Excess boiler water out of flue or back into boiler?

[karen222]

I have a Remeha combi boiler and was wondering if anyone on here knows if a boiler can be damaged if the surplus water that it produces comes out of the flue. The flue is in the loft and has brackets to support it to the front of the house, while the boiler is in the back of the house. Should the brackets be positioned so the water runs back into the boiler rather than out of the flue?

I have had several boiler engineers to give advice but some say yes other no...

I don't want the boiler to get damaged.

Any help please? Thanks

 

[Billy Bob Bob]

are you saying its a vertical flue?

 

[metaldust9]

what model is it ,why is it on brackets to bring it forward if its a condensing boiler it usually goes back into the flue,some flues are on an angle so it comes back into it

it must be gas man as brackets holding it,its a bit unclear i thought she ment boiler held with brackets

 

[karen222]

Hello

The boiler is placed in a bedroom at the rear of the house. The flue is vertical from the boiler for a metre or so until it reaches the loft area, then horizontal for several metres along the length of the loft. The flue is supported by 3 or 4 brackets along the length of the loft until it reaches outside. The angle seems to be wrong possibly as excess water drips out onto the front garden intermittently. Should the flue be angled slightly higher to enable all the excess moisture to run back through the boiler?

I hope this is clearer. Thanks!

 

[metaldust9]

would need to check me corgi book but defo should be on 45,s not horizontal or on a 90 defo certion it shou;dnt be several metres

 

[oldplumber]

didnt understand the last post but the flue should be sloping 3 to4 degrees back to the boiler so that all condensate goes back into the boiler to exit via the condensate drain and not drip out of the flue.max flue length for a 60/100 flue on a 28 combi is 6metres dont forget to deduct 1.4metres for each 90degree elbow though.

 

[pauls]

obviously my question cant be answered without seeing the job etc. but i cant help but wonder why the flue has been taken into the loft etc and not out the wall if in bedroom

 

[WHPES]

If its a condensing boiler I would expect the condensate to run back into the condensing module and then into the drain via the condensate trap. It is normally undesirable for condensate to drip outside as it stains brickwork and patios.

 

[Reg Man]

Yer absolutely; The condensate must drain back to the boiler and through its waste system. So think of the flue as being a waste system for water as well as a passage to safely remove products of combustion. If water is running out of the flue terminal, this is an indication that the flue runs the wrong way and will cause problems. Most flues require 2.5 degree's fall, I think? Thats off the to of my head; check with the manufacturer instructions.

 

[Billy Bob Bob]

but theirs the caveat of a fan on the end so some water will be pushed back to the end of the flue its unavoidable and inevitable

 

[Reg Man]

Depends how much.

 

[kirkgas]

would need to check me corgi book but defo should be on 45,s not horizontal or on a 90 defo certion it shou;dnt be several metres

you are mixing up a RS boiler with OF rules, i dont know this boiler so cant comment on the total flue length but ALL RS boilers can be done with 90 bends and horizontal flue runs

 

[metaldust9]

old plumber by the sounds of it its a vertical flue

 

[metaldust9]

is that true kirkgas cos doing my acs right now and there sayin 45,s only fitted a 30 cdi last week and that was the same 45,s only no 90,s dont think room sealed has out to do with it ,its the length

 

[Reg Man]

Sounds like a Remeha Avanta, which is a RS with concentric flue.

 

[RoryD]

Hello

The boiler is placed in a bedroom at the rear of the house. The flue is vertical from the boiler for a metre or so until it reaches the loft area, then horizontal for several metres along the length of the loft. The flue is supported by 3 or 4 brackets along the length of the loft until it reaches outside. The angle seems to be wrong possibly as excess water drips out onto the front garden intermittently. Should the flue be angled slightly higher to enable all the excess moisture to run back through the boiler?

I hope this is clearer. Thanks!

The config sounds ok...the manufacturers instructions will dictate just how far (distance) the flue length can be. It MUST be supported every 1.8meters. If it is a condensing boiler the flue MUST tilt back to the boiler. If it isn't a condenser it can,very slightly,tilt away to prevent rain ingress.

 

[Billy Bob Bob]

90 bends not allowed on open flued appliances ,they are allowed on fan assisted room sealed appliances, metal dust mate you are getting confused with bend resistances regarding how far you can run a combi flue for example 90 bend 1 meter 45 500mm dependent on mi

 

[Reg Man]

60/100 flue 5m to 8m depending on boiler model. 80/125 flue 25m to 30m depending on boiler model. subtract 1.4m for each 90degree bend, don't include the boiler flue turret. Subtact .65m for each 45degree bend.

 

[RoryD]

oops! didn't think it's an open flue...musta missed that bit

 

[kirkgas]

is that true kirkgas cos doing my acs right now and there sayin 45,s only fitted a 30 cdi last week and that was the same 45,s only no 90,s dont think room sealed has out to do with it ,its the length

with all due respect if you are doing your ACS just now it is ideal to get this clarified now to sort it out in your head, check the MI of the 30 cdi, i dont know it, but i think you will find you are allowed 90 degree bends on ALL RS fan flued boiler, but the "effective" running length of the boiler needs to take into account reductions in length for each bend fitted, it is EVERYTHING to do with being room sealed as the fan will overcome the resistance of the horizontal runs and bends, when on an open flue it is preferred to have initial 600mm rise before 1st bend, and again it is preferred to not use 90 degree bends, as under some conditions it will pass or fail a spillage test, obviously fan fleud does not have this prob, i use bpec books but im sure most are similar, bpec have 3 modules on flues, it is all in your training notes somewhere

 

[Billy Bob Bob]

with the performa its even more sever 30he 3 meters inc bends 24he 3 meters inc bends this is on 100mm/4inch vertical section not part of the equation after this you have to step up to 125mm

 

[kirkgas]

oops! didn't think it's an open flue...musta missed that bit

it isnt an open flued appliance, metal is just having a moment

 

[metaldust9]

cheers kirk gas but think ill stick to the gas engineer i no and the acs centre am using ,no disrespect,havnt read anything on it yet but will do also ive know for years about 45,s and 90,s from working in city plumbing and speaking to tech lines ,get all the stuff on open flues, distances ect just never seen a 90 on a r/s except straight away were it comes out the boiler anfter that 45,s but if am wrong ,sorry to ye if i am

 

[kirkgas]

cheers kirk gas but think ill stick to the gas engineer i no and the acs centre am using ,no disrespect,havnt read anything on it yet but will do also ive know for years about 45,s and 90,s from working in city plumbing and speaking to tech lines ,get all the stuff on open flues, distances ect just never seen a 90 on a r/s except straight away were it comes out the boiler anfter that 45,s but if am wrong ,sorry to ye if i am

no prob, i can keep this post as long as i need to !!!!!!!!!!!!!!!!!!!!!!!!!!!!
seriously have a chat to both the gas guy and the centre, it is easy for ONE of us to get mixed up technically there isnt a restriction to the amount of 90 degree bends you can use on a fan flued boiler as long as you take the appropriate "equivalent length" off the total allowed, although 6-8 bends are potential seal leaks at a later date

 

[Billy Bob Bob]

cheers kirk gas but think ill stick to the gas engineer i no and the acs centre am using ,no disrespect,havnt read anything on it yet but will do also ive know for years about 45,s and 90,s from working in city plumbing and speaking to tech lines ,get all the stuff on open flues, distances ect just never seen a 90 on a r/s except straight away were it comes out the boiler anfter that 45,s but if am wrong ,sorry to ye if i am

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your very wrong,9o degree bends on r/s fanned flued appliances are as common as muck