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Positive Head or Negative Head: Which Will Be Appropriate for Your Boiler System

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Positive Head or Negative Head: Which Will Be Appropriate for Your Boiler System

The cold storage tank (also known as ‘cold water cistern’) in an open vented water system is typically located in the loft. People often confuse cold storage with hot water cylinders; the hot cylinder is situated in an airing cupboard or utility room on a lower level and supplies hot water across the property. People often install shower pumps, to increase the water supply and get an excellent showering experience. If you want to install or repair a shower pump, hiring a professional boiler specialist can be beneficial for you.

In this blog, you will learn how and why cold water tanks/cisterns directly affect which type of shower pump is appropriate for your property.

Impact of Cold Water Tanks/Cisterns on Your Choice of Shower Pumps

Shower pumps have two variants, such as positive head and negative head (also known as ‘Universal’ pumps). Negative head pumps can be used in both cases. which shower pump can be suitable for you depends on the flow rate from the cistern, the distance between the cistern and pump and the highest water outlet. The water pressure and flow rate depend on the height difference between the cold-water tank and the highest point where the water is used, such as the highest shower head. In many cases, a shower pump is necessary to ensure acceptable water pressure and flow for the bathrooms, showers, taps, and other water outlets.

Which One Should You Choose: Positive Head or Negative Head (Universal) 

A gravity-fed system requires either a positive or negative head shower pump, depending on the natural flow rate of the water in the property. To activate a positive head pump, 1 litre per 30 seconds of water is required to flow naturally through the pump and out of the taps and outlets. If this flow cannot be achieved naturally, a negative head pump will be required, which is slightly more expensive than a positive head pump.

Negative head pumps are required when the water flow to a tap or shower is insufficient. This can occur if the first outlet is too close or above the height of the cold water tank. Negative head systems are usually found in loft installations where the cold water tank is positioned on the joists. A negative head pump is necessary if the distance between the bottom of the cold water tank and the highest point of the first water outlet is 2 feet (610mm) or less. This is because there is not enough natural gravity to activate a positive head pump. Negative head pumps are slightly more expensive but are a reliable choice for any property, as they work regardless of the height of the cold water tank and water flow.

Wrapping Up

Please let us know your thoughts on this blog. To get an excellent shower pump installation or repair, you can contact us or leave a comment below.

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