For most modern homes, a boiler flow temperature of around 50–60°C for heating and about 60°C for hot water is a good starting point for comfort and efficiency.

Key temperatures at a glance

  • Heating (radiators, condensing boiler):
    • Typical efficient range: 50–60°C flow temperature.
* Older or poorly insulated homes, or very cold weather: up to about 60–65°C.
  • Hot water (taps and shower from boiler or cylinder):
    • Common recommendation: about 60°C to reduce bacteria risk while avoiding excessive scalding risk.
  • Very low or very high extremes:
    • Below roughly 50°C, radiators may feel lukewarm and struggle to heat the house in cold weather.
    • For traditional hot-water boilers measured in Fahrenheit, “low” heating ranges are roughly 120–160°F and “high” winter ranges around 180–200°F; going above 200°F increases overheating risk.

Why the “right” temperature varies

  • Boiler type matters (combi vs system vs heat-only); many guides quote about 70–75°C flow for older system setups but lower (50–60°C) for modern efficient condensing boilers.
  • Insulation and radiators : well‑insulated homes and larger radiators can run cooler; older, draughty homes often need higher flow temperatures to feel warm.
  • Season : in winter people often raise the heating temperature; in milder weather you can drop it for better efficiency and lower bills.

Simple step‑by‑step way to set it

  1. Set your boiler heating flow to about 55–60°C.
  2. Leave your hot water at 60°C.
  3. Use your room thermostat (e.g., 18–21°C target indoors) to control comfort.
  4. If rooms don’t reach the thermostat setting or heat too slowly, nudge the boiler flow temperature up a little (e.g., toward 60–65°C in cold spells).
  5. If the house is easily warm and your bills are high, experiment by lowering the flow temperature a few degrees and see if comfort stays acceptable.

Safety and when to get help

  • Do not push traditional hot‑water boilers above about 200°F (≈93°C) , because that significantly increases the risk of overheating and leaks.
  • If you are unsure of your boiler type, or you have any error codes, strange noises, or very old equipment, ask a qualified heating engineer to check and set it safely.

TL;DR: Start at about 55–60°C for heating and 60°C for hot water , then fine‑tune based on how warm your home feels and your energy bills.

Information gathered from public forums or data available on the internet and portrayed here.