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    • CommentAuthorRex
    • CommentTimeMar 28th 2018
     
    What ho one and all,

    I own a first floor maisonette that does not have an extractor fan in either the kitchen or bathroom. when we lived there, we never encountered a problem, but the tenants are asking for fans.

    Obviously, the best route is through the wall, but unfortunately, the f/f is tile hung so that is a problem. or is it?

    My thought is to go through the plasterboard ceiling and duct the outlet to the end wall, which is block inner and brick exterior. But the distance from the bathroom to the external wall is around 7 meters. it is slightly less from the stove location.

    Is there any issue with running an extractor fan over this distance in a domestic situation? And rather than two holes in the wall, is there any reason that the two extractors could not be ducted into one outlet?

    Toodle pip and thanks

    Rex
    • CommentAuthoradam_w
    • CommentTimeMar 28th 2018
     
    Rex,

    Would the simplest and probably cheapest solution not be to swap the extractor for a carbon filtered recirculating version?

    Regards,

    Adam
  1.  
    Posted By: adam_wRex,

    Would the simplest and probably cheapest solution not be to swap the extractor for a carbon filtered recirculating version?

    Regards,

    Adam

    Cheapest solution would be to say NO!
    Otherwise a carbon filtered recirculating version might work for the kitchen but not for the bathroom.
    If you are stuck with providing the fans I don't see why the length of run would be a problem - other than a loss of efficiency which would mean a higher wattage fan for the same effect. The kitchen fan would need a (good) filter at the kitchen end to keep the particulates out of the duct. I don't thing one duct would do without non-return valves to stop back flows between kitchen and bathroom and by the time you have sorted (efficient) non-return valves it is probably easier to run 2 ducts. From experience with extractor fan ducts - run the ducts under the insulation and sloping slightly down towards the outside to stop any condensate running back into the room. The last one I did had a 3m run and 90 deg. down turn on the exit with an insect grill over it. the extractor fan had an electrically powered grill to close off the vent to stop extraction via wind etc. when the fan was not on. It works well. (bathroom vent)

    Sorry I don't know of an easy way to go through a tile hung wall.

    Oh and update the rental contract to make the tenants liable for the periodic replacements of any filters
    • CommentAuthorTimSmall
    • CommentTimeMar 28th 2018 edited
     
    Most extractor fans will not cope with a 7M duct run (unless you use large diameter duct) - the blade design on "inline duct fans" are better suited for that type of installation.

    I once drilled a 50mm waste through hung tiles from the rear (very very slowly and carefully with a new sharp core bit), when there was no alternative, so it might work...

    "Open the windows", plus a recirculating carbon filter kitchen hood?

    Single room heat recovery?
    • CommentAuthorsam_cat
    • CommentTimeMar 28th 2018
     
    With tenants, you need to assume that they WONT open windows so ventilation is a good idea. And that they wont do the regular maintenance needed.

    Insufficient ventilation (usually) = higher risk of mould.

    Bathroom extractor, wire to run when the lights on with a 10 minute overrun OR use humidity sensor. Duct fan rather than ceiling (as its quieter) and use fixed ducting rather than flexible. Electronically opened flaps is a good idea as well, then the fan doesnt have to overcome the resistance of the flaps springs.

    Recirculating kitchen extractors need more regular maintenance than an exterior vented option, so again worth the hassle up front to exterior vent.
    •  
      CommentAuthorfostertom
    • CommentTimeMar 28th 2018
     
    Don't put a HRV fan in a bathroom - as well as extracting it's blowing in, and the incoming air is by definition a little or a lot colder than the outgoing - not comfy for naked wet bodies!
    • CommentAuthorTimSmall
    • CommentTimeMar 28th 2018
     
    Someone I know has operated a single room MVHR in a flat for several years (it's set to continuous trickle - about 10 watts - plus manual boost), and it's fixed humidity problems in the place.
    • CommentAuthorRex
    • CommentTimeMar 28th 2018
     
    Gentlemen (or to be politically correct) People1

    Thanks for the suggestions. Have not considered the pressure issue with a 7m duct run. But because there is good loft access, and plenty of space, a larger diameter non-flexible pipe would be no problem.

