Controls for a ecotec plus 428 boiler

[scoobydo123]

Press i and plus on the front panel you should then see d.0 press the i button and it will display the current rating will range from 5 - 30

 

[jeffridj]

Be careful with what you choose as you could be in for a whole world of pain. Can you do a test for me, call for CH when up to a flow of say 65c turn the boiler down to say 50 the boiler will then switch off. Now crank up the boiler stat again to 70c and see if the boiler only fires for around 15 seconds only? You can also do a similar thing with the DHW stat ie when satisfied turn the tank stat up a bit and wait for the flow and return to get near to target temp. Then turn stat down so the boiler goes off, then up it again and see if you get another short cycle. If your boiler cannot get past the 50 seconds intial burn after the first extended burn you may well find going for advised controls may give you a headache.

Just did this. Turned CH temp to 65. When it reached 65 it turned off and the radiator symbol started flashing I then turned it up to 70 and after a few minutes it fired up again went to 65 then it seemed to increas the output even more and went to 70 and turned off after a total of 1 minute 15 seconds. Does this sound OK?

 

[scoobydo123]

At least it got past the first 50 seconds. What you heard was the boiler firing at a stupidly high level for the first 50 seconds did it modulate down as I owuld have expected it to have modulated down ie get less noisy instead of cutting out.What rating is your d.0


Ps when it got to 65 how long did this take? It should have took quite a while you can also view the return temps of the boiler with d.41 realistically when it stopped at 65 the return should have been around 62ish give or take. Note that when cranking around with the temps it alters how long the boiler will wait before firing again due to the anti-cycle algorithm.

Try the test again but only say crank it back up to 66 you will probaly find it will short cycle.

 

[jeffridj]

I did try setting the CH water temp to 60 and increased to 65 when the boiler shut off and when the boiler refired it only went for about 20 seconds before it shut off again.

Found out how to read the values now
The D0 value is 30. Should I turn this down?

The CH water temp is set to 70 and when the boiler stops and goes into anti-cycling mode the D41 is around 55. The boiler was on for around 10 mins and was modulating down to what seemed a very low level. The anticycling time at the moment is 3mins and the max anti cycling time is set to 20 mins.

I used to have the CH water temp up full (75) but will now leave it at 70 and see what happens.

 

[scoobydo123]

Sorry just re read my tests and have mislead you. What we are trying to do is reproduce when the boiler has been on for a while on the first burn and then runs out of modulation range (inevitable on most systems). The system will switch off and go into anti cycle mode. When it refires it will rapidly rise back to target flow and then overshoot as it is nigh on impossible to get the heat away quick enough given that the boiler has cycled. So if you want to test again let it come up to temp boiler will then switch off when it runs out of modulation headroom. The boiler will then countdown given the value of d.2 and what the temps are. It will then fire at a high gas rate and you will see the flow rise rapidly and probably the boiler will not have fired long enough to go into modulation mode where it can go to around 5kw you will then be stuck with it firing for very short periods. This also gets worse as the house gets up to temp with the system graudally getting smaller and smaller due to TRV's closing. Have a listen to it and see how it behaves



What is you normal flow temp set to?

 

[Agile]

You could prove its undersized by seeing what d0 in the boiler settings is currently at. Then reducing it to d0 = 16 kW which is far more likely.

Tony

Select the d0 current value and then use +/- buttons to reduce it to 16 kW and then press "i" to save the new value.

Then run boiler on heating time how long it runs and goes off for over a number of cycles.

That will give an indication of the amount of power the house needs.

If it were to stay on all the time then it needs more than 16 kW !

Tony

 

[jeffridj]

Scooby - I normally have the boiler temp flat out at 75c but I have now reduced it to 70c and at the moment it seems to be working OK although it's taken longer than usual for the house to get up to temp as expected.

Agile - will try lowering the boiler output tomorrow and try again.

Both - do you think a VRT392 with a VR65 would be a sensible solution given what we have found so far?

Thanks for your help so far.

