Tue, 28 Apr 2026 15:01:39 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134594#Comment_134594 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134594#Comment_134594 Thu, 09 Feb 2012 22:08:36 +0000 borpin
It is using the Airflex Pro pipe (discussed elsewhere) and the DV 90 SE unit http://www.airflow.com/AIR1-SHOP/pdf/Heat_Recovery/Duplexvent_90SE.pdf.

House Volume 485 m3, Ac rate 0.44 (213 m3/h), balanced in/out.

Do these figures sound right for an airtight house?
How does this HRV unit compare to others (efficiency etc)

Any input much appreciated.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134618#Comment_134618 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134618#Comment_134618 Fri, 10 Feb 2012 07:59:11 +0000 jms452
Not sure how much the unit costs but with efficiency 80% and fan power 0.7W/L/s there are definitely better out there that don't cost a bomb.

if you have tortuous paths that would need lots of 90° bends then their ducting may be the best bet but if you can do it with simple straight runs I'd go for larger bore rigid.

How does there unit cope with sub-zero exterior temperatures? I know that some Aluminum heat exchanger HRV units just bypass the heat exchanger which seems nuts to me.

Also note that there test certificate states that there test data is taken with large bore rigid tubing.

I have no complaints with this unit and not that expensive for a whole house unit.
http://www.nuaire.co.uk/Product/Residential_Products/Heat_Recovery/MRXBOX95-LOFT

J]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134627#Comment_134627 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134627#Comment_134627 Fri, 10 Feb 2012 09:18:42 +0000 borpin https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134630#Comment_134630 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134630#Comment_134630 Fri, 10 Feb 2012 09:27:30 +0000 docmartin Martin.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134655#Comment_134655 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134655#Comment_134655 Fri, 10 Feb 2012 11:01:13 +0000 jms452
its disposable fine paper concertinaed up probably approaching 1m2 of it - I imagine that you could replace it with a block of washable of open cell foam after the warantee had expired for less than cost of two replacement filters (I think £50),]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134772#Comment_134772 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134772#Comment_134772 Fri, 10 Feb 2012 23:35:14 +0000 docmartin
the vaillant filters are a similar concertina catridge of fleece, 390 x 180mm. I estimate the surface area to be .01728m2. The fresh air side is far cleaner than the exhaust as it has a pre-filter. The soiling of the exhaust filter is significant at the 3 monthly maintanence when I vacuum and replace. There is no way I could envisage the filters being efficient for 5 years without maintanence,
Martin.
Edit: Oops! decimal point, should be .1728m2.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134777#Comment_134777 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=134777#Comment_134777 Sat, 11 Feb 2012 03:40:59 +0000 borpin https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136339#Comment_136339 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136339#Comment_136339 Wed, 22 Feb 2012 22:20:43 +0000 GreenPaddy
hope I'm not stating the obvious, but have you looked at the sap appendix q website - lists all the "approved" units (for inclusion in SAP calcs), with the operational characteristics, efficiencies etc. Really useful to have it all in one place.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136398#Comment_136398 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136398#Comment_136398 Thu, 23 Feb 2012 09:20:06 +0000 dhutch Posted By: GreenPaddy...have you looked at the sap appendix q website - lists all the "approved" units ... Sounds good, do you have a link?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136401#Comment_136401 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136401#Comment_136401 Thu, 23 Feb 2012 09:26:11 +0000 dhutch https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136407#Comment_136407 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136407#Comment_136407 Thu, 23 Feb 2012 09:54:43 +0000 tony
In would say 0.44 is too low if that is the maximum.

You should be able to purge the house and have a party mode over 1.0 ach mine is 1.5 (actual) I think

I run at more than 0.44 during active periods during the day and drop down below that only at night

I would think a higher capacity unit would be safer especially if the house is one with low infiltration rates as all houses should be

Please check our where this 213m3/h comes from is it for the unit or the whole system there is a big difference, you dont want to find out after you have got it in.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136467#Comment_136467 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136467#Comment_136467 Thu, 23 Feb 2012 15:09:21 +0000 borpin Posted By: tonyPlease check our where this 213m3/h comes from is it for the unit or the whole system there is a big difference, you dont want to find out after you have got it in. It comes from the House volume x .44 (see OP).

Your thoughts are where my concern comes from. having seen on here where a 'specialist' seems to have got it so wrong I wanted to do a sanity check.

@greepaddy Thanks for that I'll take a look.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136569#Comment_136569 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136569#Comment_136569 Thu, 23 Feb 2012 22:50:19 +0000 GaryB
The best units are around 0.5 to 0.6 W/l/s. Avoid anything higher than 0.8

The SFC figures make a big difference to the SAP calculations and hence EPC ratings.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136709#Comment_136709 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136709#Comment_136709 Fri, 24 Feb 2012 20:24:41 +0000 borpin Posted By: GaryBDon't forget to look at the specific fan power, not just the efficiency. After all, you pay for the electricity. Ah excellent info, thanks.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136795#Comment_136795 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8591&Focus=136795#Comment_136795 Sat, 25 Feb 2012 17:40:40 +0000 chriskemp
Then boost rate is the summed rates of the number wet rooms - so 13l/s for a kitchen, plus 8l/s for each wetroom.

(assume no infiltration to be taken off - if you're building a very airtight dwelling)

Filters should be changed annually (or cleaned) to ensure flow rates are maintained = "adequate ventilation".

Otherwise you need a unit with constant duty function - which increases duty to overcome system resistance (blocked filters).]]>