split post: biasi boiler

[Opel Fruit]

Thanks for the continued support both...

The system was flushed thoroughly. Twice before the boiler was fitted and then after. The water is a always very clean, even now.

It seems odd that the noise a) started 6 months after commissioning and b) coincided with fitting the 15th rad.

I will try moving the internal return pipe once again.

No problem with the Protex - I prefer F1 anyway!

 

[chrishutt]

It seems odd that the noise a) started 6 months after commissioning and b) coincided with fitting the 15th rad.

That's why I thought it might be debris in the neat exchanger. When you fitted the extra rad you would have at least partially drained the system and this might have dislodged some debris. Are you sure it was thoroughly flushed? How was it done? A thorough flushing isn't just a drain-down.

 

[Opel Fruit]

Backflushed via drain offs.

Any recommendations for "cleaning" the H/E?

 

[gas4you]

I've now tried to read through all previous posts!

Going back the gas inlet pressure it sounds as if your entire gas carcass is under sized if you get a greater pressure drop when other appliances are turned on. This will not help any lean mixture droning problems. I feel you need to get the pipe size corrected as a basic first.

Forgive me if this has already been said and I have missed it

 

[Opel Fruit]

Hi Dave - I know jack about old gas meters - this one is 1993. I presume they are sized by flow? Perhaps there is a combination of tired meter/governor and fluctuations in the normal gas supply pressure? Any way I can tell if this meter is "low flow"? if that indeed exists...

The supply pipe from the meter is all 22mm, two 90deg elbows, one gentle 90deg bend and the total length from the meter outlet is 2.6m

Interestingly - just ran the bath for youngest, full chat (great flow here - I have had to use an Arrow flow restrictor) and no noise.....

Not jumping for joy just yet....

 

[Rob]

Surely the working pressure at the appliance would have been the first thing to check?

 

[gas4you]

Agree with rob to a point, but with such a short run of 22mm copper and only the bends you mention then the pressure drop in theory should be minimal.

As you previously said you were noticing fluctuating pressure drop depending on whether other appliance were used I would suspect a faulty meter govenor that is randomly sticking. If it is sticking as to give a low pressure then this could cause the 'foghorn' sound you were complaining about as the mixture would be too weak.

I wuld recommend calling NG on 0800 111999 and say you have a faulty govenor. It should be a 2 hr call out and is free of charge. Hopefully they should just replace it, definatley if it is a J88, G910 or a donkyn as these have to be replaced as they are discovered.

 

[Opel Fruit]

J88, G910 or a donkyn

are these meters or governors?

BTW, the inlet pressure was checked- I mentioned this earlier on

 

[gas4you]

Govenors. I know you said it was checked but I feel it may not be giving a consistent output. You shouldn't be noticing varying pressure drops at inlet points.

 

[Opel Fruit]

It's a Sperryn G910

I'm now waiting for the Gas Gorilla to arrive....

 

[Agile]

However short the gas supply pipe is the gas at the inlet to the boiler should be checked under all operating conditions.

It should not vary by more than 2 mB between min and max boiler power. 1 mB in the regulator and 1 mb in the pipework.

If its more this boiler can be almost impossible to set up.

However, although we still dont know for certain, the OP seems pretty certain that its not a foghorn noise but a mechanical resonance in the pipework.

If its due to a blockage in the HE then the way to treat it is to use sulphamic acid ( DS3 ) and citric acid DS40 in equal quantities of about 40g in the boiler only on DHW delivery at 6 li/min and at min temp slowly raised to maximum temp over about 30 minutes.

However I am not convinced that is the problem!

One of the difficulties of doing a remote diagnosis is that although we ask for information we do not get a full scientific report on relevant aspects like the inlet gas pressures. An RGI would immediately identify if it was an inlet resonance or mechanical resonance.

A mechanical effect would be somewhat dependant on the system flow and turning off some rads would have an effect.

Tony

 

[Opel Fruit]

Regulator now changed.

Fitter said they do change the 3 types as they come across them, although this was due to a part failing in the south of the UK only...!

Anyway, I will keep an ear open. He has managed to fit the governor and pull the supply pipe out of the wall ties.....

 

[gas4you]

If nothing else it is another basic problem that has been eliminated

 

[Opel Fruit]

Just checked the boiler inlet pressure - my mate with the WG appeared...

21mB off, 19.5mB at full power. Before it was 26mB off, 19mB at full power. And it isn't fluctuating a little like it used to, Matey described it as a "stiff" supply.

There is still some sound, but not anything like as bad - although this was OK last night too as I intimated a few posts ago.

I'll report any changes. Matey with the WG reckons that the varying gas pressure from the old sticky governor and the slight cleansing action of the Fernox F1 and the reduction in aerated water from the recent refill may have done the trick.

To be continued....!!!

Thanks guys so far, particularly for your kind persistence.

 

[Agile]

If the supply pressures have been changed then the CO² percentage should be rechecked with the FGA !

The inlet gas pressure will only have an effect on a foghorn sound and not to any mechanical resonance.

The foghorn is an acoustic resonance of the air inlet silencing tube on the inlet to the fan compressor.

I have encountered a "shuddering" combustion effect if the mixture is not set correctly and the supply pipe is very short. It can be quite loud.

The latter is likely to be reduced or eliminated if other gas usage e.g. from a gas hob is occuring.

Tony