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Home >> Other Services >> Secondary Circulation << Accumulators and Pump Sets >> Consultancy

A very common misunderstanding, by both customers and installers, is that a Megaflo system will create a high pressure (and high performance) water system. This is incorrect. - a Megaflo (or unvented) system does not create pressure. It simply takes advantage of the existing pressure and flow from the incoming supply (typically the mains water supply).
A significant proportion of our enquiries concern poorly performing systems, which are generally attributable to poor design and specification, or incorrect installation.
Unfortunately, installing a nice new Megaflo system will not guarantee high performance showers, baths, taps, etc. Furthermore, the prro results only become apparent once everything is completed with system is up-and-running. Symptoms are: pressure drops when other outlets are used - washing machines, dishwashers or flushing a WC. Also fluctuating shower temperatures whenever another outlet is used. Basically unusable and far from ideal!

To address issues of poor performance, there are several options. Every case is different and the best solution depends on various factors; water pressure, flow rate, household water usage, number of bathrooms, number of occupants, etc, etc.

Usually the water source (and input to the Megaflo) needs to be improved; either by boosting the pressure, increasing the flow rate, or both! You cannot pump the output of a Megaflo Unvented system, so the solution needs to be applied upstream of the unvented cylinder.

Accumulators, Pump Sets and Water Boosters

Performance of Megaflo unvented water systems rely on a combination of water pressure and flow rate. Legally, the water undertaker only needs to supply a minimum of 1 bar pressure and 9 litres per minute flow rate, at the suppliers stop tap. This was absolutely fine for traditional gravity systems, but is not suitable for modern mains pressure Megaflo systems.

For Megaflo and other brand unvented hot water systems, manufacturers typically recommend a minimum of 1.5 bar pressure and 20 litres per minute. This may be fine for small, single bathroom properties, but for multiple bathrooms we certainly recommend higher pressures and flow rates. These would be calculated according to customer requirements.
If the water supply cannot keep-up with the water usage during peak times, then opening one tap may adversely affect another, flushing a toilet may affect someone showering, or it may identify as generally disappointing performance overall.

Where the mains water supply is insufficient to 'power' an unvented hot water system or cannot deliver the desired performance, then an Accumulator, Pump Set or Water Booster will offer the ideal solution, together with some additional benefits! There are various benefits in specifying an accumulator over a pump set or vice versa; each one has it's own advantages depending on the particular situation. Almost all jobs are unique, but the principles are the same!


Guildford Megaflo Accumulator

Accumulators offer a cost effective way to improve the supply pressures by providing a buffer of stored water. Air within the accumulator, contained within a rubber diaphragm, is compressed by the incoming water pressure, or charging pump (where necessary). When a tap is opened, the water is forced out from the accumulator to the tap; it can be compared to blowing-up a balloon, and then letting the air out quickly.
Accumulators are an ideal solution for properties where the mains water supply cannot keep-up with the required demand; this is often the case with larger properties where multiple bathrooms may be in-use simultaneously.
Improved performance of a Megaflo or unvented system is often the driving factor for the installation of an accumulator or pump set. In this scenario, the design and installation are key factors. Pipe sizing, choice of components and technical design will greatly affect the overall performance. Accumulators are modular. They can be added to at a later date in increase capacity (assuming the design and layout allow).

Sizing is important too; an accumulator can run out of water! It won't do any harm, but when empty, it will revert back to the original supply flow rate until it has re-filled. Once all outlets are closed, the accumulator will automatically begin refilling and stop once the supply pressure is reached.

Following a long conversation with the technical department of a major pump and expansion vessel manufacturer, we quickly realised that even the Industry Specialists fail to underdstand the basic principles!

This prompted us to record this demos video below to prove it works.


Boost a Main Accumulator

The video below demonstrates the benefit of an accumulator with a charging pump; the results are extremely impressive! This shows a single shower, and then a second, third and forth are switched on, and the flow reverts to a barely a dribble. Switch on the accumulator, and you instantly have full flow to all four showers. When designed and sized correctly, accumulators can service as many outlets as required.



Pump Sets

Water Booster Set A pump set is made up of booster pump(s), a cold water break tank, an accumulator vessel, and some controls. They are ideal for areas with poor or unreliable mains pressure, or where the water supply cannot be made large enough to feed multiple outlets at once.

Water BoosterTypically, two pumps are used to provided duty/assist operation, with both pumps only running together at maximum load. Addtionally, the use of two pumps also allows water to be provided should one pump fail - this is very important. The cold water tank must be sized to provide both hot and cold supplies at times of peak usage. A large ball-valve in the cold tank is used to maximise the input from the mains.

The accumulator is essentially a pressure vessel that stores a volume of high pressure water, and prevents the pumps from having to run when someone is only brushing their teeth.

The larger the accumulator, the more water can be drawn without the pumps operating; this helps reduce wear on the pumps and 60 litres is a typical size. The controls provide the duty / assist operation using pressure switches, but will also alternate which pump comes on first to even out the wear, and also provide pump over-ride and protection. Pump sets generate as much water, and pressure as you specify.

Water Boosters

Water Boosters are used to improve the water supply to domestic properties with Megaflo or Unvented hot water systems. These typically consists of a storage tank with one or more pumps to provide a neat and compact solution. Additional storage tanks may be required depending on the usage.

Megaflo Home BoosterGuildford Megaflo Water Booster

Pump Noise

Modern pumps are generally very quiet, but where possible we recommend keeping them away from living and sleeping accommodation. A garage or outbuilding is ideal!

Below is a video of a DAB Esybox pump installed in a garage. It's no louder than a washing machine, and you can even hear the water refilling whilst the pump is running.


Please contact Megaflo Unvented to discuss your requirements or to arrange a free on-site survey.

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