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Install Whole House Pumps

There are many ways to install a whole house pump, however, there are certain rules that will work for all whole house pumps, no matter which make or model.


Below you will find basic guidelines to demonstrate how to install a twin impellor pump, I have based this installation guide on a Salamander RHP 75 whole house twin impeller pump.

pumping both your hot and cold water supplies to a house to boost the gravity fed supplies. If you need specific pump details you can now download the installation instructions for each model on the individual product pages (see our whole house collection here), you may also want to have a look at our Pump Comparison Guide showing the key features of each model.


A couple of important notes for choosing a pump that will be for a whole house application, if there are any low flow devices of less than 1 litres per minute for either the hot or cold side or there is high usage where supplies are on/off many times you should choose a negative head model, another consideration is to use a quieter centrifugal pump like the ESP or RHP pumps as tend to give a better flow rate. I would always try to put items like toilets onto mains supplies to save the pump from coming on when you need a midnight leak, also the cold side of the basin taps so you are brushing teeth in fresh water.


For the ultimate in whole house pumping use two single pumps of the same pressure, the installation pipe work will be the same configuration as this description.


*Please Note: Most shower pumps are not suitable for whole house pumping.


Cold Water Supplies and Connections.

Standard Gravity Fed System

First rule of thumb is to make sure that you are storing enough cold water for the property. 225 litres or 50 gallons is normally adequate for a bathroom add on 60% (135 litres or 30 Gallons) more for an en-suite, so a bathroom and an en-suite will require 360 litres (80 gallons) of stored cold water.

If you have two bathrooms or more you will need to ensure that the cold water supply to the hot water cylinder is at least 28mm.


Next consider the position of the pump it should always be fitted with at least 600mm from the bottom of the cold water storage tank to the top of the pump motor / impellor casing. As shown in our drawing the best position for the pump is at the base of the hot water cylinder and as close as possible to the cylinder.


The installation of the water supply from the cold water storage tank to your pump is straight forward. Use a separate 22mm outlet connection from the cold water storage tank, we recommend this is drilled on the opposite side of the tank to the float valve (to make this connection use a 22mm compression tank connector).


It is good plumbing practice to next fit a 22mm full bore isolating valve in your new cold water supply pipe. You should always include a way of isolating the water supplies both at source and locally to the pump you are installing (please refer to our drawing).


This supply can now feed the pump inlet, if there are no isolating valves fitted to the pump anti-vibration couplers (the flexible pump connectors) then fit them just prior to the pump. It is important to note that all our pumps are supplied complete with av-couplers.


It does not matter whether the pump has 22mm or 15mm connections, by supplying the pump with a 22mm supply complete with the full bore valves the suction side of the pump will not be restricted.


Our RHP and ESP 75 model is a good example of a pump with 22mm I would not recommend a 15mm pump for whole house applications as they will not have the adequate flow rates required for running more than one outlet at a time.


Hot Water Supplies and Connections.

Pumped Whole House Plumbing System


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


There are many described ways of connecting to a hot water cylinder, but there is one way that is the best. We recommend you install a separate connection that is not restricted and ensures that very little air can get into the pump impellors. It is important to note that excessive air will 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 and is best for 22mm pumps, if you are fitting a 15mm pump a Surrey or S-Flange will be sufficient.


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


Flush Pipe Work Prior To Connecting to the Pump.


Once you have connected the supply pipes to the pump it is now time to prime the pump. Firstly, with the electrical supply off run one bucket of water out of both the hot and the cold sides of the pump until the water has run clear and there is no apparent air.


You can now run the pipes to the rest of the hot outlets in the house, first you will need to disconnect the old pipe from the hot water cylinder, this will be located off of the vent or expansion pipe (see Drawing), it is extremely important to keep the vent pipe functioning, so if there are any hot supplies that come off of this pipe you will need to disconnect them all, The disconnected supply pipes can now be connected back to the hot outlet of the pump.


Please Note: If the pipes from your pump to an appliance run back up to the loft then you will need to fit air vents in the highest pipe position and a non return valve fitted to the hot outlet side only.


Now that you have reconfigured your pipes as per the diagram make sure that they are all flushed as best as possible.


That’s it you now have a high pressure system……


Salamander Whole House Pumps