Boiler notes: the figures that matter
A few short heating notes, gathered from the questions customers ask most often.
Flow temperature
A short note on Flow temperature. Expect 60 to 65 C on a condensing boiler; in practice, the lower setting lets the boiler condense and recovers a few per cent of gas.
Manufacturers publish their own limits in the manual, and those take precedence over any general figure.
Write down what you find before calling anyone, so the conversation starts with facts. In short, Flow temperature is worth understanding before it becomes an emergency.
Combi boilers
If you are looking into Combi boilers, start with this: 24 to 30 kW, for a home with one bathroom. The practical point is that they heat water on demand so there is no cylinder to find room for.
That figure is a typical value for a UK home rather than a rule; a good engineer will confirm it for your system.
Check the boiler's own display or manual first; most of the time it tells you what it needs. That is the whole of Combi boilers for most households.
Frost protection
Frost protection in one line: 5 C built into most boilers. Beyond the number, the boiler fires briefly to protect itself when the house is empty in winter.
Treat the number as a starting point. Older systems, larger houses and hard water all move it.
Keep the service record with the boiler manual; it is the first thing a buyer or a warranty claim will ask for. Knowing this about Frost protection saves a call-out more often than you would think.
Balancing radiators
Balancing radiators: the figure most people need is the lockshield valve, opened a turn at a time, and the radiators nearest the boiler are throttled so the far ones get their share.
Manufacturers publish their own limits in the manual, and those take precedence over any general figure.
If a job involves the gas supply or the flue, it is Gas Safe work and not something to attempt yourself. In short, Balancing radiators is worth understanding before it becomes an emergency.
Landlord gas safety
A short note on Landlord gas safety. Expect every 12 months by law; in practice, the record must be given to tenants within 28 days of the check.
That figure is a typical value for a UK home rather than a rule; a good engineer will confirm it for your system.
Do the cheap checks before the expensive ones: pressure, thermostat setting, timer, then the engineer. That is the whole of Landlord gas safety for most households.
Magnetic filter
If you are looking into Magnetic filter, start with this: about 100 to 150 pounds, fitted on the return pipe. The practical point is that it catches the iron oxide that otherwise settles in the heat exchanger.
Treat the number as a starting point. Older systems, larger houses and hard water all move it.
Write down what you find before calling anyone, so the conversation starts with facts. Knowing this about Magnetic filter saves a call-out more often than you would think.
Power flush
Power flush in one line: 300 to 600 pounds for an average house. Beyond the number, it clears sludge that makes radiators slow and boilers noisy.
Manufacturers publish their own limits in the manual, and those take precedence over any general figure.
Check the boiler's own display or manual first; most of the time it tells you what it needs. In short, Power flush is worth understanding before it becomes an emergency.
Figures are typical UK values; your boiler's manual and a Gas Safe registered engineer take precedence.
This note is part of the Eco Gas search lab, a set of short heating notes used to study how search engines read pages.