Inset gas fire, opening in fire place is too large

Hi,

Any thoughts, ideas, advice are appreciated.

I have a homemade/handmade fireplace (real chimney behind it as once there was an open fire).

I have decided to remove the old valor external gas fire and replace it with an inset Kinder (glass fronted if it matters). My problem is the opening where the fire has to go through is bigger (both height and width) than the fire (and for this matter any gas fires I have found).

That is, the existing opening is width = 460mm height = 600mm

Gas fire based on its flange needs Width maximum = 450mm Height maximum = 570mm

All I can think so far is to create a stainless steel flange (two sides plus the top) and put on the back of the fireplace and create a smaller opening. Is it a likely solution? (Waiting for a heating engineer to come next week).

How solidly would it have to be placed on the fireplace glued? screwed/bolted? (I might as well break the back plate of the fireplace and be done with it).

How do inset fires get placed in the opening so they are sealed for gases escaping back in the room? (normal chimney).

TIA Charles

PS. I do not intend to fit the gas fire myself, but I have so little feedback from the supplier/fitter company that it gives me the impression they are not interested.

PPS. A wide flange would not be an aesthetic issue as it would be bigger than the surround of the gas fire ... fire and flange would be steel.

you need to reduce the size of the opening to those stipulated in the manufacturers installation instructions, preferably by bricking up and plaster the outer surface so its flat to form the seal on to the fire box of the fire using the foam seal. If you have a flat surround that is on the wall this would give you a better surface for the fire box and its seal, but you most seal all around the inside of the surround back, and hearth i.e. between the wall and surround back and any other openings which could let air flow in to the chimney, air must only enter the chimney thro the fire. First of all make sure your chimney is in good condition by performing a smoke flow test with a suitable smoke pellet, again smoke should depart the chimney only by the correct suitable pot and not any where else such as the pointing etc. Or is the problem that you already have some kind of surround you are trying to preserve?

Many of these fires use cables fastened in to the back of the opening that pull the fire back so stainless flanges may not be suitable as thy would be pulled back, they are sealed simply by a foam seal around the outer flange of the fire box compressed as the fixing cables are tightened.

Hope this helps.