In simple terms – if your shower head is positioned lower than your cold water storage tank, you can use a positive shower pump. If the shower head is higher than the water tank (e.g. a loft conversion), a negative pump is needed. Where a gravity flow of water is in excess of 0.6 litres per minute, this is known as a Positive Head condition.
Do I need a positive or negative head shower pump?
The bathroom on the bottom level needs a positive head pump as the water has more than 600mm to travel between the water tank and the shower head. If the shower is more than 600mm, about two rulers, below the cold water tank, then you need a positive head shower pump.
What is a negative head pump used for?
A negative head pump is used where the pump will be situated either level with or above the cold water tank. It then sucks water from the tank to feed the shower.
How does a positive shower pump work?
A positive shower pump pushes the feed of water into your shower. It does this by relying on gravity to feed the water from your water tank into the pump. This flow kickstarts the impellers which then pump the water to the shower.
What is a positive head condition in a shower?
Where a gravity flow of water is in excess of 0.6 litres per minute, this is known as a Positive Head condition. In this situation, a positive shower pump can be used. A Negative Head condition is when the gravity flow is water is less than 0.6 litres per minute.
Why do I need a negative head shower pump?
A negative head pump is used where the pump will be situated either level with or above the cold water tank. It then sucks water from the tank to feed the shower. This type may be needed in bungalows, for example, where there is insufficient head below the tank.
Can pump head be negative?
2. Distance of the liquid source above or below the pump inlet, measured in feet: can be positive OR negative. Positive suction head occurs when the top of the water source is above the suction Inlet of the pump. Negative elevation refers to suction lift (like from a pond, tank lower than the pump, etc.)
What is a negative shower head?
Negative head shower pumps are designed for cold-water tank outlets that are below or near-level with the shower head. They function by creating a negative vacuum which draws water through from the tank and pushes it towards the shower.
How do I choose a shower pump?
Deciding the type of shower pump needed in an installation is determined by the position of the cold water tank in relation to the outlet point. As a general rule, if the cold water tank is above the outlet point and there is a flow of at least 0.5 lpm from the outlet, a positive head shower pump is required.
Do I need a positive or negative shower pump?
If you want to pump a system where the tank is above the pump, you generally need a positive head pump. But if you have a situation where the outlet (i.e. your tap or shower) is above the tank, then you need a negative head pump. This is because a negative head pump (also known as universal) doesn't rely on gravity.
What happen if pump run opposite direction?
A common myth is that in reverse rotation, the pump causes backward flow, that is, IN the discharge and OUT the suction. In reality, a pump operating in reverse rotation because of wiring or phase change will pump in the normal direction. Now, it won't pump very well. Its flow will be reduced, as will its head.
What is the difference between 1.5 bar and 2 bar shower pump?
1.5 bar shower pumps - A 1.5 bar shower pump is best suited to normal showers needing more pressure. 2 bar shower pumps - A 2 bar shower pump is also best for low pressure showers.
What does negative pressure head mean?
What Does Negative Head Mean? Negative head is a condition of negative pressure or vacuum which occurs when the pump outlet is at the same level or above the level of the cold water storage tank.
What is negative pressure in pump?
A negative pressure at the pump means that the hydraulic grade at pump is below its elevation. Generally this occurs on the suction side of the pump if pumping from a reservoir. It denotes the suction side which is a negative pressure point.
How do I know which pump to use?
Before you can select a pump that will fit your needs, you must know four things: 1) the total head or pressure against which it must operate, 2) the desired flow rate, 3) the suction lift, and 4) characteristics of the fluid.
Can a shower pump be too powerful?
Shower Pumps Too Powerful A flow that is too strong can end up damaging the plumbing system. It can waste a lot of water, leading to much higher water bills than you were expecting. It can use stored hot water way too fast, leaving none for the rest of the household.
How do I know which water pump to use?
The most important factors to consider when sizing a water pump come down to GPM/PSI ratings, inlet/outlet size for water and hoses, how high you'll need to pump the water (measured in vertical feet), referred to as total head lift, and how far you'll need to pump the water horizontally.
Can you have a negative total head?
The suction static head (∆HSS) can either be negative or positive, depending on whether the pump centerline is below the suction fluid surface or above, and the value of suction tank fluid surface pressure head (H1).
