Bind – Gas Safe Engineers, Somerset & Wiltshire


Boiler Installation | Boiler Servicing & Repair | Central Heating & Hot Water Installation


Welcome to Bind, your trusted Gas Safe registered heating and hot water engineers serving Somerset and Wiltshire. In this guide, we’ll dive into the various types of hot water systems that play a crucial role in your home’s comfort and functionality. Our team of home heating and hot water professionals are dedicated to ensuring that your domestic hot water systems operate efficiently and reliably.


Types of Hot Water Systems

When it comes to domestic hot water systems, there are several options available, each with its own set of benefits and considerations. We’ll be focusing on three main types:

1. Mains Pressure Combi Boiler

A mains pressure combination boiler (combi boiler) is a popular choice in the UK for its cost, efficiency and convenience. This system features a ‘combination’ or ‘combi’ boiler, usually installed somewhere nice and snug and compactly housed within a single unit. It serves most homes as both a high-efficiency water heater and a central heating boiler.

Operating under mains pressure, this system heats water directly from the mains upon turning on a tap. Consequently, there’s no need for a hot water storage cylinder or a cold water storage tank in the loft. With a typical output of around 1.8 bar, the mains pressure combination boiler ensures a strong and consistent flow rate from your taps and showers.

2. Unvented Hot Water System

Mains pressure unvented systems are commonly found in properties where space constraints prohibit the installation of a cold water storage tank, usually located in the loft. This setup involves a boiler and a separate hot water storage tank.

In this arrangement, mains pressure water is stored in an unvented hot water cylinder often situated in an airing cupboard. The water can be heated through immersion heaters integrated into the cylinder’s side or by a wall-mounted central heating boiler. As taps or showers are activated, the incoming cold mains water pressure disperses the hot water to the outlets.

Due to the maintained pressure from the incoming mains cold feed, hot water is delivered at a pressure similar to that of the mains supply. This unvented system typically operates at 1.5 – 1.8 bar pressure, providing ample water flow rate and strong pressure for a satisfying experience with taps and showers.

3. Low-Pressure Gravity System

The low-pressure gravity system, commonly found in older homes, involves providing hot water to your home using a mix of gravity and pumps, where needed. This system needs two water tanks, situated high in your home, usually a loft, and a boiler to heat this water which is then stored in a hot water cylinder.

The pressure and flow rate in this system are influenced by factors like mains pressure to your home and the vertical distance between the cold water tank and the outlet. Pressure is calculated in bars, with approximately 0.1 bar pressure generated for every 1-meter fall in height.

For showers and baths, it’s important to consider the impact of this system’s pressure on outlets. A vertical distance of 5 meters between the cylinder base and an outlet yields roughly 0.5 bar pressure. However, bends, lengthy horizontal runs, or indirect routes can reduce available water pressure.

Installing a combi boiler will remove both hot water and cold water tanks and offer higher-pressure hot water throughout your home. If you want to increase the pressure of hot water in your home, speak to one of our local Gas Safe engineers, we’d be happy to help.


Bind – Heating and Hot Water, Somerset & Wiltshire

At Bind, we’re committed to delivering professional hot water, home heating and local boiler services that cater to your unique needs. Whether you’re considering a mains pressure system or are unable to manage with a low-pressure gravity setup, we have the expertise to assist you.

Contact us today for expert advice and solutions tailored to your domestic hot water installation, servicing and repairs.

We also offer some amazing new boiler deals, after-sales boiler servicing and system checks too!