Boosting Pressure and Flows in Gravity Systems with Mains Pressure Cold

ShowerPowerBoosters are a great solution for anyone who wants a good shower and tap flow and has gravity hot and mains cold. If your cold is mains supply and your hot is gravity then we recommend you double boost the hot with a twin pack SP21S pump kit .  Four out of five customers fit a single ShowerPowerBooster and fit a SP2B on the hot and this will give a good shower but the SP21S will give a great shower with close to the equivalence of mains pressure on the hot.

For a very challenging kitchen tap or a downstairs shower a SP21S is the best solution. You can double boost the hot as there is no chance that this will imbalance the cold, so go for a SP21S.

The majority of mixers will balance differential pressures of 4 or even 5 to 1 so no problem. For some shower/tap mixers there is a requirement for balanced flow (similar pressures on hot and cold). If you have a shower mixer which needs balanced flow the high pressure cold restricts the low pressure hot, a SP2B (single boost) or a SP21S (double boost), should balance hot and cold pressures.

You can always try just the one pump and then upgrade with a SP1U but getting the job done in one hit is often favourite.

Detailed drawings and instructions are in the booklet sent with the pumps but you can download  the online version of this guide using the orange link on this page.