Choosing A Heat Recovery Ventilation Unit

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What is an MVHR Heat Recovery System?

The main advantage of a mechanical ventilation system is with heat recovery (MVHR) is to remove stale air from your house, recover a percentage of heat from it, add the heat to fresh air and pump it back into your house.

  • Air extract grilles and vents are mounted in warm, humid rooms in your house, ie your kitchen, utility room, bathrooms, toilets, wet rooms etc. This is to ensure that heat is captured as close to source as possible.
  • Air supply grilles are mounted in other areas of your house to supply fresh warmed (heat recovered from your extract air) i.e. your living and sleeping rooms.
  • Your mvhr heat recovery unit transfers the heat from your extracted air, to your fresh, air and then reintroduced into your house.

Typical heat recovery ventilation system

How does a heat recovery system work?

Inside your heat recovery unit is a air-to-air plate heat exchange cube. This cube is constructed from layers of heat absorbing material. The layers provide two separate air paths, one for extract air, and the other for supply air. The airflows do not touch each other, only the heat is thermally transferred from one air path to the other.

Cube heat exchanger

A quick couple of notes about heat recovery cubes.

  • The slower the airflow passes over a heat recovery cube, the more efficient your heat recovery system will be. This is because heat has more time to pass from your extract air to your supply air. When purchasing a heat recovery unit, larger mhrv units running at lower speeds will be the most effective than smaller ones.
  • It is inside your heat recovery cube that the most amount of condensation occurs as it is at this point that hot air meets cold air.
  • Heat recovery cubes become very inefficient when dirty. Remember to replace your filters and clean your hear recovery cube regularly.

Why choose a Heat Recovery Ventilation System?

The more insulated (air tight) your house is, the more you will benefit from having mechanical heat recovery ventilation. A well insulated house without ventilation will generate a huge amount of condensation and create a terrible indoor environment. Installing a heat recovery system will not only eliminate condensation build up by extracting stale air from your house, it will recover the heat from the stale air and pump fresh heated air into your house, vastly improving your indoor environment.

Which Heat Recovery Ventilation Unit Do I chose?

Heat Recovery Units are generally chosen based on how many wet rooms you are extracting air from. Here is a list of the common sizes:

  • K+1 (extracting from 1 kitchen and 1 wet room).
  • K+2 (extracting from 1 kitchen and 2 wet room).
  • K+3 (extracting from 1 kitchen and 3 wet room).
  • K+4 (extracting from 1 kitchen and 4 wet room).
  • K+5 (extracting from 1 kitchen and 5 wet room).
Please note that you can supply air to as many rooms as you like but it is best practise to provide an evenly balanced flow of air through your house.

What is Appendix Sap Q Listing?

In order for the Government to assess the energy rating of dwellings, SAP is the Standard Assessment Procedure.

It is used to demonstrate compliance with building regulations for dwellings - Part L (England and Wales), Section 6 (Scotland) and Part F (Northern Ireland) - and to provide energy ratings for dwellings.

Heat Recovery Units that have been submitted and approved by the BRE will have published test results along with energy saving information. Here is a list of Fantronix Appendix SAP Q Approved Mechanical Heat Recovery Units.

Blauberg Komfort Ultra EC-L300 MVHR Unit
Blauberg Komfort Ultra EC-S300 MVHR Unit
Blauberg Komfort EC SB 160 MVHR Unit
Blauberg Komfort EC SB 250 MVHR Unit
Blauberg Komfort EC SB 350 MVHR Unit
Blauberg Komfort EC SB 550 MVHR Unit

Do I need a Sap Q Approved Heat Recovery Unit?

To meet new Building Regulations, yes. However, we sell a large proportion of units for other reasons such as:

  • General condensation problems.
  • To reclaim heat from rooms with a wood burning stove to utilise in other areas of a dwelling.
  • As an addition to existing, traditional ventilation.
  • To reclaim heat from steam rooms, swimming pools and saunas.

Single Room Wall Mounted Heat Recovery Fan Units

Single room, wall mounted heat recovery ventilation fan units are ideal for bathrooms, toilets, wet rooms, shower rooms, kitchens, utility rooms and small offices.

Some times it is not possible to loft/void mount a heat recovery units so a wall mounted option is more practical.

Here is a list of best selling single room heat recovery units:

Blauberg Vento Expert A50 Decentralised Heat Recovery Fan Unit
Blauberg Expert Duo A30 Single Room Heat Recovery Fan Unit
Blauberg UK Komfort D 105 Loft Mounted Single Room Heat Recovery Fan Unit

Best practise tips for installing a heat recovery ventilation systems?

  • Try to use solid ducting where possible.
  • Keep flexible duct runs tight with large radius bends.
  • Use acoustic ducting for better thermal and acoustic performance.
  • Use adjustable air valves so you can control your airflow in and out of rooms.

 
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