Baxi Combi 100HE plus.
Electricity going in to boiler, no warning lights illuminating. Hot water from tap is hot and thermostat for rads calling for heat.
Is there anything I can check before I call a plumber?
The water pressure is also ok although I did top up from about half bar to just over 1 bar.
Stuck 3-port valve?
How do I check that?
Can you confirm that the radiator icon or similar indicator on the boiler is ON or flashing when the thermostat is turned up? And Off when the thermostat is turned down?
There are 4 LED lights
Nothing changes when I turn the thermo up or down. If I use the hot tap then the tap and the flame icon illuminate so the boiler fires up for tap hot water.
Have you checked that the stat's call for heat is actually present at the boiler itself?
John, I havent a clue what to look for at the boiler end, I can say though that the stat is hardwired and not wireless if that makes a difference.
What kind of stat is it? A digital programmable one, or a old rotary click click type?
Modern stats tend to have "volt free" contacts (i.e. they act like a switch - closing when calling for heat, and opening when satisfied).
Some older mains style stats generate a 240V live when calling, and nothing when not. (i.e. much the same idea, but with one side of the switch already connected to mains live for you). Others let you chose how they operate by including a link wire or not.
The boiler may have two different sets of contacts for each type of stat (or if its a recent model it may not support the mains type directly).
With modern stats, the connection to the boiler is via a pair of contacts on the boiler. It usually comes with the terminals shorted with a short loop of wire, and you remove that to connect the stat contacts between the two terminals. You can test this by disconnecting the wires from the boiler and measuring resistance across the wires. You should see it go from open to closed circuit when the stat operates.
With the older mains style ones, testing is easier - just attach one meter lead to neutral and probe the call for heat end on a volts range. You should see it go live when the stat is calling.
As it turned out it was the stat that was faulty, noe replace and up and running again.
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