Item
Vaillant ecoTEC plus 418 fully condensing boiler

Problem
Extremely loud ~ 1KHz whistle

Fault Conditions
Only when boiler fluid is cool ~ 13 Deg C AND outside air temperature
is below 10 Deg C

History
Boiler is about 2 years old
The problem started shortly after installation
Vaillant sent a technician very quickly at the first request. Nice
helpful chap but he had never seen the ecoTEC before and had no idea
what was causing the noise.

The noise is a pure tone i.e. sinusoidal. The volume is hard to
believe and is mostly emitted from the balanced flue. I have not dared
ask but I am sure that the neighbours are unimpressed. It really is
deafening.

The fix
Mr technician stayed for a couple of hours and eventually decided he
would change some software settings to limit full throttle. This
appeared to work and the lower throttle setting was not a problem. I
tried power cycling the boiler to make sure it would not 'forget' the
new settings and it was ok. Probably uses flash memory.

Current Situation
Problem came back this morning with a vengeance (outside temp 7 Deg
C). Reducing throttle further is not my preferred option. Mr
technician said if the problem comes back he would replace bits one at
a time until problem goes. This he said is standard Vaillant procedure
and I bear the cost which will be significant.

Research
General web searches. Boiler noises seem to be mostly attributed to
kettling, fan noise and thermal expansion.

Experiment
Exploring the theory that the exhaust tube was resonating I tried
making a baffle - long tube with holes along its length which I
lowered into the vertically mounted exhaust. This was intended to
absorb sound but more importantly change the resonant frequency.

Result
No change

Request
Any ideas?

Regards
Brian

In article ,
Brian Drury writes:
Item
Vaillant ecoTEC plus 418 fully condensing boiler

Problem
Extremely loud ~ 1KHz whistle

Fault Conditions
Only when boiler fluid is cool ~ 13 Deg C AND outside air temperature
is below 10 Deg C

History
Boiler is about 2 years old
The problem started shortly after installation
Vaillant sent a technician very quickly at the first request. Nice
helpful chap but he had never seen the ecoTEC before and had no idea
what was causing the noise.

The noise is a pure tone i.e. sinusoidal. The volume is hard to
believe and is mostly emitted from the balanced flue. I have not dared
ask but I am sure that the neighbours are unimpressed. It really is
deafening.

The fix
Mr technician stayed for a couple of hours and eventually decided he
would change some software settings to limit full throttle. This
appeared to work and the lower throttle setting was not a problem. I
tried power cycling the boiler to make sure it would not 'forget' the
new settings and it was ok. Probably uses flash memory.

Current Situation
Problem came back this morning with a vengeance (outside temp 7 Deg
C). Reducing throttle further is not my preferred option. Mr
technician said if the problem comes back he would replace bits one at
a time until problem goes. This he said is standard Vaillant procedure
and I bear the cost which will be significant.

Research
General web searches. Boiler noises seem to be mostly attributed to
kettling, fan noise and thermal expansion.

Experiment
Exploring the theory that the exhaust tube was resonating I tried
making a baffle - long tube with holes along its length which I
lowered into the vertically mounted exhaust. This was intended to
absorb sound but more importantly change the resonant frequency.

Result
No change

Request
Any ideas?

Excellent problem description. Looks like you've had some formal
problem resolution training?

I don't have an Ecotec, but I have a Keston. When first installed,
that gave a very deep note, sounding like a 32' organ pipe, so not
quite the same as your 1kHz. I found that the supposedly preset
mixture control was miles out, and after adjusting it (requires a
flue gas analyser), the problem went away. I think the sound was
generated in the gas/air mixer. On the Keston, the gas valve has
a simple on/off solenoid control, and uses the inlet pressure in
the gas/air mixer to modulate the gas flow, and that in turn is
controlled by the fan speed, which is thus the modulation control.
I suspect that when incorrectly adjusted, there was a positive
feedback oscilation around the control loop formed by the gas/air
mixer pressure and the gas flow control, which hit the resonant
frequency of the mixer and associated tubing.

I have since spoken to one or two other Keston users who had the
same problem and called Keston out. In those cases, Keston extended
the air inlet tube to the gas/air mixer, which will have changed
the resonant frequency.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Thu, 02 Oct 2008 20:10:27 +0100, Brian Drury wrote:

Any ideas?

Google "Sale of Goods Act"

--
John Stumbles

Testiculate [v.t]
To wave one's arms around while talking ********.

Brian Drury wrote:
Item
Vaillant ecoTEC plus 418 fully condensing boiler

Problem
Extremely loud ~ 1KHz whistle

Fault Conditions
Only when boiler fluid is cool ~ 13 Deg C AND outside air temperature
is below 10 Deg C

History
Boiler is about 2 years old
The problem started shortly after installation
Vaillant sent a technician very quickly at the first request. Nice
helpful chap but he had never seen the ecoTEC before and had no idea
what was causing the noise.

