Pumps - Technical information
Do I need a pump?
The pleasure of swirling water is the essence of the modern bathroom. Every time you step into the shower or turn on the tap, there should be a pulse of enjoyment. Without adequate pressure and water flow this is impossible.
In continental Europe and America water supplies in the house are connected to the mains water supply (unvented systems), often giving very high water pressure (in excess of 2 bar). Due to historical reasons, British water systems are generally connected to a water tank in the loft. These are referred to as low pressure vented gravity systems, relying on the height of the cold water storage tank in the loft to provide the pressure and water flow in the house. Given the restriction on the height of the tank, such houses suffer from low pressure (often less than half a bar).
Britain is the only western country that routinely uses gravity systems. Consequently, all research and development by tap and shower manufacturers concentrate on high pressure mains systems, leaving the British consumer "high and dry". Realistically, the modern bathroom requires 2 or 3 bar pressure, making a pump in the UK a necessity rather than a luxury. Luckily modern electronics has now produced a pump that avoids most of the technicalities and reliability problems traditionally associated with domestic water pumps. Given the relatively low cost of these modern pumps, there is now no reason to continue suffering the lousy British shower.
Can I have a pump
The majority of homes in the UK have low pressure gravity systems. These use a cold water storage tank in the loft to provide the pressure and flow of water throughout the house (excluding the kitchen tap, which is connected to the outside main for fresh drinking water).
It is essential to pump gravity systems if you want a modern bathroom. Check with your installer that your cold water storage tank is big enough (minimum of 50 gallons, but for large homes we recommend 100 gallon tanks. The 50 gallon tank is the standard UK domestic tank). Also check that the hot water cylinder is large enough to prevent the heated water running out halfway through that long "hot" bath. For a normal family home a 27 gallon (36/18) cylinder should be sufficient, but a larger home may require a 37 gallon (48/18) cylinder. In other words, the 27 gallon cylinder will give roughly 2 baths/showers of hot water, and the 37 gallon will give 3 baths/showers. Upgrading either a storage tank or hot water cylinder should cost approximately £400 parts and labour.
UNVENTED MAINS SYSTEMS (often called MEGAFLOW)
Some new build homes use the continental method of using mains water to pressurise the water system in the house. These cannot be pumped, but luckily the pressure supplied by the water board should be sufficient for modern bathroom equipment. Mains pressure does vary from region to region, season to season and the time of day. If you have any doubt your local water board can provide minimum and maximum mains pressure for your street. Remember, you need a minimum of 2 bar.
COMBINATION BOILERS / INSTANTANEOUS WATER HEATERS
Flats and small dwellings often use combination boilers to heat the water directly from the mains. The main advantage of this is the supply of unlimited hot water. Unfortunately these boilers are not suitable for larger homes. Given the lack of stored water these systems cannot be pumped. However, given that they use mains water pressure channelled through a combination boiler the pressure is often good enough to power modern taps and a shower valve. A good modern combination boiler with average mains pressure will give approximately 1.5 bar pressure, but old boilers or very basic models may provide less than this. We do not recommend the use of body jets, diverters or 4 function shower heads with combination boilers, as such items cause severe restrictions to the water flow. 2 bar pressure should be the minimum.
How can I tell what system I have
Check if you have the following:
- A cold water storage tank (usually in the loft).
- A hot water cylinder (usually in the airing cupboard).
- Gas boiler - if you use gas central heating you should have a boiler (usually floor-standing).
- Electric heating - the hot water cylinder will have an electric immersion heater to heat the water.
COMBINATION BOILERS / INSTANTANEOUS WATER HEATERS
- Wall-mounted boiler that fires up when you turn on the hot tap.
- Unlimited hot water.
- No hot water cylinder.
- No cold water storage tank.
- You cannot use a pump with combination boilers - sorry!
- No cold water storage tank.
- Pressure expansion vessel on top of the hot water cylinder.
- The label on the hot water cylinder often says 'Megaflow' or 'pressurised system'.
NOTE: It is possible to convert a gravity system to an unvented mains system, but this usually costs in excess of £2,000. If the mains pressure does not exceed 3 bar, or if it is variable and/or intermittent, then it is best to retain a gravity system and use a modern digital pump "low" or "pressurised system".
Where do I put the pump?
A pump is good at pushing water, rather than pulling water. A good analogy would be that it is easier to push a car, rather than pulling it by the bumper. It is therefore important to install the pump next to the hot water cylinder.
What is a bar of pressure?
Pressure is measured in bars (metric) or in feet (imperial). In simple terms a foot of water pressure is the pressure of having the cold water storage tank 1 foot vertically above the tap/shower outlet. Therefore, if the bottom of the cold water storage tank is 5 feet above the shower head outlet, this would give 5 feet head of pressure.
One bar is approximately 33 feet of pressure i.e. the cold water storage tank is 33 feet vertically above the shower head outlet.
Is the pump noisy?
All pumps create noise, but some more than others. Regenerative pumps like Stuart Turner pumps use a system of little buckets scooping up the water rather like an old water mill. This technology is inherently noisy.
Whole house digital centrifugal pumps
The first intelligent whole house and shower booster pumps with electronic sensor protection - capable of anticipating the unforeseen and unexpected.
Digital centrifugal pumps are not only quieter, but also allow the whole house to be pumped, from the shower to the bath to the taps and the WC cisterns. Normal pumps are not suitable for use in situations where only one side (i.e. cold or hot water) is used, as this leads to the unused side of the pump running dry, causing premature failure over time. The ESP pumps have a self lubricating device that ensures the pump does not run dry, even for functions like filling a WC cistern with cold water. This extends the working life of the pump.
Electronic sensor protection
This pump is digitally controlled with a diagnostic panel, which indicates using lights the cause of malfunction should there be a problem i.e. if the heat sensor shuts down the pump due to excessive hot water. Once the cause of the failure is rectified the pump will reset itself. This diagnostic device leads to quick and easy fault detection, saving time and money for the installer and preventing damage to expensive equipment.
The most ingenious feature of these pumps is the built-in pressure vessel, allowing the pump to be used in both positive and negative head situations i.e. in the basement or the loft conversion, in an urban flat conversion or a country mansion. This is a rather technical consideration that does not need explaining here. Suffice to say that these pumps are suitable for both situations leaving installation simple and trouble-free. About time we had an intelligent pump!
It is essential that you have a thermostat installed on your hot water cylinder, and that this is set at no more than 65°C. Temperatures greater than this will over time damage your taps, shower valves and the pump. Any rubber or plastic components like washers degenerate in such extreme temperatures, leading to premature failure.
Not withstanding these considerations, water in excess of 65°C could lead to severe scalding of little children or guests. Excessively hot water is a health and safety issue.
Heating and storing water above 65°C is also very inefficient, leading to much higher fuel bills and unwarranted pollution.
The new digital ESP pumps have a sensor to detect excessively hot water, automatically shutting down the pump to protect your bathroom equipment and the pump itself. Once the temperature returns to normal the pump will reset itself.
For technical help or advice consult PumpWise on 08453 779 160. PumpWise is a complete free advice line to help you:
- Select the right pump for your system
- Eliminate the risk of an incorrect installation
- Secure a third year warranty FREE