What's the difference between single and twin impeller Grundfos shower pumps, and which one is likely right for you?

Twin impeller pumps boost both your hot and cold supplies at once, which keeps a mixer or thermostatic shower stable and is what you'll normally want for modern mixer showers. Single impeller pumps only boost hot or cold, useful if only one feed is underperforming (if only the hot feed is gravity-fed and needs a lift). If you use a mixer shower or want balanced pressure into a mixer valve, a twin impeller pump is the safer choice.

What do positive, negative and universal head mean, and why does it matter for your shower's performance?

Positive head pumps are used where there is some existing water pressure at the shower; negative head pumps are made to work when the supply tank is lower than the shower outlet and the pump must lift water; universal head pumps work in both situations. The correct head type ensures the pump can prime and deliver the stated boost reliably, so choosing the right type avoids loss of flow or cavitation. Several Grundfos models are offered in positive, negative and universal heads, giving you flexibility depending on how your water feeds are arranged.

How much extra pressure will I get from these pumps and which bar rating makes for a stronger shower?

Grundfos pumps on this page are rated at 1.5, 2, 3 and 4 bar. A 1.5 bar pump gives a modest, steady boost suitable for a small bathroom or low‑flow shower; 2 bar is a sensible mid‑range lift; 3–4 bar delivers a much stronger flow for larger showerheads or multi-outlet setups. If you want a powerful rain or multi‑jet shower, aim for the 3–4 bar models.

Are Grundfos pumps noisy, and how do they reduce vibration and sound?

Grundfos designs these pumps to be quiet in use: compact dimensions, integral controls and anti‑vibration feet all help keep noise to a minimum. You'll find the anti‑vibration feet particularly useful in reducing the transmitted vibration into pipework and bathroom fittings. In practice that means a noticeable reduction in rumble compared with older, non‑isolated pumps.

Should you pick a brass or plastic construction model?

Both materials are offered: four brass and four plastic models in our range. Brass bodies are heavier and more robust, so they're a good match for busy family bathrooms and long service life; plastic options are lighter, often cheaper and resist corrosion. For a high‑use shower you may favour a brass pump, while a plastic model can be a sensible, cost-effective choice for lighter use.

Grundfos Shower Pumps

Grundfos Shower Pumps are a selection of specialist pumps which have been designed specifically to increase the water pressure to bathroom fittings and in particular showers. There is a pump to suit every sort of application from single to twin impeller and negative to positive head which are all straightforward to install and benefit from compact dimensions and integral controls. Anti-vibration feet keep noise to a minimum too. If your shower is underperforming and needs a bit of a boost then you’re most likely in the market for a Grundfos shower pump. Start enjoy your time in the shower again.

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Grundfos Amazon 3.0 Bar Twin Impeller Positive Head Shower Pump - STP-3.0 B

5.0

14 ratings

£373.94 inc
VAT

Grundfos STR2 1.5C Twin Impeller Positive Head Shower Pump - 98950216

4.9

16 ratings

£111.94 inc
VAT

Grundfos Amazon Twin Impeller Positive Head Brass Pump 4.0 Bar - STP4.0B

£580.57 inc
VAT

Grundfos Amazon 2.0 Bar Twin Impeller Positive Head Shower Pump - STP-2.0 B

4.8

35 ratings

£469.91 inc
VAT

Grundfos Amazon Twin Impeller Universal Head Shower Pump 3.0 Bar - STN-3.0 B

5.0

6 ratings

£458.48 inc
VAT

Grundfos STR2 1.5CN Twin Impeller Universal Head Shower Pump - 98950219

5.0

7 ratings

£399.67 inc
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Grundfos STR2 2.0CN Twin Impeller Negative Head Shower Pump - 98950220

4.8

8 ratings

£405.32 inc
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Grundfos SSR2 2.0CN Single Impeller Negative Shower Pump - 98950231

4.8

11 ratings

£280.57 inc
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