Wind Blowing Boiler Out

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lilly_kitt | 15:45 Sat 29th Dec 2007 | Home & Garden
17 Answers
I have a Ferolli Modena combi boiler and whenever its windy it blows the light out so the hot water disappears. Anyone have any idea how we can fix this ? Is there anything we can buy or adjust (obvisously with someone who knows what they are doing) ?



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Before I suggest what might be causing your problem � the following is a pr�cis of what happens when your boiler should fire up.

Once either a demand for central heating or hot water is made on the boiler, the boiler switches on the fan (to the combustion chamber). The combustion chamber can be considered as box containing the gas burner & heat exchanger. To operate correctly, the fan must be drawing air through the combustion chamber and expelling the exhaust fumes (via the flue ducting) out of the house. To ensure this is happening, the boiler is fitted with a pressure switch, which is monitoring the pressure differential between pressure within the combustion chamber and that within the exhaust flue.

The boiler will only ignite if this switch detects the minimum required pressure differential. If the required pressure differential is not achieved within a specified time, or drops below the minimum level for some reason, the boiler will shut down and require re-initialisation. This is an important safety feature of the boiler, otherwise poisonous fumes can be given off by the boiler.

Based on the above working of a combi-boiler, your problem may be caused by a number of things:-
If it really is strong winds causing the problem, it might be that your fan is on its way out.
Other possibilities include the tubes connecting the pressure switch being perished (leaking), giving a false pressure reading, or the pressure switch itself being faulty, a further possibility is that the (cover) seal on the combustion chamber is leaking.

Bear in mind that combi-boilers are complex things � you may have some other fault, leading you to believe that strong winds are blowing the flame out � this should never happen with the fan being powerful enough to counter any external pressure changes (due to the wind).
are you saying the burner goes out while the boiler is actually running the hot water or when the boiler is at rest?

if it is when it is at rest and its the pilot light that is blowing out then it could be a weak pilot and the pilot injector, head and supply tube need cleaning (by a corgi engineer)
I don't think this bolier is fitted with a pilot light - and has an electronic ignition system.
[Whenever the bolier requires igniting, a piezo spark lights the main burner]

However, if it has a pilot light, Gucciman may be correct in that the pilot is not correctly adjusted/set.
Question Author

Sorry its not a pilot light as such and has an electric re-ignition system. The boiler could be on as in the central heating but this is also affected whent he wind is blowing. for examply yesterday when there was no wind it was absolutely fine, yet the day before the hot water would not stay on for more than a few seconds before running cold. It is definitely the wind that is affecting it.... It affects the heating also but dont feel it as much as the hot water as the radiators stay warm.
If you are certain it is the wind, then I think there is a very good chance that the boiler is switching off due to not seeing the required pressure differential between the combustion chamber and the exhaust flue.

The wind change being enough to make the pressure switch trip. This could be due to any of the reasons given earlier.

If you are competent at removing covers etc. I would recommend you take a look at the condition of the pressure switch tubing.
Before removing any covers, disconnect the mains supply to the boiler.
The pessure switch is located towards the top right of your boiler (with one red and one white/clear air tube). Normally these will perish close to their ends. If found to be defective, sometimes it is possible to cut a small piece off at the end, with the length still being sufficient. Otherwise a make-shift fix can be achieved with sticky tape.

Please advise whether you have model 80E or 102, and I may be able to offer you more advice.
Question Author

thank you for your response i have a modena 80E boiler.
Providing you are happy to remove covers to look at the condition of the air pressure tubes, first switch off the mains electricity to the boiler and allow the boiler to cool. Note that the air pressure switch on this model is connected to the mains circuit and not the low voltage circuit.
You may need a small step ladder to reach the relevant parts if your boiler is located high on a wall, plus a torch to examine parts closely.

