Your heat pump should include electric heat strips. At least one, anyway.
An electric heat strip might be the only thing standing between you and frozen, burst pipes. Or your home getting so cold when the heat pump breaks down that you have to leave and go elsewhere.
Most heat pump systems should have them. They are used primarily as emergency heat or backup heat for times the heat pump itself breaks down or cannot keep your home warm.
What are electric heat strips?
Electric heat strips are electric resistance heaters, like huge space heaters, installed in the air handler of a heat pump system. If the heat pump fails in winter, the heat strips are activated for emergency heat. They might not keep your home as warm as you’d like, but they should produce enough heat to keep the indoor temperature above freezing.
Where are We Going Here?
Heat strips have several purposes, and they’re all explored here:
Electric Heat Strip FAQ:
What are Electric Heat Strips in Air Handler Units?
As you can see from the image, an electric heat strip looks something like the element in a space heater, only larger – much larger in some cases. It has more wiring because an air handler is more complex. Electric furnaces use heat strips just like this to create heat.
Electric heat strips are made in sizes from 3kW to 25kW for residential air handlers. The most commonly used sizes are 5, 7.5, 10, 15, 20 and 25 kilowatts. See Heat Strip Options below if you’re interested in knowing how those numbers equate to BTUs of heat.
HVAC technicians recommend heat strips based on two related criteria:
- The size of your heat pump system – bigger system, bigger heat strip. And the size of your heat pump is based on the next two.
- The size, configuration, construction and other details related to your home.
- Your climate – the colder your climate, the more kW of heat strips you should have.
Where are Heat Pump Heat Strips Installed?
In the air handler. Your heat pump system is made up of 3 main components – or 4 when heat strips are included.
- The outside unit, which is commonly called the heat pump, is technically called the condensing unit. In winter, it’s coil and refrigerant gather heat outdoors. Keep that in mind for the later discussion of heat strip purpose.
- The air handler is the indoor unit. It has a blower motor and fan. The fan sucks air into the system to heat in winter or remove heat from in summer, and then pushes “treated” air through ductwork and grates into your home’s living space. This is why these systems are called “forced air” HVAC systems.
- The indoor coil is installed in or directly connected to the air handler. Refrigerant cycles from the condensing unit to it and back through copper refrigerant lines. In summer, the indoor coil collects heat and takes it outside, effectively cooling the air indoors. In winter, it disperses the heat into the ducts that the outdoor coil absorbed.
- The electric heat strip or strips are installed in the air handler. When they come on, so does the blower. The heat created is pushed into your home’s rooms, and cool air is sucked into the air handler through return ducts to be warmed.
What is the Purpose of Electric Heat Strips in Air Handler Cabinets
Why are the heat pump heat strips on?
That’s a common question we get.
The simple answer is that electric heat strips provide heat when your heat pump cannot capture and pump enough into your home.
There are two normal scenarios for heat strips being activated.
- Your heat pump isn’t working.
We’ve completed a Trouble-shooting Guide for Heat Pumps and ACs that you might find useful.
When your heat pump fails for whatever reason – electrical issue, control board failure, refrigerant leak, etc., it won’t deliver any heat.
Some systems automatically switch to the electric heat strip for heating. Other systems require that you manually switch the thermostat to Emergency Heat.
The Emergency Heat should help considerably – by that, we mean it should raise indoor temperatures by 15-25 degrees depending on outside temperatures and the kW rating of the heat strips.
When the system is running on heat strips only, then it is essentially an electric furnace. That’s the most expensive form of heating compared with a heat pump and gas/oil/propane furnace – but it beats frozen pipes or freezing your tail off.
- Your heat pump can’t keep up with cold temperatures.
This should happen rarely, if ever. If your heat pump is properly sized, then it should be able to pump enough heat to keep your home warm almost always.
But South Florida occasionally gets freezing temperatures. Sometimes the temps in Tempe or Phoenix dip into the 30s.
If the heat pump is properly sized in those areas, then it should have trouble keeping up with temperatures that cold.
Why? The short answer is that a properly sized unit in warm areas simply won’t pump enough heat in bitter cold temperatures. If it could keep up in those rare, really cold stretches, it would be too big for 95% of the days.
A heat pump that is too large causes a lot of indoor comfort issues. This is explained in more detail in the Sizing a Heat Pump section of our Heat Pump Reviews.
One of our readers recently shared this comment: “My lennex [sic] heat pump when the temperature outside drop below 40 degrees the heat pump keeps running and won’t shut off like it struggles to heat the house up it a 4 ton.”
That is to be expected, at least somewhat. Juanita’s heat pump is either slightly too small or just the right size – if this scenario is rare for her.
