Learn why shower water may turn cold when the kitchen hot tap is opened. This article explains heater capacity, pipe layout, pressure balance, return loop design, and hot water circulation pump selection.
Why does the shower turn cold when the kitchen hot tap is on?
The shower can turn cold when the kitchen hot tap is opened because the hot water system may not have enough heater capacity, pipe flow, pressure balance, or return circulation for two outlets at the same time. The cause may be pipe layout, undersized pipes, poor mixing control, weak return loop design, or incorrect circulation pump selection.
For small residential or light commercial hot water return systems, AIKON CMS(L)25-6T1M-I can be considered as a reference model with DN25 threaded connection, max flow 3.3 m³/h, max head 6 m, and 100 W power. Final selection should be confirmed by pipe length, required flow, head, water temperature, voltage, number of outlets, and return loop design.
