Guides ยท Showers
Shower pumps compared: positive head, negative head and a single outlet
How to choose between the positive head, negative head and single-outlet pumps Wickes lists, using the head type and figures on each listing, and why a combi or unvented cylinder is usually a different problem.
Affiliate links: Leatmere is an Amazon Associate and earns from qualifying purchases. We also earn from some links to Wickes through the Awin network. You do not pay more. How this works.
This page is a buying comparison. It is not a ranking, and we have not tested any pump. The job of the page is to put the differences Wickes publishes side by side: positive head or negative head, one supply or two, and the one inline booster that is not a twin shower pump. How to tell which head you have is in shower pump sizing, which also has the browser check.
Gravity-fed systems only, for the shower pumps
The twin and single shower pumps below are described by Wickes as suitable for gravity-fed systems: a cold cistern and a vented hot cylinder. A combi boiler or an unvented cylinder is already at mains pressure. Do not buy one of those shower pumps for either unless that model's own page says it is for that system. Boosting the mains is a different product and can be a regulated arrangement. See low water pressure and unvented cylinder basics. Any work on a gas boiler is for a Gas Safe registered engineer.
What to line up before you compare bar figures
Wickes's Salamander pumps buying guide says a positive head pump only works on a positive head system, and a universal (negative head) pump works on both. It states that the minimum flow for a Salamander positive head pump is 2 litres of water per minute. That figure is Salamander's, as Wickes reports it. It is not a figure for the Bristan pumps.
A higher bar number is not automatically the better buy. It has to suit the shower valve, the head, the cylinder and the cistern. The sizing guide explains why. If an existing pump has become loud, see shower pump noise before replacing it.
Some listings also give a decibel figure. Wickes does not describe the test behind those figures, so they are not a league table.
The listings side by side
| Listing | Head, as Wickes describes it | What it boosts | Figure on the listing |
|---|---|---|---|
| Salamander CT50 Xtra | Positive head, gravity-fed | Hot and cold to a thermostatic mixer. Twin ended | 1.5 bar |
| Salamander CT55 Xtra | Positive head, gravity-fed | An individual hot or cold outlet. Single ended | 1.5 bar |
| Salamander CT Force 30 TU | Positive and negative head, gravity-fed | Hot and cold, and Wickes says up to 6 outlets. Twin ended | 3 bar |
| Bristan twin negative head | Positive and negative. It does not need a gravity flow to start | Two supplies. Twin impeller | Title says 2.0 bar. The specification table lists a maximum pressure of 4 bar |
| Salamander TapBoost | Mains or gravity. This is not a twin shower pump | One outlet: a tap, a toilet or an appliance | 7 to 11 litres per minute, depending on incoming flow |
Positive head twins and singles
Buy a positive head pump only when water already flows from the outlet without a pump. If you are unsure of the heights, Wickes's buying guide says to choose a universal pump. The measured heights and the pump maker's instructions still decide. Our sizing guide is the place to check the system before you use that shortcut.
The CT55 features list also has a general line about boosting hot and cold. The more specific line says it boosts an individual hot or cold outlet. Read both before you treat it as a mixer-shower pump.
Negative head and universal
A negative head or universal pump is the one to read when the shower is level with the cistern, above it, or does not run on its own. The CT Force listing says it suits positive and negative head gravity-fed systems. The Bristan negative head listing says the same kind of thing, and adds that it does not need a gravity flow to start.
On the Bristan page the title says 2.0 bar and the specification table lists a maximum pressure of 4 bar. We have not tried to resolve that. Ask Wickes or Bristan which figure is the rated boost.
The inline booster is a different product
TapBoost is the odd one out in the table. Wickes says it suits mains or gravity, and that it boosts a single outlet rather than a hot and cold pair. A flow of 7 to 11 litres per minute is what Wickes says it can add, depending on the incoming flow. Fitting a pump to the mains is a water-fittings question. Ask a plumber and your water company before you buy one for a mains-fed tap. The Water Supply (Water Fittings) Regulations 1999 apply in England and Wales. Scotland and Northern Ireland have their own rules.
A whole-house mains booster is a different product again. See mains booster pumps.
Who connects it
The pipework is a job for a competent plumber. A pump needs a fixed electrical supply. New electrical work should be done by a qualified electrician. In England, some of that work falls under Part P. Electrical Safety First recommends an electrician registered with a government-approved scheme. We do not give wiring instructions.
Pumps at Wickes
We haven't tested this. Figures are as the maker states them (checked 13 November 2026).
Salamander CT50 Xtra, positive twin, 1.5 bar. Wickes says it suits positive head gravity-fed systems and boosts hot and cold to a thermostatic mixer shower. The features list 52.5 dBA. Four 15mm anti-vibration hoses are included.
Salamander CT55 Xtra, positive single, 1.5 bar. Wickes says it suits positive head gravity-fed systems and boosts an individual hot or cold outlet. The features list 44.5 dBA. Two 15mm hoses are included. Check the general "hot and cold" line against that more specific line.
Salamander CT Force 30 TU, universal twin, 3 bar. Wickes describes a twin ended brass pump for positive and negative head gravity-fed systems, and says it can boost up to 6 outlets. The features list 52.5 dBA and four 22mm hoses.
Bristan twin ended negative head. Wickes says it suits domestic positive and negative head applications and does not need a gravity flow of water to start. The title says 2.0 bar. The specification table lists a maximum pressure of 4 bar. Check which figure applies.
Salamander TapBoost, single outlet. Wickes says it suits mains or gravity fed systems and boosts one outlet, with a flow of 7 to 11 litres per minute depending on the incoming flow. The features list 34.2 dBA. It is not a twin shower pump. Ask a plumber before using it on the mains. The electrical supply is for a qualified electrician.
Do I need the 3 bar pump?
Only if the shower, the cylinder and the cistern suit it. Wickes's 3 bar listing is the universal twin above. A higher bar figure is not a reason on its own. Use the sizing guide and the maker's instructions.
Can I use a positive head pump if the flow is very weak?
Wickes's Salamander buying guide says a Salamander positive head pump needs 2 litres a minute to start, and that a universal pump covers both heads if you are unsure. Measure, and check the maker's page for the pump you actually buy. The Bristan listings are separate.
Is TapBoost a shower pump for a mixer?
No. Wickes describes it as a single-outlet booster for mains or gravity, not as a twin pump for a mixer shower. A standard shower pump is the wrong product for a combi or an unvented cylinder.