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Michal greenwood Posted on Nov 27, 2016
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When em heat is on my outside unit runs but when not on em heat it doesn't. Which setting is best to use?

1 Answer

Bill Long

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  • Master 606 Answers
  • Posted on Dec 17, 2016
Bill Long
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Joined: Mar 17, 2009
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Has this always been this way? When the emergency heat is on the outside unit shouldn't run. When in normal heat, no emergency heat, the outside unit should be running unless the temperature is below the balance point ( usually around 35 degrees). If this has always been this way and the outside temperature is above 40 degrees you might have your 1st stage and 2nd stage wires switched.

5 Related Answers

Anonymous

  • 288 Answers
  • Posted on Mar 15, 2008

SOURCE: ruud heat pump outside fan

You may be right in looking at the motor. It uses a different speed on heat than cool. The heat cycle uses low speed, usually red. Some manufactures use blue (medium). Cool uses black, high speed. If you are confident, switch the low speed wire with the high speed and see if this changes anything. If the fan motor isn't the problem, check the other setting (cool) if the overload trips, you may need to look into a new capacitor or compressor, if so, you can install a hard start kit. these are start boosters, and are inexpensice, sometimes they will give another year out of the comp. but I've put them on and they have lasted 5 years.

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TheMazz

Kevin

  • 79 Answers
  • Posted on Oct 28, 2009

SOURCE: What's the difference between EM HEAT and AUX HEAT?

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!

Anonymous

  • 1 Answer
  • Posted on Dec 19, 2009

SOURCE: During heating (outside temp. 2 deg C), outside

Get the charge tested, check the sub-cooling across the outdoor coil.

Anonymous

  • 37 Answers
  • Posted on Jan 11, 2011

SOURCE: unit set to heat but

If it is a heatpump, the outside unit should not turn on below 35degrees or so. Below that temperature, the unit cannot effeciently exchange heat. When the outside temperature is low, the system automatically switches over to auxillary heat which uses the same heating elements as emergency heat.

jisake1

Ken

  • 19 Answers
  • Posted on Aug 26, 2011

SOURCE: Unit for downstairs is running

Are you saying you have two HVAC systems or one? If you have two indoor units, you must have two outdoor units. Which outdoor unit is running. You said it is running hot. Assume the fan in running to cool the condenser. If so it should be about 20 degrees warmer than outdoor air. If not maybe you have a dirty condenser coil. Need more information.

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0helpful
2answers

I just moved into this home and am wondering what EM heat is compared to just Heat and my outside unit is full of frost what do I need to do?

Hi, EM stands for emergency heat. You should only need to use it if the outdoor unit does not operate. You have what we call a heat-pump. If the outdoor coil is iced up, it should go into a defrost cycle to melt away the ice. You will know when it does as you will see steam coming up from the unit as though it is on fire. The outdoor fan will also shut down during this process. These units will defrost using time and temperature to defrost the coil. If the ice continues to build-up, and does not defrost every couple of hours, I would say you have a faulty defrost board or defrost thermostat. There is not alot you can do as these are very complicated systems to work on. You will more then likely have to call out a service tech to check this outdoor unit for you.It also should have heat strips in the outdoor unit for EM heat if the outdoor unit fails. If it is iced up it is on and running. Thats what I would do is keep an eye on it to see if it does defrost, and if not, you will need to get a tech out to check it. It takes special equipment to check these units. Please keep me posted.
Sincerely,
Shastalaker7
1helpful
1answer

I have arcoaire thermostat (not digital) with Comfort Air FBA series system, vintage 1998. The bottom of thermostat has selections: ''EM Heat'' ''Heat'' ''Air'' ''Off''. I am not original owner. Q. Should...

yes go into electric heat for awhile. sometimes a heatpump will run constantlly when temps outside are not high enough./em heat mode untill temps rise or unit recovers.your unit should of gone into hot-gas defrost this maybe what your hearing. but remember electric heat is expensive to operate go back to your heatpump mode after system has a chance to recover.
0helpful
1answer

Heat pump runs in em heat when outside temperature is low

Yes, you may turn to em heat only. May this confirmation help you.
0helpful
3answers

Goodman package- no heat below 30 degrees outside

I believe the unit you are describing is a heat pump. Heat pump are great when the temperature isn't below 30 With low ambient temps. outside it is much more efficient and comfortable to run aux. electric heat from the heat pump.
0helpful
2answers

The transformer on my central AC/heater (luxaire model # A236A344T LH) keeps going out. There are 4 settings on the wall. Cool, off, heat and EM. Heat. The setting switches to EM. Heat each time the...

You might have some thermostat wires that are touching meaning the insulation has been broke off and getting a direct short. Check the wiring going to the outside unit and replace any wire that is in bad shape. let me know okay. Ken
38helpful
5answers

What's the difference between EM HEAT and AUX HEAT?

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!
0helpful
2answers

Furnace runs on heat, air conditioner does not

If you have a Gas furnace in the Attic then the answer is yes. The outside condenser will not run if in fact you have a gas furnace.
1helpful
1answer

Compressor fan not running

Does it look like the coils are frosting over? Is it steaming? Keep watching, after about 30 min does the fan come back on?

If yes to any/all the above then the unit is probably in defrost mode and yes the fan will stop blowing during that time, but restart when the unit goes back into regular heat mode.

During this time you will likely notice warmer heat from the vents than normal and the "AUX or EM HEAT" light will be on.

That is your backup heat system. It should automatically come on during a defrost cycle.
0helpful
1answer

Furnace not running along with heat pump

Someone did not program your thermostat to operate according to your heat and air requirements.
Have it programmed correctly.
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