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Install Single Pump to a Shower Valve

Installing a single impeller pump for a shower is in essence a simple operation if you are using it to boost the hot water supply there are some important point’s to note though.


Most shower valves will mix temperature well when a balanced supply is achieved but if you have a unbalanced supply e.g. 3.0 bar on the cold mains supply and you are using a pump with a pressure of say 1.5 bar then to achieve a good mix can be difficult, for this reason we usually will recommend a twin pump boosting both hot and cold supplies to the same pressure allowing for a good mix.


I am basing this installation how to on a Salamander 2.4 bar single impeller pump as this is one of our best sellers and the theory is the same whichever pump you choose , it will be assuming that you are pumping the hot water as this is the most common function.


Cold Water StorageSingle Impeller Shower Pump Diagram

First rule of thumb is to make sure that you are storing enough cold water for the shower, 225 liters or 50 gallons is normally adequate for most shower applications.

If you intend to run more than 1 bathroom then you need to allow 50 gallons (136 liters) for each bathroom and 30 gallons (136 liters) for each shower room or en-suite.


Next consider the position of the pump it should always be fitted at least 600mm from the bottom of the cold water storage tank to the top of the pump motor/impeller casing.

The best position for the pump is at the base of the hot water cylinder as close as possible to the cylinder.

If you are fitting the pump above the hot water cylinder you will need to install a anti gravity loop as per loft pump shower diagram otherwise follow single impeller shower pump installation diagram.


Hot Water Supplies and ConnectionsSingle Impeller Shower Pump in Loft Diagram

There are many described ways of connecting to a hot water cylinder, but there is one way that is the best, that is to have a separate connection that is not restricted and ensures that little air can get into the pump impellers which will if excessive damage the pump.

With this in mind use a dedicated flange to connect to the hot water cylinder a non stop Essex flange will give the least resistance best for 22mm pumps or if using a 15mm pump a S-Flange will be sufficient.

As you have followed this advice then you will only need to fit 1 separate full bore isolating valve on the supply pipe as your pump will be within reaching distance of the cylinder.


Flush Pipe Work Prior to Connecting to the Pump!


Now connect to the single impeller pump the hot water feed, fit the supplied AV (Anti-Vibration) couplers open the isolation valve on the inlet and close the outlet isolation valve, open all other valves and check for leaks.


Priming the Pump

You can now prime the pump and supply pipe work of air to do this you simply drain off a bucket of water through the pump with the electrics off using the outlet isolation valve as a tap.


Connecting from the Pump to the Shower Valve

*Note: If your pipes are going to run up into the loft it is important to fit a manual air vent to the highest point of the pipe work.


Connect to the outlet of the pump to the shower. You will notice that in both drawings I have added a non-return valve on the supply pipe to the hot side of the shower. You will have to do this if the shower valve you are installing does not have built in non-return valves.

Non-return valves will stop the flow from the mains pressure of the cold supply entering the hot pipe-work reversing the flow and making the cold water storage tank over flow when the valve is in use (manual valve) or in the case of thermostatic shower valves were the thermostatic control and the on/off control are separate the water actually mixes before the stop valve so the tank can overflow when the valve is not in use.


That’s it happy showering………


Salamander RGP120 Pump