Odd chimney arrangement

[jdsnape]

Hi!

We are in the process of buying a thatched 15th century in farmhouse. The previous owners did a great job restoring it (we've checked permissions etc.) so I don't anticipate a lot of work, but there is one thing I can't quite figure out whether we'd be able to resolve and I thought I'd see if anyone had any ideas.

The house is a hall house, and in the middle is large inglenook fireplace with open fire.


The chimney was rebuilt, but is unlined - as you can see from this photo taken straight up:



The vendors had it partially re-built and re-pointed a few years ago, so I'm not too worried about its state with an open fire.

However, the house also has a solid-fuel rayburn, which I think is probably about 50 years old. Its flue simply goes through the side of the chimney breast and into the open chimney:


When talking to insurance companies, one of their stipulations is that chimneys must be lined for the rayburn to be used. I don't think I can claim that is the case here...Clearly it's worked ok for the last half a century, and the people who live there now do use it (it was on when we looked round - although I suspect they might be in trouble with their insurers if it was on and they had a fire...)

We still want the house and can live with not using the rayburn, but it might be nice to have available for the depths of winter. However, I can't really see a way you could add a flue for the rayburn to comply with insurance requirements and continue using the open fire, unless anyone has any ideas?

 

[a twig]

One option is that you would have to fit a gather for the open fire, solid pipe up to a swept tee to join the Rayburn in and then liner on up to the top.

Will be expensive as all of it other than the gather will need to be a 904 grade of stainless that copes with multi fuel and will still have the risk of condensed gases from the Rayburn running down into the open fire. And the gather will be a custom fabrication to fit your chimney, probably looking at £3-4k ish for all the metal work with prices these days.

Only other option if the existing chimney is wide enough would be to run two liners up, a gather and a cheaper 316 liner for the open fire, and then a separate 904 for the Rayburn.

 

[jdsnape]

Thanks - I'd considered joining the rayburn in but I don't think it'd meet building regs, as they say you can't have appliances in different rooms connected to the same flue.

I guess two liners would have to the the approach if there's space and I can get approval - I guess they might not like the idea of two chimney pots appearing on the top!

Since posting I came across the Eldfast chimney lining product which is in effect a re-parging of the chimney with a ceramic lining. I wonder if anyone's had any experience of that? My guess is that lining the chimney with that would satisfy the insurance requirement. The rayburn still wouldn't comply with modern regulations but as it's not a new installation I don't think I'd be required to bring it up to spec?

 

[a twig]

Would be a tricky argument as generally in my experience if you are making significant changes to something then you are expected to bring it up to modern standards.

Insurance aside, I would have thought that the biggest risk from the Rayburn install is more about gases, CO etc coming back down and out the fireplace as there will be a huge drop in gas velocity as it comes out into the cold large volume of the open chimney. I wouldn’t be overly comfortable with using it installed like that to be honest.

If you really wanted the Rayburn could you run a new twin lined flue a different route?

 

[CliffordPope]

Insurance aside, I would have thought that the biggest risk from the Rayburn install is more about gases, CO etc coming back down and out the fireplace as there will be a huge drop in gas velocity as it comes out into the cold large volume of the open chimney. I wouldn’t be overly comfortable with using it installed like that to be honest.

Our Rayburn had been installed like that decades ago, probably when they got rid of the old range. The pipe had been cemented into the stonework from the outside and at some point about half way up the gable wall it met another old flue from an open fire, still in use.
Neither fire nor Rayburn drew properly. The Rayburn was very prone to blowing smoke back down into the kitchen, and when not in use the vent created by the cold Rayburn flue pipe reduced the suction from the upper chimney section of the open fire, so that smoked in the adjacent sitting room.

We were able to put in a new insulated flue for the Rayburn up the corner of the kitchen into the small fireplace in the corner of the bedroom above, which we removed, and then on up to the original corner stack that had served the bedroom fire.
Can you run the Rayburn flue out somewhere else, if necessary changing the outlet direction at the box on to of the Rayburn?