I know the "grown ups" know this but for new people to this part of plumbing. This is in layman's terms.
Important!! Please be aware that I've had no training in this - I just learned the hard way and each time I go to sort out wiring I end up in another sweat!! However, following the system logically with pen, paper, wiring diagram and multimeter you can usually sort things out before too long.
(If anyone spots an error in this please point it out and Iāll edit it or perhaps a moderator can? Ta!)
Safety first! Make sure you know where the main switch is for the wiring centre and when working on it, take the fuse out and put it in your empty back pocket. It is too easy to turn the power on and off and forget to turn it off. If you put the fuse in your pocket you won't spend hours looking for it and be tempted not to remove it. Remove that fuse!!
The next safety aspect is to use a reasonable quality multimeter and test the voltage, both when off and on. If you think it's on but it's showing 0v, remember to turn the thermostat up to call for heat. That should produce 240v. You must know you have isolated the system before you start working on it. (See multimeter below)
Covering my bottom here; there are proper procedures for isolating electricity. Please look them up if you donāt know the safe way of isolating electricity.
On to the interesting part:
This bitās for pure beginners:
Normally (but not always), there is a box containing loads of spaghetti. (Gas mark 4 for 10 minutes ...) This is the wiring centre. (Sometimes there can be two or three wiring centres for different parts of the system.) As far as the "chocolate box" is concerned it doesn't matter which side the wire goes in or comes out. Also the screw is your testing point. And I bet you there are plenty of people who'd have loved to have asked that question but didn't dare!!)
While many systems are wired according to a standard wiring plan, many are not! There's no shame in using a pen and paper to write down what each wire does and where it goes. Sometimes wires are connected in a remote location and different colours are used. Sometimes electricians avoid these systems and ask a plumber to sort it out. If they do tackle the system, even they have to work out what all the wires are doing.
Before changing wiring, ensure you have some spare fuses because if it goes wrong the fuse will blow (to protect the bits and pieces) and if you ain't got a fuse it's often a long walk to Woolly's (oh they shut didn't they?)
One other part ā is it quicker to undo everything and rewire? No!!! Most problems can be sorted within a half day. Re-wiring can bring in all sorts of other problems and cost you money and take much more than a day to solve. Customers wonāt be impressed either!
The Wires
Generally, all the earths join up and all the neutrals join up. The earths will join to the main power earth and the neutrals to the main power neutral. So thatās 2/3rds of the wires sorted!! Use the bleep test to test for continuity (ie are they joined up?)
The live circuit follows this route:
Main power switch for circuit -> Programmer -> Thermostat (room or cylinder) -> Zone Valve -> Switched live to boiler and pump. Unless pump is wired direct to boiler for pupm overrun.
That is, the power has to be on for the programmer to work.
The pump will start once the timer on the programmer says it should (e.g. on/off/timed)
The zone valve will open to allow water to pass through - it works in conjunction with the thermostat
The thermostat will "call for heat" if it's cold or be "satisfied" if it's warm enough
..... If calling for heat it will send a "signal" (ie 240volts) via the zone valve to the boiler - this signal is known as a switched live (ie it turns on and off) When cold the zone valve opens (the lever goes all floppy)
..... If satisfied it will stop the signal and the zone valve closes (it is stiff to push across)
The calling for heat wire is white or grey (depending on whether it's for heating or hot water)
The switched live wire is orange
What does this all mean? Think logically and work out the route of the live wire. Here are some potential problem areas:
If the orange wire has 240v then it means that all is working and this is the signal for the boiler to fire up.
If the orange wire has 240v and the boiler isnāt working, the problem will probably be an electrical one in the boiler. (Itās got electricity coming into it, hasnāt it?!) Or has it run out of fuel? You did check first, didnāt you?!! Course you did!
If the orange wire isnāt giving 240v then, assuming the thermostat is working, the problem is likely to be the zone valve if the pump is working.
Multimeters and testing
I confess to not know much here so apologies for my ālanguageā. A decent multimeter will have a bleep test or continuity test on it. If you join turn the dial to this, put one end on a live something (e.g. wire) and the other end on something to create a circuit it will bleep when a circuit is made. For example, if you join an earth cable to a pipe (on copper plumbing, and not this modern plastic claptrap) youāll create a circuit and will also know if your pipes are earthed.
In the chocolate box you can use the bleep test but itās much more informative to use the AC 700 setting which will give you voltage rates up to 700volts. You poke on a screw one terminal and a screw of another terminal. If thereās a working circuit it will show between 230 and 250 volts (usually around 235 volts).
By following a wiring diagram, you can see what should be live and not by turning the thermostat up/down as needed. For example, joining the main 240v input live with the orange wire will produce 0v unless the heating/hot water is calling for electricity in which case it will show 240v.
My coffeeās gone cold.