Can Net Positive Suction Head be negative?
If the NPSH calculation resulted in a negative number, there would not have been enough atmosphere pressure to keep liquid in a liquid state during operation at the design condition point.
What does a negative hydraulic head mean?
A downward flow component is indicated if the gradient is negative, meaning the hydraulic head is less at depth. Conversely, an upward flow component is indicated if the gradient is positive, meaning the hydraulic head is greater at depth.
What does negative pressure mean pump?
A negative pressure at the pump means that the hydraulic grade at pump is below its elevation. Generally this occurs on the suction side of the pump if pumping from a reservoir. It denotes the suction side which is a negative pressure point.
What is a positive head condition?
Where a gravity flow of water is in excess of 0.6 litres per minute, this is known as a Positive Head condition. In this situation, a positive shower pump can be used.
Do negative shower pumps work?
Negative shower pumps will work in both positive and negative head conditions. So for example, in a situation when there is a shower head above and below the water tank level; one negative shower pump can be used for both, as shown in the diagram below.
How to remember the difference between a positive and negative pump?
The best way to remember the key differences between a positive and negative pump is to think push or pull.
Why do shower pumps differ so much in price?
The general rule is the more expensive you go, the higher the bar rating. The higher the bar rating, the stronger the water flow you can expect from your shower head.
What is a shower pump for?
A shower pump increases the thrust in your shower system, pumping more water through your pipes and increasing the pressure you experience at the showerhead.
What are the different types of shower pumps?
For most amateur bathroom fitters, this is where stuff starts to get a little complicated.
What pump brand should I buy?
That covers the basics, and now comes the next part: choosing from the various brands. The amount of choice can seem a little daunting, but in our opinion, there are three brands that stand out from the competition for their combination of high performance and low noise levels.
How do I reduce noise vibrations from my shower pump?
Noise is one of the most common complaints about older shower pumps. The banging. The vibrating. Quite annoying if you're trying to sleep while a family member showers.
What is an impeller shower pump?
A single impeller shower pump is used to boost one water supply. Most installations of this design are for pumping hot water, but it’s not uncommon to use a single design for pumping cold water either.
Which is better, a centrifugal or regenerative shower pump?
Water is propelled around the casing surrounding the impeller blades and the energy created is used to draw more water into the pump. Centrifugal pumps are generally quieter and more efficient while regenerative shower pumps are cheaper and easier to install.
What is a shower pump?
In a centrifugal pump, the most common type, water is moved in and out by centrifugal force. The direction of the flow out is at right angles to the direction of the flow in. When the pump is activated, water flows in onto the impellers and these push the water out at high speed.
How does an impeller pump work?
Each impeller (like a tiny propeller ) is fed by either the cold or the hot water supply and it delivers both hot and cold to the mixer at an equal flow. This type of pump should be sited, ideally, in the airing cupboard to reduce noise. The pump should be installed within 13ft (4 metres) of the hot water cylinder and should be at least 1ft (300mm) ...
How far should a shower head pump be from a hot water cylinder?
The pump should be installed within 13ft (4 metres) of the hot water cylinder and should be at least 1ft (300mm) below the cold water tank. The decision on positive or negative head pumps is fairly straightforward and is entirely dependent on the head (or lack of it) between you cistern and your shower rose.
What are the two main categories of shower pumps?
Shower pumps can be broken down into two main categories: positive head and negative head pumps ; and then a further two categories – twin or single impeller.
Is a regenerative pump better than a centrifugal pump?
If you’re planning to put your pump up in the loft or otherwise above the hot water cylinder, then a regenerative pump may well be a better solution for you as these types are less likely to be affected by the air that can become trapped on top of the water in the hot cylinder. But be aware that these can be noisier than the equivalent centrifugal pump.
Do you need a twin impeller shower pump?
However, if your supply isn’t so well balanced – and this will be the case for most houses in urban areas where mains pressure cold water enters the property at between 4.0 and 5.0 bar – then you’ll need a twin impeller shower pump to balance the supply to the shower. Otherwise, your hot water could be overwhelmed by the amount of cold and you could have trouble getting a comfortable temperature from the shower.
