What is VWART?
VWART stands for Volume Weighted Average Return Temperature.
This is the average temperature that is circulated back to the network from the Heat Interface Unit (HIU) across both heating and hot water modes over the course of an annual usage period.
How is VWART calculated?
A UK standard for VWART was introduced in 2016 by BESA (Building Engineering Services Association), typically no higher than 33°C. The figure itself is calculated by recording returned temperature alongside the corresponding volume of water over a given time period and multiplying the two together. Then, the results are divided by the total recorded volume for the period.
The figure is often calculated automatically by most modern HIUs and gives a realistic measurement of the heat network’s performance.
Why VWART matters for heat networks
A lower VWART total means more heat is being used in the building before the water returns, which can improve efficiency and reduce running costs. The lower flow rates typically means that smaller pipe work is needed, which can reduce associated heat loss and therefore, delivers an efficient system.
Implementing an efficient network with Baxi’s HIU
At Baxi, our HIUs are installed with efficiency in mind. Each utilises data from the innovative Mercurius software, giving real-time analytical information and operational information to give you an accurate view of how the heat network is performing.
Our AquaHeat HI/HWI 4/50 & 14/50 HIUs have achieved outstanding VWART results in testing for summer and winter operation, and have an extremely strong Primary Flow lower temperature of 55°C.
Contact our experts to learn how we can support you with installing an efficient, effective heat network with our HIU at the heart of it.
Take a look at Baxi's AquaHeat HIU
For homes fed with heat from a heat network, the Baxi AquaHeat is the answer to your apartment’s heating and hot water requirements. Perfectly suited to supply heat to communal and commercial premises in your development.