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Green Building Bible, Fourth Edition
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    • CommentAuthormarkocosic
    • CommentTimeApr 27th 2014 edited
     
    I have my eye on this:

    http://www.ebay.co.uk/itm/VENTILATION-HEAT-RECOVERY-SYSYEM-UNIT-3500sft-MITSUBISHI-LOSSNAY-MVHR-EXTRACTION/191140682464

    http://www.kievclimate.com/content/installationmanual/IM_LGH-50RSDC-E_EN.pdf

    I'm considering using it as a glorified extractor fan. Is this madness? Are there better options for similar outlay?


    This is a shared house. 4 people/4 double bedrooms and 2 bathrooms in 80m^2. The unit would be set to extract from the two bathrooms and supply fresh to the landing. Operate with timer switch operation on trickle speed then use a flow switch on the hot water outlet of the combi for boosting it:

    http://uk.farnell.com/jsp/displayProduct.jsp?sku=1006772

    This prevents lodgers from defeating it or having to faff about with (notoriously unerliable) humidistats. It also avoids noise during midnight toilet stops. (trickle is more than enough) With the the flowrate available it ought not to need any run on for showering.


    Positives:

    +Bathroom humidity control and heat recovery. Sucking air from the rest of the house ought through the bathroom doors ought to feel less draughty than an open window on a single room HRV unit.

    +Overheating control. It has an auto summer bypass and some useful settings to control overheating. Supplies cool air to the landing and anybody else's room that's been left open during the day.

    +Quiet and low power compared with the usual crappy pieces of plastic with AC motors.

    +Control of pollen and airborne dust for hayfever suffering occupant.

    +£550 is a decent price for DC commutated equipment with auto summer bypass.


    Negatives:

    -£550 is an expensive extractor fan

    -It isn't exactly small (part of the reason they are cheap I think, as you can't stick it through a standard loft hatch)

    -It has no intake air preheat to avoid icing.

    -It has no condensate drain.


    Will we fill it with condensate if operating it in the manner envisaged? Can a hole saw and some plumbing fittings create a perfectly functional condensate drain for emergency purposes?

    Realistically will the unit ever ice up, or are intake air preheaters on only moderately efficient heat exchangers just a gimmick in the UK climate?
  1.  
    Says you have 26 minutes to bid - very good but max humidity 80% - hence I personally would buy as your reasoning is good - think condensate drain needed and possible as diy - goferit but only at a good price
    • CommentAuthormarkocosic
    • CommentTimeApr 28th 2014
     
    He has plenty such units available outside eBay. ;-)
  2.  
  3.  
    Just to pick up on this - it would appear that this unit uses a special membrane for the heat exchange core Mitsibushi call "lossnay" which allows water molecules to travel between the fresh and stale air streams but blocks larger molecules. The idea being that as water vapour can migrate between the streams it won't condense within the core and therefore no condensate drain is needed.
    • CommentAuthorgooday
    • CommentTimeJan 7th 2015
     
    I bought one of these units a while back and its sitting in my loft ready to be connected to the vents, that have been gradually increasing as we renovate/extend our house.

    Has anyone else bought one and got it working?
  4.  
    What price did you pay? I'm considering my options also, I want two extracts and one input...
    • CommentAuthorgooday
    • CommentTimeJan 7th 2015
     
    I think it was around 550?
    • CommentAuthordb8000
    • CommentTimeJan 7th 2015 edited
     
    Posted By: markocosicI have my eye on this:

    http://www.ebay.co.uk/itm/VENTILATION-HEAT-RECOVERY-SYSYEM-UNIT-3500sft-MITSUBISHI-LOSSNAY-MVHR-EXTRACTION/191140682464" rel="nofollow" >http://www.ebay.co.uk/itm/VENTILATION-HEAT-RECOVERY-SYSYEM-UNIT-3500sft-MITSUBISHI-LOSSNAY-MVHR-EXTRACTION/191140682464

    -It isn't exactly small (part of the reason they are cheap I think, as you can't stick it through a standard loft hatch)


    I wonder if it will come apart?

