you are in. North/Northeast generally have oil heat, other regions have gas, and still others have to use electricity to heat. In Texas, we usually use electricity as the supplementary heat on heat pumps. VERY EXPENSIVE!

Now the "Emergency Heat"...this is exactly as stated in Solution #2. This is manually turned on by YOU at the thermostat when your heat pump fails. This turns on the auxilliary heaters and turns off the heat pump (remember, the reverse air conditioner). Again, this can be quite expensive to run if your heat source uses electricity! Gas and oil may be cheaper. The emergency heat is only designed (normally) to keep the house livable (not comfortable) until the Heating Tech can get out to you and fix your heat pump.

Something else you should know. It is normal for a heat pump's outdoor coil to frost up during heating mode. It will detect this and go into DEFROST mode and melt the frost off the coil. While it is doing this, it will turn on the auxilliary heater to keep the air blowing in the house at a reasonable "warm" temperature, but it will not be as hot as normal. In fact, heat pumps produce a lower temperature heat than traditional heaters. So the air may feel cooler during heating than you are use to anyway. This is normal and is not a sign of a problem.

So what do you do: Set your thermostat to the temperature you want and set the controls for HEAT/COOL and FAN-AUTO/ON and leave the EMERG HEAT off unless your heat pump breaks.

As always, keep your filters clean and your outdoor unit's coils clean and free of debris.

Hope this explains your question for you!

Heat pumps in cold climates suffer a number of limitations stemming from the fact that they are designed for air-conditioning applications. As climates become cooler and heating becomes more of the primary HVAC function, one may find that conventional heat pumps lose capacity and do not satisfy the load of the conditioned space. In colder temperatures, a conventional system’s need to defrost can further detract from heating performance. The use of resistance heat or fossil fuels to supplement or replace the vapor cycle. The additional use of supplemental heat to temper cold air blowing into the space during defrosts. As it gets colder outside, the delivery air temperatures inside begin to fall when no supplemental heat is being used. Supply air temperatures that are warmer than the return temperatures add heat to a space, but discomfort occurs when these supply temperatures drop below skin temperature. The air movement can feel cool or even cold. While the heat pump may be operating exactly as intended,the consumer will desire a more comfortable environment.

Heat pumps in cold climates suffer a number of limitations stemming from the fact that they are designed for air-conditioning applications. As climates become cooler and heating becomes more of the primary HVAC function, one may find that conventional heat pumps lose capacity and do not satisfy the load of the conditioned space. In colder temperatures, a conventional system’s need to defrost can further detract from heating performance. The use of resistance heat or fossil fuels to supplement or replace the vapor cycle. The additional use of supplemental heat to temper cold air blowing into the space during defrosts. As it gets colder outside, the delivery air temperatures inside begin to fall when no supplemental heat is being used. Supply air temperatures that are warmer than the return temperatures add heat to a space, but discomfort occurs when these supply temperatures drop below skin temperature. The air movement can feel cool or even cold. While the heat pump may be operating exactly as intended,the consumer will desire a more comfortable environment.

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