Electric bill suddenly high in Casselberry, Florida

If a Casselberry electric bill jumps in winter, the usual answer is electric strip heat - the standard build in this city's 1970s and 80s housing, and resistance heat costs several times what a heat pump does. A summer jump is more often a failing capacitor, a dirty coil or duct leakage.

Diagnosis

What is most likely wrong

Likely causes, ordered by how often they turn out to be the answer
#	Cause	How common	What it looks like
1	Electric strip heat running	Very common in winter	A January bill unlike any other month. Resistance heat is 100% efficient and no better than that.
2	Dirty condenser coil or blocked filter	Very common in summer	The system runs longer for the same result.
3	Duct leakage into a hot attic	Common	Conditioned air paid for and lost. Usually accompanied by one room that never keeps up.
4	Low refrigerant charge	Common	Longer run times, less cooling per hour.
5	Failing capacitor or compressor drawing high amps	Common	Often the last warning before a failure.
6	Heat pump stuck on auxiliary heat	Less common	A failed reversing valve or defrost board leaves the strips carrying the load. Expensive, and easily missed.
7	A rate or billing-period change	Less common	Check the number of days in the billing period before assuming equipment.

Before you call

What you can safely check yourself

Compare like with like: the same month last year, and the number of days in the billing period, not last month.
Check whether the thermostat has been left on 'emergency heat' or 'aux heat'.
Filter, and the outdoor coil.
Note whether the system is running far longer than it used to for the same setting.
If you have a heat pump, check that it actually heats without the aux strips — a hand at a supply register on a cool morning tells you a lot.

Where the licensed line is

Refrigerant, capacitors and the inside of an electrical panel are not homeowner jobs.

A run capacitor holds a lethal voltage after the disconnect is pulled. Refrigerant handling requires EPA Section 608 certification. And in Florida the work itself is regulated: an air conditioning contractor licensed under Chapter 489 may replace, disconnect and reconnect the power wiring at the dedicated disconnect, and repair or replace disconnects, breakers and fuses on dedicated HVAC circuits — s. 489.105(3). That scope exists precisely because this work is not general-purpose electrical work.

Verify any Florida licence, including ours, at the DBPR licensee search.

In Casselberry

Why this happens in this housing stock

This is the Casselberry page. 57.1% of the city’s 8,563 improved residential parcels were built between 1970 and 1989 — the third-highest share of the seven Seminole County cities — and that era built straight-cool condensers with electric resistance strip heat in the air handler as standard. Winter here is mild, with a January average high near 71°F, so builders had little reason to pay for a heat pump.

Seven Seminole County cities, one extract, one filter
City	Residential parcels	Median year built	Built 1970–89
Altamonte Springs	13,253	1981	72.4%
Longwood	4,962	1979	66.5%
Casselberry	8,563	1977	57.1%
Winter Springs	13,297	1988	51.2%
Lake Mary	5,343	1996	26.9%
Oviedo	12,263	1995	25.0%
Sanford	17,391	1995	24.8%

Forty years later the condenser has been replaced three or four times — usually with another straight-cool condenser — and the strip heat is still there. It only runs for a few weeks a year, but when it does it can double a bill.

The fix is a heat pump conversion, and it is the one Duke Energy pays the most for: up to $1,000 as published, for replacing electric strip heat with a qualifying heat pump, against $500 for replacing an existing heat pump and $300 for replacing an air conditioner. The catch is the order of operations — the free Home Energy Check has to happen first. What converting actually changes and the rebate tiers with their caveats.

Seminole County Property Appraiser CAMA extract (Parcels.csv, dated 2026-09-05). Improved residential parcels — single-family, townhome and condominium — in city tax district C1, City of Casselberry. n = 8,563.

Cost

What the fix typically costs

Researched repair ranges for this symptom
Job	Researched range	What drives it
Diagnostic visit	$75–$150	Usually credited.
Capacitor replacement	$150–$400	A weak capacitor raises running current.
Duct repairs or replacement	$1,500–$5,000	Duke pays 50% of the duct test plus up to $200 of repairs.
Attic insulation	Duke rebate up to $800	Not a repair, but the cheapest bill reduction in 1970s stock.
Heat pump conversion (full replacement)	$5,800–$12,500	Less up to $1,000 published rebate on a strip-heat house.

Read this before you use any number on this page

These are researched market ranges, not our prices and not a quote.

The dollar figures below come from published third-party cost guides — named and linked at the foot of the page — and from the City of Casselberry’s own published permit fee. They are here so you can tell whether a quote you have been handed is in the ordinary range for this work. They are not an offer, and no two houses in Casselberry cost the same to do.

Order of operations — this one costs real money

Book the free Duke Energy Home Energy Check before you replace anything.

Duke Energy requires a free Home Energy Check completed within the previous 24 months to qualify for any Home Energy Improvement rebate. Replace the system first and apply afterwards and the application is denied — there is no retroactive path back.

It is a no-cost visit and it is the single most common way a Casselberry homeowner loses a four-figure rebate. If you are within a year of replacing, book it now, before you call anyone for a quote. Duke’s rebate line is 800.254.8535.

On strip heat and tired of the January bill?

Book the free Home Energy Check before you get quotes. Doing it afterwards forfeits the rebate entirely.

Call for service Request a visit

Phone: (689) 308-3675 · Monday-Friday, 8:00 AM - 5:00 PM

Keep reading

Sources

Where the facts on this page come from

Every figure above is either a primary-source document or a named third-party cost guide. All of it was checked in September 2026. Fee schedules, rebate amounts and market prices change without notice — if you are about to spend money on one of these numbers, open the source and check it.