    £425 here: http://www.ebay.co.uk/itm/SALE-Mitsubishi-Heat-Recovery-Fan-88-Summer-by-Pass-468-m3-hr-Extract-Supply/261716864726?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D28111%26meid%3D6a80fdfc7b1943de80a475400227fdad%26pid%3D100005%26prg%3D11472%26rk%3D1%26rkt%3D6%26sd%3D191468107881&rt=nc [sorry, can't work out how to make into a link]

    Would love to hear comments from anyone who has fitted one. I have the space thankfully so could fit a larger unit (loft hatch problem aside!)
    • CommentAuthorEd Davies
    • CommentTimeJan 7th 2015
     
    • CommentAuthordb8000
    • CommentTimeJan 7th 2015
     
    Yes, I had both a quote and a link. So had to choose. Two consecutive posts next time!
    The link will work in the quote but not outside of it, even though on my first attempt I even put in the html tags around the link.
    • CommentAuthorEd Davies
    • CommentTimeJan 7th 2015
     
    Posted By: db8000The link will work in the quote…
    Unfortunately not - it looks like it's working but doesn't actually point to the right place. I think the general problem is the forum software mangles anchor elements in HTML posts.
    • CommentAuthordb8000
    • CommentTimeJan 7th 2015
     
    Ah no, I mean: the first link is a quote of Marko's link to ebay the particular auction though has ended - hence doesn't show what you expect now.
    • CommentAuthorrhamdu
    • CommentTimeJan 7th 2015
     
    Posted By: willie.macleodthis unit uses a special membrane for the heat exchange core Mitsibushi call "lossnay" which allows water molecules to travel between the fresh and stale air streams but blocks larger molecules. The idea being that as water vapour can migrate between the streams it won't condense within the core and therefore no condensate drain is needed.


    erm, doesn't that defeat one of the main purposes of an extractor fan or any other ventilation, i.e. humidity control?
  5.  
    Mitsubishi believe it will help balance humidity levels internally and externally. That warm wet air is still going to be shifted out of the building. I can see it being particularly good for anywhere where there is low humidity issues rather than high humidity issues though.
  6.  
    Short answer? Don't.

    The Lossnay units do use a permeable membrane, and experience has shown that as there is no condensate drain, the units are susceptible to damp, and end up smelling. Any system where there is a high source of moisture, ie bathrooms, and the Lossnay will suffer. They are cheap, but the fans are not as efficient as some other manufacturers and the Specific Fan Power is therefore not as good.

    Go for a unit with a conventional heat exchanger and condensate drain.
  7.  
    Preferred cheap alternative?
    • CommentAuthorGotanewlife
    • CommentTimeJan 8th 2015 edited
     
    Posted By: rhamduerm, doesn't that defeat one of the main purposes of an extractor fan or any other ventilation, i.e. humidity control?


    Yes! Yes YES! - it is amazing that units that don't minimise humidity are sold in the UK at anything other than hydroponics outlets. More amazing that readers of this forum are discussing them with anything other than derision.
    Posted By: VictorianecoPreferred cheap alternative?

    The Aircysle 2.1 of course....
  8.  
    Posted By: brazenscrollShort answer? Don't.
    They are cheap, but the fans are not as efficient as some other manufacturers and the Specific Fan Power is therefore not as good.


    SFP (against the Aircycle 2.2 as I can't see 2.1 listed in the SAP database)

    Aircycle 2.2 (n+4 wet rooms) 0.96 W/l/s
    Mitsubishi LGH-50RSDC (n+4 wet rooms) 0.93 W/l/s

    Yes I'm picking best case numbers from SAP, but it doesn't look like SFP is a problem with these units. They are bigger units and use larger DC fans so are going to be more efficient especially compared to anything else available at the cheap end of the MVHR spectrum.

