Intermediate · Unit 6 · Written and being checked
Protection and extras
In short
The extras round a heating system: a pipe stat in series with a frost stat, a condensate pump's alarm that stops the boiler, an immersion heater on its own circuit with its own thermostat, and weather compensation from an outside sensor. This unit is written and being checked; it opens to learners when it is ready.
In this unit
Frost and pipe stats together
A pipe thermostat wired in series with a frost thermostat. A cold night calls for heat only while the pipe is cold too; a warm pipe stops it.
How it opensOn a cold night, water can freeze in the pipes of a garage, a loft or a boiler room. Frost can damage the pipework.
A condensate pump
A condensate pump fed from the wiring centre, with its float alarm wired into the boiler's demand. When the tank fills, the alarm stops the boiler before water spills.
An immersion heater on its own circuit
An immersion heater on its own spur, wired in heat-resistant flex, never from the heating controls. It has its own thermostat, and every supply is isolated before work on the cylinder.
Weather compensation
An outside sensor wired to a weather-compensating combi. The flow temperature follows the outside air: hotter water on a cold day, cooler water on a mild one.
You will learn to
- Wire a pipe stat in series with a frost stat, as the makers draw it, and say why they ask for it
- Wire a condensate pump from the wiring centre and put its alarm contact in the boiler's demand
- Prove that the alarm stops the boiler, and say why the float works with no supply
- Wire an immersion heater on its own circuit with heat-resistant flex, never from the controls' spur
- Isolate both supplies - the controls' and the immersion's own - before work on the cylinder
- Wire an outside sensor to a weather-compensating combi and see its flow follow the outside air
- Say what Boiler Plus and Approved Document L ask of a combi's controls
- Isolate and prove dead before any wire is touched, and test the earth of what was changed before switching back on
Checks and credit
- A timed check at the end of the unit, its questions drawn at random. The score goes on your record.
- The unit earns the credential Protection and Extras (simulator).
Where it connects
The parts it uses
Wiring diagrams
Intermediate
- Underfloor and mixed systems
Unit 5, before this one
- Bus controls
Unit 7, next
Back to the Programme.
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