Frequently asked questions
What is a high efficiency condensing boiler? And will it be cost effective?
The most important advance in recent years with regards to domestic boiler has been the introduction of the condensing boiler. Condensing boilers manage 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 heating engineers in the UK only install
condensing boilers these days, this is due to change in government legislation. The majority of installers would say that they are mostly installing combination boilers.
An extra-large heat exchanger (or two heat exchangers
in some 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% and a mere 50% for most back-boiler units. The 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%, both rates will qualify for the 'High Efficiency' band however 'B' rated boilers are no longer allowed to be fitted) once again due to government legislation.
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 household.
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.
What type and what size of boiler do I need?
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 hot water usage and many other parameters such as if you plan to have any property extensions etc. once
all these considerations have been taken into account your heating engineer will be able to calculate accurately what type and size of boiler you actually need require to be installed.
Are there limitations on where I can fit a combi-boiler?
In general terms, you can position the boiler anywhere in the house or bungalow. 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. The condense pipe should preferably terminate to a waste pipe, drain or soil stack, but
nowadays can be pumped away using a condense
pump specifically designed to overcome to problem for requirements for gravity run waste pipes.
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 and whether or not sufficient flow and pressure are available from your mains water inlet.
Noise is coming from our combi-boiler and the water is cloudy, what is wrong with it?
Sometimes you would hear a noise coming from your combi-boiler that is nicknames
"kettling" (due to it sounding like a kettle coming to boiling point). 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 Power/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.
A 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 it 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).
These days’ In-line water descalers
are commonly used to combat this problem and protect the combi-boiler's plate heat exchanger.
What is the deficiency rating of boilers?
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.