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Tips on Boilersbaxi_duotec

Boilers have developed remarkable in recent years. Modern boilers are highly efficient, quiet and can handle both domestic hot water and heating (without using a hot water tank).

Heating Central is a nationwide leading installer of high efficiency boilers in the UK, bringing in years of experience in all types and makes of boilers.

Our boiler installation experts have come across many questions and queries over the years, and are happy to share some of the common questions and answers, be it an avid DIY boiler tip or a simple query.

The list below summarises the most common tips and queries our Gas Safe plumbers are being asked along with some best practice on energy preservation and cost savings.

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What Type and What Size of Boiler Do I Need?boiler_system_wall_large

Calculating the size of the required boiler needs to be done carefully, taking into account the size and the layout of the property, the number of rooms and bathrooms, the profile of hot water usage and many other parameters. Your plumber or heating engineer will be able to calculate accurately what type and size of boiler you actually need to install.

What is a high efficiency condensing boiler? Is it cost effective?

The most important advance in recent years with regards to domestic boiler has been the introduction of the condensing boiler. The condensing boiler manages to recover a substantial amount of the heat that would otherwise be expelled into the atmosphere from the flue of a standard (non-condensing) boiler. The vast majority of plumbers and heating engineers in the UK only install condensing boilers these days. Most plumbers actually admit that within this category, most are Combi boiler (see below for details).

An extra-large heat exchanger (or two heat exchangers in other cases) within the boiler is used to reclaim the heat from some of the expelled hot gases. This way the system maximises heat transfer from the burner while recovering useful heat that would normally be lost with the flue gases.

Traditional boilers have typical efficiency rating of 70%. Efficiency rating for a boiler represents the percentage of useable energy output compared to the energy input. A high efficiency condensing boiler will have efficiency rating of at least 86%. An A rated boiler will have an efficiency rating of over 90%, with a B rated boiler will have at least 86% (and both rates will qualify for the "High Efficiency" band).

According to the Government's new building regulations, all new boilers installed in England and Wales from April 2005 must be of high efficiency. High Efficiency boilers are up to 35% more efficient than traditional boilers and will substantially reduce the energy used for water heating in your house hold.

The benefits of installing a high efficiency condensing boiler are substantial and can reach 100-120 per year on your space heating and water heating bills. In addition, a quality condensing boiler will reduce your household's CO2 emission by approximately 800Kg per annum.

Are There Limitations on Where I Can Fit a Combi Boiler?

In general terms, you can position the boiler anywhere in the house. However, there are some considerations you need to take into account such as planning a path for an outside access for the flue, as well as meeting all relevant building regulations.

What is the Efficiency Rating of Boilers?sedbukrating_table

Boilers' efficiency is rated according to SEDBUK – Seasonal Efficiency of Domestic Boilers in the UK.

The scheme was developed by the government's Energy Efficiency Best Practice Programme (in conjunction with the main boiler manufacturers), to create a fair comparison of boilers efficiency and energy performance.

The scheme enables consumers and heating engineers to choose an appliance according to its efficiency and is in effect an energy labelling system for the heating and boiler market.

The SEDBUK rating bands percentages represent average efficiency achieved for a typical home, based on standard assumptions on annual usage, climate and controls.

Rating within bands "A" or "B" qualifies a boiler to be called a 'High Efficiency' boiler.

What is the Environmental Impact of Boilers' Production and Disposal?

Disposed old boilers normally get recycled through recondition and reuse of their more sturdy components in special recycling centres around the country.

New boilers are constructed to strict environmental standards, which ensure low impact when they end their useful life. The materials used are such that they do not harm the ozone layer, and minimise the release of greenhouse gases during the manufacturing process.

There are Noises Coming from My Combi Boiler and the Water is Cloudy, What's Wrong?

Combi boiler eliminates the need for hot water storage tanks, which is a big benefit in terms of space and cost savings. Since the water is being heated instantly and directly from the mains feed, the hot water reaches the user immediately as it hits the atmosphere.

During the rapid heating process inside the combi boiler, the calcium bi-carbonate inside the water is transformed into calcium carbonate, which creates carbon dioxide which appears as many tiny bubbles in the hot water stream. This is cosmetic sediment, which will disappear if you were to leave the water inside a clear glass for a little while and let if cool off a little. The situation is more acute in hard water areas or if the combi boiler is slower (or with a lower flow rate).

Sometimes you would hear a noise coming from your combi boiler that is nicknames "kettling". This is a result of the scale and sludge deposits that develop inside the heat exchanger over time. In such case you might want to consider a chemical flush, which can help resolve this problem. However, the ultimate solution for this problem is to replace the boiler and make sure that the installer is of high quality to make sure you do not experience such noises again with your new boiler.

There is Never Enough Pressure in the Shower, What is the Best Solution?

One reason can be that the water heating is powered by an old combi boiler. In such case the low pressure might be due to the old boiler having a very poor flow rate, and not being able to provide enough hot water volume to your shower. New combi boilers have significantly better flow rate and can provide much better water pressure. However, it is essential to check with your installer whether your shower is compatible with the new boiler.


This page has been written with contributions from experienced heating engineers from Merseyside and experienced plumbers from Dartford. Several of the company's Gas Safe engineers from Hertfordshire have worked on similar issues as well as some of our heating engineers from Balham and our Fulham plumbers.