MVHR - What Benefit From More Expensive Units? (a paste)

[Fallingditch]

Follows a reproduction of a useful discussion held on another forum starting November 2015 - for reference. (This is something of an experiment).

 

#1ragg987

Posted 10 November 2015 - 04:05 PM

Now selecting MVHR and it turns out not to be so straight-forward, so hoping for some input and experiences.

House is to PH standard, 330m2 over 3 stories. The options are coming in as (all include installation and commissioning):

1. Silavent HRX with 2 units and radial ducts approx £8,000

2. Sentinel Kinetic Plus with 2 units and branch ducts approx £11,000

3. Paul Novus 450 single unit estimated at £20,000 (the equipment supply only exceeds £8,000)

So what am I really getting for spending the extra money - why not just go with the cheapest option? Has anyone any experience with Silavent?

Would really appreciate any input into this - I am aware of ducting diameter, type etc and impact to system efficiency and potentially noise control - my question is more geared towards why would I spend the extra £xx and what is the benefit? 

Edited by ragg987, 10 November 2015 - 04:06 PM.

#2Alphonsox

Posted 10 November 2015 - 05:23 PM

That looks very expensive to me - I am not sure where in the country you are building but for comparison we were quoted around £3500 for our £270m² build using one Sentinel Kinetic (cost £1100 each). This included £1200 for installation which we decided was too much and decided to do ourselves. 

#3HerbJ

Posted 10 November 2015 - 06:13 PM

It is very expensive.

I have a house of almost exactly the same size and I have a proposal for design, supply, installation and commissioning of the Paul Novus 450F with latent heat exchanger for £10,500. The supply only costs are £3300 for the MVHR Unit and £2779 for the ducting and ancillaries. 

#4ragg987

Posted 10 November 2015 - 06:18 PM

Would you both mind giving me names of your suppliers? I don't know if forum etiquette permit public naming so perhaps as a personal message. I am in Aylesbury, Bucks. 

#5Alphonsox

Posted 10 November 2015 - 06:29 PM

No issue - We used BPC ventilation, not sure if they offer installation in England but worth asking

http://www.bpcventilation.com/ 

 

#6declan52

Posted 10 November 2015 - 06:33 PM

I went with bpc as well and got a sentinel b plus and all the ducting for £1500 odd. I installed it myself. About a days work and my build is 220m Search for each make online and you will see the guys doing your prices have their hand well into you. 

 

#7ragg987

Posted 10 November 2015 - 06:41 PM

Thanks declan52 and alphonsox - not come across BPC and have just requested a quote from them. They cover all of UK according to the website. 

 

#8ragg987

Posted 11 November 2015 - 01:37 AM

Just comparing the above prices (supply only)

declan52 £6.80 / m2 Sentinel b
herbj £18.50 / m2 Paul Novus (i have assumed a 330m2 house)
alphonsox £8.50 / m2 Sentinel Kinetic

Quite a spread, so back to my original question what value would the £18 unit have over the £7 unit, is it really worth the difference?

(I appreciate this is a gross simplification as no account taken of the options specified) 

Edited by ragg987, 11 November 2015 - 01:38 AM.

 

#9Alphonsox

Posted 11 November 2015 - 10:04 AM

I don't see much difference in spec between the two MVHR units. Both claim to recover around 90% of the extract heat energy. The Paul unit will extract more m³/hr which may lets you use one rather than two units which will probably reduce running costs.
The only other difference I can see is that the Paul unit is Passivhaus certified and the Vent Axia isn't. Whether this is worth anything to you depends on whether you're going for certification. 

 

#10wmacleod

Posted 11 November 2015 - 10:25 AM

 ragg987, on 11 November 2015 - 01:37 AM, said:

Just comparing the above prices (supply only)

declan52 £6.80 / m2 Sentinel b
herbj £18.50 / m2 Paul Novus (i have assumed a 330m2 house)
alphonsox £8.50 / m2 Sentinel Kinetic

Quite a spread, so back to my original question what value would the £18 unit have over the £7 unit, is it really worth the difference?

(I appreciate this is a gross simplification as no account taken of the options specified)

I wouldn't focus on costings as each install can be very different - some folk won't have extract or supply vents in every room, reducing their costs. Others may have cheaper rigid ducts but spend a lot of time installing compared to faster fitting of more expensive semi rigid.

Work out your airflow requirements first, then you can use the SAP Q database to compare the different MVHR units. The Paul unit is likely to have cheaper running costs for shifting larger amounts of air compared to two smaller units I suspect. Whether or not it can ever come close to repaying the difference in capital costs is another matter.

http://www.ncm-pcdb....chpod.jsp?id=17 

 

#11notnickclegg

Posted 11 November 2015 - 10:26 AM

Going from memory, the four main things I came up with in my selection of a Brink unit were:

• noise levels

• efficiency

• Passivhaus certification (we weren't sure whether we were going for that or not, but wanted to keep our options open)

• automatic balancing

I'm still not sure whether I made the right decision. I'm pretty sure we could have got 90% of the performance for 60% of the cost, but live and learn.

