Anyone have experience of Nuaire Positive ventilation?

[JohnW]

Hi,

Due to budget constraints we've removed MVHR from our build and the Architect has suggested a cheaper alternative, Nuaire Positive ventilation unit.

 

I'd never heard of this approach to ventilation. Have any of you had experience with positive ventilation?

 

J

[Bitpipe]

Personally I think this is a mistake.

 

MVHR is a £3-4k cost max and delivers significant benefit.

 

It can be installed DIY and self certified,

 

On a house your size (we are similar) it's a rounding error on the budget.

[Declan52]

Did you price a kit from bpc and do the install yourself???

If you go down this route have you not to make sure your house is "leaky" so the stale air can be pushed out by the incoming fresh air. Seems a piece of kit for suitable to an older house that suffers from mould/condensation.

[ProDave]

I wired a new house this year where he started out with trickle vents in the windows and mechanical extraction ventilation., but he saw the light and converted part way through the build for mvhr.

 

My mvhr unit cost just over £500 and all the ducting and vents from BPC was about £1K so you should comfortably get a system for under £2K

 

Have you got a SAP assesment of your build yet and any idea of your heating costs?   Mine I expect to cost less than £250 per year to heat it, and there are several on here with even better houses with lower costs. It really is worth putting in the detail now to get it right, ignore it now and it's a major job to improve it later.

[Ferdinand]

I have been using Nuaire PIVs since about 2012, and in the right circumstances they are excellent - of the PIV units they are relatively inexpensive, reliable and British made. I think there are more than a million units fitted in the UK. The famous product of the same type was called "Lofty".

 

There are a range of Nuaire PIV products from basic (go in the loft to change the setting), "Hall Control" (change a switch on the vent in the ceiling), and various types of remote sensor / controller eg humidity. There is a model with a heater (500W iirc) in the outlet.

 

They can be dramatically effective in condensation situations, and with single or old double glazing in an old house they can add enough background ventilation to make the problem just go away, or recede significantly. For example it may prevent pooling of condensation on windowsills in the morning, but it relies on the leakiness of the house to let the stale air and humidity escape. If you are well sealed you need to make provision to get the air out effectively. They cost pennies to run.

 

I now have them fitted in nearly all my rentals, usually paired with a trickle / boost HRV fan (normally a Vent-Axia Lo Carbon Tempra) at the other end, just to make sure that there is background ventilation as an insurance, and the atmosphere stays fresh, and condensation doesn't happen. The supply cost of a Hall Control Nuaire PIV plus a Lo Carbon Tempra is together from about £400-£550, depending on model - plus fitting which is easy. For real crunch-budget you can fit a DHEV trickle fan or two rather than a Lo Carbon Tempra. Remote sensors of gewgaws, or the thicker-wall version of the Tempra, does add up to a couple of hundred more.

 

The ones in the LBB were £280 + £150, because I went for the Nuaire PIV which can have a WiFi "is it being turned off" monitor fitted later (for £100 or so). But I did not get the extra module since I have never had the issue raised.

 

For a larger newbuild or renovation a different strategy might be best. I think I would pre-install MHRV ducting and put the PIV where a future MVHR outlet in the landing ceiling could replace it once you have the budget in a few years.

 

You need to decide whether you have the right circumstances, and how the costs stack up.

 

Ferdinand

 

Edited December 22, 2017 by Ferdinand

[jack]

You're pushing moist air outward through the fabric of the building. Is this not a recipe for wintertime interstitial condensation?

[Nickfromwales]

34 minutes ago, jack said:

You're pushing moist air outward through the fabric of the building. Is this not a recipe for wintertime interstitial condensation?

Plus the ventilation heat loss has to be offset with something, like fortifying with electricity   I'd fit mvhr and compromise elsewhere, seems madness not to IMO. 

[Oz07]

Is it not designed to push air out of trickle vents? 

[Nickfromwales]

4 minutes ago, Oz07 said:

Is it not designed to push air out of trickle vents? 

When they're open, yes. Is the idea to have permanently open trickle vents? Another bad point if so . 

[Declan52]

It sets the inside of your house at a higher pressure than outside so pushes the air out through trickle vents, plug sockets, cracks at ceiling wall junctions etc anywhere there is a gap that air can escape which in a new build there really shouldn't be hardly any if any care and attention is paid during the build.

