No hot water? Check these first

Combi, or a tank?

If you have a hot water cylinder, a large copper or white insulated tank usually in an airing cupboard, you have a system or regular boiler and your hot water is stored in that tank. If there's no tank, you most likely have a combi, which heats water as you turn on a tap.

Checks for every boiler

1. Look at the display. If it shows a fault code, look it up here, because the code tells you far more than any general checklist. Vaillant, Ideal, Baxi, Glow-worm, Viessmann
2. Check the boiler has power. A blank display usually means it has none: check the switch next to the boiler and your fuse box. See boiler display blank. Vaillant, Ideal, Baxi, Viessmann, Vokera
3. Check the gas is on. Try your hob or another gas appliance. If you have a prepayment meter, check it has credit. Worcester Bosch, Viessmann, Ideal, Vokera
4. Check the cold water is on. If no water comes out of any tap, hot or cold, the problem is the water supply, not the boiler. Worcester Bosch, Viessmann, Vaillant
5. Check the pressure gauge with the heating cold. If it's below your boiler's recommended level, top it up with the filling loop as your manual describes. our pressure guide shows the right figure for your brand. Vaillant, Ideal, Glow-worm, Viessmann, Worcester Bosch
6. In freezing weather, check the plastic condensate pipe outside. If it's frozen, thaw it safely with warm water, never boiling. Worcester Bosch, Baxi, Ideal, Viessmann, Glow-worm
7. Check the hot water temperature isn't turned right down on the boiler or controls. Ideal, Viessmann
8. Once you've fixed the cause, reset the boiler exactly as your manual describes. Vaillant, Baxi, Viessmann, Ideal

If you have a combi

• The timer normally doesn't control a combi's hot water, because it heats water on demand. Start with the checks above. Vaillant, Ideal
• If your radiators heat up but the hot taps run cold, the usual cause is the diverter valve inside the boiler. That's a job for a Gas Safe engineer. Vaillant, Baxi, Viessmann, Glow-worm

If you have a tank

• Check the programmer or timer is set to heat water now. A power cut or the clocks changing can reset it. Vaillant, Ideal, Baxi, Viessmann, Worcester Bosch
• Check the temperature setting for the cylinder. Viessmann recommends at least 60°C for stored hot water. Worcester Bosch, Viessmann
• If you've just used a lot of hot water, the tank needs time to heat up again. Ideal suggests giving it an hour. Ideal

Call a Gas Safe engineer if

• The checks above don't bring the hot water back.
• Your radiators work but the hot taps don't (likely the diverter valve on a combi, or a zone valve on a tank system).
• The pressure drops again after you've topped it up.
• A fault code comes back after a reset.
• You smell gas at any point. Leave the property and call 0800 111 999.