Vaillant Combi Boiler Noise

[Dav0]

Hi all First post,

I have lurked around a bit when choosing boilers etc a while back and see a lot of good advice given.

Having a bit of trouble with combi boiler, Vaillant Ecotec 837

Boiler was fitted about 3 years ago and have had no problems since then. but in last week started to get a high pitched whine/howl from the boiler that was carrying into the upstairs bedrooms. This tended to appear only when the house was getting up to temperature after being off overnight or when we we have been out during the day on max and the burner hit the max setting, staying there for a fair period.

I have a homecare agreement with BG and they sent an engineer out to have a look. He checked it over could not see anything and put in some boiler silencer. My wife was in when he looked at it so do not know what he actually checked. Got back at night and turned on water to fill bath and the boiler starts making a racket. There had been no noise with the DHW before only when heating.

BG called back out again and looked at it again. Different engineer, looked at it for a while before deciding we needed a new heat exchanger and telling me probably need a power flush. Didn't have the part so back next day to fit it, I was in this time, he spent ages at it it deciding it wasn't heat exchanger, thought maybe combustion problem ( said pressure was lower than recommended for boiler 16mb I think) before deciding on fan making the noise so he did not change part. I meant to say this only happen when drawing from bath or shower not from whb taps/sink. He showed me when the fan speed increased to higher levels then the vibration starts.

Back next day with fan, wasn't around again as had to work, my Dad was there this time and Eng tells him he has fixed it. Get back tonight, boiler seemed quieter not as good as before but pipe is hissing at cold water feed, the valve was only partially opened which seemed a bit strange.

Opened this up a bit and the noise in boiler returns, don't know if he replaced fan, I must presume so.

Question is should he be restricting water flow to the boiler, doesn't seem to be fixed as far as I can see.

Just want to check more knowledgeable people thoughts before going back to them tomorrow, I feel they are likely to give me the run around.

Any comments appreciated

PS He had also changed his mind about the power flush saying the water quality wasn't as bad as he thought the other day

Thanks

Ian

 

[Agile]

Limiting the water flow on DHW limits the max power boiler has to get to. So that will hide the problem. Bit naughty I think!

I dont recognise any fault from your description but perhaps otherts might.

A video with sound might help us to recognise the problem.

Tony

 

[Dav0]

Thanks for comment.

I would say noise not as bad as it was before, his work notes say he has replaced the fan. They say readings are all normal, as follows:-
9.2% CO2
0.0009 ratio
580/665 = 24.72 Kwatt (not sure about this bit his writing not so good)

He did make a bit of an issue at the weekend about the gas pressure at the meter being 23mb at the meter and dropping to 15/16mb (although I read somewhere else that with this type of boiler there is a drop form the boiler to measuring point of about 3mb?)
The gas pipe entering into the boiler is 22mm which appears to connect to a larger diameter pipe (partly hidden by partitons so can tell exactly what this is)

How do you upload a sound file, I have one now? Edit: Sorry see you need to post video, will need to look at again and upload to youtube

Edit:
Sorry also meant to say, when he first arrived he said boiler pressure was low after prev engineer and he whacked this up so it is almost top of the dial (looked high to me), when cold it showed 1.8 and when fired up it jumps to 2.6/2.7, not sure of this is relevant or not.

 

[bolshy]

He's overfilled a bit pressure-wise. My main concern is your boiler is rated at 37 kW in DHW mode, 24kW is way under. If it's gas pressure is 15mb when operating, and it's not achieving within 10% of it's rated output, (33.3 kW) then it's substantially under-gassed and is an "at risk" appliance.
Did BG bother to check what the pressure was at the gas meter whilst the boiler is running in DHW mode?
Have you got any other gas appliances? Did he check the boiler with those running?
If your meter governor if faulty and isn't maintaining gas pressure under load, then BG have just walked out on a potentially dangerous gas installation, without doing anything about it.
The manufacturers will be the first to tell you they will not guarantee the safe operation of their appliance if it hasn't got the minimum working gas pressure stated in MIs. And any warranty could be void.
You need to get a RGI in now to check out your appliances and gas pressures. Or get BG back.

 

[Dav0]

Thanks for your input

May not be correct with the 24Kw, his writings not so good. I have uploaded picture of his note.

