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Posted before but if you have a glowworm cxi and the fan pulses on and off along with the display after working on it ...get a hairdryer and heat up the pcb because theres a dodgy capacitor on the board that freaks out when cold......i thought tech were winding me up but it works. (if it doesnt the pcb's knacked).
 
Fit a vailant 937 recently and when the cold tap was turned on the boiler pump would kick in but not fire, like if a hot tap had been opened briefly...apparantly the aquasensor picks up negative pressure sometimes even through the cold so..get to the diagnostics by pressing the i + - buttons simultaneously. To access the second level diagnostic codes scroll through to D.97 press the i button scroll to 17. Press and hold the i button untill it returns to D.97. Then you wil be able to access second level diagnostics.....D.88 (adjust the sensitivity of the aqau sensor for water hammer..0=1.5l/min and no delay..1=3.7l/min with 2s delay........i adjusted with a delay, Good times..
 
Vokera Unicas and mynute he fault code 73 return thermistor faulty. The return thermistor will have corroded because the silly clip holding the flue thermostat to the conveyor has cracked the conveyor. New conveyor and thermistor easy enough done.
 
If you've narrowed down a fault to two suspect components, the faulty one will be the one you choose not to order.

Strange intermittent fault on an Ideal Icos/Isar/Istore? Check the rear of the heat exchanger, they tend to melt and can play buggery with the wiring loom.

Ferolli Modena 102 and similar firing up for seconds at a time with NO DEMAND is caused by faulty thermistors usually. Doing the same with demand, is usually caused by the venturi failing. DO NOT REMOVE unless you are 100% sure or have a replacement, 9 times out of 10 it will turn to a little pile of dust as soon as you touch it!

Ariston Microgenus, usually give a fault code relating to the air pressure switch, most of the time its the fan. They seem to be running perfectly, but they slow down with age and don't spin fast enough to operate the APS.
 
worcester 30cdi greenstar if you cant get a good co2 reading ie all over the place its usually the (not sure of the component name) little flap just after the fan, it opens and shuts when the the fans running...
 
Not quite the same but will go with it,poor hw with gled hill 2000 keep pressing sw2 button at the top of pcb until hw temp value is being read. If it reads h85 and the plate is cold then new hw thermistor required.
 
zeebeedee said:
What's that then? Don't work on valiants much.
Click to expand...
Sorry missed that vaillant water pressure switches detect system pressure but also look for a 0.3 bar spike when the pump first kicks in, if it doesn't detect the spike thinks its a pump failure. So if the pumps running but getting f75 it's a blocked up pressure sensor. Bad position on the old models bottom left now top left on the new models.
 
Ahh Gledhill! If you are ever unfortunate to come across a Gledhill Gulfstream, turn around and walk away! I'd rather try and resolve the North Korea crisis that work on one of those abortions!

DHW diaphragm on a Gionnani diverter valve not making contact with the microswitch, bit of plumbers mait and a 5p coin stuck to the top hat on the pin works as great temporary fix until you can make a permanent repair.

Heatline Vizo and similar. Hot water not working will most likely be caused by the diverter cartridge leaking into the motor. Turn the power off at the mains before you touch it, as they can blow fuses on the board, sometime the board itself, when they are moved with water in them.
 
Glowworm flexcons flow flexi bottom left hand side start leaking when the crimp clips start to get loose. Replacement flexies have jubilee clips rather than crimp clips
 
neily01 said:
Sorry missed that vaillant water pressure switches detect system pressure but also look for a 0.3 bar spike when the pump first kicks in, if it doesn't detect the spike thinks its a pump failure. So if the pumps running but getting f75 it's a blocked up pressure sensor. Bad position on the old models bottom left now top left on the new models.
Click to expand...

Changing one of these on Monday. Vaillant also say there is a filter that can be accessed and cleaned if you remove the rubber flow hose.
 
croppie said:
Changing one of these on Monday. Vaillant also say there is a filter that can be accessed and cleaned if you remove the rubber flow hose.
Click to expand...

if its an old one the part will be on the bottom left in the brass block "rubber hose type". ifs its newer it will be behind the air exhaust to the left just before the pipe goes into the main heat ex " copper connections no rubber hoses"...its a black part that has a little pin plug attached..if you undo the rubber flow hose then make sure youve got a jubilee clip to make good after. (just crunch the hoses croppie to get rid of the crap around the system).
 
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Vaillant also say there is a filter that can be accessed and cleaned if you remove the rubber flow hose./QUOTE]The filter is is plastic and i have found it very hard to remove to clean. You are better of chucking the whole piece in a bucket of descaler.
Click to expand...
 
