Are you wondering Can I Still Have My Boiler Flue Down My Chimney?
If you’re looking to upgrade your central heating system from an old, open-flued appliance (and save a significant amount of money on your energy bills in the process!), you may be used to having your boiler fluedown your chimney.
And if you could have the same set-up with minimal upheaval, it could mean a quicker, cheaper boiler installation! But hold on… with modern, sealed appliances, is it even possible any more?
The good news is, it just might be.
Below, I’m going to tel you about Worcester Bosch’s internal chimney flue system, and how to tell if it could work when installing your new boiler.
A bit of background on chimney flues
To many, having a flue down your chimney nowadays seems a bit old fashioned and alien by modern standards, but many years ago, before boilers had fan flues, the maximum length a flue could go through a wall was around 14 inches – or a standard, two brick-thick cavity wall.
With this being the case, it meant all properties with thick walls could only fit boilers with the flue (a long, flexible metal liner) going up through the chimney. Boilers fitted this way were called open-flued appliances, which meant the boiler took its air from the room and fumes naturally drifted up the chimney.
These days, open-flued appliances are becoming obsolete and are no longer available to purchase, although you may still have an old back boiler or open-flued appliance installed in your home – as years go by, they are getting increasingly rare.
Why have a boiler flue down your chimney?
As many old boilers were fitted in basement areas, kitchens and boiler rooms, it meant all the pipework, valves and wiring would also be in this location. Relocating the boiler could mean lifting carpets, flooring, expensive tiling, and opening up pipes, access hatches and pipe boxes.
Sounds like a lot of trouble, doesn’t it? So, to keepdisruption and upheaval to a minimum, it may be your only other option is to have your boiler flue down your chimney.
Nowadays, this is a fairly uncommon practice, but I do know of one way it might be possible…
Worcester Bosch’s internal chimney flue system
The only flexible room-sealed liner for a boiler that I’m currently aware of is Worcester Bosch’s internal chimney flue system, which is designed for their floor-standing Greenstar CDi regular range of boilers.
NOTE: Baxi used to manufacture a similar system for their high efficiency fire and back boiler range, but this is now obsolete. There may be other systems out there that I am unaware of.
How it works
Your chosen boiler (for example, the Greenstar FS 30CDi or FS 42CDi) can be fitted or piped just like a regular boiler, but instead of a concentric flue going through the wall with a 100mm duct drawing in air, and a 60mm duct expelling the fumes, a concentric flue goes from the boiler to the chimney.
Next, an 80mm plastic, flexible liner is fitted from the top of the chimney and connected to the end of the exhaust section of the flue, from the boiler located by the chimney. The boiler works just like any other room-sealed appliance, only the air intake is provided from the chimney drawing fresh air from the outside.
As an example, we fitted one of these on a job in Lanark recently. The client had an existing floor-standing boiler in the basement (which had a stone floor) and a flue in the chimney. He wanted a direct replacement, however all previous engineers quoted to move the boiler to the garage.
It was going to involve running a lotpipes and general upheaval, so a flue could go directly through the outside wall. I suggested the direct replacement floor standing boiler with room-sealed flexible flue liner. The cost was much the same as he had been quoted for relocating the boiler, but with a lot less fuss.
How much does it cost?
These systems are by no means cheap, and are looked on as a specialist solution for tricky situations. I’d say on average they are around £1,000 more expensive than simply replacing a boiler like-for-like. However, it could save you even more on redecoration and reinstatement.
If you have no access to an outside wall, this may be your only option to fit a gas boiler. Again, you’ll save on fuel, as fitting a gas boiler rather than a costly electric heating system will help save money overall.
Conclusion
I hope you’ve found this blog helpful when looking at all your options for installing a new gas boiler – but remember, Worcester Bosch’s internal chimney flue system is only suited to a very specific niche, and you’d need a floor-standing regular boiler. It won’t work with combi or system boilers.
They can also cost around £1,000 more than simply replacing a boiler like-for-like, so it’s wise to weigh up all your options and decide if it’s going to be worth it.
Have any questions about fitting an internal chimney flue system? Let me know in the comments section, or alternatively, get in touch with me directly. I’d love to hear from you!
I believe i may be in the situation described in your blog, as my floor standing boiler is in the kitchen and the flu goes up the chimney. years ago think there was a kitchen range there.
Useful article – thanks for posting 🙂
We have been struggling to keep an aged floor standing boiler with a flue going up a chimney going but parts are getting harder and harder to find and I am aware that we are burning a high %age of gas just heating up the local neighbourhood ! Why a replacement seems to be such a rare object surprises me – you would think there are many thousands of people with older properties with a cellar and chimney like us where it seems the obvious place to put the boiler.
P
Anyway, thanks again for the article – I have read on several other sites that Worcester boilers are recommended so to find that they also offer a chimney based solution seems good news.
Very interesting.Does your solution require several inspection hatches along its length,as we have been told?
i had exactly the same problem with my kitchen on the streeet side of a listed building in Edinburgh where a 30 year old boiler ( still working perfectly) was located. The flue was an aluminium liner going up the existing chimney. We decided to change the boiler as no one wanted to service the unit as it was deemed not to comply. However the new boiler would need to be placed on the other side of the building in a bedroom as the opening is not allowed on the street side. Scaffolding would be required to break through the 6 foot wall and all pipes to the new boiler would need to be new as well. To get to the boiler our 200 year old limestone floor would need to be lifted as would timber floors! I was horrified and I couldn’t believe there was no solution. After some detective work I found Viessmann Boilers make a combi wall monted boiler which was suitable for compliant chimney installation albeit with some length restrictions. ( around 25m depending on the model). The installation would be fully compliant as air would be drawn from above, and the boiler capable of discharging the gases. The flue would be one piece i.e. no joints.
The installation has just been completed with no problem except soot when the chimney was cleaned! The boiler is working very well and all our water is now mains pressure with no hot wate cylinder!
Hi Andrew, I would really appreciate knowing which model of Viessmann combi boiler allows a vertical flue as I have space issues and my current boiler is installed in the fire place in the kitchen, an ideal position.