Heat pump system/ emergency mode.

[cassidy]

I have a all electric house with a heat pump unit, been here for 5 years no problems. I noticed this morning the emergency heat light was flashing on the thermostat, it was 27* this morning. It has been alot colder than that around here, like down to -10* and I never noticed the emergency heat light flashing. How cold does does it have to be for these to go into emergency heat? Do I have problem on my hands?

 

[offroadsteve]

I would suspect its normal, unless its on all the time. I have a heat pump system as well.

Because the heat pump "moves" heat from outside to inside, your outside unit gets really cold during operation, and can accumulate a lot of ice if its humid outside.

When it ices up, the heat pump will go back into "cool" mode, where its moving heat from inside to outside, and melts the ice because the coil gets hot. I'm not sure if the units have a sensor that detects the ice, or if its just a timed thing.

But - since its cold and you don't want the A/C running, the electric heat strips in the furnace turn on, hence the "emergency mode" indication.

 

[Rockhead261]

The indoor fan should not be running in defrost mode. If it's not that cold outside and you're running in e heat it's probably an indicator that the mechanical heat has failed. Make sure the thermostat isn't set in e heat and call a tech.

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[cassidy]

So if there is a problem the e - heat light will be on solid? I will check it out more when I get home.

 

[cassidy]

The indoor fan should not be running in defrost mode. If it's not that cold outside and you're running in e heat it's probably an indicator that the mechanical heat has failed. Make sure the thermostat isn't set in e heat and call a tech.

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So the blower in the furnace should not blow air while in defrost mode? I'm confused as to how this works then, how then if the blower doesn't run in defrost mode how does it heat the house?

 

[cassidy]

I would suspect its normal, unless its on all the time. I have a heat pump system as well.

Because the heat pump "moves" heat from outside to inside, your outside unit gets really cold during operation, and can accumulate a lot of ice if its humid outside.

When it ices up, the heat pump will go back into "cool" mode, where its moving heat from inside to outside, and melts the ice because the coil gets hot. I'm not sure if the units have a sensor that detects the ice, or if its just a timed thing.

But - since its cold and you don't want the A/C running, the electric heat strips in the furnace turn on, hence the "emergency mode" indication.

Have you noticed your e - heat light coming on and off?

 

[Rockhead261]

Have you noticed your e - heat light coming on and off?

No. I have gas heat.

So the blower in the furnace should not blow air while in defrost mode? I'm confused as to how this works then, how then if the blower doesn't run in defrost mode how does it heat the house?

Defrost mode only initializes every couple of hours and only last few minutes tops. I meant to say that neither the indoor nor the outdoor fan run in defrost mode. Read this.

So if there is a problem the e - heat light will be on solid? I will check it out more when I get home.

More info (make/model) on your system and stat would help here.

 

[Dkramer]

So the blower in the furnace should not blow air while in defrost mode? I'm confused as to how this works then, how then if the blower doesn't run in defrost mode how does it heat the house?

You are correct, the indoor blower will run during the defrost cycle. It needs to run in order to pick up heat from the house and deliver it to the outdoor coil in order to defrost the ice. Your strip heat / aux. / emergency heat will turn on to temper the air coming into the house.

More info (make/model) on your system and stat would help here.

Yep brand name of h.p and thermostat will really help in this.

 

[acmikee]

check your outdoor unit. its probably not running and your using your strip/electric heat to heat your house now that why its in emergency heat.

 

[Rockhead261]

You are correct, the indoor blower will run during the defrost cycle.

Not in all cases. But, in ALL cases, the outdoor fan will stay off initally then start up after enough heat has been generated, usually sending a cloud of condensation into the air and freaking people out.

Waiting on make and model information.

 

[cassidy]

Here you go, thanks for the help guys.

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[Rockhead261]

Go to this link and read the section for York Stellar flash codes.

http://www.hannabery.com/faq9.shtml

This also covers resetting. Should be a good start.

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[cassidy]

Go to this link and read the section for York Stellar flash codes.

http://www.hannabery.com/faq9.shtml

This also covers resetting. Should be a good start.

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Thanks for the help, when I got home from work the outside unit was running normally and the e heat light was not flashing anymore so I'm not sure what it was doing this morning. Is there a way to tell how old the unit is by the info on the tag?

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[Rockhead261]

3rd position of S/N, "H" = 1999

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[Charles (in GA)]

You are correct, the indoor blower will run during the defrost cycle. It needs to run in order to pick up heat from the house and deliver it to the outdoor coil in order to defrost the ice. Your strip heat / aux. / emergency heat will turn on to temper the air coming into the house.

My HP system does this, air handler circulates air, usually fairly cold out of the vents, and outside the condenser fan DOES NOT operate. The ice on the coils of the condenser leave as vapor/steam. I think my backup strips do come on, but the air out of the vents is still cold.

Charles

 

[pseudorealityx]

My HP system does this, air handler circulates air, usually fairly cold out of the vents, and outside the condenser fan DOES NOT operate. The ice on the coils of the condenser leave as vapor/steam. I think my backup strips do come on, but the air out of the vents is still cold.

Charles

Then the strip heater isn't on. The air coming out is the temperature of the air return + any heat added via the strip heater. Even a 3 KW heater on a 2 ton unit should heat the air ~ 12 degrees. Assuming a t-state at 68, it should output 80. Not enough to heat the house, but not 'cold'.

I typically size heat pump strip heaters at a 20-25 degree delta T.

 

[cassidy]

3rd position of S/N, "H" = 1999

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Cool thanks, what's the average life span of these units?

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[Rockhead261]

Cool thanks, what's the average life span of these units?

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What's the average lifespan of a car? There is no average. It depends on the climate, the installation, and how they're used/maintained. I've seen five year old units with rusted cabinets and 30 year old units in museum condition.

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[volleyball]

yours is elderly

 

[Rockhead261]

FWIW, my outdoor condensing unit turns 20 this year. No plans to replace it.

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[volleyball]

Who replaces a working unit? My 15 year roof was upgraded to steel at 30 years. And it still didn't leak. But it was still old when it was 15.

 

[Rockhead261]

Who replaces a working unit? My 15 year roof was upgraded to steel at 30 years. And it still didn't leak. But it was still old when it was 15.

I've replaced many working units.

Many businesses depreciate equipment as an expense, then replace it when it becomes valueless on their books.

Many well heeled homeowners would rather plan a replacement than have a unit **** out on them in the middle of a summer heat wave.

Others who need A/C as a matter of health (severe allergies, heart/lung ailments, etc) also upgrade equipment preemptively.

Some of the stuff is still in great shape when it comes out, and I've repurposed more than a few working units for friends.

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