Em Heat: The Button Every Homeowner Should Understand Before Winter
On your thermostat, next to Heat, there is a setting most Keystone homeowners have never touched: Em Heat — emergency heat. When your Daikin electric heater starts acting up — a burning smell from the vents, heat that cuts in and out, a system that will not keep up — that button becomes the most important and most misunderstood control in your home. Used right, it keeps you warm safely until the repair. Used wrong, it hides the problem and runs up your bill.
This is the field guide: what Em Heat actually does, when to reach for it, when to leave it alone, and what your need for it tells a technician about the underlying failure.
What Em Heat Actually Does
Em Heat — emergency heat — tells your system to stop using the heat pump’s outdoor unit entirely and heat only with the electric heat strips inside the air handler. It is a deliberate downgrade: the efficient heat pump sits idle while the power-hungry nichrome elements do all the work. The house gets warm, reliably, at a noticeably higher operating cost.
Think of it as the spare tire of heating. It is not designed for the season; it is designed for the failure. Every hour it runs, it is doing the job the heat pump should be doing — which means every hour it runs is also evidence that something upstream needs attention.
When to Reach for Em Heat
There are exactly two situations where Em Heat is the right call. The first: the heat pump has failed or is behaving dangerously — blowing cold air it cannot explain, making new mechanical noises, or showing an error — and you need heat tonight before a technician can arrive. Em Heat bypasses the suspect equipment and gives you safe, simple electric heat.
The second: a technician has diagnosed the outdoor unit and told you to run Em Heat while parts are on order. This is a prescribed use, not a guess — the tech knows what failed and has confirmed the strips and their safety chain are sound.
In both cases, the rule is the same: Em Heat is a bridge to the repair, not a substitute for it. If you find yourself running it for days, the bridge has become the destination, and the underlying failure is going unrepaired while the strips do expensive work.
When Em Heat Is the Wrong Answer
Do not use Em Heat for a burning smell. If the smell is coming from the electric heat strips themselves — dust burn-off, a failing sequencer, an overheated element — switching to Em Heat runs the strips harder and longer, which is the opposite of what the situation needs. A burning smell means turning the heat off and getting an inspection, not switching to the mode that leans on the strips.
Do not use Em Heat as a comfort upgrade either. Some homeowners switch to Em Heat because the heat pump “does not feel hot enough” — heat-pump air runs cooler than strip heat, and that is normal. Running the strips because you prefer hotter-feeling air is paying a premium for a sensation, and it masks the early signs of a heat pump losing capacity.
And do not use Em Heat to avoid a repair you know you need. Strips that run for weeks straight accumulate their own wear — sequencers cycling under constant load, elements running long hours — and a system kept alive on Em Heat arrives at the eventual repair in worse shape than it would have otherwise.
What Your Em Heat Use Tells the Technician
When we arrive at your Keystone home, one of the first things we ask is whether you have been running Em Heat — and the answer is diagnostic gold. A homeowner who needed Em Heat because the heat pump went cold tells us the outdoor unit is the suspect. A homeowner who has been on Em Heat for two weeks tells us to check the strips’ condition too, because they have been doing marathon duty. A homeowner who switched to Em Heat for a burning smell tells us to inspect the strip circuit first, because the strips were the scene of the problem all along.
The full inspection then follows the power path: breaker and disconnect sizing and terminal condition, sequencers and contactors watched as they pull in, element resistance readings, limit switches tested to confirm they open at rated temperatures, and airflow measured across the filter, coil, blower, and return path. We carry genuine Daikin sequencers, contactors, elements, and wiring on the van, so the repair that the Em Heat was bridging usually completes in the same visit.
The Honest Economics of the Spare Tire
Electric strip heat costs substantially more to run than a working heat pump — that is the entire reason heat pumps exist. A few nights on Em Heat during a repair wait is a reasonable, small premium for staying warm. Weeks on Em Heat is a different story: the strips become the primary heat source at primary-heat cost, and the unrepaired heat pump fault sits there getting no cheaper to fix.
This is why we treat an Em Heat call as time-sensitive. We serve Keystone with same-day dispatch, our electrical work is done to code at correct ratings, and our repairs are warranty-safe so your manufacturer coverage stays intact. If you are running Em Heat right now, the system is telling you something — and the cheapest time to listen is today.
Is Em Heat safe to use?
Yes, when the strip circuit is sound — it is a designed operating mode, not a hack. But it is not the answer to a burning smell: if the strips themselves are the problem, Em Heat runs them harder. When in doubt, turn the heat off and call for an inspection first.
Why is my bill so high on Em Heat?
Because electric strips are the most expensive way to make heat in your system. The heat pump moves heat; the strips manufacture it from raw electricity. Em Heat is priced like the emergency tool it is — fine for days, punishing for weeks.
Can I leave Em Heat on all winter?
You can, but you should not. Beyond the operating cost, long Em Heat runs wear the sequencers, contactors, and elements under constant load, and the underlying heat-pump fault goes unrepaired. Em Heat is a bridge to the repair, not a heating strategy.
My heat pump air feels lukewarm. Should I switch to Em Heat?
No — lukewarm-feeling air is normal for a heat pump, which delivers lower-temperature air over longer runs. Switching to Em Heat for hotter-feeling air costs a premium and can mask a heat pump that is actually losing capacity. If the house is not reaching temperature, that is a repair question, not a mode question.
What should I tell the technician about my Em Heat use?
When you started using it, why (what symptom drove you to it), and how long it has been running. Those three facts point the diagnosis at the outdoor unit, the strip circuit, or both — before we open a single panel.
Does using Em Heat damage my system?
Short-term use does not. But weeks of continuous strip operation add real wear to the electrical components, and any fault the Em Heat is covering — in the heat pump or the strips — continues developing underneath. The safe move is always: bridge with Em Heat, then get the repair.