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?

He has plenty such units available outside eBay. ;-)

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.

What price did you pay? I'm considering my options also, I want two extracts and one input...

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!)

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.

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.

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.

Preferred cheap alternative?

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.

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!

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.

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.

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 :)

Till quite recently (5yrs?) AFAIK, MHRVs sold in UK were generally non-condensate-drained because cheap - only expensive ones had drains.