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A gravity-fed system is either positive or negative head. In a positive head system a water flow rate of at least 2L/min exists from gravity alone. In negative head systems the water flow rate is less than 2L/min.

When choosing which pump you need it is important to know if the system is positive or negative head as incorrect selection can mean the pump won’t work.

A positive head pump will only work in a positive head system and a negative head (universal) pump will work in both a positive and negative head system, so if you are not sure choose a negative head pump.

Click here to learn how to determine if your system is suitable for a positive head pump.

A positive head pump will activate when a minimum flow of water passes through the pump and out of the pumped outlet, such as a shower or tap, naturally (without assistance from the pump). The minimum flow rate required for our positive head pumps is 2 litres of water per minute (L/min).

You will need to measure the flow rate to determine if a positive head pump is suitable for your system. You will need to test all outlets, such as showers and taps, that are going to be pumped to determine if they have the required minimum flow rate of 2L/min. Watch our video to learn how to measure the water flow rate.

If you cannot measure the water flow rate, then you can check if the system is suitable for a positive head pump if there is more than 600 mm between the base of the cold-water storage tank and the highest point in the system after the pump.

If you are unable to achieve the minimum flow rate of 1 litre per 30 seconds from all outlets that are to be pumped you will need to install a negative (universal) head pump.

Centrifugal pumps, such as our Right Pump range, use centrifugal force to increase water pressure within a system. Water enters through the inlet on the end of the shower pump, filling the impeller chamber and the impeller. As the impeller spins, water is thrown outwards using centrifugal force, this builds higher pressure within the chamber which forces water out the top of the pump.

This method of increasing pressure results in a higher flow efficiency than with a regenerative shower pump, so installations with multiple bathrooms can benefit from installing a centrifugal pump.

Air causes a range of problems in pumps and can ultimately damage or break the pump.  The best way to prevent air getting into the pump is to ensure that a flange is fitted on the hot water cylinder.  Salamander sell an ‘S’ flange, which is a device used to remove air intake from the hot water cylinder from where the pumps draws hot water.  The ‘S’ flange sits on top of the hot water cylinder and will need to be installed by a competent and trained installer. Click here for further information on the S falnge.

Most of our pumps must have a flange fitted to ensure longevity of life of the pump and for the warranty to remain valid. Click here for further information and exceptions to this.

Please ensure that the pumps’ warranty and installation guide book is checked before pump installation.

If the pump is activating but there is still low/no pressure to the shower this is likely  caused by a restriction after the pump, this could be:

• Blocked filters – these are found on the inlets to the pump. Click here to find out how to clean them.
• Shower head is partially blocked with limescale.
• Twisted hose to the shower head.
• Possibly the wrong pump has been installed e.g. you have a positive head pump but there is not enough natural flow, so you need a negative head (universal) pump. Click here to find out the difference between positive head and negative head systems.

If the pump is slow to switch on it could be because there is something restricting the flow of water.  This could be:

• Blocked filters – these are found on the inlets to the shower pump. Click here to find out how to clean them.
• Shower head is partially blocked with limescale.
• Twisted hose to the shower head.
• Possibly the wrong pump has been installed e.g. you have a positive head pump but there is not enough natural flow so you need a negative head (universal pump). Watch the video to find out the difference between positive head and negative head.

When a shower pump starts to display any of the following, an ‘open-ended’ test can be carried out to check that each side of the pump is functioning as it should:

Low pressure on hot, cold or both sides of the pump

Hot, cold or both sides of the pump will not activate.

Watch our video to learn how to carry out the open-ended test.

When a shower pump starts to lose pressure or stops activating on hot or cold water, then turning the pump around can help diagnose the problem.

Watch our video on turning the pump around.

This is usually down to the natural flow of water, either the hot or the cold supply of water is not generating enough flow to activate the individual flow switches.  Salamander Pumps require 2 litres per minute per side to switch on.

If this is a persistent problem it may mean that you need a universal pump.  You can upgrade your shower pump to a universal shower pump by contacting Salamander Pumps.