Ideal optia,basically a early condensing classic. Water staining and rusting on the inside of casing running down centre of the boiler. HAd two o these with good fga readings of about 20ppm co and 0.00 ratio so thought it could not be inner flue! Wrong! break the top section of secondary hex and withdraw to find the pipe adaptor corroded through leaking all over the back of boiler. God knows how the fga wasn't going crazy?
 
Gloworm betacom 24/30c short cycling..... Check flame electrode hasnt bent into burner so flame isnt recognised.

No ignition on ferroli tempra, remove a wire from aps and if fan kicks and ignition commences in you know you have a sticking aps.
 
IDEAL LOGIC+ you can find the last 10 faults and also current reading, flow rates, temperatures etc in the installer settings.
all you have to do is turn both dhw and ch potetiometer knobs to minimum and hold the reset for about 2 seconds
 
neily01 said:
Sorry missed that vaillant water pressure switches detect system pressure but also look for a 0.3 bar spike when the pump first kicks in, if it doesn't detect the spike thinks its a pump failure. So if the pumps running but getting f75 it's a blocked up pressure sensor. Bad position on the old models bottom left now top left on the new models.
Click to expand...

Found out today Vaillant do an F75 kit which moves the sensor from the flow to the return just after the pump.

It's about £120.00

Should be free!
 
baxi 105/24,instants,performa,main 30-24 all HE VARIANTS NOT SE
flame failure light intermittent,fan fault neon on 99% aps has failed or rubber boot on combustion box cracked
pump pressure switch illuminated,pin not lifting,its normally a blocked hole under the diaphragm at fault
no ignition aps or gas valve multiplug fault
cant keep water in it gauge drops instantly,HE hex split,check condy pipe with the boiler off water going down confirms it
heating fault gets up to 60 degrees,kettling ,shuts down,thermistor reading 11k when cold,return filter blocked
fan noisy-plastic boots on plugs faulty does sound like the fans going
baxi duotec1/HEA,plat1,potterton gold,tit,heatmax,promax
E168 pcb internal coms failed,as a temp fix remove all the plugs,have a cuppa,re fit plugs,re set it,will add more as time allows
 
Not really a fault as such but if you get asked to service a powermax (the older version 155 i think) take the burner gaskets with you and take the burner out. 9 times out of 10 the baffels in the heat exchanger have fallen to bits. They are about £17 each and there are 8 of them. (read in manuall you are suposed to replace the baffels every 2 years!) To remove once cracked you have to remove the sump and its a good few hours. Boiler classed as ID. The last 3 powermax boilers I have serviced have all resulted in winning new boiler changes.
 
Biasi 24s/m96 unusual one I had. Boiler intermittantly cuts out on temperature and wont reset but does not lock out. The green led flashes fast allowing you to go to diagnostic mode by flipping the dip switches on the PCB. Check BP on heating, ramps up to full and goes out on temperature. Heating NTC at fault.

Biasi 24s (older one) no heating, hot water okay. Heating fires up briefly then goes out indicating a flow fault. If fuse spur is turned off on this model you sometimes need to push up one of the dip switches on the PCB and leave for 10 mins, then flick back. Only found out from technical but have since had this fault twice. Then the heating stays on and works fine.
 
southcoastboile said:
Not really a fault as such but if you get asked to service a powermax (the older version 155 i think) take the burner gaskets with you and take the burner out. 9 times out of 10 the baffels in the heat exchanger have fallen to bits. They are about £17 each and there are 8 of them. (read in manuall you are suposed to replace the baffels every 2 years!) To remove once cracked you have to remove the sump and its a good few hours. Boiler classed as ID. The last 3 powermax boilers I have serviced have all resulted in winning new boiler changes.
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Some of the guys in work checked with Powermax and they said that it's only NCS if the baffles aren't replaced as long as it isn't having an effect on combustion as they are only there to make the boiler a bit more efficient.

Also, you can sometimes get away with getting some condensate pipe and pushing it down on to the broken baffles at the bottom and then they'll pull out with the condensate, and you can get some really long nose pliers - never work on Powermax myself but the guys that do never seem to remove the sump to remove the old baffles.
 
Ariston Clas HE - If there's been a power cut it can sometimes cause the PCB to lose it's memory, if you look in the manual, there's a ridiculous amount of parameters - go through them all and make sure they are correct or the boiler will be causing all sorts of problems.
 
bewsh said:
Some of the guys in work checked with Powermax and they said that it's only NCS if the baffles aren't replaced as long as it isn't having an effect on combustion as they are only there to make the boiler a bit more efficient.