I would also definitely go for a single unit it you can get away with it. We have a Brink 400 Excellent Plus for our 290sqm house. I believe they've recently released a 450 model which I'd expect to be capable of managing a 330sqm house. 

Incidentally, I had a couple of sellers (of Passivaus certified products, of course!) tell me that the Passivhaus performance requirements for things like noise and efficiency were more stringent than the UK standard. The efficiency numbers bear that out - our unit has higher efficiency according to the UK SAP calcs as compared with the Passivhaus numbers.

Jack 

 

#12DeeJunFan

Posted 11 November 2015 - 10:34 AM

The PAUL is passivehaus certified. 

The rules within PHPP state that is the unit isn't certified you nee to take 15% off the efficiency. So a unit with a 90% rate would drop down to 75%

I think it only really matters if you are going for certification.

Most important thing is to size the unit for your build. 

 

#13crozier84

Posted 11 November 2015 - 11:22 AM

I've just had a look at the quote I received from BPC for my 250m2 house.

For the Vent Axia Kinetic plus B; 

For ducting, fixings etc - £1,190
For Heat Recovery system - £1,200
1st Fix - £900
2nd Fix - £300
Commisioning - £150

Total - £3,740

Declan, do you reckon it is pretty straighforward to install yoursel? I wouldn't say I was the handiest but between me and my brother who is a plumber we could handle it? 

 

#14Alphonsox

Posted 11 November 2015 - 11:45 AM

How easy the install is depends very much on the structure of your build. In the main building we have Posi-joists on the first floor and double battened ceiling upstairs. The install was pretty took us a couple of days but critically we didn't have to cut or drill anything to run the ducting.
We also have an annex with insufficient ceiling space for the radial ducting - This is causing us headaches at the moment but BPC have been very helpful. 

 

#15bitpipe

Posted 11 November 2015 - 12:12 PM

 ragg987, on 10 November 2015 - 06:41 PM, said:

Thanks declan52 and alphonsox - not come across BPC and have just requested a quote from them. They cover all of UK according to the website.

I am considering going with BPC also - they are NI based and my understanding is that they supply but not install in mainland UK (I'm in Berks). They will rent you a flow monitor for commissioning (£40) and sign off the install to satisfy BC. 

 

#16wmacleod

Posted 11 November 2015 - 12:28 PM

Just over £1000 for ducting and fixings is not a lot. For a 250m2 house I think you would need to double check exactly where the vents are going to go and making sure they have allowed enough ducting for each run, over estimate this rather than under because you invariably find obstacles that need routing around and that can use a lot more pipe than shown on plans. Bear in mind that some wet room extracts may need two runs of pipe per plenum as well. BPC don't sell joiners either so you will have wastage on each 50m roll of ducting. 

 

#17ragg987

Posted 11 November 2015 - 01:28 PM

Update spoke to BPC and they say installation (non-ireland) is via partners only or they will provide sign-off as bitpipe says. Awaiting a quote.

Chap I spoke to says that PH units are less leaky (air) and hence stronger / heavier due to the standards, but he thinks there is no long-term advantage PH vs not. Hopefully will have more in a few days.

Thanks for the feedback and link to the database.

 DeeJunFan, on 11 November 2015 - 10:34 AM, said:

The rules within PHPP state that is the unit isn't certified you nee to take 15% off the efficiency. So a unit with a 90% rate would drop down to 75%

I read this as "if not certified we will err on the side of caution and assume it is not very efficient in working out the PHPP". I don't think it means that non-certified units are 15% less efficient. 

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#18declan52

Posted 11 November 2015 - 02:39 PM

POPULAR

 crozier84, on 11 November 2015 - 11:22 AM, said:

I've just had a look at the quote I received from BPC for my 250m2 house.

For the Vent Axia Kinetic plus B; 

For ducing, fixings etc - £1,190
For Heat Recovery system - £1,200
1st Fix - £900
2nd Fix - £300
Commisioning - £150

Total - £3,740

Declan, do you reckon it is pretty straightforward to install yourself? I wouldn't say I was the handiest but between me and my brother who is a plumber we could handle it?

That price is a bit better than before.
As far as installation goes when you have signed the deal and paid for the goods you will get a plan showing you the duct layouts and where the vents need to go. Just make sure you get accurate measurements of the unit and make sure it will fit. There are access holes on the top and side on mine so you use whatever one suits your build. Double check it fits as his duct run layout will be from this spot. 
You will have 4 pipes to and from the unit. Feed and exhaust from outside so you will need vent tiles or wall vents whatever way you are connecting to the outside. The other two are the fresh air back into the house and the extract from the house. You will have a larger diameter pipe maybe 150mm from the unit to a manifold maybe a meter long depending on your layout. From the manifold then it will have a duct going to each extract. They basically twist and clip in very easy to do. I had the full 50m reel downstairs between 2 trestles and a pole through it and just pulled the duct along to where it needed to go. Leave a bit extra just in case and you can trim it to size when it's all in and secured.
Measure all where your duct ends are and record this so when you are cutting the holes in the ceiling you know the exact spot where they are. You can use a hole cutter or a pull saw whatever suits you.
Keep the system of till all the work is done or it will get clogged up with sawdust and all the other airborne materials. Get his flowmeter and adjust the vents to suit. Some adjust at the manifold others on the ceiling. 
It's def not a hard job to do just awkward as you are wrestling with a 20m length of duct that never seems to want to go where you need it to go. Get all your ducting in first before the plumbers or sparks arrive as it will make your life easier. Both plumbers and sparks will want to be first to make their routes easier but look after number 1 and get in first.
If the ducting and manifold are in a cold area like the eaves you will have to cover the ducts and manifolds with the like of rockwool or you will get condensation in them.

