‘Tis the season for warming stews, and there’s no easier way to make them than in a slow cooker. The original 1970s gadget has made a welcome comeback into our homes.

[Read more: 12 deliciously warming dishes we’re looking forward to cook this autumn]

But if you’re new to slow cooking, or want to replace your old one, what should you look for and is there any health risk in using them?

What to think about when buying a slow cooker:

1. Size

They vary in size from as small as 1.5 litres, to feed one or two people, right up to 6.5 litres for big families or dinner parties of six to eight – so make sure you choose the right one to sut your needs. It’s also worth noting that you won’t actually get 6.5 litres of food out of it, as you can’t fill them to the brim.

2. The lid

Ideally this should be made of transparent glass, so you can easily check on your dish without having to lift the lid and let out heat – which will slow down the cooking.

3. The pot

The actual pot inside can come in a variety of materials, including ceramic, metal and porcelain. If you’re going to be browning meat, go for a ceramic inner pot, which can be used on the hob safely for this purpose. Removable pots make cleaning much easier too.

4. Heat distribution

This affects how long your dish will take to cook. Some slow cookers have a heating element which extends up the side of the base, meaning the heat is distributed more evenly, while others are just a pot on top of a heating unit, meaning you’ll have to stir your dish more often. As a rule of thumb, the smaller the pot, the more even the heat distribution.

[Read more: The best meal planning, cooking and recipe apps]

5. Are slow cookers safe to use?

There have been reports of lead leaching out of the smooth glaze on the inside of slow cookers into the food, which could cause health issues.

However, this mainly affects older models, which used compounds like lead oxide in the glaze. Many brands these days will state that their slow cookers do not contain leaded glaze, but if you have an old one, it’s definitely worth digging out the box to check.

6. Slow cooker tips to get the best results

- If you’re cooking with rice, use easy-cook varieties and make sure you thoroughly rinse it (so the water runs clear) before cooking to remove the starch, as otherwise you’ll end up with a very sticky dish.

- Don’t take the lid off too often, as you’ll lose heat and your dish will take longer to cook and make sure your inner pot is at room temperature before you start to cook.

- Because of the lid, there is no loss of liquid from dishes when you use a slow cooker, so make sure you use recipes especially adapted to slow cookers, or reduce liquid content by a third.

- The colour of stews made in a slow cooker can be quite pale, so use Marmite to give richer colour to meat recipes.