It is not necessary to switch off the gas supply to the boiler. Remove the Outer Case by removing the two securing screws from the rear bottom corners and lift off.
Now remove the Room Sealed Cover (which is a large ribbed plate, covering the upper part of the boiler), retaining screws at top & bottom. This must be done with care, as it contains the flue & air test points/ports and a seal around its edge � which must be correctly aligned when replacing. Once removed, you will see the air pressure switch to the top right of your boiler, with one red and one white/clear air tube, plus an electrical connection to the switch. Carefully examine both tubes along their length for splits or perished areas � especially at each end. Don�t pull too hard in testing the integrity of the tubes, as this may cause the tubes to break.

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Continued from Previous Post....

If a tube is split/perished then it should be replaced. Your local plumb/heating centre should be able to supply the correct tube type. A temporary fix can be achieved with sticky tape or other suitable material. Bear in mind that it gets very hot within the volume enclosed by the Room Sealed Cover.
Note that the Room Seal Cover is not the Combustion Chamber Cover � even so, it has a sealing edge which should also be in good condition (and could be causing your problem).

Carefully refit the Room Sealed Cover and the Outer Case. Reconnect to the mains supply and check that the boiler works OK.

If no problem was seen with the air pressure tubes or Room Sealed Cover, then further investigation is required. Unfortunately this requires use of a multimeter and competent knowledge of the boiler. You will need to arrange an engineer to take a look.

To carry out the above procedure, an engineer would want at least �50 to cover their time � should parts require replacing (fan, pressure switch etc), you won�t see much change from �200.
Question Author
thanks will give it a try and hope that its not the fan,
Question Author
have checked the tubes and all is well, looks as though its going to be an expensive one then ??
There are a few things you could try - I have a pdf copy of the service manual. The manual has a fault finding section, but when you have an intermittent fault, it can be quite difficult.
However you seem quite confident/keen at looking at the boiler. I am not a Corgi engineer, but have taught myself how comb-boilers work and saved myself a fortune in repair call outs on my boiler.

I could send you a copy of the manual - but would not like to divulge my e-mail address on such an open site as this.

Do you have any thoughts as to how we could make contact privately?
The Answer to my last post:-

You can contact me via the person selling item no: 170182722379 on ebay (An Epson compatible ink cartridge).

Contact the seller and I will contact you.
Question Author

i have the service manual which came with the boiler, my fiance is fine to look at things but we're abit skeptical about some engineers as they may change something which doesn't need changing and as soon as the wind blows it goes off again (has happened before).
-- answer removed --
Yes - I know a few Corgi engineers who I would not let loose on my push-bike, let alone a combi-boiler.

With an intermittent fault like this, you stand a very good chance of paying loads of money for no fix.

OK, if my theory is correct and it is the pressure switch being activated for some reason - this needs to be proved.

As I said earlier, this switch is in the mains circuit and is normally open; when the minimum pressure differential is reached the contacts close. So in operation with 0V across the switch all is OK, and with 240Vac across the switch, the pressure is no good.

If you are very, very confident with electrics, this is what I would do:-
Temporarily wire a mains neon across the switch, such that the neon can be observed in normal boiler operation. This will give a clear indication of the switch state. When the wind is blowing out your flame, you will be able to see what the switch is doing. If my theory is correct, the neon should illuminate just before the flame is extinguished (since it is this that is switching off the gas to the burner). I reckon its got to be worth a try.

[The reason is must be a neon and not a standard lamp is that the switch is in a sensing circuit, the sensing circuit would detect the lamp as a short circuit across the switch]

Let me know how you get on.
you really really should not be messing about with a combi boiler if your not a corgi registered competent gas engineer. not only do you have live gas and electricity and water present but my merely taking the front combustion chamber cover off you are breaking the seal which is there to protect you from the products of combustion. when we break this seal we have to test it upon re-assemblance to ensure the boiler is still room sealed.
if you dont want to get ripped off then get ferroli to send one of their engineers out.
Just to support the previous question. I also have a boiler that blows our in heavy wind. It doesn't happen for weeks but then on a really windy day like today its blowing out all the time. Showering is a nightmare. My boiler is an Alpha HE25 Condensing combi-boiler. My only thought has been that as my boiler flue exits immidiately outside the house that maybe a longer flue may prevent the 'blow-back' that puts out my boiler.

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