    Just to add as well that the figures quoted elsewhere for the SFP are far lower (down to 0.475W/l/s on tickover) but SAP is probably more balanced for real life usage with regards to ducting and filters.
  9.  
    I can see gotanewlife and brazenscroll both are advising against these units, can you tell us anything of specific installations you know about that have issues rather than generic warnings - from first appearances it would appear that they are going to need a intake pre-heater to be useful in the winter and it looks like it would be sensible to control the fan speed via humidity sensor in wet rooms to ensure levels don't rise too high and..... the price is very tempting.
  10.  
    Yes the SPF thing is relevant but IMO if it's under 2 it's OK (in real world non GBF retrofit scenario) what is critical is that taking water vapour that has been collect from the house and then deliberately feeding some of it back into the house is criminally stupid in the UK environment.

    The aircyle is actually really compact compared to other whole house HR units (say suitable for well over 100m2) - I know as I have one in a shallow airing cupboard!
  11.  
    Posted By: GotanewlifeWhat is critical is that taking water vapour that has been collect from the house and then deliberately feeding some of it back into the house is criminally stupid in the UK environment.


    What I want to know is if this is a real issue. How much water vapour does it transfer in a domestic setting, how well can it manage humidity? How does the lossnay core work in the real world when it is installed correctly in a domestic setting? i.e. ensuring that the unit is properly set up to ensure the exchange core doesn't freeze and the air coming from wet rooms doesn't exceed 80% humidity. Those people that have problems with their units, what controls are they using and are they keeping them within the units parameters? Are any of them using preheaters? Are they using the bypass at all?
  12.  
    Found on a NZ forum quoted as a response from Mitsubishi which suggests the units works as I imagined and that most of the moisture is going to be going straight out in the air stream if there is an excess in the house - another poster had positive feedback from their own lossnay unit. I'd still be interested in anyone here who has direct personal experience of lossnay units in a domestic environment in the UK.

    Mitsubishi quote: (from http://www.ecobob.co.nz)

    Lossnay is indeed an ERV system. Lossnay has been designed to improve the indoor air quality in the home and this includes targeting a healthy humidity level. A humidity range between 40-60% is healthy for the body with both over dry and over moist air being a concern. Lossnay is the only product on the NZ domestic market which has the ability to deal with both issues.

    Lossnay ventilates your home by exchanging the stale air inside your home for fresh out door air to maintain indoor air quality. As the air moves through your home it will actively reduce moisture and vent the moisture laden air outside. In areas with high humidity Lossnay will not only vent the moisture outside from the home (as vapour) but as the core is made of a permeable material it can also return the moisture from the incoming air to the outgoing air (outside). The warmer the indoor temperature the more moisture will be picked up by the moving air and vented out side.

    With other systems when the air stream hits the aluminium or plastic core the moisture condenses and water will sit on the core and this may affect the heat recovery capabilities of the unit. With Lossnay this moisture laden air is vented straight outside.

    In areas with dry air due to temperatures being below 0 ° such as central Otago or Canada Lossnay uses the same principle but the difference in the four variables (indoor temp, indoor RH, out door temp, outdoor RH) result in the principle working in the opposite direction to achieve the same result- a healthier home.

    Humidity control across a wide range of conditions is one of the principle advantages of using the Lossnay (moisture permeable) core. We have looked at aluminium and plastic cores but decided against using such a blunt tool when trying to achieve a healthy home.

    The success of Lossnay in Canada, Europe and Asia displays the range in which the system can operate. Lossnay has been extensively tested in Wellington, Christchurch and Auckland where the average humidity is around 80%RH.

