TECH TIPS: Heat loss calculation

TECH TIPS: Heat loss calculation

Utilising heat loss calculations to gain an understanding of the required heating output for each individual project is a must for any installer, as it ensures the most efficient heating solution is delivered. Craig Ord, Product Manager for Myson, offers some advice.

Before undertaking any heat loss calculation, it is vitally important that the information provided is accurate and will deliver the correct result for the project in which the calculation is required. For example, installers should collate all of the correct design data, which should include U values, design temperatures, air change rates and emitter flow and return temperatures.

The engineer then needs to select the best mean water temperature for the individual project, as in some cases certain heating solutions can operate at different flow and return rates. For instance, a product such as an LST radiator may operate on a 82ºC flow / 72ºC return system, as well as a 70ºC flow / 50ºC return system, but the surface temperature shall still remain at <43ºC, due to the differences in the flow and return temperatures. This still ensures it is safe enough for the user, while also complying with NHS Guidance Notes 1998.


Now, the property in question needs to be considered. Installers need to ensure they have all of the property data, which includes dimensions of each room, floor level, ceiling height, the age and construction of the property, the size and number of windows, internal and external doors, insulation levels and required room temperatures. If the heating solution is only required for one room, the engineer will only have to include the calculations for this room, whereas if it is for the whole property, each individual room will need to be taken into consideration.

Once this information has been collated and checked for accuracy it is vitally important that any heat loss calculations are carried out in accordance with BS EN 12831 Energy Performance of Buildings – Method for Calculation of the Design Heat Load. This ensures correct guidelines and regulations are being followed.

Engineers should now be ready to calculate the heat loss for the project. To do this, we would always recommend using a recognised heat loss calculation programme, such as the Myson Heatloss Calculator. By doing so, all of the information can be collated on to one programme, which details each individual room, along with all of the design data.

Based on the information provided on the property, the mean water temperature, heat up factor and outside air temperature heat loss is then calculated for each room listed within the property. Once the engineer has all of this information, they can begin to consider how best to deliver the heating solution.

A helping hand
To aid these decisions and offer installers support when it comes to choosing the correct solution, the Myson Heatloss Calculator is equipped with software which lists suitable products. For example, the required heat loss is listed in both Watts and BTUs for each individual room, alongside a number of heating solution options. Each option is given a rating out of 100% to show how close they are to the required room output. This information is then collated into a summary page and the best matched heating solution(s) for each individual room are then listed with the product name, dimensions and order code.

The use of heat loss calculations, especially those which are carried out on software such as Myson’s calculator enable installers to understand immediately what the required heating solution should be for each project. It also ensures correct guidelines are being followed, eliminating the chances of poor or inadequate heating solutions being installed.

Myson’s Heatloss Calculator
STEP 1: Enter design data

STEP 2: Select the room, enter required temperature and air change information

STEP 3: Enter all required information on the chosen room

STEP 4: Solutions which meet the heat loss requirements will be listed. Add the chosen solution


STEP 5: A summary page will detail the solution required, alongside order codes and product information

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