Listed below are some frequently asked questions and their answers.
Is My Boiler Energy Efficient?
If your boiler is 10 years old or more then it probably isn’t. A boiler with a stated SAP (Standard Assessment Procedure) efficiency of 90% or more will generally use a third less fuel than an older boiler.
To check out the efficiency of your boiler go to www.boilers.org.uk
Is My Boiler a Condensing Boiler?
Your boiler has a flue which protrudes out from the back of the boiler through an external wall. If the flue is plastic and a white plume puffs out of it when the boiler is switched on, then it is likely to be a condensing boiler. Non-condensing boilers have metal flues, because their exhaust gases are much hotter, and except in cold weather the exhaust gases will not be visible.
Is My Boiler a High Efficiency Condensing Boiler?
A condensing boiler recovers some additional heat from the waste gases which escape via the flue, because of this they are much more efficient than non-condensing boilers.
In order to be able to evaluate between boilers, they are rated according to how efficient they are in converting fuel to heat, and this is expressed as a percentage. SAP (Standard Assessment Procedure), which replaces the old SEDBUK rating scheme, provides the best estimates of annual average efficiencies of boilers when installed in typical domestic conditions in the UK. You can check out the SAP database at www.boilers.org.uk
Unfortunately most older boilers in the UK have an energy efficiency of below 70%.
The best high efficiency condensing boilers convert more than 90% of their fuel into heat – only these boilers carry the Energy Saving Recommended logo. Simply put, only £10 in a £100 energy bill is wasted.
Installing a new high energy efficiency boiler can reduce your heating bills and CO2 emissions by up to a third.
To check out the efficiency of your boiler go to www.boilers.org.uk
I intend to replace my boiler – should I fit a condensing boiler?
Legislation introduced by the Government on 1st April 2005 stipulated that all new boilers must have an energy efficiency of 86% or above. Only condensing boilers reach this level of efficiency. This legislation therefore, effectively permits only Condensing Boilers to be installed (with some minor exceptions).
I intend to replace my boiler – should I choose a conventional condensing boiler or a combination condensing boiler? / Is a combination condensing boiler more efficient than a conventional condensing boiler?
A ‘Combi’ boiler has two key components, a conventional boiler and a water heater which heats water almost instantaneously as it is demanded. You do not need a separate hot water cylinder (in your airing cupboard) to store hot water. Because water is only heated as you require it, it is not stored in a hot water tank where it will gradually lose heat (although the heat will be lost more slowly if your tank is well insulated). In this sense ‘Combi’ boilers can be more efficient.
However, hot water from ‘Combi’ boilers flows more slowly, and while such boilers can provide enough water for most homes, they can not cope with heavy demands for hot water. So for example, if your home has multiple bathrooms it is probably better to install a conventional boiler with a separate hot water tank. An alternative would be to use a gas saver in conjunction with a heat store.
Your gas engineer will be able to assess your needs and advise accordingly.
If I fit a ‘Combi’ boiler will this result in low water pressure?
Because of the manner in which a ‘Combi’ boiler heats water ie it is heated instantly and directly from the mains feed when you turn on your hot water tap, this typically results in a lower pressure of water. New ‘Combi’ boilers have a significantly better flow rate (ie they can heat more water more quickly), and therefore can provide much better water pressure than older ‘Combi’ boilers. However, you should discuss your requirements with your gas engineer who will be able to advise.
How can I tell if I have a regular or combination boiler?
If you have a ‘Combi’ boiler, you will not have a hot water tank (or over-tap electric water heater), or a cold water storage tank. With a ‘Combi’ system the boiler will start up every time the hot water tap is turned on.
What is the plume coming out from my condensing boiler?
The flue gases from a condensing boiler are identical to those emitted by a non condensing boiler. A white plume is visible because in a condensing boiler much of the heat in the gases has been recaptured, hence the resultant waste gases are much cooler, and therefore contain condensed water vapour which is visible as a white plume.
What is a Power or System Flush and do I need one?
Power Flushing is a newer and more effective means of cleansing a central heating system than a conventional System Flush. A clogged up system will prevent your boiler from operating at peak efficiency, meaning that more fuel will be needed to heat your home.
A power flushing machine is connected to the heating system. The high velocity flow of water through the system will dislodge built-up deposits commonly referred to as sludge. Clean water is forced through the heating system loosening the sludge and pushing the contaminated water out through a waste valve. Central heating radiators are individually flushed, without disconnecting them from the system.
On completion of the power flushing process, the system contains only clean water.
Power Flushing has many advantages:
- When installing a new boiler – this will ensure that the new boiler operates within a clean circuit. Failure to adequately clean the system prior to new boiler installation can lead to the invalidation of your boiler warranty.
- When some of your radiators, or lower areas of your radiators are cold – a Powerflush will unblock the system, distributing heat effectively once more.
