It is the most often asked question; What size heat pump do I need? or How do I size a heat pump system for my property?
Simply put, there is no ‘one size fits all’ solution. Installing a heat pump system is an engineering exercise, rather than simply buying an appliance for the building. The various sizes of heat pump amongst manufacturers, coupled with the huge amount of period building stock in the UK, means that it is much harder to determine the required size of a heat pump system for existing UK homes, than in new-build properties.
Complication
When retrofitting renewables, it is tempting to estimate the heat load of the building. To do this. one could look at the size of the existing boiler system. As fossil fuel boilers are less expensive to install, their installers are usually more concerned about a peak heating requirement. Quickly heating a building from 15-16°C in the morning up to 21°C in 20mins, meaning boilers are two times too big. So this does not show an accurate estimate of what a property may actually require.
Heat Pump Sizing
The common method is then to estimate a peak heat loss per square metre of building area across all floors. Take for instance a 200sqm new-build. This property may only require a maintenance load of 30 watts of energy per metre squared. The calculation being 200sqm x 30W/m2 = 6,000 watts or 6 Kilowatts (6kW). Conversely a 200msqm Victorian home may require 65W/msq, 13kW.
The Solution
The heat loss per metre can therefore only be determined accurately by carrying out a formal heat loss survey of the building. During this process an energy surveyor will look at the fabric of the house, the external wall area, window sizing, glazing type and air changes amongst many other variables to determine an average W/sqm figure for an individual property. After this a heat pump size be accurately assessed and designed correctly.
Contact Baystar as an MCS accredited heat pump installer today, to find out if a heat pump system may be suitable for your property.