    The other option is to have the outlet in the soffit, pointing downwards. But since there is very restricted loft access at the internal soffit corner, I think fitting a 90 degree bend and pipe could be a problem. I will have a look, it may be a possibility.
    • CommentAuthortony
    • CommentTimeMar 29th 2018
     
    How about straight up through the tiles, they make vent tiles suitable for extract fans now that go with most types of tile, in the old days we sometimes used a lead slate and mushroom terminal.
  2.  
    I did that as the first option on one vent and had no end of problems with vapour condensing in the vent pipe and dripping down through the fan into the room. I had to relay the whole thing horizontally as I described above to solve the problem.
    • CommentAuthorgyrogear
    • CommentTimeMar 29th 2018
     
    Posted By: Rexthe tenants are asking for fans


    Why ? Are they not airing the flat ?
    First thing might be to "extract" RH information from them - "determine their level of objectivity"
    Online USB RH logger HERE...
    https://www.lascarelectronics.com/easylog-data-logger-el-usb-2/

    (I suspect there are cheaper ones around...)

    Then perhaps they need to buy a dehumidifier / cheap and works great.

    Depending on output info, I'd offer to put a "free" impeller in one window if possible, & basta.


    @ PIH : "Sorry I don't know of an easy way to go through a tile hung wall".
    +1
    Neither do I, or I'd have done it a long time ago !
    (However, now that Tim Small has set a trend, I just might get tempted...).

    gg
    • CommentAuthorTimSmall
    • CommentTimeMar 29th 2018
     
    For the hung tiles (this was 10+ years ago), I used a TCT toothed core drill (quite slender - looked more like a hole saw than most core drills do) to go through relatively soft clay tiles. You might want to try to get some expanding foam in behind the tiles to stop them rattling against each other. Go very very very slowly (I didn't have any option in this case).
    • CommentAuthorgyrogear
    • CommentTimeMar 29th 2018
     
    Posted By: TimSmallFor the hung tiles (this was 10+ years ago), I used a TCT toothed core drill (quite slender - looked more like a hole saw than most core drills do) to go through relatively soft clay tiles. You might want to try to get some expanding foam in behind the tiles to stop them rattling against each other. Go very very very slowly (I didn't have any option in this case).


    Thanks for the details ! It all adds to my "mind-project"

    What interests me, is the "from the rear" bit - what kind of *wall* did you have to penetrate ?

    In my case it is 8-inch concrete blocks, 50 cm long by 22cm high.
    So your toothed cylinder saw sounds like the right tool, OK.
    I would not actually be penetrating my tiles (they are in fact slates...); I'm actually interested in getting into the cavity between the blockwork and the slate cladding...

    With the obvious requirement of scrupulously avoiding the rafters...

    It is for pulling air, so I'd need a fair diameter - 5" would be a good start.

    Cheers,

    gg
  3.  
    If you google
    how to repair a slate hung wall
    There are a couple of ways to repair tile/slate hung walls without striping all the way up which my make the option of carefully going through the tile hanging more attractive.
    • CommentAuthorgyrogear
    • CommentTimeMar 30th 2018
     
    Cheers, PiH, brilliant idea (one learns something every day on here !).

    gg
  4.  
    Why not just pull out 2 or 3 with a slate ripper and dress lead/lead substitute round the vent? You might end up with a couple of tingles (copper straps) but you can keep them quite discreet.
  5.  
    Oh and unless the internal location is v. critical go from the outside so that you can avoid going through any of the battens.
    • CommentAuthorRex
    • CommentTimeMar 31st 2018
     
    Gentlemen,

    Again, thanks for your thoughts. I found this from a Google search:

    http://www.lapvent.co.uk/mechanical_extraction.html

    Not so sure about it, if for no other reason that I don't really want to cut through perfectly sound tar lining material.

    To answer the questions regarding how they are ventilating the flat, they only moved in this week. In the past, when My wife and I were living there, we never had a dampness / mould problem, and much to my amazement, nor have any of the tenants in the past six years. However, in the past, there has only been two in the flat, now the couple have two children, which is likely to make a considerable difference.
    •  
      CommentAuthordjh
    • CommentTimeMar 31st 2018
     
    Not sure how the Lapvent thing would be relevant? Not to mention that the use of the corrugated flexible ducting is generally an indication of poor quality and problems ahead.
  6.  
    Posted By: RexTo answer the questions regarding how they are ventilating the flat, they only moved in this week. In the past, when My wife and I were living there, we never had a dampness / mould problem, and much to my amazement, nor have any of the tenants in the past six years. However, in the past, there has only been two in the flat, now the couple have two children, which is likely to make a considerable difference.

