Vaillant Issues

[Agile]

I am always amazed at the ineptitude of so many installers!

Yesterday, I saw a 637 beautyfully fitted with 28 mm gas and heating pipes! But all in a house with a heat loss and radiators of just 12 kW.

All under a BG service contract but the earth bond went 2 m and stopped there. The unvented seems to have an orange EXV.

 

[MrV]

you guys are in no position to tell me to do anything...

It is good enough for me that Vaillant product managers have seen my installs and not raised any concerns about them the components installed or specifically the pump size

If you want me to expand on that I will do so but not in a public forum. I and you frequent the combustion chamber so you can start a thread there!

Errr... Who has told you to do anything???... A question was simply asked Alec... why are you trying to avoid answering it? It's not a big secret that the public mustn't know. If you are blaming the boiler for being at fault here... Then surely you can substantiate it?? if you are struggling with working it out, i'm more than willing to help...
I'm not trying to get at you Alec, in fairness I agree with your principles of weather compensation.. Well, the bits that you get right at least.... But this............ This fault is basics..... whatever the make of boiler, it makes no difference..

 

[Bunnyman]

Hey oh off to the combustion chamber I go, this thread now dead as Alec has been found out and not only that has documented that he doesn't have a clue excellent! Product managers are great and the one you speak of has great experience and will certainly know what's wrong,. But as you don't listen to anyone has probably given up , I can tell you that there is no problem that Vaillant are interested in as they don't want to retrain you it is not there job! And where are your calcs? I have done mine

 

[ALEC1]

see the combustion chamber for more

 

[UpgradeME]

see the combustion chamber for more

For the benefit of the OP (and anyone else reading who cannot access the CC (me included))

The following formula gives you the answer:

Flow (l/min) = Power (kW) ÷ 4.18 (kJ/l/K) * 60 (s/min) ÷ ΔT (K)

Assuming an average return temp delta of 25°C, then the flow rate through the boiler is 9.76 litres per minute. The manufacturers instructions specify 20.3 as the "minimum flow rate" however, I believe that is based on the MAX kW output (28.2kW on the 428).

Based on my own experience (and the MI's) I calculate 0.72 l/min per kW (20.3÷28.2=0.72), so if D0=17, the MIN flow rate through the boiler needs to be 17 * 0.72 = 12.24 l/min

OP, I would therefore agree with MrV that your pump is too small/not on correct setting!! - I have to also disagree with those that say there are no issues with the 400 series! (see the vailant cycling blog mentioned earlier for further details).

 

[Bunnyman]

Thank god upgrade me well done ! As mr v said Alec's tan op Tryin to get boiler to work outside its parameters , u can forgive op but not Alec that's y he scuttled back to cc an trust me he's gettin stick there as well!!

 

[ALEC1]

there is a question there for you bunny man and MrV in the CC I am sure you can answer it..

 

[ALEC1]

bunnyman and mrv...are you going to answer... or perhaps you cant...

 

[UpgradeME]

bunnyman and mrv...are you going to answer... or perhaps you cant...

What's the question? - I have a few technical questions such as why is the burner is so high during the first xx seconds!? (If this is due to a EU reg on emissions, what specifically is the reg?) & what is the modification to prevent this behavior? that I'm sure some knowledgeable engineers know the answers to!?

BTW, for anyone technical watching/reading this thread, here's some alternative formula's which may help you!?

Power (kW) ÷ flow (l/min) ÷ 4.18 (kJ/l/K) × 60 (s/min) = ΔT (K)
ΔT (K) * 4.18 (kJ/l/K) ÷ 60 (s/min) * Flow (l/min) = Power (kW)

 

[MrV]

Alec,
I never realised that you would take a simple question so badly. I'm sorry for you that your customer ended up having to respond to a technical query where you could not. I appreciate that it doesn't make you look very good and that you may feel you need to redeem yourself. However, asking rhetorical questions and pasting only the bits that suit you on the public server is not the way to do it. That is if it was meant as a rhetorical question?

However, If it is a genuine technical query you have and you are looking to find a solution for the benefit of your customer, supply ALL the details in the Combustion chamber where there is a wealth of knowledgeable engineers that can try and assist you with it in a constructive manner. That is what they do best after all.

 

[ALEC1]

Here is the question:

Bunnyman and MrV, the issues I have with the two 400 series boilers are not related to flow at all. If you could be bothered to read the blog:

http://vaillantcyclingproblem.blogspot.com/

you would see that the issue that these boilers have relate to micro and short firing, not flow through the boiler. My calculations have shown that the pump is the correct size, given that there is a low loss header. The header is less than one meter, piped in 28mm and with a 15/60 pump...the speed of which has not effect on the micro firing, or the effect that the boiler will burn continuously at above 43c, but micro fire at 42c. Al this from Vaillants own diagnostics tool vr dialogue. The controls are the vr 430 and the vr 65

To make it clear my installs do not get the s.53 in diagnostics. They just mis behave with vaillant's own controls. That is the cause of my gripe...and should concern any reasonable installer or member of the public.

 

[ALEC1]

so please explain why this install gets a continuous burn at 43c, but micro firing below...

see no flow issues no s53 and no pump issues...

 

[vince101]

FWIW...I don't know ALEC1 and have had little contact with installer. They have done their best to resolve but are clearly out of their depth.

I really appreciate the recent messages that confirms my suspicion that the pump isn't right. (although the installer relaced it..).

In meantime I've contacted Vaillant who are going to send an engineer out.

Main message for me is anybody thinking about about instlaling a Vaillant on an existing system must have a well experienced installer who knows about the issues...which I thought I had but in practice ended up being a real nupty (reverse flow and using expansion tank as a radiator). I must have drained the sytem down a dozen times with all the hassle of taking days off work etc! Also I now have to replace the cylinder to get it to work on hot water only. How I wish I'd kept the original Potterton! I could write a book on this!

Will keep you posted.

Vince

 

[ALEC1]

Come on Mr V and Bunnyman say something...(sensible...if you can!)

 

[Bunnyman]

I give up with u Alec it's no good comin on strong now u had a chance to google the answer to the calcs lol! The people in the know think ur off ur rocker