Vaillant ecotec plus cycling on HW only demand

[scoobydo123]

Ok stored water temp this morning was 62c mains is 12c (figures I doubt widly different from the other day).

Pump still not turned up!

Had a spare 15mins before work and run the following test d.0 set to 30 target temp 75

CH set to on, HW off (note I have the same symptoms on CH as with HW when d.0 set to 11).

time d.40 D.41
0:17 41 30
0:22 44 28
0:30 43 27
0:36 42 27
0:43 41 27
0:49 41 27
1:09 50 28 boiler now running at d.0 perceived by fan noise
1:17 51 28
1:24 51 28
1:29 51 28
1:35 52 29
1:41 52 29
1:47 52 29
1:55 53 30
2:01 53 30
2:07 53 30
2:15 54 31
2:25 54 31
2:31 55 32
2:37 55 32
2:43 55 33
2:49 56 33
2:58 56 34
3:02 57 34
3:10 57 34
3:14 58 35
3:21 58 35
3:26 59 36
3:32 59 36
3:41 59 37
3:47 60 37
3:57 61 38
4:20 62 40
4:27 63 40
4:32 63 40
4:41 64 41
4:46 64 42
4:55 65 42
5:02 65 41
5:07 66 43
5:14 66 43
5:21 67 44
5:27 67 44
5:34 68 45
5:40 68 45
5:46 68 46
5:51 69 46
6:05 69 47
6:11 70 47
6:18 70 48
6:26 71 48
6:31 71 49
6:37 72 49
6:43 72 49
6:49 72 50
6:57 73 50
7:02 73 51
7:07 74 51
7:12 74 51
7:18 74 52
7:27 75 52
7:34 75 53
7:40 75 53
7:53 75 54
8:15 75 55
8:21 75 56
8:31 75 56
9:10 75 58 boiler modulating
9:32 75 60
9:55 75 61

At this point I reduced target temp as I did not have much more time left


On refire the boiler fired at a reduced fan noise compared to when it was running @ d.0 setting and then tried to ramp up to d.0 and then overshot and boiler cycled. Obviously this what not quite a real word scenario as I had moved target temp by quite an amount due to time constraints. But did prove I believe that d.0 is being ignored during initial x seconds.

thanks

 

[gaswizzard]

Had a spare 15mins before work and run the following test d.0 set to 30 target temp 75

How did you set d.0 to 30? this is a 428 correct? , the only way d.0 can be set to 30 is when DSN has been changed , your treading dodgy ground here and shouldn't be messing around with 2nd level diagnostics.

 

[scoobydo123]

I haven't changed DSN. Perhaps this is my issue? If you want send me a PM so as not in public forum. Havent got my manual with me but I seem to remember DSN table on my manual saying 428=13, just looked in a manual online and it says DSN should be 2 for a 428.

PS d.77 is also 30 which seems like default for the DSN I have.

Have you found the fault? Factory reset in order perhaps was thinking this all along as I have always suspected PCB but didn't want to factory reset without understanding how to input DSN as I assumed if factory defaulted the PCB thus becoming a generic board again.

 

[gaswizzard]

Sorry Scoob I can't comment on this , get someone who knows this boiler to take a look and go through it all , all I'll suggest is d.0 should be set at a max of 28 , what is the max kw rating in d.0? if it's 30/37/38 then someone has been playing!

 

[scoobydo123]

30 so assume it hasn't been set for 38kw boiler? Figures above are still indicating only about 17L p/m I believe. What about my delta it seems good apart from towards the end? Should it have modulated earlier and then perhaps on following fire so much heat would not be in the system and it wouldn't overshoot, or is normal logic to bring return up to same temp as flow then shut off.

PS it was serviced recently and cp12'd I really hope you have nailed it

 

[gaswizzard]

Go to your local plumbers merchants and pick up a grundfos 15/60 circulator.

 

[gaswizzard]

just looked in a manual online and it says DSN should be 2 for a 428.

2 is for a 618.

 

[scoobydo123]

from a manual online all cut from the same PDF

These instructions are applicable to the following
ecoTEC plus boilers, available in Natural Gas.
All ecoTEC plus boilers can be converted to LPG.
APPLIANCE MAXIMUM OUTPUT
ecoTEC plus 415 15kW
ecoTEC plus 418 18kW
ecoTEC plus 428 28kW
ecoTEC plus 438 38kW

Appliance Device specific number
ecoTEC plus 415 0
ecoTEC plus 418 1
ecoTEC plus 428 2
ecoTEC plus 438 3
Table 11.1 Device specific number

But I am 99% certain mine was set to 13 hope this is wrong?

 

[gaswizzard]

612=0
615=1
618=2
624=3
630=4
637=5

415=11
418=12
428=13
438=14.

These are in the MIs which can be downloaded so no problem posting them on here.

d.96 will not change DSN.

 

[gaswizzard]

But I am 99% certain mine was set to 13

So you have been into d.93 then?

 

[gaswizzard]

30 so assume it hasn't been set for 38kw boiler?

Correct , it's been set for a 630.

 

[scoobydo123]

Yes from memory (it was set to 13) after I found out that the PCB was common across the 4x range I checked to see if it matched the table in the service and install manual. I could be owing you a beer here, do you take paypal ?

I really hope you are correct but I am pretty sure it was set to 13

 

[gaswizzard]

If DSN has been set to 13 then d.0 would max out at 28 and NOT 30+

 

[UpgradeME]

I really hope you are correct but I am pretty sure it was set to 13

I think it will be as well... as Gaswizzard's quoted above 13 is the CORRECT DSN setting for a ecoTEC plus 428! - Checking d.76 on my system corresponds with the above table i.e. d.76=12 on my ecoTEC plus 418.

You earlier tests also mathmatically confirm the boiler was firing at 28.2 kW (as per the MI), your flow rate is 17.5 l/m and for the first 50 seconds, the boiler's MAX kW was 62% of the boiler's maximum output (17.5kW) - You have not yet ruled out if lowering d.0 has any effect on the initial 50 seconds (unlikely based on Thebunny831 getting a similar % from a 418 but possible).

 

[scoobydo123]

Gaswizard seemed pretty confident that d.0 should not be able to go above 28 I am hanging onto this thread of hope that something is wrong (hence strange PCB behaviour). Perceived gas rate if d.0 set low does not seem to alter for start up.

Pump not turned up still

Loathed to buy another until the one I ordered is declared lost by parcel farce.

How does my delta look? Is that behaving how it should.