If you have a Megaflo direct cylinder and your electricity bills look high, the timer is almost certainly the reason. Setting it up properly is one of the cheapest savings available in a house like this.
What a direct cylinder actually is
A direct cylinder has no boiler heating the water. Instead it has two immersion heaters built into the tank.
Think of them exactly like the element inside a kettle. They use electricity to heat the water directly.
Because they run on electricity rather than gas, they are expensive to run if left on all day. That is why off-peak programming matters so much here, far more than it does on a gas system.
Step one: find out when your electricity is cheapest
Before touching the timer you need to know your off-peak window.
Call your electricity supplier and ask what hours your off-peak rate applies. On Economy 7 or Economy 10 this is commonly somewhere between about 1am and 8am, but the exact hours depend on your plan and region, so it is worth confirming rather than guessing.
If you are on a single flat rate you will not have an off-peak period, but the timer is still worth setting so you are only heating water when you actually need it.
Step two: set the off-peak timer
The Megaflo timer is the small digital box connected to the cylinder.
- Set the clock. Make sure the time is correct first, since everything else depends on it. Use the directional buttons and press select.
- Go to off-peak programming. Navigate to the off-peak section of the menu.
- Set the on time. Program it to switch on at the start of your cheap rate, for example 1:15am.
- Set the off time. Program it to switch off at the end of the cheap window, for example 8am.
The cylinder has its own thermostat. If the water reaches temperature before the off time it shuts itself off, so you are not paying to heat water that is already hot.
Step three: use the boost function properly
The boost is for when you run out during the expensive part of the day.
If you know you will need hot water for dishes and evening showers around 7pm, set the boost to come on at about 5:30pm. An immersion heater generally needs thirty minutes to an hour to bring the water up.
There is also a manual boost button on the timer for a quick top-up whenever you need one outside the normal schedule.
When to call someone
If the cylinder is not heating at all, is heating very slowly, or the timer will not hold its settings, that is worth having looked at. Immersion heaters do fail, thermostats drift, and on a direct cylinder a fault shows up immediately as cold water and a high bill.
Frequently asked
What is a direct cylinder?
A direct cylinder has no boiler heating the water. Instead it has immersion heaters built into the tank, working exactly like the element in a kettle. Because they run on electricity directly, they are expensive to run if left on around the clock.
How do I know when my off-peak hours are?
Contact your electricity supplier and ask. Economy 7 and Economy 10 tariffs have specific windows, commonly somewhere between about 1am and 8am, but the exact hours vary by plan and region.
What if I run out of hot water during the day?
Use the boost function. Set it to come on around an hour before you need the water, since an immersion heater generally takes thirty to sixty minutes. There is also a manual boost button for a top-up outside the schedule.