Ventilation Requirements For CH Boilers .

[Stuart]

I have a floor standing Potterton CH boiler of at least 20 years age and it sits in a fireplace with a flue up to the chimney head .

For reasons best known to myself I took out a maintenance agreement with BG and when they eventually ( at least 2 months later) came out to do the initial inspection the guy said ,after checking that parts are still available ,said that a highrise corevent would need to be installed in an outside wall before he could do the inspection and gave me a quote at 50% of normal,this reduced amount being £66. Presumably this requirement is something that has become necessary since the boiler was originally installed .

I am not proposing to take up this offer and will be cancelling the agreement but :---

The confirmation letter came this morning and with it came another letter to a different BG customer which I inadvertently opened without looking at the address and it said exactly the same .

Anyone know anything about this ventilation requirement or is it a ploy by BG to get additional work done ?

Stuart

[John Stumbles]

...

It's not a new requirement. You need ventilation direct from the outside to provide air for the boiler to burn so that it has sufficient Oxygen (O2) to converting natural gas (Methane: CH4) to Carbon Dioxide (CO2) and water (H2O, as steam in the flue gas). If there's insufficient air (and thus Oxygen) it will produce Carbon Monoxide (CO) and that'll be the end of you. You need purpose-made ventilation equivalent to roughly one or two full-size air-bricks[1] with no fly-screen or mechanism to close the vent, direct from outside to the room containing the boiler.

I suggest you look NOW to see if you already have such ventilation and if you haven't open a window to provide it and don't close it until you have purpose-made ventilation. Also get the boiler serviced ASAP - dust and lint clogging the air intake to the boiler can also make it produce Carbon Monoxide, as can sooting up inside and/or blockages in the flue. You can clean the air intakes yourself with a paint brush and a vacuum cleaner - they're usually fine wire gauze screens at the bottom of the boiler where the air gets in to the big cast-iron lump where combustion takes place. You need to take the front cover off the boiler to get at this.

By all means avoid BG but DO get the boiler serviced properly ASAP. These types of appliance really can be killers if not serviced annually or so. I'd also be planning to replace it with something post-Jurassic soonish.

[1] actually 10cm^2 per kW of heat input to the boiler, after subtracting 7kW which is assumed to be provided by 'adventitious ventilation' i.e. draughts etc.

[Tim Morley]

Funnily has anyone ever seen a BG service man with a vacuum ???

[Mathew Newton]

What, between the ears? If so, .... ;-)

[Malc]

My boiler is also in a fireplace. I had a Corgi gas fitter tell me that it was dangerous and needed extra ventilation on an outside wall. He even went as far as switching it off and issued a notice that it shouldn't be switched on again!

However, he had come to do the cooker and hadn't actually taken the boiler apart. If he had done so he would have found that the ventilation is behind the boiler.

So if the guy from BG didn't actually carry out the inspection then don't believe him.

Malc.

[Stuart]

Much the same as me . The flue connected to the boiler goes up to the top of the chimney on the roof but I'm not sure if that counts as "ventilation" but anyway he switched it off as he said he had to and put a warning notice on as well but that was all he did .He said I should be able to get what I have paid already as he didnt do the inspection and if I didn't get the corevent fitted it wouldn't be done . The kitchen is well draughty and one of the windows is usually partly open and also I have a carbon Monoxide Alarm near the boiler .

[Gav]

look on the boiler it should have a data plate, it will tell you the heat input of the boiler in kw, assume this is groos input the take away

7(kw) multiply the remainder by five and that is the amount of cm2 free air you need from a vent, now go find one from a diy store and install it, usually by chiseling out a couple of bricks, that will the satisfy the ventilation requirements, also look for any vents that exist and have been blocked over the years, maybe you can reurect one to provide ventilation. hth

[Ed Sirett]

The ultimate arbiter for the matter is the installation manual and failing that the regs linked below.

Look as BS 5440 -2 which is the ventilation standard.

BG seem to be almost have a policy of "if it's open flued comdemn it first then send in the saleman".

The correct action should be to decide if the installation is to standard or not and then follow the correct procedure [1] based on the findings.

Having said that the pay back period for replacing this system could be around 10 years. That's a good enough reutrn to even borrow money for the heating system upgrade.

[1] Either: OK but very old. Not to current standard but no cause for safety concern. At Risk of become unsafe, needing immediate (and possibly uneconomic upgrades) Immediately dangerous. Turned off now to save life or property.

[John Stumbles]

No, that's the flue. That's where burnt gases go out: there's no way for fresh air for combustion to come in down it.

The boiler must have permanent ventilation direct from outside: a window that's close-able isn't permanent ventilation. If you'd closed the window and draught-proofed the kitchen and come home to find your family dead (but warm and cosy) you wouldn't have been too happy that he hadn't exercised his legal duty of care to you and them.

Sensible, but doesn't change the legal position and duty on the fitter.