If the temps where Juanita lives regularly drop below 40, she should probably have a gas furnace, not a heat pump.
Juanita’s situation is just one more reason we highly recommend talking through heating and cooling decision with at least 3 different companies before you decide on the right equipment for your home.
Feel free to use our Free Local Quotes or toll-free number to get advice and written estimates with no cost or obligation.
Note: If your heat strips are on when the heat pump is working and outdoor temperatures aren’t extremely cold, something is wrong.
- Control board issue? An electrical issue might be causing them to come on when there is no need for them.
- On/Off? The heat strips might be manually turned on, so check your thermostat to see if the Emergency Heat option is on.
- Somebody goofed up. Your heat pump is way too small, and somebody sold you or the previous owner the wrong unit.
What Size Heat Strips are Available?
Here are common sizes in kilowatts with their equivalent in BTUs.
|Heat Strip||BTUs||Cost||Installed Cost|
|3 kW||10,000 - 15,000||$45 - $60||Ave. $140|
|5 kW||15,000 - 20,000||$45 - $65||Ave. $170|
|7.5 kW||20,000 - 30,000||$75 - $95||Ave. $180|
|10 kW||30,00 - 40,000||$80 - $140||Ave. $210|
|15 kW||50,000 - 55,000||$125 - $225||Ave. $270|
|20 kW||65,000 - 70,000||$165 - $270||Ave. $325|
|25 kW||85,000 - 90,000||$210 - $300||Ave. $350|
As you can see, heat strips can kick out quite a lot of heat. A 1,500-watt space heater creates just 5,100 BTUs. Think about 5-15 of them running in your home!
- It would be a lot of heat
- It would send your electric bills through the roof
The type of heat created by space heaters and electric heat strips is called electric resistance heat. A heat coil is energized with electricity. The material creates resistance, a little like friction, and heat is created.
Think about three types of heat:
- A heat pump uses a small amount of electricity to circulate refrigerant – and the refrigerant does the job of absorbing and releasing heat. No heat is “created.” The heat pump uses heat already there.
- A gas furnace burns natural gas or propane to create heat. The method isn’t as efficient as heat pump heating, but it can make good use of the fuel, especially if it is a 90%-plus furnace.
- A heat strip or space heater uses electricity. The electricity is generated at the power plant using coal, natural gas or other fuel. Then the electricity is sent to the grid. It enters your home and energizes the heat strip. The electricity flow is resisted, and heat is the result. It is very inefficient, so the cost of the heat created is much higher.
For this reason, you do not want the heat strips to be on any more than they have to be. And those times are:
- For emergency heat when the heat pump isn’t working
- Unusually cold weather stretches for your area
What Size Heat Pump Heat Strips Do I Need?
The range is 3kW to 25kw for most homes.
We recommend that the heat strip be able to deliver at least 70% of the heat the heat pump does.
Competent HVAC pros properly size the heat pump equipment – the condensing unit, indoor coil, air handler blower and the heat strip.
Factors considered are:
- Your home’s size, layout, building materials, orientation and many other factors used in a Manual J HVAC load calculation.
- Your climate – how cold does it typically get in winter? What is the coldest it might get?
How Much do Electric Heat Strips Cost?
The table in the section above named What Size Heat Strips are Available shows the cost of installed heat strips to be $140 to $350. Some cost more.
We use average prices, but you can always find a more expensive product – or they’ll find you if you come across an HVAC technician that wants to maximize profit at the homeowner’s expense.
The Bottom Line
Should I install electric heat strips for my heat pump system?
Yes. Unless winter weather is never very cold where you live, you might one day appreciate what an electric heat strip can do for you.
If you’re shopping for heat pumps and the salespeople are “pushing” heat strips, they are probably giving you good advice. Not everything an HVAC salesperson might try to “upsell” you on is right for you – and we’re quite critical of those that sell homeowners stuff they don’t need.
But we do think a heat strip is essential where winter temperatures are often freezing.
Where they are cold but not freezing, an electric heat strip is a matter of convenience that might save you money too.
- In freezing weather, electric heat strip cost will be far less than the cost of replacing burst pipes and repairing potential water damage.
- In cold weather above freezing, an electric heat strip in your air handler should give you enough heat to make your home livable until the heat pump is repaired. Staying in your home rather than going to a hotel will save you $65 to $150 per night depending on your location and tastes. The cost of two or three nights in a hotel might be enough to cover the cost of electric heat strips for a heat pump.
Talk with several heat pump experts in your area, and get their advice. Getting counsel from several experienced sources, hearing their perspectives, will allow you to make the best decision for your home.