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Brink MVHR And HB+ Radial Ducting


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#1 DavidC

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Posted 18 August 2013 - 02:25 PM

I've been recommended these by a local specialist for a new-build in Somerset. Brink is a Dutch manufacturer whose units perform well according to the stats but don't have much of a profile in the UK. Of course their SAP Q listed. The HB+ Radial Ducting system puts a 75mm dedicated duct to each in/out valve, connected to a manifold "concentrator" which in turn connected to the MVHR unit.

I'm hoping some of the forum contributors will have considered and perhaps installed either or both and could share some their experiences. If you've decided against Brink or HB+, why?

I know that getting the right ducting installation is the top priority (impossible to rectify/improve after the build) so for me making the correct decision on HB+ or Rigid PVC or Galvanised steel is critical.

Looking forward to the debate!

Edited by DavidC, 18 August 2013 - 02:27 PM.


#2 jsharris

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Posted 18 August 2013 - 02:48 PM

The two figures to look at are the SFP and the heat exchanger efficiency at the flow rate that you will be operating at for your size house. You want to choose an MVHR unit that has the lowest SFP (Specific Fan Power) and highest heat exchange efficiency that you can get for your needs. This is a compromise, because size, cost and noise also play a part in the final choice, as do other factors, such as whether you want comfort cooling/heating in addition to MVHR.

The Appendix Q data is a reasonably good place to start, but there's no real substitute for looking long and hard at the detail specifications. For example, I looked at one unit that had a nice low SFP at the sort of flow rate that we needed, but then found that this was for the stand-alone MVHR unit. When the power consumption of the sensors and timer/control unit was added in the SFP didn't look as good at all. The problem here is that, because an MVHR unit is running 24/7, even small differences in power consumption can add up to a significant cost difference over the whole year.

BTW, the Brink HB+ doesn't seem to be on Appendix Q yet, AFAICS

You're spot on about ducting. Big rigid ducts with a smooth bore, insulated where required, will reduce the power consumed by any MVHR unit.

#3 DavidC

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Posted 18 August 2013 - 02:58 PM

Hi JS

HB+ is a third party ducting product, details attached. The MVHR unit is the Brink Excellent.

What do you think?

Attached Files


Edited by DavidC, 18 August 2013 - 03:06 PM.


#4 jsharris

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Posted 18 August 2013 - 03:13 PM

What flow rate do you need for the design ventilation rate (i.e. not on boost when showers are running or when cooking)? With that you can check to see what the SFP and heat exchanger efficiency is and compare it with other models.

Edited by jsharris, 18 August 2013 - 03:13 PM.


#5 DavidC

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Posted 18 August 2013 - 03:24 PM

For the whole house I need 382 m3/hr (floor area of 354 x 1.08). The installer is recommending 2 MVHR units due to layout of house (mostly single storey) with a total capacity of 700 m3/hr to ensure loading is only 55% at normal setting and 69% at boost. How do I use this to calculate the SFP?

#6 jsharris

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Posted 18 August 2013 - 03:43 PM

If you assume a normal flow rate of 382m³/hr that's 106 l/S, which seems a bit high to me. Split between two units that's about 53 l/S each. If you look at the Appendix Q figures for the Brink Renovent Excellent, then the closest figure is 51 l/S where the SFP per unit is 0.79 W/l/S and the heat exchanger efficiency is 86%. Bear in mind this is without ducting, so the true figures will be worse, but that applies to any MVHR.

In terms of running cost, with an SFP of 0.79 per unit, then at the assumed normal flow rate of 106 l/S total you're looking at about 84 W continuous power consumption, or just over 2 kWh per day. In practice the power consumption will be a bit higher than this, because of the duct losses and also because the MVHR will be at a boost setting some of the time.

It's worth looking around at some others and comparing the performance figures, as there is a fairly wide variation. I'd be inclined to not over-size the MVHR units too much, as some have a higher SFP when they are run at low fan speeds (although doing this does tend to make them run more quietly).

I'd also double check the ventilation requirement against the actual house volume and air change rate per hour, or perhaps design for building regs minimum ventilation rates (given in table 5.1b in Part F), as I think you may be designing for a ventilation rate that is a bit higher than needed, which will push up your running costs.

Edited by jsharris, 18 August 2013 - 03:44 PM.