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Fitting gas fire into old fireplace - gas man's advice


 
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Chapster

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PostPosted: Tue Feb 23, 2010 11:55 pm Reply with quote

Hi,

If anyone has the time and doesn't mind helping, here's a brief background of the issue: got an old fireplace which contained a Baxi back boiler with integral front gas fire until recently when central heating was fitted. I have a new gas fire I would like to put in the fireplace hole that's left.

When the gas men were here fitting the central heating, I asked for advice on doing as much work as I could installing the fire. Here's the fireplace which seems to be regular house bricks and mortar with a concrete plinth base:

The fire has no closure plate, it just has a letterbox slot in the back. The gas man said as it was second-hand, the closure plate probably stayed with the previous owners, but that we could make one from sheet metal and just cut a letterbox opening to match the fire's one.

The chimney has a liner which attached to the old Baxi boiler's circular flue vent pipe:

He said that first I had to make a plate from sheet metal with a hole in it for the liner pipe. I should fit this up in the chimney just above the opening hole level and seal around where the liner passes through the metal sheet with fire cement, leaving a portion of the liner exposed. He then said that we could either just have the flue gasses passing through the letterbox opening made in the closure plate into the cavity and up through the liner, or buy an adapter to fit over the letterbox opening of the plate, converting it to a circular flue to attach to the liner.

He also said that regardless, I would have to render the entire inside of the fireplace with fire cement, ensuring it created a sealed space with no gaps for gasses to pass through between bricks, etc. The problem is that I'd have to buy 10 or more tubs of fire cement to render all of the inside of the fireplace and it's not that cheap. Does it really need fire cement when the original fireplace is nothing more than bricks and mortar of the regular kind?

And is his advice sound? He was a Gas Safe registered employee of a large firm. But is it the best method to do the job? I don't mind getting it inspected and the actual gas connection made by a Gas Safe chap but want to save the pennies by doing the rest of the work myself ready for inspection.

Any advice greatfully received, thanks
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wotan

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PostPosted: Wed Feb 24, 2010 10:05 am Reply with quote

Heed the advice he gave you, no matter what the fire cement costs, it's cheaper than being poisened by C02.
I would also get the adaptor plate that converts the letter box slot, back to round so that it can be fitted to the existing flue liner, you will then have two lines of defence.
Have you tested the liner with smoke pellets, to make sure it's drawing ok? as there would be little point in continuing, if the liner was blocked or inadequate.

Wotan
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lifesagasman

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PostPosted: Wed Feb 24, 2010 4:48 pm Reply with quote

do you have the manufacturer's instructions to go with the pre-owned fire?
do they tell you how the fire may be connected to the flue? they are the only valid instructions which may be followed. if they don't allow direct connection to the liner then the flue pull may be too strong. if you can't get the insructions from somewhere you shouldn't be fitting the fire. simples

i was just sitting here eating my yellow-sticker pork pie, and i began wondering, why do closure plates have that little hole cut into the bottom? is it to let spiders in and out??
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joinerjohn

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PostPosted: Wed Feb 24, 2010 6:29 pm Reply with quote

I asked a very similar question on another forum a few weeks ago. My father was having a new gas fire fitted (to replace his existing one). He had been told that the flue liner had to come out.
From the responses I got , it seems that the fitter has to be sure that the existing liner would last the lifetime of the new gas fire. As it's near impossible to ascertain this then the liner has to come out. I personally couldn't see the point in taking a liner out though. Just seems like added expense (as the company wanted another 100 to do this)

In your photo, I assume the pipework at the back of the opening was for the original back boiler but has been altered.
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lifesagasman

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PostPosted: Wed Feb 24, 2010 6:33 pm Reply with quote

so many things to do with gas add expense
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Chapster

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PostPosted: Wed Feb 24, 2010 7:41 pm Reply with quote

Thanks for the replies, I'll try to answer all points raised:

I wasn't thinking of not rendering the inside of the fireplace as I understand the reason is to stop CO leaking through any gaps, but I wrote my post above late last night after losing the original when the computer crashed and missed things out. I meant to ask if it would be permissible to render with ordinary sand/cement render instead of fire cement. For a start, the fire cement states on the tub that it requires a fire to be lit in the fireplace after application, for the high temperature required to cause the stuff to set. Then there's the price... I just didn't think it'd get hot enough in there to warrant fire cement, especially since it was built, and used decades ago, as an open fireplace with bricks and mortar and nothing more.

I don't have any manufacturer's instructions, but plan to get them if possible.

The 22mm pipes in the photo: these were indeed altered when the central heating was installed 3 weeks ago. Originally they were flow and return pipes from the back boiler for heating and hot water. Now they've been jointed across and re-routed to supply the downstairs radiators with flow and return lines.

Regarding the liner, I asked a Gas Safe colleague at work about that. He pointed out that many liners were added in these properties in this area for back boilers due to the chimneys leaking. He's right about the leaking, because my attic still had a slight smell when disturbed, and the sooty remnants beneath the old fibreglass, of smoke coming through from the terrible chimney brickwork (1950s house). The liner looks to be in good condition... Until 3 weeks ago, it was connected to a fully working and often used back boiler and gas fire.

I've checked the draw and it's strong, using supplies from the gasmen at work. Of course, we have a CO alarm as a precaution as well from when the back boiler was there. Of course, I'd expect the gas man to check such things as well after doing the gas connection.
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lifesagasman

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PostPosted: Wed Feb 24, 2010 8:43 pm Reply with quote

sand and cement are commonly used, but if the chimney will be lined why not fit a flue box?

regarding the flue pull, it probably will be strong with a liner, but the point was does the manufacturer allow the fire flue to be connected directly to the liner with an adaptor, as someone has suggested, and the answer will possibly be NO.
that's why you need the MIs, they are the legislative documents regarding how the fire may be fitted, if you need secondary air via the closure plate, diameter of liner, etc, etc, etc
one other point, regulation 29 of gas regs requires that any person who installs a gas appliance (new or pre-owned) shall leave for the use of the owner all instructions provided by the manufacturer accompanying the appliance, which is a formal way of saying that if you fit an appliance without MIs you are actually breaking the law. that's why many installers won't fit used apps with no MIs. It's a legal minefield out there.
it will be you that has to live with it, so it's worth getting it right, no?

stay safe
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kirkgas

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PostPosted: Wed Feb 24, 2010 10:00 pm Reply with quote

the cut out at the bottom of the closure plate is to allow air into the catchment area
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lifesagasman

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PostPosted: Wed Feb 24, 2010 10:23 pm Reply with quote

does it act as a draught diverter?
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