Worcester Bosch 40Cdi Bad Vibration

[Groover75]

So my four year old boiler (conventional) has developed a very bad vibration. When it is heating up and when it is shutting down it sounds like a dirt bike.

The service people are stumped. They have changed the fan and the bearing plate and it didn't help. Worcester's only suggestion is to buy some kind of special brush for cleaning. The service people are skeptical but they are going to try it anyway.

Other than the noise the boiler is heating up the water and operating fine. Once it has ramped up the temperature the noise goes away.

I have a 15/50 pump, 14 rads, quite a large house, TRVs everywhere.

Any suggestions to give them as I'm getting tired of the multiple visits...?

Thanks, Andy

 

[Gasguru]

Is it combustion noise or the heat exchanger kettling....your system is full of sludge and the pump is almost certainly undersized.

If your service people haven't even got the cleaning kit then they obviously don't do much servicing and repairs on these models, the heat exchanger has been around for at least 10 years....perhaps time to get another boiler repair engineer or are you locked into using Help Link? The fan's the last thing I'd have changed.

A 4 year old boiler is unlikely to need much cleaning though on the combustion side.

Have they checked the burner?

Have they considered the gas valve?

Have they checked working gas pressures and the combustion at max and min output? Did you see them use a flue gas analyser ?

Did they do a final combustion check with the case on?

 

[Groover75]

They checked working pressures and the fan negative pressure and used a flue analyzer. They say the boiler is working normally.

They mentioned that the gas pressure drops from 20+mb to 15mb when the boiler is ramping up. At first they said it was strange then they said it was normal!

We had a new governor put on the gas meter (by Gas Networks) last week as HelpLink found it was faulty. The pressure was 17mb at the meter.

We have a lot of sludge and I clean out the TF1 regularly. I'm currently getting quotes for a powerflush. We bought the house four months ago and it seems it's been neglected (big surprise...)

I think HelpLink have only one service person for the entire county as we always get the same guy!

Do you think we need a 15/60 pump?

Andy

 

[CombustionGuy]

15/50 seems small for 14 rads. I service loads if Worcester and I dot. Carry the service kits I did my first full strip down yesterday been working on them 5 years I service maybe 7-8 a week. It sounds like fault on gas valve or combustion setting I would get another gas engineer in. You could always speak to Worcester and ask them who is the local approved engineer or get Worcester them selfs out to it .

 

[boilerdoktor]

i ll bet any money your people checked the flue gases on max but not minimum. that will be the problem, it should be 9.8 max and 9.2 min. think they ll find minimum at about 7-8

it sounds like a beginner playing the trumbone?

 

[Groover75]

I thought you guys would get a good laugh out of my situation.

So Help-Link came out with the wrong cleaning kit. The instructions state that if the heat exchanger cleaning panel is removed then the seal has to be replaced - but they didn't have one.

Tech 1 says I need a 15/60 pump and it will be ordered.

Meanwhile I get a local company to do a powerflush (6 hour job). They say the system was sludged up. Add in Fernox chemicals, etc. They tell me that 40kW is too large for the house and they have range-rated it down to 20kW. Also they tell me the bearings in the pump are going. They say the noise is kettling.

Ok, no more noise from the boiler because it isn't doing this massive boost/ramp up thing now.

Today I get a visit from Help-Link tech 2 to replace the pump. But no heat exchanger seal. He says "your boiler is too large and needs to be range-ranged to 20kW, that is causing the noise". I tell him the powerflush people have already done that.

He goes away. Then Help-Link tech 1 arrives. Wrong seal! He says that the boiler needs to be 40kW, he has "no clue" how to get it back to 40kW and the noise is caused by the pipes being too small for 40kW (I think they are 22mm). He goes away.

However he tells Help-Link about the range-rating.

I get a call from Help-Link "we are dropping you from our plan because you have had another company mess with the boiler and our tech doesn't know how to get it back to 40kW".

I ask about the seal because the cleaning wasn't done following the Worcester procedure. They go away and think about it then call me back and say "we want to keep you on our plan and we will see if we can change the seal AND upgrade the pipework at no cost AND keep you on our plan. But because we can't get the boiler back to 40kW we might need your plumber to fix their screw up".

So to summarize: one help-link tech agrees with the plumber - drop to 20kW, and the other says it needs to be 40kW with larger pipes! Aarrgh!

Note: I did do the house size calculator and it was 37kW or thereabouts.

 

[Groover75]

Duplicate

 

[bazdaman]

37 kw for 14 rads i would be checking that again unless the rads are huge!

 

[Gasguru]

They're all clueless...I wouldn't want them back, so much incompetence.

This is the cleaning brush set...you get a front heat exchanger seal thrown in with the kit.

https://www.heatingspares247.com/images/77190019960-w.jpg

However, it would appear the boiler is kettling due to sludge and probably an undersized pump and undersized pipework. Unfortunately the majority of "installers" are unable to understand the calculations or the concept of flowrates/pipe friction/heat exchanger friction etc and assume 6m pump will work on all domestic properties.

As for adjusting the Kw range rating....it's all in the manual

http://www.worcester-bosch.co.uk/cache/file/1/greenstar-cdi-service-booklet-for-engineers.pdf parameter 1.A

37Kw is a large system...you'd expect a lot more than 11 rads unless they're huge rooms and all large double rads. You sure the calcs. are correct?

 

[Steelmasons]

i ll bet any money your people checked the flue gases on max but not minimum. that will be the problem, it should be 9.8 max and 9.2 min. think they ll find minimum at about 7-8

it sounds like a beginner playing the trumbone?

+1.
Hopefully the 'muffler' is still in place.

 

[muggles]

Sounds like you should do everything you can to get dropped by unhelp-link, the described incompetence so far is staggering

 

[Groover75]

Thanks for the responses. I think I will just get my local plumber to check the flue gases on min and install the seal. It's probably worth paying them just to keep Help-Link away.

BTW both techs from Help-Link turned up at different times with the wrong cleaning brush. It looked more like something for a fish tank to me...



Andy

 

[Agile]

All those companies seem to be the ones giving too cheap breakdown cover.

They only manage those prices by employing people who find it difficult to get a job and have to accept their lower pay and worse working conditions.

You can hardly expect them to be very competent or bring the right tools and spare parts.

Tony