can i make my own flue system



hello to all,
i have a trianco eurostar 90/110 oil boiler, the boiler can be used with many types of flue.

what im trying to understand is why i cant make my own flue based on the spec of the boiler.

i wish to place my boiler next to a external wall with either a flue going through the wall at boiler height or a little higher at 2 metres say.

now ive had a heating engineer out to view the boiler and he says i cant make a 5 " stainless flue with a 2 metre verticle pipe followed by 90 degree shallow radius bend onto another 600 mm horozontal pipe exiting the wall with a wind shroud to protect from wind gusts.

at first he said i couldnt do it, then we discussed how the pj boiler worked which is fan driven and he then decided my flue would work, a little confused hearing i cant do it followed by i can from the same engineer.

the balanced flue system i can get (but costs far more than its worth) reduces my exhaust down to 4" with the remaining 1" used for the fresh air intake, i read articles here saying that their boilers fail with seals and if they take of the air pipe that the boiler then runs fine, this means the 4" part of the sealed flue is all thats being used for the exhaust, if this is the case why cant i make a flue the same. ie a 5" flue without the fresh air intake (as mine can draw elswhere) i cant see the difference.

the pj has a fan and therefore would push the gases out, all i wouldnt be doing is using a air intake from the flue as in a balanced flue for example.

i have a freind who is a gas engineer and he will set up the air and co once everything is installed to tune it all to work.

so my question is why cant i do this and if i cant could someone tell me why and sujest a way i can do it, i am an engineer so farication isnt a issue but i woulldnt want to put my life or others at risk.

if i speak to anyone they all say oh no you have to use the right part and nothing else but dont know why.

at the end of the day everything we buy is made by someone and i really dont want to spent 300 pounds on a flue kit i can make for 50 pounds

any help or advise would be gratefull and if anyone has a balanced flue kit i would be interested in buying it

Sponsored Links
Oil boilers are designed so that the combustion chamber remains at a set positive pressure by means of the baffle plates and flue ways which are designed with this in mind, so I would advise you to use the recommended flue kit, if you don`t your guarantee/warranty would definitely be void.

hi thankyou for the reply, i understand your coments, i have the technical spec for my boiler so i can ensure i have the correct exhaust flow rates and set the height of the flue acordingly to achieve the parimetres the spec say it should be.

it also says the boiler is unafected by different types of chimney, and ive looked at several flue options and the rear exit flue is the same unit used as the high level kit which just has 5" 1000mm lengths fitted acordingly to enable you to fit it where you want, or it can go into a chimney and houses are all different in heights and it can be side flued, chimney flued, low level flued or high level flued.

so if it can be used in this many ways and all are 5" in diamtre but of varing height it kind of throws out how balanced the flue would be, different heights would have different effects on exhaust draw etc etc.

i used to build exhaust systems for cars and motorcycles for racing where i built systems to suit different engine specs for different tracks for different performace requirements and also inter cooler systems for turbo's so i have some experience in air flow and i feel i could build a flue to suit.

i was going to install temp probes at varying heights and exit points to measure the temp of exhuast gases, if you can keep this even throughout the flue to exit point then you would have achieved a flue that works, what you dont want is a flue that loses so much exhaust heat the gases wont travel up the flue, having said the a pj is a fan assisted system and therefore push the gases out providing your flue isnt a mile long lol.

my other theory is if i have the correct co and exhaust emisions then i must have built a correct flue.

are my thoughts right or am i missing something. ? :confused:
Sponsored Links
The simple answer is that, with correct materials, skills and patterns - you can. The problem is that to be compliant, it must be tested and approved, and thats gonna cost more than 250 notes.
thankyou for the replies, i get the impression that this sort of project is taboo, i understand you probably cant coment on my questions, perhaps i should have thought of that before posting my questions.

i live in south west wales in a failry rural area and i cannot believe what building practices i see here compared to the east of the country.

so much here is just get things working wothout too much thought for saftley or engineering.

the cottage i bought was badly altered over the years but two things really anoyed me to the point where i took action against those involved.

