Grundfos Twin Impeller Shower Pumps (Hot & Cold)

A twin impeller pump boosts both the hot and cold supplies feeding your shower, so you get stronger, more consistent flow and better temperature control while you shower. That means less chance of sudden temperature drops when someone turns a tap elsewhere. fitting a 3.0 bar twin impeller (such as the STP‑3.0 B) will give a noticeably firmer spray and steadier mix than an unboosted gravity system.

Use the bar rating as a guide to how forceful the spray will be: 1.5 bar for a gentle boost, 2 bar for moderate improvement, 3 bar for a strong, invigorating shower, and 4 bar for maximum power. If you favour a large overhead head or a powerful handset, a 3.0 or 4.0 bar pump will give the best performance; for a modest mixer or small shower head, 1.5–2.0 bar is often sufficient.

Yes. Brass pumps are typically more robust and long‑lasting, particularly in busy family bathrooms, while plastic models (three included in our range) are lighter and usually cheaper. If you expect daily, heavy use, brass is a sensible choice; for an occasional guest bathroom a plastic pump can be a cost-effective option.

The Grundfos STP‑3.0 B at the current product price gives a strong 3.0 bar boost and has very good customer ratings, making it a solid mid-range option for most homes wanting a powerful, reliable shower. If you only need a small lift, the STR2 1.5C at at the current product price offers good value for a modest boost, while the 4.0 bar Amazon twin impeller (STP4.0B) is there if you need maximum power.

Yes, because it raises both hot and cold supplies, a twin impeller pump helps maintain balanced flow into your mixer or thermostatic valve, improving temperature stability when other taps are used. with a 2.0–3.0 bar twin impeller installed you should notice fewer temperature fluctuations than with an unboosted gravity supply.