Vent for back boiler

[delboybully]

I have had a single story extension added to my terraced home. The living room opens directly onto the extension with no doors, just a large opening. In the living room I have a back boiler with a fire on the front. I used to have a vent on the old external wall (this wall is now gone). I told my builder I wanted/needed a vent in the new external wall of the extension as a vent for the boiler.

The builder has fitted what he calls a 'hit and miss vent' on the inside of the wall. Its one of those vents that you can manually open and close. I told him this isnt correct and the vent needs to be continually open due to the regulations for my gas boiler. I have had my boiler serviced before the extension was added and they have checked the previous vent and said it was ok as it could not be closed. When I had cavity wall insulation put in, the installers took off the inside part of the previous vent and they found a fly screen on it and this had to be taken off

The builder says that this 'hit and miss' vent is ok. He said what is the point of puttin all the insulation in if you are going to leave a large hole in the wall. He also said what if you get a gale force wind coming through it

I think i am right and the builder is wrong. Can any gas registered installer (used to be corgi) tell me which type of vent is legal

On the ouside of the vent hole he has put one of those bricks with lots of square holes, this brick vent is one brick in length and 2 bricks in height. Is this ok. The hole throught the wall is the same size and the brick vent- not a round tube

 

[expertgasman]

[
The builder says that this 'hit and miss' vent is ok. He said what is the point of puttin all the insulation in if you are going to leave a large hole in the wall. He also said what if you get a gale force wind coming through it

You are right. the bulider has committed an offence (seriously!). The vent must be pemanently open. 5cm2 perKw over 7kw of maximum boiler input.

 

[delboybully]

The boiler was installed about six months before they stopped making back boilers (im not sure but i was told they were banned), it is about 7 years old or so

Its a baxi and its output is 55,000 BTUs for the boiler plus the fire

 

[kirkgas]

The boiler was installed about six months before they stopped making back boilers (im not sure but i was told they were banned), it is about 7 years old or so

Its a baxi and its output is 55,000 BTUs for the boiler plus the fire

contact the builder and tell him he has contravened Regulation 8 of the GSIUR (the gas regs) and if anything was to happen to anyone in the property from a CO poisoning he would be held liable as he has altered the ventilation to the detriment of the gas installation, (therefore increasing the % of CO poisoning as he has reduced the vent) this is very urgent and you need to demand it is rectified ASAP, if he is adament it is OK get a Gas engineer in (who will confirm you are right) then bill him and report him to building control and Citizens Advice and gas safe register who might/might not/probably wont get involved, whatever or whoever attends to this it is vital it is done NOW as there is a potential problem for you and yours, and your builder is a chancin scumbag who doesnt know what he is talking about and rather than pay £40 to get a gas safe guy to check/sort you out he would rather risk your families life,
when deciding on ventilation it is the INPUT that is required not OUTPUT (MAX HI-7x5 gives cm2 ventilation required, supplied by a gas approved vent type) to determine how much air is getting in the vent measure area of 1 vent hole (LxB in cm) then multiply by the total number of holes in the vent to give total, then permanently open or remove the closable inside bit, HOWEVER this is still not 100% correct as the air brick cannot be properly connectedd to the sleeve(which should be fitted) through the wall, but may allow you to use it until rectified, however i would urge caution in checking the vent unless competant

 

[delboybully]

I knew i was right

Ok so i have measured the double air brick (on the outside) and it had 40 square holes in it and each one is about 1cm by 1cm which makes 40cm squared. I have been doing a little research on the internet and it seems Stadium do a vent (BM700) that is anti draft and does 100cm squared.

http://www.gasproducts.co.uk/acatalog/Stadium_BM700-5_Black_Hole_Brick_Ventilator.html

This, i think, this will do the job and reduce wind blowing into the room and at less than £25 including delivery

If the builder wont fit one then i am going to get a gas engineer to check it out and if (when) he says its wrong i am going to present this to the builder and he can pay the gas engineers bill and the cost of coreecting the vent

 

[expertgasman]

I knew i was right

Ok so i have measured the double air brick (on the outside) and it had 40 square holes in it and each one is about 1cm by 1cm which makes 40cm squared.

You need 45cm2 of free air. Is your external vent masonry or plastic? If masonry, the hjoles generally taper down square holes in into he interior. One must measure the smalest part.

You could use the following to report the builder, although it talks of illegal gas worker, rather than builder. It will, however, get the attention of Gasafe, and it MAY do some good. Theres no point in reporting AFTER it's rectified as there wil be no evidence. In the meantime, leave a window ajar, to the extent of having 45cm2 of air available. It actually isn't a lot.
http://www.gassaferegister.co.uk/report_business_form.aspx

 

[45yearsagasman]

Is the input of the fire not taken into consideration when calculating vent requirements of a fire and bbu?

