Does a hot tub need a heat pump?

Wood-fired hot tubs in Latvia are becoming increasingly popular — they provide a SPA experience in your own yard in any season. However, this raises a very specific question:

How to ensure that the water in the hot tub is always warm while keeping maintenance economical?

Many start with a wood stove or electric heater, but after the first season they begin looking for a more efficient solution. This is exactly where a heat pump for a hot tub comes in.

In this article you will learn:

• when a heat pump for a hot tub is really necessary,
• how much electricity it consumes,
• how to choose the right capacity.

Why does hot tub maintenance often become inconvenient without a heat pump?

The volume of a hot tub is usually only 1–2 m³, which means two things:

• the water heats up relatively quickly,
• the water also cools down very quickly.

In Latvian conditions, even in summer heat losses during the night are significant. If the hot tub is outdoors:

• in one cool night the temperature can drop by 3–6°C,
• in windy conditions — even more,
• without a cover — faster than expected.

Result in practice:

• you must reheat before each use,
• electricity or firewood consumption increases,
• spontaneous evening bathing is often not possible.

For regular use, a hot tub heat pump becomes an essential comfort element.

What exactly does a hot tub heat pump provide?

A modern inverter heat pump for a hot tub does not simply heat the water — it maintains a stable temperature with minimal consumption.

Main benefits:

Stable water temperature

• automatically maintains the required temperature,
• no large temperature fluctuations,
• the hot tub is ready for use at any time.

Significantly lower operating costs

• electric heater → 1 kW electricity = 1 kW heat
• inverter heat pump → 1 kW electricity = 5–10× more efficient in favorable conditions

This means significantly lower bills in the long term.

Quiet and automatic operation

• no need to fire up,
• no need to monitor,
• no smoke or ash,
• modern models operate at ~30–40 dB.

Longer hot tub season in Latvia

• early spring,
• late autumn,
• cool summer days.

Models operating down to -10…-12°C significantly extend usability.

Which heat pump capacity is needed for a hot tub?

• up to 1.5 m³ → ~5–6 kW
• 1.5–2.0 m³ → ~6–8 kW
• 2.0–3.0 m³ → ~8–9 kW

If the heat pump is mainly intended for temperature maintenance, lower capacity is sufficient; if regular heating from cold water is planned, a more powerful model is recommended.

3 factors that most affect consumption

1. Thermal cover

• reduces heat loss by 50–70%,
• significantly reduces heat pump runtime,
• speeds up heating.

2. Inverter technology

ON/OFF heat pump:

• frequent start/stop,
• louder,
• less efficient in maintenance.

Full Inverter:

• operates at 20–100% power,
• quieter,
• especially efficient for hot tubs.

3. Operation in low temperatures

If you plan to use the hot tub outside the warm summer months, choose a model designed to operate at least down to -10…-12°C.

When might a heat pump for a hot tub not be necessary?

• you use the hot tub very rarely,
• you don’t mind firing it up each time,
• temperature fluctuations don’t bother you,
• priority is minimal initial cost.

UX vs PBS vs PX — which heat pump to choose for a hot tub?