Skip to content
Description
If one shower runs weak when other taps are open, or the temperature jumps the moment someone uses water elsewhere in your home, and you have a combi boiler — then the SP2B is likely the best pump for you.
Combi boilers heat water on demand, so every open tap competes with your shower for the same supply. The result is pressure that surges and fades, temperatures that jump, and a shower you can’t rely on. It’s one of the most common combi complaints in the UK.
Whilst you may have heard there isn’t a pump that can fix that, there now is.
The SP2B for combi boilers is a WRAS-approved automatic booster pump that fits on the hot pipe feeding your shower, after the boiler. It detects flow and starts by itself — no switches, nothing to turn on. WRAS-approved is important because it means our plumbing products and materials comply with strict water supply regulations and is safe for your home.
Fitted after the boiler on a dedicated pipe, the SP2B prioritises water for that shower and prevents temperature fluctuations when other taps open. Protects flow rates up to 6 L/min for showers; 8.5 L/min for mixed tap flow.
Q: Will the SP2B work if my whole house has low pressure, not just one shower?
A: If the boiler itself is cutting out — delivering only cold or shutting off during use — that’s incoming mains pressure dropping below 1 bar, and you need the SP21S fitted before the boiler instead. The SP2B is the right choice when the boiler is fine and one shower suffers.
Q: Do I need a plumber or electrician?
A: Neither, for most people. If you can cut a pipe and tighten two compression nuts, you can fit it. The 12V supply plugs into a normal socket. If you would prefer to use a plumber, we have a list of plumbers who fit our pumps here.
Q: What if I have more than one weak shower?
A: The SP2B is the right pump whether it’s one, two or three showers — each shower gets its own pump on its own dedicated branch, up to the boiler’s maximum output capacity.