Whirlpool and hot tub in winter

This is the one rule to take from the article. A whirlpool full of water that is not heating splits in frost – ice takes up more volume than water and tears pipework, pumps and the shell. The repair runs into thousands, and the warranty does not cover it.

A power cut of a few hours does no harm; a whirlpool has a lot of thermal inertia. A cut of several days in hard frost is a problem – if you are going away, arrange something with the neighbours.

Let the circulation run continuously. Moving water freezes far less readily. Most control units have frost protection that starts the pump by itself when the temperature falls.

Use the cover consistently. In winter more heat escapes through the open water surface than through all the walls. Clear snow over 30 cm.

Do not drop the temperature below 35 °C if you are using the whirlpool. Reheating cooled water in frost costs more than holding it warm.

Watch the water level. Evaporation happens in winter too, and a low level exposes the jets, which leads to air being drawn in and the pump being damaged.

What that costs is worked through in What a whirlpool costs to run.

If you will not use the whirlpool over winter:

1. Switch off the heating and let the water cool.
2. Drain the shell – through the drain and through the pumps’ drain plugs; the latter is what people forget most often.
3. Blow out the pipework with a vacuum that has a blow function. Residual water in the jets freezes and splits them.
4. Take out the filter cartridges, clean them and store them dry.
5. Wipe the shell dry, close the cover and secure it against wind.
6. Switch off the breaker.

With hot tubs it is simpler: drain, let dry, close the cover. Drain the stove as well – water in its jacket freezes just as readily as in the shell.