Open (vented) gas fires and flues

[Chris B]

I have a relative who has lived in the same house since childhood. The house has no central heating but has several open (as in vented - rather than room sealed) gas fires.

The fires are not serviced on a regular basis but the gas man is called in when they fail to work properly.

In one location a "black Annie" style stove was removed from an alcove in the '70s and replaced with a vented gas fire, exhausting into the existing chimney. A schematic is shown here

Side view at the top and front view below. The bottom of the chimney is sealed off with a steel plate and originally the fire exhausted into a stub pipe just above the level of the steel plate. Around the late 90's early 2000s one of the repair men was unhappy with the situation hypothesising that soot could fall from the chimney and block the outlet so a sort of shroud/cap was fitted into the base of the chimney box to deflect any soot and ensure that the exhaust stayed open - as shown.

On the front of the chimney breast is an access hatch (presumably to allow the chimney to be swept) as shown in the sketch and in this photo

On the most recent visit of the gas man he is now unhappy with this hatch and wants it "bricked up". He seemed to be saying that as it is, it is unsafe because someone might take it off and let fumes into the room. I would have thought if this comes off the direction of air is most likely to be out of the room, and why would anyone take it off anyway. Is anyone sufficiently familiar with the regs and know what he might be getting at. It seems odd to me as if it is bricked up it will never be possible to inspect inside that cavity for soot or dead birds.

Any thoughts/advice welcome.

[Andrew Gabriel]

I think you have demonstrated you have more competence than the gas guy they're using - he sounds out of his depth which is worrying as he might also be overlooking some other potential issues. I agree the access hatch is required for maintenance. If the flue is operating correctly, there should be a draw at the hatch similar to that at the appliance. Obviously, that should be checked. There's usually a second door behind the visible one, held in place by the outer door. From what I recall, it would have been possible to fit a gas-tight seal around the edge of the second door, but if fumes leak from there, they will be leaking directly from the appliance too, so there's no point.

In the home as you describe, I would ensure there's a carbon monoxide detector in each room with a gas appliance, and each bedroom.

Needless to say, these appliances are horribly inefficient compared with any modern gas boiler. I still have a gas fire, not used for years but still works and available as a backup if the heating died. IIRC, it's heat input is 6kW, which translates into 4kW up the chimney, 2kW out to the room, and a cold draft into the room to supply the fresh air for the fire (although in my case, I arranged that to enter the room through the hearth under the fire, so it didn't come across the whole room as it usually does).

Andrew

[The Natural Philosopher]

The recommendation of 'safety' upgrades is governed by two impulses.

1/. The impulse to cover ones arse. 2/. The impulse to sell more shit. I caught an electrician lying to me. I wont ever use him.

[charles]

There is a 3rd reason: The "inspector" is out of his depth.

[The Natural Philosopher]

In Blair's Britain, that is a condition of employment

[Fredxx]

Remind us, how many years ago was it Bliar's Britain?

Do you always live in the past?

[Andrew]

Actually I tend to take the side of the gasman. The gas fire should have been connected to a flexi-liner that went all the way up to the chimney pot and be mechanically restrained at the top and sealed into the pot.

Radiant gas fires aren't so terribly inefficient and the Gazco fake wood burner gas fires are pretty good and need no electricity to run.