Help Required - Vaillant Ecotec Pro 28

[The831Bunny]

Doesn't matter. As long as you turn off the cold water supply. This will stop cold water entering the boiler.

Yes, leave the boiler on all the time and make sure your timeclock and room thermostat are on.

Bunny

 

[jacknicmeg]

Right, turned off stop cock and opened cold tap till nothing, closed then opend hot tap.

Boiler not gone to S4, still on S10 although it did seem to go through a scan of S numbers but then back to 10.

Have checked the second pipe in from the left and hot, very hot! checked d36 and it shows zero 0.

Could this be the problem?

 

[The831Bunny]

Please don't do extra things to what is asked!

I didn't say turn on anything. Try again and follow my post to the letter please. You sound as though you have a leak on your hot water pipework or a dripping tap/shower...

To re iterate turn OFF the cold water supply and wait. Have a cup of tea, whatever... But after a while if what you have told me is true, your heating should come on.

Bunny

 

[jacknicmeg]

Bunny sorry, what did i do wrong?

Boiler is on. Have turned off the cold water at the stop cock. have opened the hot and cold tap.

The boiler seems to be static on S10.

Have checked d36 and the display shows 0 (zero).

Have checked second pipe in from the left underneath and its very hot.

I cant see what i turned on or went wrong?

No drips from the tap?

 

[jacknicmeg]

Take that back, boiler went through a cycle, S11, S13 then back to S10, tap now dripping.

 

[The831Bunny]

You have to be sure there is no cold supply to the boiler for this test to work. Can you turn off the cold isolation valve at the boiler (small slotted brass spindle on the valve 1/4 turn). This is on the 4th pipe from the right.

Bunny

 

[jacknicmeg]

OK Bunny, 1/4 turn, now off.

 

[The831Bunny]

Off to Bedfordshire now

Will have to catch up 2moro. In the mean time check for me (and feedback the numbers you find) D.4, D.8, D.22, D.23, and D.35.

This will give me a view of whats actually occurring.

Bunny

 

[jacknicmeg]

Hi Bunny,

No worries, can i turn the stop cock back on now and program heat only for the night or we will all be freezing!

The codes are as follows:

D4 = 74
D8 = 1
D22 = 1
D23 = 1
D35 = 100

Hope the above helps! Thanks Bunny!

 

[Agile]

That indicates the boiler thinks it has a hot water demand even though you have turned off the stopcock and have no flow.

The DHW demand is a rotating turbine with a pickup coil. That cannot give a false demand signal from the unit when there is no flow. The d36=0 says no flow either.

That implies to me that the PCB is operating illogically.

Or did you jump the gun again and turn the stopcock back on before checking those parameters?

To correctly diagnose boiler faults you have to extremely careful and logical.

There is no DHW flow measured by the turbine yet the boiler still shows an S10 hot water demand.

Therefore PCB is illogical and must be faulty!

Now where have I gone wrong on this one?

Tony



Now where is BigBullShit to tell us all whats wrong?

 

[jacknicmeg]

Who's BigBullShit?

No, I dindn't, "jump the gun again" not sure i ever did... Stop cock was off when I checked the d's.

 

[jacknicmeg]

Hi everyone,

I have again this morning checked for leaking taps and pipe work and none found, to confirm the control operation within the boiler I isolated the incoming cold water supply on the boiler and boiler stayed at S10.

To confirm the:

D4 = 74
D8 = 1
D22 = 1
D23 = 1
D35 = 100
D36 = 0

The pump is still active and the flow and return pipes within the boiler and a metre from the boiler are still hot but no circulation or flow through the system.

Flow is hot, return slightly cooler (conducted heat and not flow circulation).

Diverter Valve actuator remains in the hot water position?

 

[mickyg]

Have you got a multimeter? I would be checking the dhw ntc, if this goes open circuit it puts the boiler into constant hw demand, don't ask me why!

 

[jacknicmeg]

Yeah I have a multimeter, can you just explain your method, step by step on how to complete this test?

Just so we are singing from the same hymm sheet.

Thanks Mickyg.

 

[mickyg]

the dhw ntc is the one on the pipe from the plate heat exchanger, its usually held on to the pipe with a "half clip" as opposed to the wrap around type on the flow and return ntc's. Turn off the boiler, pull the tags off it and check the resistance across the 2 pins.