I am planning the flue route from a combi boiler to the world
> outside and I have to pass an obstruction - an internal plastic > sewage pipe.
Plastic sewage pipe, hot flue... hum not a combination I'd like to live with at least not at that spacing. Check with the makers of both the plastic pipe and the flue how close they reckon they can be to each other.
Look on the bright side. You'd know pretty soon if it went wrong, hence reducing the consequential damage.
IanC
As far as I know, and I've looked at a lot, combi flues nowadays are round,
100-120mm. They are concentric pipes. The inlet is on the outside so the outer pipe, which is usually plastic anyway, is quite cool. As you can safely hold such pipes when the boiler is running I can't see it being a problem near to a soil pipe. Though 60mm sounds to me like a no-no
The Keston Celcius 25 would easily flue past this. However, it isn't a combi. You could make it into a combi by adding a plate heat exchanger, diverter valve and flow switch. I believe DPS make such an arrangement (DPS Showermaster), or you could cobble it together yourself.
The other alternative is to go the whole hog and install it with a mains pressure hot water storage system, such as an unvented cylinder or heat bank. Keston sell the boiler actually preplumbed into their Spa cylinder for this. However, the price of the combined unit appears to be considerably greater than buying the two separately for some reason.
Christian.
Can't think of one offhand - Glow worm used to do a rectangular fan flue wall mounted conventional boiler but AFAIK that particular model is now discontinued.
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