Central Heating

Lessons

1. 01

   The Gas Boundary

   See how a room-sealed boiler breathes through one pipe in the wall, why its case stays on, and what to do if you suspect carbon monoxide.

   10 steps
2. 02

   Emergencies & Shutoffs

   Find the stopcock, the gas emergency valve and the consumer unit before you need them, and know which taps keep running when the mains is off.

   10 steps·Builds on The Gas Boundary
3. 03

   Heat, Power & the Water Equation

   Use one equation to explain why a combi shower runs weaker in January and what a radiator’s temperatures are telling you.

   10 steps·Builds on Emergencies & Shutoffs
4. 04

   Radiators as Heat Exchangers

   Work out what a radiator really gives out at your water temperatures, and why turning the flow down to 55°C roughly halves it.

   9 steps·Builds on Heat, Power & the Water Equation
5. 05

   Flow, Pressure & Resistance

   See why the radiator nearest the boiler can steal the far one’s heat, and why turning a TRV up doesn’t push more water through.

   9 steps·Builds on Radiators as Heat Exchangers
6. 06

   Combi, System or Regular?

   Tell which kind of heating system you have from three clues, and see why height makes the pressure in an open-vented one.

   9 steps·Builds on Flow, Pressure & Resistance, Emergencies & Shutoffs
7. 07

   Sealed System Pressure

   Read your boiler’s pressure gauge: why it rises when hot, what the expansion vessel and relief valve do, and the top-up trap.

   11 steps·Builds on Combi, System or Regular?
8. 08

   Air in Systems

   Spot where trapped gas sits in a radiator, bleed it safely, and know what it means when you keep having to.

   8 steps·Builds on Sealed System Pressure
9. 09

   Combi Boiler Behaviour

   Understand what your combi does when a tap opens, what the radiator dial really sets, why it cycles on mild days, and when to stop resetting it.

   12 steps·Builds on Sealed System Pressure, Heat, Power & the Water Equation
10. 10

    Controls & TRVs

    Work out which control senses, which changes the flow and which tells the boiler to fire, and what happens when two of them disagree.

    8 steps·Builds on Combi Boiler Behaviour
11. 11

    Changing a TRV Head

    Swap a radiator valve’s head, such as for a smart one, without touching the water, and check the new head actually closes the valve.

    8 steps·Builds on Controls & TRVs
12. 12

    Balancing Radiators

    See how a heating engineer shares the water so the far rooms warm up too, using each radiator’s temperature drop as the guide.

    8 steps·Builds on Flow, Pressure & Resistance, Controls & TRVs
13. 13

    Sludge, Inhibitor & Filters

    Recognise sludge, understand what inhibitor and magnetic filters do, and know what to ask before agreeing to a power flush.

    11 steps·Builds on Sealed System Pressure, Air in Systems
14. 14

    Joints & Sealing

    Find which of the seals on a radiator valve is leaking, understand how each one seals, and know what to report rather than tighten.

    10 steps·Builds on Emergencies & Shutoffs, Changing a TRV Head
15. 15

    Taking a Radiator Off: What It Involves

    See why closing a radiator’s two valves doesn’t make every opening safe, and what a plumber does, in what order, to take one off or change a valve.

    11 steps·Builds on Joints & Sealing, Sealed System Pressure, Combi, System or Regular?
16. 16

    Turning the Flow Temperature Down

    Decide whether every room will still get warm at 55°C, by combining radiator ratings, heat loss, condensing and balance in one real home.

    11 steps·Builds on Radiators as Heat Exchangers, Combi Boiler Behaviour, Balancing Radiators