Faced with a similar decision although I have yet to do a thorough analysis yet. I think the Kinetic has a built in humidstat whereas the Nuaire has to have room sensors - I could be wrong though so do check. If correct then the kinetic wins for me, as with 3 bathrooms we would have sensor overload!

I have the kinetic+, and I think it's great!

Love:
humidistat built in
low power
trusted make - be around a while for spares (none needed for me so far!)
automatic summer bypass & protects if <0C
Loads of programmability - based on humidity, analogue+digital inputs, time

Hate:
No CO2 sensor in it
humidistat+other inputs locked out when <0C (for safety I guess)

Practical:
Make sure it fits thru loft hatch/wherever. It is BIG
Use BIG pipes for main runs, 200mm?
Use 150mm vents for rooms (to be quiet)
They do 200mm spigots as an option

Also have the Vent-Axia Sentinel Kinetic Plus since January and been very pleased with it. Sorted our condensation problem after insulation/air tightness retrofit and the air quality in the house is much improved.

Ours runs at 20% normal and 50% boost which works fine for our house (180m^2) . On normal it consumes only a few tens of Watts. One of the secrets of keeping noise down is to get a unit that is oversized for the house so that the fan runs slowly. Agree with Rob about making sure you use generously sized ducting so that the air can move more slowly, thus keeping the noise down. We have 200mm trunks and 150 mm out to the rooms. There is nothing audible at the fresh air inlets in the rooms. Can hear it near the stale air outlet in the kitchen and bath room, but don't care about that.

Don't miss a CO2 meter there are only 2 adults and 2 kids of us and we don't have an open fire or anything that might generate a lot of CO2.

As Rob says, it locks you out of using the boost below 0 degrees and below -5 it turns down the intake of external air to keep frost off the heat exchanger. I seem to recall that ours shut down completely at -10 C or so, but that doesn't happen very often where I am based in the SW. Some of the continental models (eg Paul) have electrical heaters to protect from frost, but that probably isn't necessary in the UK climate.

It has foldable filters which can help with cleaning them if the unit is in a tight space.I just give them a gentle vacuum and reinsert.

Nigel

That's a good point, though I assume other models advise you to clean the heat exchanger at intervals as well. Anyone any experience here?

On a different note, a friend of mine who lives 5 minutes away recently measured the Radon levels in his house and found levels above the recommended safe limit, particularly in the basement. It's quite common here in the SW for Radon gas to seep out of the ground. It hasn't occurred to me that MVHR is a good way of dealing with this problem, but it's another reason I'm pleased I got one.

Thanks for all the information so far.
Borpin the floor area of the house is 2380sqft

Sorry borpin I misunderstood.
Not too sure how to do the calculations really. I had sent my plans off to a few companies and they came back with the recommended units.

thanks for that viking house, the ceilings are 2.7m in the house, so following the calculations you done: it would be 596.7m3 volume, x 0.3 = 179m3/hr.
The efficiencies range from 87 to 92% according to the info online, and prices range from €3000 to €4500

Posted By: Viking HouseHi Jonny, Your house is 220m2 floor area x 2.5m ceiling height = 550m3 volume.
550m3 x 0.3 airchanges/hr is 165m3/hr.

Also calculate the occupants and choose the largest figure, so 25m3 per person x 4 persons = 100m3.

So you would choose a unit that can handle 165m3/hr.

Building regs requires capability for 0.44 ACH, I think?

I agree that running MVHR all year seems a bit silly, as the HR is probably good for 5 months in England (SE). Wouldn't it be better to trickle vent intake with MVHR boost extract in the summer and use full MVHR the rest of the time? Lots of people turn heating and a/c on / off in summer winter, so I don't see it being too tricky for the average user. Maybe a few additional controls could make this simple.

Posted By: djh The latest GBM has an article about the pros & cons of turning MVHR off and on.

What are the main points Dave? I don't get the magazine.

.

<blockquote><cite>Posted By: jms452</cite>
Without filters efficiency will rapidly degrade - this must be true of the fiwi too?

And even if people are stretching out the filter life it shouldn't effect heat exchanger efficiency (negatively) - it just means they are then working slightly below building regs air flows which some people here seem to advocate anyway...</blockquote>

When filters start to clog the fan efficiency will drop, quite dramatically. Fan efficiency is strongly dependent on total pressure ratio, so anything that restricts flow (and hence increases the fan pressure ratio) will hit power consumption.

A partially blocked filter will cause a flow restriction, which will increase the amount of power that the fan consumes for a given ACH.

Posted By: jms452 Our MVHR has a 5 year filter life with a suggested yearly vacuum clean, and then there are the washable filters and the fact that MVHR sales are probably ramping up fairly steeply...

Point taken and accepted!

Posted By: jms452Without filters efficiency will rapidly degrade - this must be true of the fiwi too?

Why do you think efficiency degrades without filters? I'd say efficiency degrades with filters!

Posted By: jms452And even if people are stretching out the filter life it shouldn't effect heat exchanger efficiency (negatively) - it just means they are then working slightly below building regs air flows which some people here seem to advocate anyway...

It affects the Watt/litre/sec figure.

If you have your MHRV controlled by humistats and CO2 detectors wont the unit switch itself off when not required, i.e. windows and doors open in summer?

Posted By: chriskempMVHR needs to run 24/7 to comply with building regulations - especially in buildings <3m3 airtightness.

Where in the building regs does it say that? I don't believe I've ever seen it.