Intermediate · Unit 2 · Written and being checked
Swapping controls
In short
Controls changed on wired systems in use, the safe way every time: the method (isolate, prove dead, photograph, label, remove), a programmer swapped for a dual channel receiver based on the Hive on the S-Plan and on the Y-Plan, a volt-free programmer for a mains-switched one, a wired room stat for a wireless one, a cylinder stat with the other numbering, and the practical from memory. It earns the credential Control Swaps (simulator). This unit is written and being checked; it opens to learners when it is ready.
In this unit
The swap method
Before any control is changed: isolate, and prove it dead the full way with the two-pole tester at the programmer's plate. Then photograph the wiring and label every core. Only then does the old unit come off. Every swap in this unit follows this method.
How it opensOn the canvas is an S-PLAN heating system: one valve for the heating, another for the hot water. It is wired and in use. Its PROGRAMMER is the clock that decides when its two channels may run: central heating (CH) for the radiators, and hot water (HW) for the cylinder. The customer wants it changed.
A programmer swapped for a wireless receiver on the S-Plan
The programmer based on the Honeywell ST9400C swapped for a dual channel receiver based on the Hive with its thermostat: isolated, proved dead, removed, fitted on the white universal plate by its printed names, earth tested, proved in all three states - heating only, both, hot water only.
The same on the Y-Plan
The programmer swapped for the receiver based on the Hive on a Y-Plan: one wire more, HW OFF to the grey's block, and the proof that the grey drives the valve to A.
A programmer swap with different numbers
A volt-free programmer based on the Horstmann H27XL, its links L-2-5 fitted, swapped for one based on the Drayton LP722: the printed numbers differ, the jobs do not. Five wires relanded by job, the links not needed.
A wired room stat to a wireless one
The wired room thermostat taken out and a thermostat based on the Hive Mini with its receiver fitted: the receiver is VOLT-FREE, a live to its common from block 4, the call from its 3 to block 5. The receiver sits by the wiring centre, where it has L, N and E; the thermostat, on batteries, goes where the old stat was.
A cylinder stat with the other numbering
The plain cylinder stat swapped for DrawWarm's dual cylinder stat, made for an unvented cylinder, which calls on its block printed 2: isolated, proved dead, the Manual read, C and the call landed, the call wire tested before the power, proved calling and satisfied, with the meter on the call.
The practical: a swap from memory
A Y-Plan laid out differently, its programmer based on the Drayton LP522: isolate, prove dead, remove it, fit the dual channel receiver based on the Hive and reland every wire by job, switch back on and prove all three states. No hints. Recorded.
The practical · recorded, no hints
In the simulator, you practise how to
- Isolate and prove dead before any control is changed, then photograph and label every core, and prove the tester before and after
- Swap a programmer for a dual channel receiver on an S-Plan and on a Y-Plan, the Y-Plan's HW OFF to the grey's block
- Reland every core by its job when the new unit's printed numbers differ from the old
- Fit a volt-free wireless receiver in a wired room stat's place: the demand on its common, the call from its ON
- Fit a cylinder stat that calls on a different number, from its own label
- Test the earth of what was changed before switching back on, and prove every state of the system after
Checks and credit
- A timed check at the end of the unit, its questions drawn at random. The score goes on your record.
- A practical with no hints, every step recorded.
- The unit earns the credential Control Swaps (simulator).
Certificates of completion and credentials are DrawWarm’s own. They record practice and tests in the simulator. They are not a formal (regulated) qualification, and they do not show that anyone is competent to work on a heating system.
Units based on makers’ products
The units in these lessons are the simulator’s own, simplified for teaching. Each is based on a maker’s product and may differ from it: on site, read the unit’s own instructions.
- Based on the Honeywell ST9400C
- Based on the Secure / Horstmann H27XL
- Based on the Drayton LP522
Makers’ names and model numbers are trade marks of their owners, used only to say which product a unit is based on. DrawWarm is not affiliated with, or endorsed by, any maker named on this site.
Where it connects
The parts it uses
Intermediate
- Reading branded units
Unit 1, before this one
- More zones
Unit 3, next
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