Also, you can sometimes get away with getting some condensate pipe and pushing it down on to the broken baffles at the bottom and then they'll pull out with the condensate, and you can get some really long nose pliers - never work on Powermax myself but the guys that do never seem to remove the sump to remove the old baffles.
Click to expand...

When I spoke with Baxi tech regarding the broken baffels they said it is classed as ID (not that they seem to know much themselves about these boilers) as they are there to slow the gasses down and it would effect the flame. I have replaced the baffels before by pulling them through the bottom but the time it takes to do that and the cost of them makes it seem like a bad choice in my opinion. Plus the fact that if you leave a powermax turned off for more than a day several components seem to fail at once for some reason.
 
If you fit a vaillant and theres no display and not working on initial fireup. dont get carried away and start swapping pcbs/display boards. Check the pressure sensor (slug) by unplugging it and replace. Dont know why faulty slugs cause this but they can..
 
Ravenheat CSI 85at, pump running, but nothing else - primary ntc sensor or the loom to it are no good.

Same boiler as above. Boiler lights, but goes out again - bad connection on condense trap. Cut it off and join the PCB end to the spark end.
 
Worcester greenstar
If fan fails to pulse after power up. It usually points to fan failure

From memory you need to check for 240v on purple wire. But if no pulse it's usually dead
 
Fan running constant on a FAN modulation boiler - ideals isar, etc, Worcester greenstar, etc... Usually points to fan failure

It's a failure of the tacho PCB on the fan and it can't regulate the fan speed
 
Poor flame on pilot

If the flame is not a pronounced crisp blue flame on the pilot then then injector is usually on the way out.


You shouldn't try and. Clear this with a pin Etc. you should always replace
 
Ideal isar (combi version) evo he etc

The display keeps on saying D then c

You have a very small passing of water on the DHW or a faulty thermister
 
FOR COMMERCIAL

If visiting a Hamworthy boiler with a HSI
You must check the resistance in ohms.

It must be between 80-120 ohms. Of it is outside of this range it is prob on its way out. But also it may cause PCB damage
 
ideal classic

If you find the boiler lighting and then going out within a few seconds.

The fault is not always linked to the flame dectection. It is mostly linked to the APS.

Give the fan a good clean and the heat exchanger and this should cure the problem
 
Potterton prima, pilot lights then clicks constantly without going to main flame. Pcb, aps and slow fan can cause this. Also seen the tubes to the aps becoming hard and blocking the air flow to the aps. Usually when you drop the pcb housing it kicks in. Also check for the housing pressing on the overheat stat and causing a false reading.
 
Baxi Duo Tec HE or HEA/Potterton Promax Combi HE or HEA/Main Combi HE or HEA.

The serial numbers on these boilers all begin with 3 letters, followed by some numbers. The first 2 numbers are the build year, the second 2 the build week. The rest are random. So for example, a 28 HE A Duo Tec built in the 23 week of 2010 will be CAC1023XXXXXXX.

E119 - Low water pressure - Look for water leak coming from the water pressure switch of the diverter valve spindle. Also check and re-charge the vessel if required.

E133 - Failure to ignite - On older models built pre 2010, the ignition electrodes warp with the heat. They are now re-designed and much better. As a temporary fix, bend them back to make the gap the thickness of a pound coin.

E131 - (not listed) - Can be caused by a few things, sometimes if 2 fault codes come up together, such as E133 (failure to light) then E119 (low system pressure). It can also be caused by power failure during fault code.

E168 - Communication Error (not listed) - Most likely the PCB. Check the voltage and polarity before ordering a replacement.

E160 - Fan fault - Most of the time the fan is faulty. Check the loom to it. If you unplug the rectangular connector block, the fan should run at fall speed. If it doesn't and there's power going to the fan, it is definitely goosed.

E20 - CH NTC sensor fault - Most likely needs replacing. Check resistance on the pins, it should be about 10k when cold.

E50 - DHW NTC sensor fault - Most likely needs replacing. Could have been caused by a leak from it's gasket. It can then corrode the sensor and the loom. This fault should still provide CH, just not DHW.

E110, E125 and E193 - Circulation fault - Pump could be seized or faulty. Also worth checking is the filter located in the return isolation valve behind the blanking cap or (if fitted) the integral filling loop.

Another fault that I have come across a couple of times is with boilers fitted with a verticle flue. The boiler doesn't provide enough hot water. When it fires up, the boiler becomes noisy and eventually goes out. Check the air intake side on the flue test point. If the CO rises the plastic flue exhaust could well be cracked. You'll have to pull the flue apart to check it.

The gas valve on these boilers also need adjusting, the CO2% should be 8.7 on high and 8.4 on low. Adjustment is made on the front of the gas valve, the throttle for high is behind the blue cap, the offset on low is behind the brass flat headed cap. You'll need some Allen keys to do the adjustment. The throttle is a small allen key, the offset slightly bigger.

