any one help i have a biasi combi that refuses to start. igniter sparks for a fiew seconds then lockout light comes on as tho theres no gas, fan working so is the air pressure switch help its freezing! 
biasi 24s
- Thread starter anders
- Start date
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Take edge connector off side of gas valve measure impedance across coils, I think it's top two pins and bottom two pins, but don't have a manual (manual also required to tell you what impedance should be). If open circuit, confirm you need a new gas valve by checking for dc voltage (again manual would tell you what voltages to expect, but most boilers are low voltage here nowadays 24v or so) on corresponsing edge connector if present you need a gas valve. £139 plus vat from Parts Centre.
Of course you first check no sachels have caught on the main control valve in the cupboard under the stairs, and that you have adequate working pressure at the input test point of the gas valve.
Of course you first check no sachels have caught on the main control valve in the cupboard under the stairs, and that you have adequate working pressure at the input test point of the gas valve.
Replacing the gas valve is a job for a CORGI engineer and the min and max gas pressures have to be set up.
The resistance ( not impedance ) of the gas valve coils are about 2.7 K and 1.3 K very roughly from memory.
They are powered by 230 v raw DC but sticking test meter probes into the ignition circuit will usually damage the connectors as they are designed for 1 mm diameter pins. Different voltage readings can be obtained depending on how the DVM responds to raw DC.
The gas valve can also be sticking if the coils and applied voltage are correct.
Tony Glazier
The resistance ( not impedance ) of the gas valve coils are about 2.7 K and 1.3 K very roughly from memory.
They are powered by 230 v raw DC but sticking test meter probes into the ignition circuit will usually damage the connectors as they are designed for 1 mm diameter pins. Different voltage readings can be obtained depending on how the DVM responds to raw DC.
The gas valve can also be sticking if the coils and applied voltage are correct.
Tony Glazier
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and haven't we all been there
Whiter, if the o/h stat under the black cover had been tripped than it would not get as far as sparking.
If its sparking then the gas valve will have been powered unless there is a fault in the ignition PCB.
Tony.
If its sparking then the gas valve will have been powered unless there is a fault in the ignition PCB.
Tony.
tested top 2 pins and bottom 2 pins on gas valve no resistance open circuit (top 2 pins should be aprox 1 260 ohms bottom 2 pins should be 3 000 ohms) also tested for voltage to corisponding plug connector ( on sequence ignition device) no voltage comming out when i reset the boiler. im finding this strange that the top 2 pins and the bottom 2 pins of the coil have no resistance is this possible? is it not a case that only 1 coil would be faulty?
and that i have no voltage comming into the connector??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
and that i have no voltage comming into the connector??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
You can only test for voltage while it's sparking.
Sounds like gas valve at least.
Corgi job.
Sounds like gas valve at least.
Corgi job.
Kev,
I had one last new years day, upstairs flat on way there I noticed outside gas meter box door was open, ecv/mcv was in off position. Went up to flat to make sure all appliances were in safe condition, back down to turn gas on, back up, boiler's fixed mate!
I had one last new years day, upstairs flat on way there I noticed outside gas meter box door was open, ecv/mcv was in off position. Went up to flat to make sure all appliances were in safe condition, back down to turn gas on, back up, boiler's fixed mate!
Not sure which is the most helpless individual the one who doesn't even check his gas meter or the one who hasn't a clue what that steel brade thing is under the combi. But I'm sure both would die in the jungle.
thanx all yes it was the gas valve had it changed and started first time
testing the controll box pcb top 2 pins and the bottom 2 pins for continuity on my combi didnt work even thou it said in the manual to do it this way, as when you look at the pcb theres a wire that goes to pins 1,3,5, from top to bottom, so testing top 2 bottom 2 pins would give you open circuit anyway.
testing the controll box pcb top 2 pins and the bottom 2 pins for continuity on my combi didnt work even thou it said in the manual to do it this way, as when you look at the pcb theres a wire that goes to pins 1,3,5, from top to bottom, so testing top 2 bottom 2 pins would give you open circuit anyway.
You cannot test the ignition pcb "for continuity". Yes, you can test it for voltage out if you can measure about 230v raw DC. Most people do that by shoving 2mm diameter test probes up it and destroy the setting of the female contacts thus enabling it to never make contact with the gas valves 1 mm pins again. They then have to change the PCB at about £78.
The pin "3" is connected to earth !
The Ignition circuit only applies power to pins "1" and "5" because pins "2" and "4" are connected together within the coil assembly on the valve. In fact its only necessary to test for continuity between pins "1" and "5" with both coils in series.
A rare but occasional fault is for resistance to earth from the coils so a measurement to chassis is a useful check.
Tony Glazier
The pin "3" is connected to earth !
The Ignition circuit only applies power to pins "1" and "5" because pins "2" and "4" are connected together within the coil assembly on the valve. In fact its only necessary to test for continuity between pins "1" and "5" with both coils in series.
A rare but occasional fault is for resistance to earth from the coils so a measurement to chassis is a useful check.
Tony Glazier
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