How do you know the pump is working as good as it should be...? Mine appeared to be until i measured the capacitor. They are run capacitors so you can't tell just because it starts ok. Mines maybe 5 years older than yours. Non-condensing and no fault codes or display, so a very simple thing, it heats water and pumps it. If the PCBs for yours are as cheap as mine the worst that could happen by trying a new one was you end up with a tested to be working bargain spare. I loaded up on other spares while they are available so i should be able to keep it going until the wangers ban gas for no good reason.
Vokera linea 28. Error 04, water pressure OK. Micro switch is not pressed.
- Thread starter garnet
- Start date
I spoke too soon. Exactly the same behaviour and error 04 returned 12 hours after PCB replacement.
I will speak to the engineer on Monday, but what could be the problem?
Just spoke to a friend who knows electronics. He mentioned that if the pump is faulty - i.e. something block free rotation, this will result in increased current and the PCB will shut down power to the pump. I am not sure if this is correct, but it explains the behaviour to some extent. Even the fact that sometimes boiler will start with error 04 from shut down state - the pump needs to run and move the water in the system.
Any ideas?
if you take the bleed screw off the front of the pump, stick a screwdriver in to turn it and it spins freely then check the capacitor. If its weak it would cause low flow.
isolate the electric fully, unscrew the cover and then to access the back of the terminals to test it without having to pull the wires out another 2 torx head screws to remove the plastic plate that the capacitor is on. You would need a multimeter with uF reading though and not all do. Capacitors can hold a charge which you can clear by touching the two wires together
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Still, the problem persists.
After more observations boiler can lock out with error 04 just like that - no demand for DHW or heating. Also it will unlock itself after some time - again no action on my end. Completely random. Other cases still exist where it would lock when DHW/heating demand is on.
I will get a new pump installed. Old pump seems to rotate freely, not getting stuck, but I can get a new pump cheap.
However this got me thinking.
If this boiler has a flow swith (mounted on the distribution manifold), what tells the PCB what the pressure is? Especially when the boiler locks itself when no DWH/heating demand is present. I observed how the spindel doesnt come out of the manifold and doesn't press the switch, but when there is no demand the spindel is out of play. Something tricks the PCB to think there is low pressure.
There seems not to be a low pressure switch. The pressure gouge is connected to the manifold only and there is no electrical connection to the PCB from it. It reads the pressure, but only shows it, doesnt relate this to PCB. So how does the PCB know pressure is low and display error 04.
After more observations boiler can lock out with error 04 just like that - no demand for DHW or heating. Also it will unlock itself after some time - again no action on my end. Completely random. Other cases still exist where it would lock when DHW/heating demand is on.
I will get a new pump installed. Old pump seems to rotate freely, not getting stuck, but I can get a new pump cheap.
However this got me thinking.
If this boiler has a flow swith (mounted on the distribution manifold), what tells the PCB what the pressure is? Especially when the boiler locks itself when no DWH/heating demand is present. I observed how the spindel doesnt come out of the manifold and doesn't press the switch, but when there is no demand the spindel is out of play. Something tricks the PCB to think there is low pressure.
There seems not to be a low pressure switch. The pressure gouge is connected to the manifold only and there is no electrical connection to the PCB from it. It reads the pressure, but only shows it, doesnt relate this to PCB. So how does the PCB know pressure is low and display error 04.
pressure isn't the same as flow. Its the lack of flow which is the problem. As i keep saying if the pump rotates freely its probably the capacitor that is weak. If there is not enough flow the spindle wont come out and you'll get a lock out. Nothing to do with system pressure. What do you mean by "spindle is out of play"?
capacitors fail gradually so at some point the problem could be intermittent, does the spindle sometimes come out slowly and presses the switch, and sometimes half out? there is a rubber diaphragm in there but if that was split maybe it would never come on. Not sure
Really!
The pump is powered by a relay. The PCB operates the relay and 240 volts applied to the pump. No correct check circuit other than the fuse.
First thing that happens on the lenea to a demand, be it ch or hw, the pump runs.
Does not tell the PCB anything. That spindle has to do its thing in a set time after which if it fails to operate the switch, 04 will be shown.
I suggest you read all the posts in this thread. You are going about looking for fault where it is not.
The microswitch is telling the PCB something not right.
You know there is water in the system
You know the pump is running
You know there is no issue during CH
You know during CH the spindle comes out.
Asnswer has already been posted
I forgot about this, so its the capacitor
Read my earlier post re flow manifold
Have come across this issue many times
What one needs to appreciate is, hot water heat exchanger is inside the boiler and radiators are connected to the boiler with long runs of pipe.
Then visualise water flow though a virtual short circuit as opposed to long pipe run
Now, which circuit would exhibit greater pump differential?
Post 12 is a hint
some diaphragms are third party made from what would seem like old truck tyres. Better to get genuine diaphragm
Circuit resistance is the other way round for HW and CH
I think you missed that.
Not sure it is the diaphragm under the plunger.
Exactly that. It is one of the following:
-Boiler (re)starts, error 04 is there instantly. No demand of DHW/DH, i.e room thermostat is set to 18 deg and it is 22 deg in the room.
-Boiler starts, no error. DHW demand - error appears.
-Boiler starts, no error. Heating demand - error appears.
In either case error 04 would disapear after random time without any interaction on my side.
Until next time. Actually restarting the boiler very rarely clears the error (thinking about it - it is not the restart that clears it, but just the random timinmg as I said).
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