Is there an inexpensive MVHR diy option?

[Wadrian]

Hi everyone

 

looking for an inexpensive MvHR option. We are soon to be starting 1st fix in next few months and would not want to be spending £10k on an a full

MvHR company system.

 

if anyone has experience of doing the own set up/what units they used/was it off the shelf etc? Finally am I right in saying once installed, get an independent company to certify it? 
 

many thanks 

[Conor]

It's easy. You can certify it yourself with an anerometer and a spreadsheet. 

 

I think there is an MVHR design sheet floating around the forum somewhere. Tl;Dr, make sure your duct runs are as short as possible and your diameters are as big as possible.

[Indy]

It depends on if its a retrofit or something that needs to be passed by BC. 

 

If its the former, there are obv ways to self install, balance and no need for certification. Cost will be the parts and your labour (unpaid) if you're skilled that way.

 

Ours was the latter as giving up trickle vents and exhaust fans in the bathrooms meant that we had to get it professionally certified. That means generally finding people who will want to do the whole shebang - design, supply, install and certify. You *may* have luck in finding someone to certify a self install but those people are few and far between. 

[MikeGrahamT21]

Work out the airflow capacity you need for your volume, and then double it so you run your unit only ever at 50% (less the better for noise), and then keep an eye out on eBay, loads of units come up, many are brand new and much less than buying from a store, they’re often mis-specified units which get sold on to recoup losses

[Post and beam]

No need to spend £10k.

I am guessing that you are talking about new build.

The ducting can be physically challenging to manipulate. I used 90mm ubbink and installed it all myself. 3 x rolls of 50 metre ducting for a 200 square metre 4 bed house. That should give an idea of cost for that bit.

The MVHR unit i bought is a Brink 400 at about £1900. Located in the loft. Make sure it fits through the loft hatch. Ask me how i know.

[Post and beam]

No need to spend £10k.

I am guessing that you are talking about new build.

The ducting can be physically challenging to manipulate. I used 90mm ubbink and installed it all myself. 3 x rolls of 50 metre ducting for a 200 square metre 4 bed house. That should give an idea of cost for that bit.

The MVHR unit i bought is a Brink 400 at about £1900.                Air-Haus.co.uk  as recommended by @NickfromwalesApart from a great price on the unit, they offered to commission and certify for me once i was ready.

 

[SteamyTea]

What figures has your air leakage test given.  That is your starting point.

[JohnMo]

2 hours ago, Wadrian said:

looking for an inexpensive MvHR option

Once you get your head around it it's a pretty simple system. Pretty easy to install if you plan ahead and know your duct routes. Our whole system was around £2k installed and commissioned DIY basis except commissioning sign off.

 

To certify yourself you need a certified 

2 hours ago, Conor said:

anerometer

Then you can self certify. I paid £200 for someone else to do it.

 

[Adrian Walker]

3 hours ago, Wadrian said:

Hi everyone

 

looking for an inexpensive MvHR option. We are soon to be starting 1st fix in next few months and would not want to be spending £10k on an a full

MvHR company system.

 

if anyone has experience of doing the own set up/what units they used/was it off the shelf etc? Finally am I right in saying once installed, get an independent company to certify it? 
 

many thanks 

Who said £10K?

[Wadrian]

Think I had read £10k on earlier post on Buildhub. Would be good to know if this is wrong 

[Onoff]

This is inexpensive:

 

http://www.builditsolar.com/Experimental/DIYHRV/DIYHRV.htm

[SteamyTea]

33 minutes ago, Onoff said:

This is inexpensive

I made one a few years back. Just used it on the bathroom, it worked.

The efficiency was not to good, about 70% if I remember right. Most of that was down to using a couple of Manrose bathroom fans.  They are terrible.

Big fans are needed, area is everything when it comes to shifting air.

[JohnMo]

Our first quote was £10k - it was dismissed very quickly 

[Nickfromwales]

5 hours ago, Conor said:

make sure your duct runs are as short as possible

Not to the detriment of the functionality  A lot of "cheap" designs have fresh supply vents almost immediately above doorways of bedrooms etc, and near zero air flows across the room.

 

If you need to have a long run, and want quiet operation, you simply double up on the ducts.

 

5 hours ago, Wadrian said:

looking for an inexpensive MvHR option. We are soon to be starting 1st fix in next few months and would not want to be spending £10k on an a full

MvHR company system.

This is something sewn into the heart of the build fabric, with near zero chance of 'putting it right' retrospectively. It will also be on 24/7/365 for the rest of your life there, so maybe not somewhere to cut all of the meat off the bone  

 

Buy a good quality Brink unit from Air-Haus.co.uk, oversize it(!), and make sure to install proper attenuators on the supply and extract ports for super-quiet operational sound in the rooms. 

[Nickfromwales]

1 hour ago, Wadrian said:

Think I had read £10k on earlier post on Buildhub. Would be good to know if this is wrong 

You'll spend this, and possibly more, if you opt for a supply and fit package. DIY will save you a lot, as it will with everything else in life.

 

I've done some big houses with multiples of units, and the bill has gone above £20k, but these have all been very high spec installs, and have operated in total silence; I had to stick a bit of A4 paper to an extract, and watch it being held there, to prove it was running on one previous project. Their neighbour's (also just moved into a brand new home) couldn't believe how inaudible it was, and were resorting to turning theirs off at night as it was a lemonade job.

 

As with anything, buy cheap, buy twice, or accept the compromises and keep quiet.

[Wadrian]

I have never had a system like this. Think I will have to try the diy route though as £10k + hard to justify. 

[marmic]

if you're not going for high performance (as in insulation and air tightness to passivhaus stds or close) and this is more about healthy environment / ventilation rather than heat recovery have a look at passive and also positive input ventilation.  A LOT less money!   Assuming you are going for MVHR strongly suggest whatever you decide making sure of a summer bypass setting.  Our first summer and when it's been hot had fan speeds on full blast of a night -  cool air without the 6 legged beasts!  

[JohnMo]

Basics over size MVHR unit. So fan speed is low for your flow rate.

 

Minimise pressure drops through duct work, via large ducts and or multiple duct runs. So low velocity through ducts equal to low noise and again less fan work being done.

 

But if you're not better than 3m³/m² @ 50 Pa airtightness don't bother with MVHR. Better options available 

[Post and beam]

Our first price for MVHR supply & fit was via the timber frame company. This was £7500. Supplier would have been Rega vent of Biggleswade. Once i had seen the unit in question i decided it was a piece of junk. So i decided that if i could do the install myself for less than £7500 i would be up on the deal.

I did achieve this.

[Bonner]

DIY installed and self certified a MVHR for less than £1500 four years ago, so more like £2k now. No need to spend £10k on a simple system, like everything we get carried away with specifying equipment. The only thing I would do differently is fit noise attenuation, there is some ‘cross talk’ between rooms although only noticeable when it is dead quiet in the middle of the night. Rather than looking at the most sophisticated system, start from trickle vents and think what would be better than that? DM me if you want details of equipment.