The noise is a pure tone i.e. sinusoidal. The volume is hard to
believe and is mostly emitted from the balanced flue. I have not dared
ask but I am sure that the neighbours are unimpressed. It really is
deafening.

The fix
Mr technician stayed for a couple of hours and eventually decided he
would change some software settings to limit full throttle. This
appeared to work and the lower throttle setting was not a problem. I
tried power cycling the boiler to make sure it would not 'forget' the
new settings and it was ok. Probably uses flash memory.

Current Situation
Problem came back this morning with a vengeance (outside temp 7 Deg
C). Reducing throttle further is not my preferred option. Mr
technician said if the problem comes back he would replace bits one at
a time until problem goes. This he said is standard Vaillant procedure
and I bear the cost which will be significant.

Research
General web searches. Boiler noises seem to be mostly attributed to
kettling, fan noise and thermal expansion.

Experiment
Exploring the theory that the exhaust tube was resonating I tried
making a baffle - long tube with holes along its length which I
lowered into the vertically mounted exhaust. This was intended to
absorb sound but more importantly change the resonant frequency.

Result
No change

Request
Any ideas?

Regards
Brian
Had what sounds like the same problem. Only happened first thing in the
morning when the outside air temp was low. Installer called in a
Vaillant Tech (German) who tweaked some software settings which cured
the problem. I remebered what was done at the time and told my installer
.. Sorry but as this was a couple of years agoand anno domini is
progressing a a rapid rate, I can't remember what was done but I told my
installer & he may be able to remember if you are interested - it
involved accessing engineering codes on the boiler controls.

Malcolm

On Thu, 02 Oct 2008 23:43:17 +0100, Malcolm wrote:
Brian
Had what sounds like the same problem. Only happened first thing in the
morning when the outside air temp was low. Installer called in a
Vaillant Tech (German) who tweaked some software settings which cured
the problem. I remebered what was done at the time and told my installer
. Sorry but as this was a couple of years agoand anno domini is
progressing a a rapid rate, I can't remember what was done but I told my
installer & he may be able to remember if you are interested - it
involved accessing engineering codes on the boiler controls.

Malcolm

Thanks for the responses.

After reading the installation and servicing manual a few times I
figured that the d0 parameter which is described as 'Adjustable
heating part load in KW' is the thing my technician was playing with.

The current value is 16 so I have reduced this to 13 and the boiler
continues to heat to the same flow and return temperatures but it is
taking a little longer. This should not be a problem. The modulation
rate has also changed i.e. most of the burn is now on high where high
is now lower.

So now we wait for a cold morning and listen!

Thanks again

Brian

On Thu, 02 Oct 2008 20:10:27 +0100, Brian Drury wrote:

Item
Vaillant ecoTEC plus 418 fully condensing boiler

Problem
Extremely loud ~ 1KHz whistle

Fault Conditions
Only when boiler fluid is cool ~ 13 Deg C AND outside air temperature is
below 10 Deg C

History
Boiler is about 2 years old
The problem started shortly after installation Vaillant sent a
technician very quickly at the first request. Nice helpful chap but he
had never seen the ecoTEC before and had no idea what was causing the
noise.

The noise is a pure tone i.e. sinusoidal. The volume is hard to believe
and is mostly emitted from the balanced flue. I have not dared ask but I
am sure that the neighbours are unimpressed. It really is deafening.

The fix
Mr technician stayed for a couple of hours and eventually decided he
would change some software settings to limit full throttle. This
appeared to work and the lower throttle setting was not a problem. I
tried power cycling the boiler to make sure it would not 'forget' the
new settings and it was ok. Probably uses flash memory.

Current Situation
Problem came back this morning with a vengeance (outside temp 7 Deg C).
Reducing throttle further is not my preferred option. Mr technician said
if the problem comes back he would replace bits one at a time until
problem goes. This he said is standard Vaillant procedure and I bear the
cost which will be significant.

Research
General web searches. Boiler noises seem to be mostly attributed to
kettling, fan noise and thermal expansion.

Experiment
Exploring the theory that the exhaust tube was resonating I tried making
a baffle - long tube with holes along its length which I lowered into
the vertically mounted exhaust. This was intended to absorb sound but
more importantly change the resonant frequency.

Result
No change

Request
Any ideas?

Regards
Brian


I've not met this problem on any I've installed.
It does sound like a resonance.

It might still be just under guarantee. I'd start by check every plausible
component, flue, fan, flue terminal extensions etc.
Then check the combustion settings.
Then give the burner assembly a thorough clean out.

Finally replace parts in ascending order of cost/unlikelihood
Flue, fan, gas valve, main burner.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html