Chimney flute problem

Captain Kidd

Hi, I recently moved into a house and have no idea of past use of the fireplaces, though I do know they had been used as I had to clean them out when I moved in. I’m going to get a chimney sweep in to clean them but in the dining room fireplace I noticed something strange and was hoping someone here might be able to shed some light on it.

The dining room fireplace at one point was converted to gas but at some point this was disconnected and the previous tenant was lighting fuel burning fires in it regardless. I have attached two images. One image is the fireplace, the blue arrow is pointing to the main chimney opening and the yellow arrow points to what feels like a flat stepped ridge, one section of the ridge seems to be damaged and I can feel a type of insulation up there. The second photo shows this.

First of all, is this insulation and covering something that was put in perhaps when it was converted to gas? Or is it an original part of the chimney. I’ve used Fire cement stone in the past, could I just cover this up to patch it? Thanks for any help with this.

Danzy

It it an old back boiler looks like one.

Captain Kidd

Thanks, would I be right to say that a back boiler is part of a gas fire place that is used in heating the house in some way? This fireplace was once a gas fireplace by the looks of it but was disconnected. And has been used by the previous tenants as a fuel burning fireplace. If this is a back boiler would that mean it’s dangerous to allow a fuel fire (briquettes, coal etc) in this fireplace.

also would you recommend I fill up this hole with fire cement?

really appreciate the help,

thanks

The Continental Op

Back boiler would have been part of an open coal fire. Could have been decommissioned when the gas was put in. You can leave them in place but need to open up the boiler so it can't get pressurized and blow up. Normally the connections are left open at the back (would connect to a Hot water tank) and sometimes you see a couple of holes drilled into the front.

The back boiler often has a adjustable vent where your blue arrow is pointing (but near the middle of the choke). The vent could be opened to allow the heat from the fire to go up behind the back of the back boiler so more of the heat went into the back boiler or closed if you wanted more heat in the room. I suspect the fiberglass fills up the gap behind the back boiler.

If you aren't sure its been decommissioned properly to be sure to be sure you could drill a small hole into the back boiler. If its not metal then its not a back boiler and I'm talking rubbish ;-)

My guess is, it’s an old back boiler judging from the copper colour. The insulation looks old… hopefully not flammable!

Shine a torch up the chimney to get an indication of any hardened deposits. A chimney sweep can sweep out the soot, however, given that the fireplace had a back boiler, this can have a condensing effect on the smoke going up the chimney and lead to hard deposits forming up the flue which can result in chimney fires.

Burning a fire will be highly inefficient. If it were me I’d look into getting a stove fitted - have the back boiler removed, have the chimney scraped (out by a professional) -ideally the stove fitter would do this, insert a flueliner, new insulation and a decent cowl to prevent water dripping down the chimney. The stove will also eliminate the air of the house being sucked up the chimney (as is the case with open fireplace). With rising price of gas/elec, a stove is a great stand-by to have.

oh…one more thing- don’t drill a hole in the back boiler…if it is still connected to the water 💦…you’ll find out the hard way!

Captain Kidd

Thanks for this, apologies for getting back to this late, but I really appreciate all the comments and tips.