Vaillant ecotec plus cycling on HW only demand

[Agile]

As I said before the calibration of a cyl stat is very approximate.

In your case if the water was exiting at 62 C and the stat was at 60 C then it would have been turned off.

The obvious suggestion is to turn it down slightly so that it turns off the call for heat when the water reaches 60 C.

I cannot specifically comment on the microfiring but we know that your boiler flow rate is low and hopefully when you fit the 15-60 pump this will tend towards improving the operation.

Microfiring has insignificant effect on gas consumption or efficiency.

Tony

 

[scoobydo123]

Tony if I turn the stat down then it still does not heat the whole cylinder without a cycle (do you not expect this?). Also micro firing is happening on central heating. I bet my average burn time is very low assuming this is a setting that is available on the 4 series.

As you say flow is not meeting requirements so until this is done then I guess I have to put up with it, and hope that the new circulator can find around 40 seconds extra burn time or make the logic of the PCB start behaving itself (doubtful).

 

[scoobydo123]

Pump finally came, all fitted and getting a marginal increase in flow optimistic 19L when boiler rated at d.0 of 30 like the previous measurements. So still not quite making the min requirements unfortunately. So I think without a change in the start up logic from hot then I am stuffed.

Still finding it hard to believe that if I could get the flow up to save even 30L p/m that from a relatively hot system ie boiler has just cycled that it would take the load that the boiler gives on subsequent startups without over shooting given that I only get 4 second burns with my paltry 19L per min.

Thanks

 

[scoobydo123]

Guess what, I had a service plan with Vaillant that I forgot I took out! Anyway called them out and first tech changed NTC's and new PCB same behavior. He said he had never come across the issue before but was happy with temp difference etc.

He referred it to 2nd line support who paid a visit and he was also happy with the installation in general and admitted that he has seen many issues like what I have with no resolve. The boiler is working as designed and nothing could be done, I said this is not acceptable so he changed a setting for fan offset that seemed to reduce start up speed and I guess burner input but still have short cycling if not enough hot water is drawn albeit much less often. However if I set max temp to 80 then I tend not to short cycle as it will not overshoot in the first 50 seconds. I guess though this may have a negative impact on gas usage and also the HEX as default is 75max.

For the Vaillant experts is this the mystery setting that changes the start up behavior (but makes the boiler out of spec) or is there something else that can be done, it seems so close now to sorted but not quite there.

 

[ALEC1]

Microfiring has insignificant effect on gas consumption or efficiency

any research to substantiate this... Tony? Its certainly unnecessary wear and tear on the valve and fan...

 

[scoobydo123]

I have two very similar installs. One with a Gloworm Ultracom 2 and the difference in useage is not that great I havent monitored closely ie during summer months when only DHW is being used but they do have quite similar usage. I was more concerned with as you say the extra wear and tear and it just didn't seem right.

With the current settings I dont see it will have any issue when CH demand comes into play. However I would like to go for the more advanced controls VRC xxx but with the issues I have I think I might be opening up a can of worms, but I would really like to reduce flow temps when on CH but not sure if I would get severe microfiring if a target temp of 50deg was called for.

 

[ALEC1]

I imagine you saw this:

http://vaillantcyclingproblem.blogspot.co.uk/

the solution seems to be with ebus controls is to run the heating with a minimum demanded flow temp from the 430 or 470 as high as 44c and alter the setting to thermostat i.e. with indoor temperature setting...

 

[scoobydo123]

I have seen the posts on this site as well as the blog. I think it would really struggle with relatively low target flow temps. Will check to see how quick it ramps up to 50 deg to get a feeling of how it might perform. But it does look like I have issues with my configuration with simple on off controls yet it appears like others have not complained specifically about the issue with HW only demand.

Tks

 

[ChrisR]

Quote:
Microfiring has insignificant effect on gas consumption or efficiency

any research to substantiate this... Tony? Its certainly unnecessary wear and tear on the valve and fan...

On the contrary, Is there any research to show that there's a wear problem? Why are you certain about this wear?
There's no shortage of working fans and gas valves which have been switching on and off for the last 30 years.

"Clever" Boiler management systems at one time relied on micro firing to increase efficiency. I don't remember anyone complaining it made them wear out.

 

[ALEC1]

Chirs, mechanical thing do wear out that is an undeniable fact, micofiring must reduce life span as the valve as constanty openng and closing, where as long burns. Not withstanding that many gas valves will do the service..

Flame ignition does start with a phase of unburnt gas, UNCONTROLLED microfiring of less than a second which is what I have seen on the 400 series must be less efficient than a long slow ...

 

[ChrisR]

Chirs, mechanical thing do wear out that is an undeniable fact,

Whenever you go on about "undeniable facts", "the fact of the matter" etc etc, we know there's going to be a pile of poo following again, as here.
It's when you haven't got a scrap of evidence but want to build a case for the same silly statements.
Lot of things do NOT wear out in the life of a system.
So if a component's mean ultimate life is reduced from 100 years to 90 years, it doesn't matter. So it's NOT something to be wittering on about over and over and over again.

Your constant invention and dissembling does make the argument look completely silly.

Microfiring of less that a second is obviously not what was intended, even Vaillant admit that.
But this is NOT a 400. This is NOT uncontrolled microfiring.
But to suggest that the gas which is released in the first part of that fraction of a second doesn't get burned, is laughable. You ought to look at a boiler some time, they go "woomf" . In any case, it's not what was being discussed here.

So once more, the comments are
1) wrong
2) irrelevant
3) silly
$) trying, but failing yet again, to bolster Alec's business' mantra.


Typing a quick bit of nonsense (and never even bothering to use the spell checker) like that just pollutes the forum.
Like Spam, really.

 

[ALEC1]

Chris I was always taught that in the nano second before ignition the un ignited gas away from the probes was a cause of wastage, and control strategies attempted to avoid repeated firing of a boiler. Indeed thats why it is so important that boilers modulate right down...

I may be wrong on this, but would you be prepared to explain how any micro firing could be efficient...design principals of all burner controllers seek to avoid cycling...why is this?

 

[ALEC1]

Oh and an installer in a reduced part of London I don't have a business mantra or an interest in promoting it here where most people are outside of London!

 

[ChrisR]

I don't have a business mantra or an interest in promoting it here

The evidence appears to be to the contrary.

Ah - a quantification of wastage - nanoseconds. Oh dear. Fails a test of relevancy then?

all burner controllers seek to avoid cycling...why is this?

Not all.
Of those that do, & it depends on your definitions of microfiring, cycling etc.
You presumably have quantified answers to your questions, to back up your assertions.
That's all we're asking for.

 

[ALEC1]

ok I should have put all modern PCBs on condensing boilers seek to minimise short cycling and presumably micro firing.

Agile suggested that micro firing doesn't reduce overall efficiency, I was asking why he said that and whether he could quantify it. You responded.

As the vaillant 400 series does micro fire for fractions of a second and the post is about a 400 series boiler I would say this is highly relevant.

No I can't back up what I say with quantified answers but nor it seems to you or Agile...there is precious little research about any heating technology in the public domain... for a reason it must be...I wonder what that is?