 

[Agile]

We really need more information on your system.

It sounds as if your rads are hardly able to get your house up to temperature.

How much can you reduce the heat losses?

Tony

 

[jeffridj]

I dont think there is any problem with insulation or radiator output. The house gets up to 20c + even if its -10 outside without any problem. The problem only comes when the whole house is nice and warm and the heating seems to go to sleep for 30 mins or so. This is long enough in this weather for the temp to drop below comfort level (goes down to about 19.5) In fact, this has only started happening since I had an extra foot of insulation put in the roof.

The walls are all brick and 6inch thermalite block and all windows and doors are aluminium with themal break and double glazed. House floor area is about 8mtrs x 17mtrs.

 

[jeffridj]

Scooby - as you say now trv's have closed the boiler is coming on for about 15-20 seconds and then shuts down in anticycling mode. It then waits for another 3 mins. The result is that the living room which has the thermostat in and has no trv is starting to cool down again despite the thermostat still calling for heat.

I have just done some more checking and the d41 temp is still saying 56c but the radiator in the living room is almost cold (the AQ6000 says 40c). Could this be something to do with the by-pass pipe being open too much?
The radiator in the living room is the furthest from the pump and is also the biggest rad - 500 x 2400 double.

 

[scoobydo123]

Welcome to Vaillant silly logic. It will do the same on HW only demand. I would be vary wary of spending out on the advanced controls. What will happen is that when the room comes near to target temp on the room stat, but the boiler will be running at a lower flow temp (which is much more efficient) however when it finally runs out of modulation range it will turn off it will then come back on once the anti cycle timer has expired but as the requested flow temp will be lower you will more or less be guaranteed to over shoot the target flow and then you get stuck in the loop.

I would up d.1 pump over run to say 12 mins
Ensure circulation pump is set to max (this is done on the pump) what pump do you have?
d.2 needs to be set to 60 this will make the anti cycle time longer (will not be 60mins dont worry)
Change d.0 to say 15kw in the hope of it burning for longer as clearly you have the infamous Vaillant bug
Try flow at 68c this will also make the anti cycle timer longer given the above d.2 parameter it will be around 11.5 minutes.

 

[scoobydo123]

Ps have looked at the Stat and it looks like it has some options for external stats etc. Are you using these maybe you should look to disconnect these and run the Stat in normal mode. Maybe one of these are reporting wrong temps. With the way the Vaillant behaves it is very difficult to recommend a stat if yours is faulty as the clever stats will get very confused with a boiler that only fires for 15 seconds or so. As you can imagine if it has proportional control it will expect a good length burn on both the first burn (which isn't a problem) but when it goes to proportional control it will struggle.

 

[jeffridj]

Hi,
The pump is a Grundfos super selectric 15-60 and is set on the max setting (3). I have set all the figures as you have suggested and will see how it goes.
Thanks again, your help is appreaciated.

 

[jeffridj]

Just saw your 2nd note and not sure what it means. The AQ6000 has an external temp sensor and a flow and return sensor as well as the tank sensor. The control unit is set for hot water priority and the anti cycling control in it is set fully anticlockwise about 8 times per hour I think but not sure as I don't have a manual any more. However, when all this happens, the AQ6000 is still calling for heat, it just seems the boiler just keeps going into anti-cycling. I will report back later today and see how the changes you suggested work.
Cheers, Dave.

 

[scoobydo123]

Turn all the extra stuff off on the stat so it works normally ie simple on off. This boiler will cycle easily for 8x in the hour with the stupid start up routine that it has.

Looks like whoever commissioned the boiler paid no attention to setting up the boiler correctly so far everything is at default.

Either way I don't see you getting it working 100% fine due to the default behaviour of the boiler being suspect. Have asked a few questions on the forum for people who say they have it working 100% fine but never get a full answer to my questions. Quite possibly with a commercial circulator it may be possible for CH but DHW generation I just cannot see how it cannot suffer from micro firing when nearing full tank regeneration