If two TapBoost pumps are installed in-line (one after the other) will they deliver double the flow?

No, two TapBoost pumps in-line will not deliver double the flow and TapBoost must not be installed in this way. If a single TapBoost does not provide adequate flow, please consider one of our other products:

Our MainsBooster range features larger inline pumps and accumulator tank which will provide greater flow rates in mains-fed systems.

Our GravityBooster range includes pumps which will deliver higher flow rates in gravity-fed system