    So why are the tenants asking for powered vents when presumably there are (open-able) windows. If the past has not shown problems then say no now and resolve the problems (fit ventilators) if and when they arise.
    • CommentAuthorRex
    • CommentTimeApr 1st 2018
     
    They are new tenants, only moved in on Wednesday. I guess in their previous place, they had an extractor. With summer approaching, it is less of an issue as I'm sure they will have windows ajar.

    Two adults and two children, there will certainly be more bathroom activity and more washing.

    Looks like a centrifugal fan in the loft, vented to the soffit is the way to go. Guess if the fan is sufficiently powerful, I could branch an ceiling extract from the kitchen?
    •  
      CommentAuthorDamonHD
    • CommentTimeApr 1st 2018
     
    We put in MHRV (single room) in out bathroom, hung tiles outside:

    http://www.earth.org.uk/MHRV-mechanical-heat-recovery-ventilation.html

    Rgds

    Damon
    • CommentAuthorgoodevans
    • CommentTimeApr 3rd 2018 edited
     
    If a single room mhrv is not an option then I think I would go for a continuous extract option such as from these people https://www.envirovent.com/trade/products/mev-systems/eco-dmev/

    These units have a dip switch to set the extract rate between 6l/s and 15l/s as I recall - and will extract that volume regardless of duct length (within limits - using just enough power to reach the desired extract rate). Some variants have an additional boost switch or humidity switch.
    • CommentAuthorKenny_M
    • CommentTimeApr 4th 2018
     
    Our main bathroom has no extractor, and on moving in around a year ago found that the small top casement window had been screwed shut (wonder why there was a dampness problem). The screw was taken out right away, but you have to climb on to the window ledge to open it and with 600mm thick stone walls and a few other issues I haven't got round to an extractor.

    My temporary solution was to leave my Ecoair DD1 dehumidifier in the bathroom permanently set to around 50%ish RH. It comes on automatically when the relative humidity rises and turns off when it reaches the set point. Its made me wonder whether this isn't actually a better solution than a standard extractor fan, I mean as opposed to extracting all that warm air, which must in turn draw in cold air somewhere else? A dehumidifier is also at least 100% efficient as a heater. Ecoair appear to have a wall mounted dehumidifier for this purpose.
    • CommentAuthorgoodevans
    • CommentTimeApr 5th 2018 edited
     
    don't be fooled - that dehumidifier will eat 300 watts or so and will remove 7 litres of water a day.

    a 6l/s continuous extractor will get rid of around 2 litres of water per day (at 4g/m3 difference) and will use about 5 watts for the fan and an average heat loss of approx 72watts for air heat - assuming an avg 10 Kelvin difference inside to out and 1.2 joules/(K*l).

    The units can be turned down to around 4 l/s continuous and with a humidity sensor it will boost only when required.

    It's small, simple, silent and can be wall/ceiling mounted and left alone. And with a humidity sensor to boost it will shift more moisture than a dehumidifier.
    • CommentAuthortony
    • CommentTimeApr 5th 2018
     
    +1
    • CommentAuthorKenny_M
    • CommentTimeApr 5th 2018
     
    Ok but in the winter when the room needs to be heated anyway 100% of the energy used by the dehumidifier is converted to heat. In a house that is heated using electricity it must be more energy and cost efficient, although with gch it might be cheaper to heat the cold air being drawn in, although I can't see how it would be more energy efficient?

    P.S. I had to post this about 5 times before it would take, so I hope it doesn't appear 5 times later!
    • CommentAuthorgoodevans
    • CommentTimeApr 5th 2018
     
    Yep a fairly good argument as far as I can see. Both will cost about the same in energy per litre of water removed but the dehumidifier returns that in useful heat during the winter. If you have the space and plumbing for the dehumidifier it looks like it has the advantage over the dmev.
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