firstly a 300 year old aok timbered 15tonne slate roof sat on a 8"x8" A frame that sat on a 4" timber lintel over a window frame that was passed by building regs, it bowed so bad it broke the windows, i couldnt belive it.

secondly a rayburn was in the kitchen and the farmer next door told me he would come over and lite it during the winter to keep the damp out the cottage, i lit the rayburn and the room filled with smoke, something was blocked you might think, so i removed the elbow at the rayburn end where it went into the wall, and thats where it ended, just plastered into the wall, all plumbed in to hot water tank and rads but just ended in a plastered wall, i dug it out to reveal a full open fireplace and chimney that was blocked from floor to ceiling and filled 2 large skips with rubble and took 3 days all days to clear it, that farmer talked rubbish and i went mad, dont forget he lit it each year over the winter to keep the damp out, what a load of boll****, he put my family at risk, anything to get a sale.

so although everything has to be hunky dory and meet regs and rules etc in the normal world, it certainly isnt like that here.

what i do is over engineer everything i do for saftey but i wont pay top money for something that is simply built and someone with a little comon sense can do but i guess that why are the rules are inplace, not enough common sense.

thnaks to all that replied
The bit you're missing is the bit where, if your house happens to burn down and it can be attributed to the boiler, or another boiler fault occurs causing damage to persons or property, your insurance will show absolutely no interest at all in giving you any money if you've got a custom uncertified flue system on there.
If the exhaust went on your car would you make your own or pop down to Kwik Fit? ... no don't answer that, I can hear you reaching for your pipe bender.

In my opinion there is only one way to flue your boiler, and that is with the correct flue from the boiler manufacturer.
hi yes i understand the point fully, however if comisioned by a oil engineer i would be sure of saftey, the orignal owner had the boiler installed in a chimney with just one piece of metre length flue entering up into the chimney, thats it, it was installed that way years ago, all the service engineer did was check gas levels internaly and in the rooms where the chimney went through.

i thought it would have required a little more of a flue than that, in fact his new boiler was installed the same.

i just don want to use my chimney to as my flue as i have a log burner in there, so i thought a high level flue going out the wall would be better than just putting it up a chimney.

thnaks for the replies, if anyone has a flue kit or balancd flue kit for a eurostar 90/100 oil boiler i would be interested

At last we`ve found someone who nows it all, thats me made redundent. :cry: :cry: :cry: :cry:

i like that reply, yes i would make or repair my own exhaust, if i used to design and make exhausts for racing which are conciderably more specific than the ford focus of now days, why on earth would i go down to kwick fit.

like i said before, everything is made by someone so why not yourself.

but your right i do have a pipe bender of sorts, a little more posh than the average pipe bender though, lol


ps cant get house insuranc anyway, i live on a flood plain, thats another story of engineering, lol
spraggo, no need for coments like that, i thought the idea of a forum was to have conversation, dont make it into a slagging match, i only wanted to understand the principles involved, i hope you never have need to ask me something i know about and that you dont, i would remind you of your sarcastic coments. :D
to be honest, we all have a duty of care. any sensible person would be very reluctant about giving you advice on making your own flue.

you can do what you like, just don't expect anymore to help in your misadventure. :LOL:

dodgy flues have a habit of killing people :oops: wouldn't want you to wake up dead one morning do we :LOL:
I can assure you that I was not being sarcastic, you have proved that you know your stuff and. I was praising you for it. I really do think you should reconsider your remarks that you gave in return for the sound advice that we have given you though.

All the Best.

i take all your coments on board and i can see where your coming from.

i probably konw more about presure, flow rates, gases, exhausts, monoxide, co2 etc than most boiler engineers, if i can design exhaust manifolds for F3 and world superbikes then im sure i can build a flue.

what i dont know about is the construction and principles of making a flue, i thought it would be available for discussion on this forum.

i understand its not.

i hadnt thought of having anything made compliant, food for thought.

i wont be asking any more questions.


ps still no need for sarcastic coments :D

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links