Green Building Forum - Considering MVHR - Toshiba unit Tue, 19 Dec 2023 08:25:49 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Considering MVHR - Toshiba unit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271192#Comment_271192 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271192#Comment_271192 Fri, 23 Nov 2018 21:54:22 +0000 smokeyjon Sorry for another MVHR newbie post I've been reading up a bit but I can tell that u all understand this better than me!

So I've been thinking about MVHR for a while. We've been renovating a 60s bungalow (concrete block, insulated cavities) and extending the basement to create a house (300cu m) for a while and I'm yet to fit out new bathroom and utility downstairs, both of which will need MV.

We also suffer high humidity (typically 60+% if not using dehumidifier) with mild damp issues and are allergy sufferers. We're in Plymouth, so could just be the marine climate?

I was planning to see if things got better once we've expanded into 2 floors (kids will have affection each then, and we'll have a kitchen extract at least!)...

..but then a friend of mine said he'd got a Toshiba MVHR unit ( vn-m150he) from work and it'll be available cheap...
So it's partly the usual questions ie:
- is it worth bothering as an extract system when we probably can't get fully airtight (we have pv which'll offset the cost/carbon footprint during daylight hours), and bearing in mind that it's probably too small a unit for our house (exchanging half its volume per hour)
- does anyone know anything about these units eg whether they're any good etc

I'm just after a steer as to whether it's worth looking into more. If so I will need to figure out where to mount it and duct routes etc (it won't fit through loft hatch but may slide between rafters if I strip and relay some roof.

Many thanks in advance for any thoughts...
John]]>
Considering MVHR - Toshiba unit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271193#Comment_271193 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271193#Comment_271193 Fri, 23 Nov 2018 21:56:06 +0000 smokeyjon Considering MVHR - Toshiba unit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271194#Comment_271194 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271194#Comment_271194 Sat, 24 Nov 2018 00:14:48 +0000 djh Posted By: smokeyjon..but then a friend of mine said he'd got a Toshiba MVHR unit ( vn-m150he) from work and it'll be available cheap...
So it's partly the usual questions ie:
- is it worth bothering as an extract system when we probably can't get fully airtight (we have pv which'll offset the cost/carbon footprint during daylight hours), and bearing in mind that it's probably too small a unit for our house (exchanging half its volume per hour)
- does anyone know anything about these units eg whether they're any good etc
Can't help very much but:

- how airtight do you think your house is? Are there draughts everywhere, or average, or it feels 'tight'? The better it is, the more use an MVHR is, versus continuous mechanical extraction etc
- too small is generally not good, since it will make more noise when its working hard. But 150 m³/hr with a volume of 300 m³ is better than the building regs minimum of 0.44 ACH so it is a possibility
- Toshiba doesn't even appear as a brand in the SAP Appendix Q database, so it's not exactly a mainstream option in this country at least.

It depends on how cheap it is, but it might be better to consider spending a bit more on something more mainstream. Definitely check out maintenance and guarantees if you still want to go ahead.]]>
Considering MVHR - Toshiba unit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271198#Comment_271198 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271198#Comment_271198 Sat, 24 Nov 2018 11:09:05 +0000 smokeyjon I reckon we could get REASONABLY airtight... Downstairs is pretty much underground plus new extension that I insulated with my OCD approach. Building regs wanted trickle vents downstairs though and we're fitting axwoodburner withnno option for dedicated air supply. Upstairs is pvc double glazed with no trickle vents and suspended timber floor insulated from underneath with earthwool.

I noticed Toshiba wasn't on the databases that I found in another link. Its from a commercial installation I think and the manual suggests it can be used alone or with a/c units. Perhaps it's more typically used commercially?? They retail at £945 but I'm hoping I'd get for half that. Still there's a lot of cost in ductwork and controls I expect plus the faff. I do like faffing though... Unless it comes to nothing useful!!

I'll have a look into maintenance etc but I may well let it pass unless I can find out anything more encouraging about the unit!!! I'm not sure we're committed (or airtight) enough to go for a full cost solution so I guess my question was also whether MVHR is an all or nothing thing or whether there can be merit in persuing a half hearted approach over a couple of new regular extractor fans!!]]>
Considering MVHR - Toshiba unit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271203#Comment_271203 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271203#Comment_271203 Sat, 24 Nov 2018 20:57:23 +0000 djh Posted By: smokeyjonwe're fitting axwoodburner withnno option for dedicated air supply
Forget any ideas of airtightness then! By the time you've made the big hole in the wall for airflow that will be required, you'll have draughts a plenty.

I guess my question was also whether MVHR is an all or nothing thing or whether there can be merit in persuing a half hearted approach over a couple of new regular extractor fans!!

Regular extract fans aren't designed to be run continuously. You'll do better to look at something called Mechanical Extract Ventilation (MEV) or Decentralised Mechanical Extract Ventilation (DMEV or D-MEV). There's also something called Positive Input Ventilation (PIV), which is very popular in places like Sweden but has for some reason been deprecated here.]]>
Considering MVHR - Toshiba unit http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271224#Comment_271224 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15933&Focus=271224#Comment_271224 Mon, 26 Nov 2018 19:30:58 +0000 gravelld
If you have any design on high performance I think you should consider a wood burner with a dedicated air supply (and a suitably impressive looking certification).]]>