Boiler cases and room seals

simond said:

The first bit is correct. Your second comment regarding combis etc does not make sense.

Most small domestic gas boilers have a similar concentric flue intake like you show.

Nb: your plastic Avanta is more often used with a two pipe flue in the Netherlands, so the white elongated box on top of the boiler is a concentric adaptor for other markets.

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If you compare the exploded parts diagrams for the Avanta OV and System/Combi boiler you will see what I mean. Only the OV version has the elongated box.

Thanks for posting your opinion regarding my last post.

The risk of taking the case off and not resealing it properly is not really a combustion issue per se in most cases. A gap in the case seal could potentially cause the air pressure switch to still operate and allow the boiler to operate when the flow of air through the appliance should cause it to fail safe. This could cause very high co readings and a route directly back into the property. On most modern condensing boilers (but not all) it is more soundproofing.

steelmasons said:

Is your stance on this any different now DH?
Would you advocate front case removal.

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I wasn't taking a stance; just asking a question.

As for removing the front case, it would depend on the boiler. If the case was the primary protection, so removing it meant the boiler was no longer room sealed (I believe my old Apollo was in this category.), then no, I would not advocate removing the case.

Here's a conundrum:

Home owner's boiler goes wrong and he thinks it as an electrical fault, so he calls a (non GSR) electrician. Electrician turns up and identifies the fault as an electrical problem within the boiler. Does the electrician say "Sorry, I can't open the boiler as I'm not Gas Safe Registered. You'll have to get a GSR man to check the boiler." or does he ignore the fact that, legally, he can't open the boiler, and go ahead and carry out the repair?

Alternatively, the home owner calls in a (non Part P) GSR man, who also identifies it as an electrical fault in the boiler. Does he say "I can't touch the electrical side as I'm not Part P registered. You need an electrician.", or does he ignore the "rules" and go ahead and carry out the repair?

steelmasons said:

Thanks for posting your opinion regarding my last post.

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Not very patient, are you?

D_Hailsham said:

"I can't touch the electrical side as I'm not Part P registered. You need an electrician.", or does he ignore the "rules" and go ahead and carry out the repair?

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Part P does not apply to repairs to the electrical / electronic components inside an item of equipment. ( Part P registered TV or computer technicians ? ).

D_Hailsham said:

I hope this is not straying into CC territory, but I am confused.

In another topic someone wrote:

As far as i know doesn't the case that provides the room seal for this model have to be removed to get to the electrics, not really diy territory.

The boiler in question is a condensing boiler which gets its oxygen supply via the external air intake and discharges the products of combustion via the flue to the outside. So why does the case need sealing?

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Haven't seen the topic in question, but as a general rule it depends on the boiler

If the front case also provides the primary room seal, al la Vaillant/WB/Intergas/Ideal etc then the homeowner/user should not be removing it, and nor should anyone else who does not carry CENWAT. If the front case does not provide the room seal (IE there's another panel behind it...Baxi/Glow-worm etc) then unqualified people may remove it.

Consider the situation where a condensate drain arrangement internal to the boiler and before the trap has lost its integrity. This is under positive pressure from the fan and contains products of combustion. An incorrectly refitted case would cause a high buildup of CO as the boiler rebreathes its own air, and this toxic air could then leak out of the badly-fitted case into the room

This is very worrying.

I too previously thought the case on my ecoTEC was under negative pressure so any leaks would be inward.

I have my boiler serviced annually and recall on three occasions (by at least two different engineers) that I had to refit the cover afterwards because the engineer had not seated it properly. I only noticed this because the boiler is the other side of my bedroom wall and the fan noise was noticeably louder.

I will be sure to check before they leave from now on!

It is usually under negative pressure. It is when an extraordinary event occurs that the room sealed design starts to deliver results, it usually fails safe.

If the cover isn't on, it can't fulfill that function.

Note: I'm only talking ecoTEC above.