The boiler has been serviced twice by BG since install where they are supposed to check gas pressure, plus also 2 further engineers in last week where they have checked system, so I would hope they know what they are doing!

I have requested another Engineer now booked for Friday and a Senior engineer I understand has also been requested to attend. Key thing is to make sure boiler is safe.

I also have linked youtube video to show noise (now more of a throbbing vibration that comes and goes), you may have difficulty hearing it as the bath is running, boiler located in bathroom unfortunately, but hopefully loud enough to make out

http://www.youtube.com/watch?v=LDOnPt8eN2Q&feature=youtu.be

//www.diynot.com/network/Dav0/albums/

Edit:
Also meant to say pressure rose into the red this evening 2.8 and had to bleed a radiator to bring pressure down, not sure if linked but will keep an eye to see if rises again. Just trying to be forearmed with as much info as possible before they return on Friday

 

[bell824]

heat exchanger has blocked pathways and does need to be replaced (some guys on here have had success cleaning but doubt b.g would try),
yes they are correct it is dirt in the system and normally will howl more when in hot water mode!

pressure rising into red isn't linked but is another problem search F.A.Q's for expansion vessel!

 

[bolshy]

Your DHW and pressure control problems are not priority, the safe operation of your gas appliances is.

 

[Dav0]

Your DHW and pressure control problems are not priority, the safe operation of your gas appliances is.

Also your previous comments "If it's gas pressure is 15mb when operating, and it's not achieving within 10% of it's rated output, (33.3 kW) then it's substantially under-gassed and is an "at risk" appliance"

How do they check what rate its burning at so I can ask to see it, is the 33.3kW the minimum it should be? Are there any specific questions I should be asking?

Engineer noted on his last inspection sheet that the boiler is operating within tolerances?

 

[bolshy]

To have it running at full rate, you can open a couple of hot water outlets, or there may be a diagnostic to initiate full rate burn. I would expect a boiler this old to achieve bang on it's designed rate of 37kW.
When the boiler is at 100%, BG should be checking the working gas pressure at the boiler. If it's low, they should also be checking working pressure at the meter which will identify whether the problem lies with the meter governor/ incoming gas supply or your gas pipework.
Your model's MIs state the minimum working pressure at the boiler test point is 17mb. This pressure should be achievable with the boiler and all other gas appliances running at maximum rate.
I get fed up with having to explain to customers what's wrong with their gas supply even though a big company has been looking after their appliances for years.
Some gas engineers either don't know to check, don't know how, or simply haven't got the time before their next job. Decent independent or sole traders only have themselves to rely on, and because of this, tend to be more thorough.
In any case, you don't walk out of a home with low pressure to gas appliances without finding out why and taking appropriate action.

Your manufacturers instructions state your boiler should not be put into service unless it has 17-25 mb working pressure at the test point.

 

[Dav0]

thanks for comments bolshy

did a couple tests tonight and calculated output using method in FAQ's

firstly ran bath and two other taps in the house and got 37kW which is bang on boiler rating

Second test I had bath running, living flame fire and burning one of the rings on the gas cooker just under 7kW for fire + 3 kW for hob giving total 47kW. test worked out at just over 46kW so seemed within reasonable tolerance. Our oven is electric so would say that is about the max we would be using at any one time.

On that basis it looks like the gas isn't being unduly starved which is something but obviously don't know what the pressure is at the boiler.

will see how it goes with BG tomorrow

 

[Bunnyman]

Blimey bolshy u write a lot of nice stuff unfortunately ur figures are wrong minimum working pressure for 837 is 15mbar !

 

[bolshy]

No it's not, it's 17mb

 

[bolshy]

You're not BG are you bunnyman?

 

[Bunnyman]

Dear o dear bolshy if u give info u gotter make sure it's correct! Vaillant state ecotec 837 minimum working 15mbar 831-824 16 mbar before it is deemed AR , please be careful about giving wrong info in public forum!

 

[Bunnyman]

Just in case ur still watching this thread I am only trying to guide u, I'm not sure if ur gas registered or not? You seem to be confused between standing and working pressure.. The makers instruction state DO NOT START APPLIANCE if pressure on inlet not between 17-25 mbar, this is standing pressure ie the boiler is not started... Then u fire it an if WORKING pressure drops below 15 mb it's at risk, I hope you haven't AR any at. 17 mb