Curves in all the right places - Greenwood


1 January 2016

Curves in all the right places


Find out what other key question we should be asking when it comes to Heat Recovery Ventilation.

When it comes to Heat Recovery Ventilations the most common questions we get asked are: What's the SFP? and What’s the heat exchanger efficiency? 

Both are plausible questions for one variable – SAP. 

But what other things that affect the outcome of whether a heat recovery system is fit for purpose?

  • The size of the dwelling;
  • The number of rooms;
  • The amount of ducting;
  • The place where the unit will be installed;
  • The environment where the unit will run 24 hours per day, 365 days per year.

Guaranteed Installed Performance (GIP)

GIP is about getting it right in the installed application. So, the other important considerations are crucial to getting the right product that is fit for purpose, in other words, it delivers the correct airflow without noise.

Can the unit handle the pressure of the environment it is going to be installed in? 

The pressure or performance curve (see chart below) tells us many things about a Heat Recovery Unit, and crucially how it is going to handle the pressure of the system, which includes the ducting.

The yellow line is the benchmark as detailed in Regulations and the new NHBC Guidance recently published about Best Practice in Heat Recovery Ventilation.

Airflow Chart MVHRRun the unit at 60% max.
In Free Air or 0Pa, every unit will look great, but if you start applying pressure based on the amount of ducting and you will start to see some heat recovery unit performance falls off very quickly - approach with caution as they will lead to unhappiness.

Noise makes us unhappy and that is what will happen with a unit that isn’t sized correctly to the dwelling.

Three Considerations

In all, consider more than SFP and Heat Exchange Efficiency when selecting a Heat Recovery Unit - choose one for;

  • Guaranteed Installed Performance;
  • Low noise and efficient airflow;
  • Curves in all the right places.

Are you a Heat Recovery Professional? Why not join in our discussion on LinkedIn.


Click here to register for our latest promotions


Facebook Twitter Pinterest Google Plus Linked In

Zehnder Group