Fireplace question

Martron

I know it will be hard to say either wa about this but......

i have a house built 4 years ago and it has a chimney. and a precast fireback. but was intended for a gas fire.

the question is ..... can i light a real fire in it? there is a gap between the flue and the precast backing. i can put my hand in it and feel down behind the precast fire back. . i am wondering will this be a hazard?

who can i call to inspect the chimney/fireback to see if its safe?

there is a gas pipe in the middle of the floor of the fire but there is a gas valve well away from that and its not an issue.

the fire heath has a joint in it so i am not worried about it cracking with the heat.

any advice? number of people that can help. i live in rush dublin.

( i see a neighbour of mine has smoke coming out of the chimney...... so its not impossible but does not mean they have done it right either)

Mad_Mike

Its not necessarily a hazard, but just a few points.

If I was lighting a fire in the fireplace, I'd disconnect the gas pipe at some stage along the line, regardless of whether there is a valve in place or not. That's just a personal thing. I wouldn't trust a valve!

Its odd that a precast fireback was used for a gas fire. They are normally used with a ceramic fibre fireback which is almost like board.

Is the wall behind your fireplace an inside or outside wall?
Firebacks should be filled behind with an insulation material. So if for example its on an outside wall and you light a fire, all the heat will pass through the fireback and out the back wall. It will also be hard to get a fire going in it as the back of the fire will be constantly cold.

The best thing to fill behind the fireback with is perlite (insulation material) mixed about 6:1 with cement. Let me know what the story is and I'll see if I can point you in the right direction anyway

Martron

there is a gap of about 50mm to 75mm of fresh air between the fire back and the wall joining to the neighbours house.

i was going to get the gas tapped off if it was possible.

my worry is the gap between the firback and the chimney and the fact that this goes into a gap behind the fireback.

Mad_Mike

Well first of all, the gap behind would have to be filled
1. To stop heating your neighbours house! and 2. If there is a gap that large, you risk soot falling down the chimney and catching fire behind.

Its actually very very simple to do and right on the top you slope it down towards the fire so if any soot should fall down, it falls into the grate area.

I'm in Mullingar myself. Only place I know any way near to you would be a place called Clifford Fireplaces in Dublin itself

sinjim

I know im late in to all this but i actually work for Cliffords Fireplaces (thanks Mad Mike:) ). Firstly you say there is A joint for solid fuel your hearth should be in 4 pieces, secondly its not unusual to use a fireclay fireback in fitting a fireback, then a fireback should be filled with a VERMICULITE, cement, and water mix in 6,1,1 perlite will do but its not as good of an insulator.
All in all make sure your hearth is in 4 pieces, the gap at the top simply fill with sand and cement as Mad Mike said, with a good slope down, turn off the gas at the valve to the side and remove the gas pipe from the fire opening.

Mad_Mike

Hi sinjim. Thanks for posting on here for Martron.
Just one interesting point, regarding Perlite & Vermiculite.
It's actually Perlite which has a higher insulation value.
It's R-value is 2.7 per inch compared to 2.08 for Vermiculite
I always thought Vermiculite was better too until it was recently pointed out to me

Martron

so the sacks of perlite....... can i just pour that into the void or will i have to bind it with cement?

( have not got around this yet...... but intend to before the winter. )

sinjim

Hi again, the perlite,vermiculite argument rages on . Perlite is a better insulator when it comes to standard cavity filling, ie dry poured into a wall cavity, vermiculite however preforms better as a ''wet mix'' or so i've been told ,mad mike im very open to correction id love to rub it in some of those architects faces who constantly insist on vermiculite, especially with the price per bag now as it has recently become a traded commodity in asia! .
Martron weather you use vermiculite or perlite there both the same mix 6,1,1(vermiculites a bit less messy and more readily available) there both around €25 in our place

sinjim

Mad_Mike wrote: »

Hi sinjim. Thanks for posting on here for Martron.
Just one interesting point, regarding Perlite & Vermiculite.
It's actually Perlite which has a higher insulation value.
It's R-value is 2.7 per inch compared to 2.08 for Vermiculite
I always thought Vermiculite was better too until it was recently pointed out to me

I wasn't sure what an R value was mike, seems to be just an american version of our U values. The higher the u uvale the more heat travels through the element which as i understand it to mean that more of the heat from the fire would essentially travel into the perlite therefore the vermiculite would be a better insulator??
e.g a window with a u value of 3 would allow more heat escape from a house than a window with a u value of 1 ?
Again i could be wildly wrong and am open to correction

Buford T Justice

Martron wrote: »

so the sacks of perlite....... can i just pour that into the void or will i have to bind it with cement?

( have not got around this yet...... but intend to before the winter. )

Mix it up with a sand / cement mix, and drop it down the back of the fireback and fill up the void.

sinjim

Fingers McGee wrote: »

Mix it up with a sand / cement mix, and drop it down the back of the fireback and fill up the void.

No sand, just cement water and perlite/vermiculite

Buford T Justice

Aah, i was close.