The DTB automatic by-pass valve is designed to maintain a minimum flow rate in heating systems fitted with thermostatic
radiator valves. When all the TRVs are open the by-pass valve remains closed, allowing the full boiler output to circulate
around the heating system. As TRVs sense that selected room temperatures are reached and start to close, the by-pass valve starts to open, maintaining optimum flow through the boiler and so eliminating possible damage to the boiler and pump. Installation of the DTB by-pass valve will minimise noise often experienced when flow through the boiler decreases.