Table of Contents
- 1 What does negative head pump mean?
- 2 What is the best pump for a shower?
- 3 What is positive pump?
- 4 What is a Surrey flange?
- 5 Can a shower pump be too powerful?
- 6 What is the difference between positive and negative displacement pump?
- 7 What is the difference between a positive and negative head system?
- 8 What is the flow rate of a positive pump?
What does negative head pump mean?
The term ‘negative head’ means the cold water tank outlet is below or near-level with the shower head. Negative head pumps have a pressure switch to recognise when the shower is turned on even when water is not flowing.
Can you use a negative head pump?
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.
What is the best pump for a shower?
In a Rush? Here are the Best Shower Pumps in 2021
- Showermate Eco Twin 4650 — best overall value for your money.
- Bristan ST PUMP15TN — top budget pick for a gravity-fed system.
- Salamander CT85XTRA — balances power (2.5 bar), quiet operation, and costs.
How do positive head shower pumps work?
A positive shower pump relies on gravity to feed the water from your tank into the pump. This flow starts the impellers which pump the water to your shower. It’s recommended that your water tank should be approx 1m above your shower head so the water will have enough speed to get the pump working.
What is positive pump?
What is a positive displacement pump? A positive displacement pump provides a constant flow at fixed speed, regardless of changes in pressure. The pump makes the fluid move by trapping a fixed amount and forcing the volume into the discharge pipe.
What is a positive head water system?
This system normally features a cold water tank in the loft and a hot water cylinder tank in an airing cupboard. This is called a positive head system because the cold water tank is positioned 600mm higher than the shower, so water flows downwards via gravity.
What is a Surrey flange?
A Surrey flange is a fitting on a hot water cylinder which prevents a device, such as a shower pump, from being damaged by air. It does this by drawing off water via a tube which dips down into the main body of hot water. When water in the cylinder is heated by the coil or the immersion heater, air bubbles form.
Do I need positive or negative shower pump?
If the shower is more than 600mm, about two rulers, below the cold water tank, then you need a positive head shower pump. If the shower is less than 600mm below the cold water tank, then you need a negative head shower pump.
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.
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.
What is the difference between positive and negative displacement pump?
What is a positive displacement pump? A positive displacement pump provides a constant flow at fixed speed, regardless of changes in pressure….Difference between a positive and non-positive displacement pump.
| Positive Displacement Pumps | Non-Positive Displacement Pumps | |
|---|---|---|
| Performance | Flow is constant with changing pressure | Flow varies with changing pressure |
What is the difference between a positive and negative shower pump?
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.
What is the difference between a positive and negative head system?
A positive head system occurs when there is more than 600mm from the bottom of the cold water tank to highest point in the system. A negative head system occurs when the distance from the bottom of the cold water tank to the highest point in the system is less than 600mm.
Do I need a negative head pump for my bathroom?
As you can see, there are two bathrooms on different levels. The bathroom on the top level needs a negative head pump as the water has less than 600mm to travel between the water tank and the shower head.
What is the flow rate of a positive pump?
Key learning: A positive pump needs a flow rate of at least 0.6 litres a minute and relies on gravity to start the impellers to pump hot and cold water. What is a negative head system? However, if the distance between the cold water tank and the shower head is no more than 600mm this is called a negative head system.