 

Edited December 22, 2017 by Declan52

[Oz07]

Not ideal for new builds but perfect for older tenanted properties as @Ferdinand says 

[Ferdinand]

1 hour ago, jack said:

You're pushing moist air outward through the fabric of the building. Is this not a recipe for wintertime interstitial condensation?

 

Imo not a problem, as it is constant ventilation so most of the time the air being pushed through will be relatively low in moisture .. unless there is an utterly constant source of moisture.

 

Or you can turn it up to setting two or three or four. 

 

 

Edited December 22, 2017 by Ferdinand

[Nickfromwales]

33 minutes ago, Ferdinand said:

 

Imo not a problem, as it is constant ventilation so most of the time the air being pushed through will be relatively low in moisture .. unless there is an utterly constant source of moisture.

 

Or you can turn it up to setting two or three or four. 

 

 

Where does it draw the air from ? If it's not pre charged with any heat then it's forcibly pushing heat out as well as moisture.  

[Ferdinand]

13 minutes ago, Nickfromwales said:

Where does it draw the air from ? If it's not pre charged with any heat then it's forcibly pushing heat out as well as moisture.  

 

Normally the loft.

 

I think it has been pointed out previously that the heat capacity of dry is here air is relatively very low. If it is humid that is much higher. Does anyone have a calculation of heat loss for say 10 cubic m / hr at say 40 and 70% then.

 

So the effect should be smaller than we might think. 

 

But that is one reason I go for HRV.

Edited December 22, 2017 by Ferdinand

[JohnW]

Thank you very much for all the very constructive replies.

You have all convinced me that PIV has it's place in older/leaky houses and that by installing it in a new build (without trickle vents) I am doing the wrong thing.

 

My build is by main contractor and the cost I've been given to install & commission MVHR is around £5k, so it's a significant potential saving.

BPC have given me a price £2,500 for parts and £1,450 to install & commission which brings it down to £4k (if the builder is happy for me to organise the MVHR separately).

 

Thanks again for all the help. 

 

[Nickfromwales]

7 minutes ago, JohnW said:

Thank you very much for all the very constructive replies.

You have all convinced me that PIV has it's place in older/leaky houses and that by installing it in a new build (without trickle vents) I am doing the wrong thing.

 

My build is by main contractor and the cost I've been given to install & commission MVHR is around £5k, so it's a significant potential saving.

BPC have given me a price £2,500 for parts and £1,450 to install & commission which brings it down to £4k (if the builder is happy for me to organise the MVHR separately).

 

Thanks again for all the help. 

 

Just ask the main contractor to simply omit it from the schedule. Your the boss remember. . 

[JohnW]

2 minutes ago, Nickfromwales said:

Just ask the main contractor to simply omit it from the schedule. Your the boss remember. . 

Thanks @Nickfromwales, it's easy for a duck-out-of-water to forget that 

[Stones]

28 minutes ago, Nickfromwales said:

Just ask the main contractor to simply omit it from the schedule. Your the boss remember. . 

 

+1  It's unlikely he'll be bothered, and the worse he'll do is ask you to confirm in writing that he isn't responsible for any warranty issues / sorting out any problems with it.

[Declan52]

Unless it's a hotel your building your talking 1 day to pull the ducts to where they need to go and once plastered out then depending on how many vents you need cut out then another day maybe 2 if you have lots of vents. All of which you can easily do on your own. All you need is a step ladder, a  saw for cutting the ducts, a plaster board saw for cutting the holes in the ceilings and a swear box. 

Just get a price from bpc to commission it or if I am correct there is the tool floating about between members that you can use to do it yourself.

[JohnW]

7 hours ago, Declan52 said:

Unless it's a hotel your building your talking 1 day to pull the ducts to where they need to go and once plastered out then depending on how many vents you need cut out then another day maybe 2 if you have lots of vents. All of which you can easily do on your own. All you need is a step ladder, a  saw for cutting the ducts, a plaster board saw for cutting the holes in the ceilings and a swear box. 

Just get a price from bpc to commission it or if I am correct there is the tool floating about between members that you can use to do it yourself.

Cheers @Declan52, might just do that and save myself £1,300, thanks.