#19notnickclegg

Posted 11 November 2015 - 03:43 PM

Great advice Declan. With I'd had it before I did mine!

declan52, on 11 November 2015 - 02:39 PM, said:

It's def not a hard job to do just arkward as you are wrestling with a 20m length of duct that never seems to want to go where you need it to go. Get all your ducting in first before the plumbers or sparks arrive as it will make your life easier. Both plumbers and sparks will want to be first to make there routes easier but look after number 1 and get in first.

I'd add one caveat: drainage runs in particular might have restrictions as well, so ideally get your plumber to note any critical areas and agree on what you both need before either of you starts work. We had a nightmare getting around a couple of drains. Everything would have been a lot easier if we'd discussed routing with the plumbers beforehand.

Jack 

#20declan52

Posted 11 November 2015 - 03:49 PM

Forgot about them bits. If you have pipes from toilets etc then you might need to move to the next joist spacing. Where ever in your house the fuse box will be there will be a lot of cables in that area so that would be another one to avoid. 

 

[Bitpipe]

I'm no DIY expert but I did my own MVHR first fix install using BPC sourced materials - BPC are keenly priced and as there was some uncertainty on exactly where the distribution boxes would go, they sent additional steel and plastic ducting  - in the end I used all 350m of flexi and just a few metres of the steel.

Got it all in (just) ahead of electrical and plumbing first fix - some tight squeezes, especially where the ducts come together but it's pretty doable.

[oranjeboom]

I'm looking to get a MHVR into my reno/extension project. Not decided on what system to buy yet for my 175sqm-ish space, but can I install the ducting already to get that out of the way? Are most ducting systems compatible with the units? Most of the ducting will be easy to route as it's 80% loft.

[worldwidewebs]

On 10 June 2016 at 08:10, Bitpipe said:

I'm no DIY expert but I did my own MVHR first fix install using BPC sourced materials - BPC are keenly priced and as there was some uncertainty on exactly where the distribution boxes would go, they sent additional steel and plastic ducting  - in the end I used all 350m of flexi and just a few metres of the steel.

Got it all in (just) ahead of electrical and plumbing first fix - some tight squeezes, especially where the ducts come together but it's pretty doable.

How long did it take you?

[jack]

If it's a cold loft, then your ducting will need significant insulation, which I suspect will be a tedious process unless you can get pre-insulated ducting

[oranjeboom]

13 hours ago, jack said:

If it's a cold loft, then your ducting will need significant insulation, which I suspect will be a tedious process unless you can get pre-insulated ducting

If I lay circa 400mm of loft roll on top of ducting would that be adequate?

[Stones]

1 minute ago, oranjeboom said:

If I lay circa 400mm of loft roll on top of ducting would that be adequate?

That's what I did in my last house and it worked for me. One of my friends doing a whole house low energy refurb did likewise and hasn't had any issues either.

[Bitpipe]

On 6/14/2016 at 10:23, worldwidewebs said:

How long did it take you?

I'd say about  2-3 solid days spread over a few weeks. A bit of pencil chewing along the way to decide plenum positions and duct routes etc. If you have a mate to help with the ducting then it will go faster as quite often the duct gets snagged on the joist webs or struggles around a sharp bend and needs a shove from behind as well as a pull.

I put the plenums in first - save all your 50mm batten off-cuts as these are very useful to fix to the top chord of the joist and then fix the plenum to these. You may need to angle them to go through the webs.

Give some thought to where downlights will be and make sure you don't foul their locations, if in doubt, locate the plenum further away from the distribution box as it's easy to shorten the duct but hard to extend it.

When I'd done this I started running duct from the distribution box area to the plenums, leaving plenty of excess at the box end. I then made the connections at the box - this was the trickiest bit as it got very tight, there was a bit of fiddling with the duct runs too to get them to lay flat against each other as much as possible.

I also got all the radial steel duct through the walls ahead of insulation pumping and rendering the outside  - the MBC boys did this as a favour.

By comparison, the steel ducting is easy enough to work with (buy a cheap jigsaw from Screwfix and a few metal blades)  although the insulation used to wrap it is pretty itchy stuff. I made sure to dry fit each section with duct tape to get the bends correctly aligned before glueing and taping. Just the last few runs to the unit itself to do but this is a second fix job!

I have loads of 180mm steel radial and quite a few 90 bends, tape, insulation etc left over but used almost all 350m of the duct.