Should You Turn Your Boiler Off in Summer?
In most homes, you shouldn’t turn your boiler off completely in summer. The better option is usually to leave it on but switch the heating off at the controls, so you still have hot water without wasting energy.
Below, we’ll explain why this approach works best, when it’s okay to turn it off fully, and how to set your boiler up properly for the warmer months.
What Happens If You Turn It Off Fully?
Switching your boiler off for months at a time can sometimes cause small problems that only show up later.
Boilers have moving parts inside, like pumps and valves. These parts are designed to move regularly. If they sit still all summer, they can become stiff or stick. That’s one reason some boilers struggle to start again when the weather turns cold.
Older boilers are more likely to develop faults after being switched off for a long time. When turned back on, they might show an error code, fail to fire up properly, or even start leaking slightly.
If you have a hot water cylinder, there’s another thing to think about. Stored water should be heated to at least 60°C regularly to reduce the risk of legionella bacteria. Leaving the boiler off for long periods means that water may not get hot enough often enough.
When Is It Okay to Turn It Off?
There are times when switching the boiler off fully makes sense.
If you’re going away for a few weeks and won’t need hot water, you can turn the boiler off at the appliance or switch. This will save a small amount of electricity and gas.
If you don’t use the boiler for hot water in summer — for example, you have an electric shower and don’t rely on stored hot water — you may not need it running.
Very old boilers with a permanent pilot light can waste gas just by being switched on. In those cases, turning them off during summer can save money. Just make sure the boiler is checked and started properly before winter.
Even if you switch it off, it’s a good idea to turn it back on briefly before autumn to make sure everything still works.
What’s the Best Option for Most Homes?
For most modern homes in Edinburgh and across Scotland, the safest and simplest approach is this:
- Leave the boiler powered on
- Turn the heating off at the controls
- Keep hot water running if you need it
This way, your radiators won’t come on, but you’ll still have hot water when you need it.
If you have a hot water cylinder, keep it set to heat up at least once a day to 60°C or above. That keeps the water safe and fresh.
You can also lower the boiler’s flow temperature slightly in summer so it doesn’t work harder than it needs to.
What Is Summer Mode?
Many modern combi boilers have a setting called “summer mode” or “hot water only.”
This setting turns off the heating but keeps hot water working. The boiler will only fire up when you open a hot tap.
Some newer systems, including those from Worcester Bosch, can also adjust automatically depending on the outside temperature, so they run less in warm weather.
If your boiler doesn’t have a summer mode button, you can usually do the same thing by turning heating off at the thermostat or programmer.
Does Boiler Type Make a Difference?
Yes, slightly.
Combi boilers don’t store hot water. They heat it when you turn a tap on. In summer, just switch heating off and leave hot water on. There’s usually no need to fully power down.
System boilers with a cylinder should keep heating the stored water daily to maintain safe temperatures. Turn heating off, but keep hot water active.
Older regular boilers are usually fine with heating switched off at the controls. Lowering the boiler thermostat can be better than fully switching off.
What To Do In Summer With Different Boiler Types:
Different boiler types behave differently in summer, so the ideal approach depends on what you have.
| Boiler type | How it works in summer | Best summer approach |
|---|---|---|
| Combi boiler | No cylinder; provides hot water on demand only when taps open. | Use summer/hot-water-only mode; heating off, hot water on; do not fully switch off unless away and not using water. |
| System boiler + cylinder | Sealed system with separate hot water cylinder. | Turn heating off, keep cylinder at 60°C+, run at least once daily to maintain hygiene and movement. |
| Regular/open-vent boiler + cylinder | Older “heat only” with tanks in the loft and a cylinder. | Usually fine to turn heating off at controls; consider lowering boiler stat rather than fully off so hot water stays safe. |
| Older pilot-light boiler | Constant pilot burning gas. | May be worth fully switching off in summer if safe and you have alternative hot water; get it checked before winter. |
Simple Advice for Scottish Homes
For most households, the safest and most sensible summer setup is:
- Leave the boiler on.
- Turn central heating off.
- Keep hot water running safely.
Only switch it off completely if you’re away for a long time and won’t need hot water.
This approach reduces energy use, keeps the system healthy and avoids unpleasant surprises when the cold weather returns.
FAQs: Using Your Boiler in Summer
Will turning my boiler off in summer damage it?
In most cases, switching your boiler off for a short period won’t cause damage. Problems are more likely if it’s left off for several months without being run at all. Moving parts can become stiff, and small faults may go unnoticed until autumn. That’s why many engineers recommend running it briefly from time to time.
Does leaving the boiler on all summer waste a lot of money?
For modern boilers, the standby cost is usually very low. When heating is turned off at the controls, the boiler will only fire when hot water is needed. Gas use during summer is typically much lower than winter, so leaving it powered on doesn’t usually add a large cost.
Should I turn the boiler off at the mains switch?
If you’re staying at home and still using hot water, there’s no need to turn it off at the mains. If you’re going away for a longer period and don’t need hot water, you can switch it off at the appliance or fused spur. Just make sure you know how to restart it safely.
Can I turn the gas supply off to the boiler in summer?
There’s generally no need to turn off the gas supply unless you’re carrying out maintenance or leaving the property empty for an extended period. Turning off the heating at the controls is normally enough.
Should I adjust my thermostat in summer?
Yes. You can lower or switch off your room thermostat so the heating doesn’t come on. If you have smart controls, you can also adjust schedules so the system only runs when necessary.
Is summer a good time to service my boiler?
Yes, summer is actually one of the best times to book a boiler service. Engineers are usually less busy than in peak winter months, and it means your system will be clean, efficient and ready before colder weather returns.