 

[delboybully]

The outside air brick is of the masonary type.

The builder put the vent in tuesday and when i got in on tuesday evening i phoned him to tell him it was wrong and he said it was alright.

Today i phoned the gas engineer who installed the boiler and he said i needed the same vent as i found on the net last night (the one in the link i inserted)

So i then phoned the builder and told him the vent is wrong and needs to be changed and that i could get one for less than £25 delivered. The builder then said to get it and he will fit it and knock the cost of the vent of off the final bill. I didnt even need to mention about the advice you all gave and what the gas fitter said. Either he has checked and found the vent installed is the wrong time or it may be because after the sub floor has been install its final payment time!!!!


I currently have the 4 velux windows open a jar to help dry out the paster so i am ok for air flow at the moment!!!

 

[Agile]

The holes in the air brick are usually 9 mm as I recall from assessment calculations we have to tediously redo every five years.

That is fine! But it does need to be tubed through to the inside so it does not communicate with the cavity.

The inside plastic grill is available for about £4 at Wickes and has the words "Gas vent, do not cover".

There is no need for the Stadium vent.

Builders are not gas trained and although many know about boiler ventilation many dont!

Tony

 

[expertgasman]

Is the input of the fire not taken into consideration when calculating vent requirements of a fire and bbu?

Well spotted. Of course it is, my mistake. so would be about 18Kw, so allow 55cm2

 

[OLLIE20]

Air bricks are not ok for a gas vent. The holes go smaller from one side to the other, even with the inside vent correct, it would be classed as At Risk, with an air brick outside

Dont forget the Back boiler/ fire will need a spillage test carrying out once the vent is done, as combustion air has been effected and needs rechecking, ofcourse you're builder is qualified 2 do this

 

[delboybully]

Builders are not gas trained and although many know about boiler ventilation many dont!

Tony

This is true but i would of expected the builder to either to know what the correct type of vent is or to have got someone in who does.

I had told him that i needed a vent for my back boiler when he quoted for the job, its on the plans and i have mentioned it several times to him. It is lucky for me that I knew the inside vent he installed was wrong. Having said that if he had installed the correct vent on the inside then i wouldnt have found out that the vent as whole was wrong i.e. the air brick and no tube from one vent to the other.

Anyways i have ordered the Stadium vent and once it arrives the builder is going to fit it

Once the extension is finished i am going to get a gas engineer to service my boiler and i will also ask him to do a spillage test whatever that is. Does a normal boiler service include a spillage test or will i have to pay extra for this

 

[MrGassafe]

Air bricks are not ok for a gas vent. The holes go smaller from one side to the other, even with the inside vent correct, it would be classed as At Risk, with an air brick outside

Billhooks. Where did you get that information from?

You did get the bit about the holes tapering from outside to inside right. You calculate the hole size from the smaller side.

Terra Cotta air bricks are ok for permanant air vent.

Just make sure enough holes to get correct vent size or insert more air bricks.

 

[OLLIE20]

Air bricks are not ok for a gas vent. The holes go smaller from one side to the other, even with the inside vent correct, it would be classed as At Risk, with an air brick outside

Billhooks. Where did you get that information from?

You did get the bit about the holes tapering from outside to inside right. You calculate the hole size from the smaller side.

Terra Cotta air bricks are ok for permanant air vent.

Just make sure enough holes to get correct vent size or insert more air bricks.

So how do you know which is the smaller size, if the brick is fitted with the big holes outside, you cant measure the inside, are you telling me you presume the size of the holes, Leaving yourself wide open

You can not use Air bricks as a gas vent

 

[Stamina]

Air bricks are not ok for a gas vent. The holes go smaller from one side to the other, even with the inside vent correct, it would be classed as At Risk, with an air brick outside

Billhooks. Where did you get that information from?

You did get the bit about the holes tapering from outside to inside right. You calculate the hole size from the smaller side.

Terra Cotta air bricks are ok for permanant air vent.

Just make sure enough holes to get correct vent size or insert more air bricks.

So how do you know which is the smaller size, if the brick is fitted with the big holes outside, you cant measure the inside, are you telling me you presume the size of the holes, Leaving yourself wide open

You can not use Air bricks as a gas vent

http://www.transtools.co.uk/store/p...onument-2580u-vent-sizing-gauge-5mm-10mm.html