To ACCESS SERVICE MODE - Turn the potentiometers to min, then turn the DHW potentiometer to the 3 o'clock position and back to the 12 o'clock position twice. The display should change briefly to SF, the LEDs flash and the boiler should light up. Turn the CH potentiometer to MAX (will display 00) for max fan speed and turn back down to MIN for minimum (will display 0). The temp should then cycle with the letter P. To get out of service mode, turn the DHW potentiometer to any position from 12 o'clock (min).
 
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arran197 said:
Baxi Duo Tec/Potterton Promax Combi HE/Main Combi HE.

The serial numbers on these boilers all begin with 3 letters, followed by some numbers. The first 2 numbers are the build year, the second 2 the build week. The rest are random. So for example, a 28 HE A Duo Tec built in the 23 week of 2010 will be CAC1023XXXXXXX.

E119 - Low water pressure - Look for water leak coming from the water pressure switch of the diverter valve spindle. Also check and re-charge the vessel if required.

E133 - Failure to ignite - On older models built pre 2010, the ignition electrodes warp with the heat. They are now re-designed and much better. As a temporary fix, bent them back to make the gap the thickness of a pound coin.

E131 - (not listed) - Can be caused by a few things, sometimes if 2 fault codes come up together, such as E133 (failure to light) then E119 (low system pressure). It can also be caused by power failure during fault code.

E168 - Communication Error (not listed) - Most likely the PCB. Check the voltage and polarity before ordering a replacement.

E160 - Fan fault - Most of the time the fan is faulty. Check the loom to it. If you unplug the rectangular connector block, the fan should run at fall speed. If it doesn't, the fan is definitely goosed.

E20 - CH NTC sensor fault - Most likely needs replacing.

E50 - DHW NTC sensor fault - Most likely needs replacing. Could have been caused by a leak from the it's gasket. It can then corrode the sensor and the loom. This fault should still provide CH, just not DHW.

E110, E125 and E193 - Circulation fault - Pump could be seized or faulty. Also worth checking is the filter located in the return isolation valve behind the blanking cap or (if fitted) the integral filling loop.

Another fault that I have come across a couple of times is with boilers fitted with a verticle flue. The boiler doesn't provide enough hot water. When it fires up, the boiler becomes noisy and eventually goes out. Check the air intake side on the flue test point. If the CO rises the plastic flue exhaust could well be cracked. You'll have to pull the flue apart to check it.

The gas valve on these boilers also need adjusting, the CO2% should be 8.7 on high and 8.4 on low. Adjustment is made on the gas valve, the throttle for high is behind the blue cap, the offset on low is behind the brass flat headed cap.

To ACCESS SERVICE MODE - Turn the potentiometers to min, then turn the DHW potentiometer to the 3 o'clock position and back to the 12 o'clock position twice. The display should change briefly to SF, the LEDs flash and the boiler should light up. Turn the CH potentiometer to MAX (will display 00) for max fan speed and turn back down to MIN for minimum (will display 0). The temp should then cycle with the letter P. To get out of service mode, turn the DHW potentiometer to any position from 12 o'clock (min).
Click to expand...

Excellent post
 
Ideal isar/icos HE. If the boiler lights ok from cold but goes to LF during ignition when boiler is warm check the spark generator. Check for correct DC voltage into the generator and if there is a spark at the electrode. These generators can develop a fault where they only fail when warmed by the ambient heat inside the boiler.
 
southcoastboile said:
When I spoke with Baxi tech regarding the broken baffels they said it is classed as ID (not that they seem to know much themselves about these boilers) as they are there to slow the gasses down and it would effect the flame. I have replaced the baffels before by pulling them through the bottom but the time it takes to do that and the cost of them makes it seem like a bad choice in my opinion. Plus the fact that if you leave a powermax turned off for more than a day several components seem to fail at once for some reason.
Click to expand...

Have changed lots of powermax baffles there are whole estates of them round here and very few have been reg serviced so almost always have the baffles corroded and dropped inside the heat exchange tubes. I use a flexible nylon cable pulling rod to get them out. With the sump off push the cable rod past the baffle in the tube reach under the tank in to the sump hook the cable rod hook over the bottom edge of the baffle and pull out the cable rod from above. Hey presto your baffle is out and you can give the tube a good brushing.
 
common problem always asked in the private forum vokera boiler only firing when cover taken off. always a partially blocked venturi or has been in my case.
 
If you're topping up the pressure on a glowworm 30cxi best to do it slowly as they have a tendency to spit out the return filter beside the pump :(
 
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