- Reduces noise from the boiler and pipes – such noise is typically due to sludge build up.
- Increases the efficiency of your central heating system and reduces boiler stress.
Flushing your system does not need to be undertaken annually but is useful every few years.
The water coming from my ‘Combi’ boiler is Cloudy, what is the problem?
Combi boilers eliminate the need for hot water storage tanks, because the water is heated instantly and directly from the mains feed when you turn on your hot water tap.
During the rapid heating process inside the Combi boiler, the calcium bi-carbonate in the water is transformed into calcium carbonate, which creates carbon dioxide which appears as many tiny bubbles in the hot water. This is a cosmetic sediment which disappears if you allow the water to settle and cool a little. The sediment is more apparent in hard water areas or if the combi boiler has a slower water flow rate.
If I fit a ‘Combi’ boiler and I lose my hot water tank in the airing cupboard, where can I air/dry off my clothes.
Many people like the idea of an airing cupboard. If you switch to a ‘Combi’ boiler, a small radiator can be fitted inside your airing cupboard, to allow you to continue using it as such. Additionally, you will have much more cupboard space and can fit a pole on which to hang clothes, together with clothes shelves.
I need to have my boiler serviced but I have lost the Manufacturer’s Service Instructions what should I do?
Refer to our Section ‘Annual Service vs Annual Safety Check’
Why are some of my radiators hotter than others?
This usually means that your central heating system is incorrectly balanced. This results in an uneven flow of hot water to each radiator. Have your gas engineer check out your central heating system.
My radiators are hot at the bottom but cold at the top, what is the problem?
This is typically caused by air trapped in the top of the radiator(s). Over time, air can accumulate at the top of radiator(s) preventing hot water from reaching these areas. In order to remove the air you need to individually “bleed” the affected radiators. Prior to bleeding the radiator(s), turn off the central heating to prevent more air from entering the system. Hold a cloth underneath the radiator key and open the valve very slowly as dirty water can spray out. If the water is exceedingly dirty you may want to consider having your system power flushed to return it to peak efficiency.
My radiators are hot at the top but cold at the bottom, what causes this?
This is typically caused by a build up of sludge. Over time your central heating system builds up a deposit of dirt and contaminants. A sludge can form at the base of your radiators which blocks hot water from reaching these areas…hence they cannot heat fully. Power Flushing is the process by which central heating systems and radiators are forcibly cleansed using high velocity, low pressure water. Hence a Power Flush removes these deposits and the problems that they cause.
What is a thermostatic radiator valve?
A thermostatic radiator valve (TRV) allows you to control the temperature in individual rooms around your home. It also helps to improve the efficiency of your central heating system by automatically adjusting the radiator temperature once your room has reached its desired level – thereby reducing fuel bills.
I am renovating my kitchen and wish to hide the gas boiler flue behind panelling. My builder has advised against this, why should this be a problem?
In addition to inspecting the boiler / appliance itself, a gas engineer conducting an annual service is legally obliged to thereafter, examine the effectiveness of any flue and the supply of the combustion air.
Such inspections are necessary to avoid combustion products such as carbon monoxide from entering the building. To comply with this regulation, it is necessary to inspect the entire length of the flue, to ascertain its condition, and to do the same with the air intake duct.
In some properties (usually flats), the flue and airducts have been concealed behind ceilings or within other home structures. This can be a major problem given that;
- The regulations specify that no person shall install a flue pipe so that it enters a brick or masonry chimney in such a way that the seal between the flue pipe and the chimney cannot be inspected and
- No person shall connect a gas appliance to a flue which is surrounded by an enclosure unless that enclosure is so sealed that any spillage of products of combustion cannot pass from the enclosure to any room or internal space other than the room or internal space in which the appliance is installed.
If the above regulations are not complied with it is impossible for the Gas Engineer to classify the appliance as “safe”.
Are gas wall heaters and a gas fire as efficient as a full gas central heating system?
Individually, gas wall heaters have an efficiency of around 75-80%, which is the same as some older conventional gas boilers. However, the efficiency is diminished because of the lack of control – although they have thermostats to maintain room temperature, they are not generally automatic and you have to switch them on and off manually.
- In contrast, new gas boilers (central heating) have an efficiency of over 90%.
The life expectancy of these units is up to 20 years. When such systems need replacing it would be better to look at upgrading to a full radiator system with a high efficiency gas boiler – your gas engineer will be able to assist you in the choice of an ‘Energy Saving Recommended’ boiler.
Can I get a grant to help with the cost of replacing my boiler?
Grants are available to assist with boiler replacement costs. Consumers should check with the Energy Savings Trust to find out about grants and eligibility in their area – Tel: 0800 512012 www.energysavingtrust.org.uk
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Installation of Gas Cooker
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