Should You Keep Your Whirlpool Hot All Winter — or Heat It Only Before Use? A Smart Guide

If you own an outdoor whirlpool or hot tub, winter raises an important question:

Is it cheaper to keep the water hot 24/7, or to turn the whirlpool off and heat it only when you need it?

The answer isn’t the same for everyone. It depends on insulation quality, electricity pricing, outdoor temperature, and how often you use your tub. This guide explains the smart strategy for different situations — and why the “obvious” answer is often wrong.

🔥 The Two Approaches

1. Maintain Temperature

You keep the water warm (usually 37–40°C) all the time.
The heater only works occasionally to maintain the set temperature.

Pros

• Water is always ready

• Less wear on the heater

• Usually cheaper in cold climates

• More convenient

Cons

• You pay a small daily “standby” energy cost

2. Turn Off & Heat Before Use

You let the water cool (or empty the tub) and fully reheat it when you want to use it.

Pros

• Can be cheaper in warm climates

• Good for very occasional use

Cons

• Reheat time can take 2–4 hours

• Heating from near-freezing temperatures is very expensive

• More thermal stress on the system

❄️ Winter (0–5°C): Keep It Hot — It’s Cheaper

In cold weather, even a well-insulated outdoor whirlpool loses heat quickly.
If you let it cool down completely, the heater must raise the water temperature by 30–40°C each time.

For a typical premium tub, reheating from 5°C to 38°C can require:

➡️ 20–30 kWh of electricity
➡️ At €0.35/kWh = €7–€10 per heat-up

Maintaining temperature needs only:

➡️ ~3–6 kWh per day
➡️ €1–€2/day

If you use your whirlpool nightly or even every few days in winter, maintaining temperature is far cheaper.

🌤️ Mild Climates (10–20°C): Depends on Use Frequency

As outdoor temperatures rise, heat loss drops dramatically.
Here the math shifts.

The general rule:

• Use it every ≤3 days → keep it hot

• Use it weekly → turn it off (or reduce temperature)

• Heating from 12°C to 38°C uses ~18 kWh (€6.30)
  Standby heat loss in these temperatures is low — often only €0.35–€0.70/day.

☀️ Summer: Use Pattern Matters Most

In hot weather, heat loss is minimal. Your strategy depends entirely on usage:

• Use 3+ times per week → keep it hot

• Use once a week or less → turn it off

Some owners maintain the tub at 28–30°C in summer, cutting costs further and lowering heat-up time.

🧠 Simple Decision Matrix

Here’s an easy way to decide:

🛠️ Other Factors That Affect Cost

1. Insulation quality

• Premium winter-ready tubs: excellent insulation → cheap to maintain

• Inflatable or low-quality tubs: weak insulation → expensive to maintain

2. Thermal cover condition

A thick, well-sealing cover can reduce heat loss by 40–60%.

3. Jet usage

Jets mix cold air into the water and dramatically increase heat loss.
Running jets less can save money.

4. Temperature setting

Every degree counts.
Maintaining 36°C instead of 38–40°C can reduce energy use noticeably.

⭐ The Bottom Line

For most owners — especially in winter — it’s cheaper and more practical to keep your whirlpool hot all the time.
Heating from cold is only more economical when:

• the climate is warm

• you use the tub infrequently

• or the insulation is poor

If your whirlpool is a premium, winter-ready model, maintaining temperature is the smart and cost-efficient strategy in cold months.