Are you getting a new boiler installed so that your flue will exit a wall?
If this is what your engineer has recommended, I wouldn’t worry. After all, 90% of all boiler flues exit a wall – as opposed to a roof. It’s generally preferred for easier access, and it’s also easier to seal the area and make it water tight.
However, that doesn’t mean there aren’t some things you should be aware of. Especially with tighter Gas Safe regulations!
As an experienced engineer, I like my customers to be informed, which is why I wanted to write this blog post. It should tell you some of the most important things to look out for when your flue exits the wall of your property.
So, without further ado, here are six things to be aware of when your new boiler flue exits a roof.
1. Ensure the hole is drilled with a diamond hole cutter
This is important to prevent any ‘breakout’ on the other side. Imagine an ordinary drill or bullet; it looks nice enough on the inside, but outside it’d make a right mess of the stonework! Not very pretty. That’s why it’s essential to make sure your chosen engineer will use the right tools for the job.
2. The flue should be properly sealed on both sides
After the latest regulations, it’s absolutely essential that your flue will be sealed properly on both sides. This is something you should watch for, as some companies may be tempted to take shortcuts. It should be sealed using sand cement or equivalent material. It must be sealed properly so no exhaust fumes can come through into the building.
3. The flue must be at the correct angle
Especially if you’re changing from a non-condensing to a condensing boiler, engineer the engineer gets the correct angle for the flue to run back to the boiler. If it doesn’t point slightly upwards, it’ll drip down onto the street below, and possibly onto railings or cars. At the least, it’ll probably leave dirty staining down your wall. Being a condensing boiler the water vapour dripping will be slightly acidic, so should run back into the boiler and to the condendsate waste.
This is also very important for stricter Gas Safe regulations, and particularly something to watch out for in flats.
4. Joints should be properly secured with screws
This is a common one. Whenever your flue is joined to bends or extensions, it’s important to drill the flue extensions, brackets and flue pipe together. You should technically have two screws in every joint. This is something people never used to do, so the flue joints would frequently come loose and become a danger.
As per new regulations, it’s now important to properly secure any flue joints and brackets, so check your engineer will do this.
5. Ensure your engineer measures the exact length
As I’ve mentioned previously in another blog, it’s vital to ensure your engineer specifies exactly how long your flue will be. Certain flues and certain boilers allow for different lengths. Some can run up to six metres, whilst others can allow for 12 metres.
The number of bends an affect this quite a lot. Every 90 degree bend counts as two metres, and every 45 degree bend counts as another metre. He should specify in your quote that he’s measured the exact distance, as too many bends or too much distance means your boiler won’t perform correctly.
6. Access hatches are an absolute must
Finally, any flues which are boxed in must have access hatches, so your engineer can visually inspect your flue during your boiler’s annual service. This is to help ensure there are no leaks and that your flue stays looking healthy and doing its job all-year-round – without causing a danger to you and your family.
If an engineer visits and is unable to see your flue, they may classify your boiler as ‘At Risk’.
Advice from an experienced heating engineer
Speak to your engineer, and ask them about the points above. Most reputable engineers will be happy to answer any questions you may have about your flue, but it’s so important to get it done right. Ensure they are Gas Safe registered, and are willing to stick to the regulations in the book. Don’t forget to always ask for 2 – 3 fixed price quotes!
I’ve come across a few flues where upon inspection, the boiler’s not firing correctly, or gasping for air. It usually turns out the flues don’t have screws holding it firmly in place, and the brackets are disjointed. Either that, or they have sometimes been moved slightly by work that has happened on the outside of the building.
It’s vital to check every joint is screwed on and that your flue is properly secure to ensure this doesn’t happen.
Conclusion
Worried about your new boiler flue going through your wall? You shouldn’t be. Most competent and reputable engineers will be extremely experienced at fitting flues and sticking to the latest regulations. However, you should still bear in mind the points above, and get 2 – 3 fixed price, detailed quotes.
Do you have any other questions relating to this subject? Just feel free to leave a comment below. I’ll be sure to reply!
