Intermittent boiler failure / power flush

[darknite]

Hi everyone

I hope one of you guys will be able to help.

I have a 14 years old Ideal Classic N50 boiler in the kitchen, with a standard vented system with large storage tank and a smaller feed/expansion tank in the loft, and a cylinder upstairs.

It has been working fine until about two years ago when for many days we could not get a hot water or a hot rads, only lukeworm water. Then as if by magic it is back to normal with very hot stinging water.

We joined EON Central Heating Care to look into this. They changed the cylinder thermostat, then they put in a new pump without success.

Then they change the whole cylinder and the problem was solved, but, only for a few months. We were back to lukeworm water!

Another guy thought that the boiler was intermittently cutting out and put in a new sensor probe with great success, but, again for a few months!

The boiler seems to have its own mind in producing hot or lukeworm water. It will fire a way only for about 30 seconds to 1 minute then it is dead silent. Sometime it does not work in the morning but it is back to normal at night.

We checked our rads and they have no air or dirty water coming out of them. When the boiler works normally they will be very hot.

The last guy came in a few days ago and decided that enough is enough!

He thought that the most likely cause of our problem is dirt and sludge in the pipes and he advised power flush.

Do the experts here agree with his advice?

Apparently power flush does cost money. I am concerned that it may not solve the problem and I wonder whether I would be better off getting a new similar boiler or one of the new combi ones.

Any advice will be greatly appreciated.

 

[Agile]

i think you would be better off getting someone competent !

Those insurance covers use cheap contractors who cannot afford to pay enough to get the best people.

They waste money changing pumps and stats which dont solve the problems.

Tony

 

[fazedup71]

his right they are total carp, i went to a job where they sent someone out and he tried to silicon a cylinder union, needless to say it didn't work!

 

[mickyg]

well as long as you can get them to put it in writing that this will 100% cure the fault fine, but i bet they won't!

 

[gotbadgas]

his right they are total carp, i went to a job where they sent someone out and he tried to silicon a cylinder union, needless to say it didn't work!

i went to one which been denso wrapped and a leaky stop tap also had the same treatment

 

[darknite]

Thanks very much for your advice.

I will be on the look out for some one competent.

In the mean time, could you please suggest a possible cause for the intermittent boiler failure?

 

[Paul Barker]

If you mean NF 50 there are a number of intermitent faults in the boiler which would result in your occasional failures to light, but not create a total lockout so at another time it may then work without you having intervened.

So I would be stood in front of your boiler going through the ignition sequence time and again until I find the culprit.

Having cleaned the pilot jet checked the eklectrode gap, ensured the electrode and ht leed were in excellent condition, and the fan was free, I would start watching and listening to it light up.

Does the fan start every time? does the boiler go to ignition every time the fanm has started, when it goes to ignition is there a good healthy sounding spark every time? does the pilot light every time? does the main burner cross light from the pilot within reasonable time and does it do so smoothly and without a bang?

With my experience of the correct sights and sounds I would after repeated trials have an idication of the part which is beginning to go intermitenetly faulty.

Because all of the work done so far has seemed to work for a while, but in essence has not been the actual problem, my first area of attention would be as described above. Look for an intermitent failure which is preventing the boiler lighting to full flame and holding.

Yes it can be a sludge issue but there is a lot of time to be spent on the boiler before jumping to this conclusion. I haven't observed that many of the guys working for companies like this are given that time or have that tenacity. I might spend an hour and a half having exposed it making absoulutely sure I had nailed it in such a case, as I don't like recalls.

With a simple history on a first call I would spend 10 minutes to come to a decision. In a history like yours I would be part of the scenery for a while until I feel when I leave your house I will not be returning until next year
's service is due.

 

[darknite]

Dear Paul

Great many thanks for your detailed and helpful reply. I really appreciate it.

I will be on to it in the next few days checking the suggested areas.

I have to to tell you that I am not into engineering and I have to tread very carefully in the others turf.

I have always been advised that the boiler requires the attention of a professional. Please be gentle and advise me on how to get to the electrode gap and the hot leed.

What a great forum!

 

[Paul Barker]

I wasn't suggesting you do it, it is what the people you have your service contract should do if they keep so called fixing it and get called back.

It is a room sealed boiler for you to disturb the casing seal I cannot endorse..

 

[darknite]

Thanks again Paul.

I will post any new development over the next few days.

 

[darknite]

An update

Standing in front of the boiler,I called for hot water: Immediately the boiler came to life with a click and normal looking blue flame and I could hear the fan running.

After about 2 minutes the boiler went off silent.

Getting depressed, I waited for about 5 minutes, and the boiler bounced into life again but only for about 1 or 2 minutes then it was silent.

Is that what some one called a cutout?

Some one from my insurance company will pop in very soon for "General Inspection"

I will keep updating you

Many thanks for your continued interest.

 

[darknite]

Another update

The guy from my insurance company came in and had a good look at the boiler. He thought that the boiler PCB was faulty and ordered a replacement.

He did not think that power flush was required at all.

Two days later, the PCB was replaced with excellent outcome. The boiler now works normally with very hot water and rads.

We have to wait and see whether the PCB was the real problem or not. We may have to wait for some time.

But so far, the boiler is fine.

Many thanks for all of the contributors.