UKC

We've got an extractor fan system fitted above the cooker in our kitchen. The fan and filter is fitted in stainless steel trunking immediately above the cooker and the "extracted" fumes pass through some bendy flexible pvc trunking to vent through the outer wall. This pvc trunking is not encased but merely lies loose along the top of the adjoining cupboard unit.

The system has been in situ for five years and we now seem to have a permanent odour of stale cooking smells. I'm wondering whether to get the pvc trunking ripped out, replaced and enclosed/boxed in.

Anyone got any thought on this.

Sensible, INTELLIGENT replies only.

In reply to FesteringSore:

Sounds like the problem is rate of cooling of fumes passing through a long pipe run? It will cool and deposit en route.

Solution to me would seem; absolute minimum pipe run, insulate and a fairly quick fan speed. Flaps on the outside that close can take the oomph out of the air flow too.
We had something similar on our bathroom, air condensing on the metal flaps, dripping water in summer, forming ice/rime in winter, nothing climbable though.

In reply to FesteringSore:

Are your filters clean and is the mesh clean? I shouldn't get too grimy on the inside of the pvc pipe. Easy enough to replace or clean. You might even be able to get some carbon filters for it.

In reply to FesteringSore:
Are any of the joints leaking? Or maybe never sealed properly?

How clean is the motor and the filter holder and it's surrounds? Seen that the build up of cooking grease etc on the motor itself and/or the filter holder is the cause of the stale smell (i.e. room side of the trunking).

Or is the one way flap stuck and you are just getting a back flow of air when off - the trunking etc will all have a build up of grease etc?

In reply to FesteringSore:

Its a simple system to clean or replace. Have a go, it won't go wrong.
Dishwashers are handy for cleaning bits.

In reply to summo:




Yes, I see your point. However the only available route for the trunking is the existing one which is about a metre(give or take) from the top of the cooker/fan to the wall aperture. Before we moved five years ago we were in a bungalow and the trunking went straight into the ceiling, through the void above to the exit in the external wall. No odours at all.

In reply to Kevster:

Yes - I suspect that, after five years the pvc trunking is gunged up.

In reply to Bellie:

Cleaned two day ago

In reply to Climbing Pieman:




I have noticed that grease does seem to accumulate on the motor - which is awkward to get at - and drips down through the filter. I clean the motor casing as best I can but as said it's a bugger to get at.

In reply to FesteringSore:

Presuming it is not on a block of flats, can you check the pressure exiting outside, the fly net by the flaps can build up with grime, dust etc over time.

In reply to FesteringSore:


I've certainly noticed in the past that that can cause the smells to remain in the room as it is just concentrating them on and around the motor. Made worse when it heats up with use/cooking. Coupled to a problem of say back flow or partial blockage/wind resistance will make it worse.

Maybe the design of unit for your use or siting of outlet, etc is not ideal. Could be just needing a overhaul clean though.

In reply to FesteringSore:

When we re-did our kitchen I ripped out the extractor hood, tubing and fan and repaired the hole in the wall.

Now I don't have an ugly hood intruding into the space over the hob when cooking, and have much better light, both natural and artificial.

I use a Teflon coated splatter guard when frying something messy and once every 6 months or so I wipe the wall down behind the hob. Sometimes when boiling lots of things I open a window.

Despite lots of dire warnings from people this has worked out just fine. Extractors and filters are largely pointless pieces of junk that overall make things worse, assuming you can open a window and use a damp cloth.

In reply to FesteringSore:


Eat out every day. Or stop cooking.

(You don't get much more intelligent than that)

In reply to FesteringSore:

The stainless steel "trunking" will just be a 3 sided cover and not actually trunking. Is the PVC flexi hose? if so you could look at replacing it with a white 150mm pvc rigid pipe using plastiweld on the joints.


When I've been converting mills in to apartments, all the kitchens have a flexi pipe connected to the extractor, but these are boxed in.


Regarding the motor smelling(as mentioned above), try hiring a steam cleaner, it's how the professionals clean commercial kitchens.

In reply to FesteringSore:

For the catering industry, the trunking should def not be pvc. For domestic, it's ok but not the best.

after many years of cooking, the whole system will most likely be full of grease, even with filters in place. This can be a fire hazard because a fire at the cooker can reach the filers and spread up the trunking. old grease can be highly flammable. The warm air extracted when you cook is probably heating the grease inside the system and causing the smell.

you'd be best to replace the trunking. it would be a pain in the ass to clean the inside of it.

In reply to ogreville:



Rigid ("smooth bore") ducting?

Following on; does anyone know why installers use the the flexible(bendy) pvc ducting? As mwr72 suggests above, I'm thinking of replacing it with rigid ducting.

In reply to wintertree:

The problem with no extractor is that the humidity in the house is raised and this then condenses out in a cold room somewhere else causing black mould. If you do a lot of frying then your kitchen walls and ceiling will go yellow with condensed oil vapour - I know because my parents don't have an extractor.

In reply to FesteringSore:


Bump

In reply to Toerag:


Not if you close the kitchen door and open a window or two... The only mould problem in the house is related to some expired render over a porous stone wall far away from the kitchen.

If I did have a damp problem from the kitchen then I'd fit a heat recovery bidirectional ventilator somewhere away from the hob (as we have in the bathroom) in preference to an evil extractor hood.


I do a lot of frying. Between the splatter guard and a damp cloth I've had no problems.

In reply to FesteringSore:
"Following on; does anyone know why installers use the the flexible(bendy) pvc ducting? As mwr72 suggests above, I'm thinking of replacing it with rigid ducting."

It tends to be used when the duct has to pass through joists, in a perpendicular direction.
Solid duct is far better and can be used when parallel to floor joists if the duct runs in the ceiling.
Solid duct gets much better air flow than flexi and I would definitely recommend replacing what you have with rigid bends and pipe.
I would also check that the duct has been properly connected to the grille on the outside. It is possible that the duct stops short on the inside face of the cavity wall for example, or may be poorly connected to the terminal.

No need for carbon when venting to outside. Just keep grease baffles clean (as said, dishwasher is good).

Andy

In reply to Andrew Wilson:

Thanks for that. Over to rigid