    In all of these areas Lossnay was actively lowering the moisture levels throughout the winter with no exception. Even when the outside humidity reached 102% in Wellington last September the incoming air was 58%RH.
  13.  
    For some background comparison with "non-lossnay" units v's willie's question above, there is a surprising amount of moisture which goes to drain from a "normal" MVHR. Certainly a few litres each day (in winter of course). In summer the moisture won't condense, and will simply pass out in the exhaust air stream. With no other method of removing the build up of moisture (generated inside the house), I would absolutely not use one of these "clever" non-draining units.
    Frost protection - Many MVHR units simply wind back the supply fan speed, to maintain the HX temp above freezing. I argue that when it's very cold, you're probably drying more clothes indoors, cooking Christmas meals, longer hotter showers.....so exactly the time you want to maintain your air changes. Therefore I usually spec an inline elect frost coil, set at 1oC.
    Bypass - essential to prevent summer overheating (even here in the highlands). Allows the cool night/morning air to restore the house temp.
    Boost - always need to remind the clients about using the boost during showering/cooking, so at least twice a day to help give the house a good air clean, and not just rely on the hum stat. Allows them to run at lower speeds for the rest of the time, esp at night. Some units have night set-back timers for those with particularly sensitive hearing.
    Water hold-up - even normal MVHR HX's retain water at lower fan speeds, and only in boost speed does the condensate get blown out to drain.

    As ref. for my real lifeexperience with these, I have an MVHR in my own house for nearly 4 years, and I design the vent systems as part of the overall design for low energy houses.
  14.  
    I don't see how humidity recovery is suitable for a maritime climate. Granted perhaps not everywhere in the British Isles will have high RH all year round but in general I expect you would want as much moisture as possible shifted out of the house in winter.
  15.  
    Thanks for your input GreenPaddy, I agree that it would be sensible to ensure you can pre-heat the supply air in winter rather than reduce air flow. A few litres of condensate each day is a very significant amount. Do you know what the humidity levels are inside with/without MVHR running? With regards to:

    Posted By: GreenPaddyWith no other method of removing the build up of moisture (generated inside the house), I would absolutely not use one of these "clever" non-draining units.


    Mitsubishi are saying that their units will pass that moisture out in vapour form as opposed to most of it condensing within the core like other systems. As its a modified paper exchanger instead of an alloy or plastic core then I can believe that but if it doesn't do what it says on the tin then its going to turn into soggy mess. If they weren't available at a very good price I wouldn't be thinking twice about them, I'd be all for a heat exchange core that is a bit more robust.
  16.  
    Willie, I don't have experience of the Lossnay units, hence my comments re. non-lossnay for any readers who didn't have the general background. The houses I have experience of can be noticeably humid/stale without the MVHR on, with condensation occurring on 3G windows etc. So exact humidity levels I can not give, but comfortable levels sensed by the occupant is the key (the auto hum stat is usually set around 65%).
    Having looked at the Lossnay literature, I have no reason do doubt that it can transfer the excess moisture which has been drawn from the house, and put it back into the supply air in some trans-membrane technology that's beyond my knowledge (and boredom) threshold, but the fact that they are returning the moisture to the house is what I don't like the sound of. The tech documents talk about not operating it in freezing conditions - not wholly satisfactory in my opinion.
    I'm always happy to take on new techniques, but I learn from enough of my own mistakes, without looking for more risks :)
  17.  
    Willie, there are dozens of posts on here about not using a non-condensate MVHR unit. I was (I gently argued) mis-sold one and the supplier sent me a condensate version FOC posted to Italy (without the other one being collect/or sent back) without even the slightest fight (I didn't even ask for it). Aside from you, no-one has suggested they are appropriate in the UK - give it up its a terrible idea!!!! :wink:
    •  
      CommentAuthorfostertom
    • CommentTimeJan 8th 2015
     
    Till quite recently (5yrs?) AFAIK, MHRVs sold in UK were generally non-condensate-drained because cheap - only expensive ones had drains.
  18.  
    the aircycle 2.2 is £900!

    Without being funny that is not DIY friendly in my opinion, I'd honestly rather open a window and pay more in fuel there must be a cheaper version circa £150 that does the same job. A fan in a box
   
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