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We have put together some common questions with answers. Click on a question below to view the answer. If anyone has a question not in the list below, contact us with the details and we will e-mail you back with the answer.
Questions
- Do all new boiler installations have to be high efficiency condensing boilers?
- When getting a new boiler should I ask to have a combi boiler fitted?
- What is the difference between a combi and a traditional boiler system?
- Which is most reliable a combi or a traditional boiler?
- What is a powerflush and should I have one done?
- How often should I have my boiler serviced?
- When I have my new boiler fitted what controls should be fitted?
- What causes my radiators to sludge up?
- What size of pipes do my radiators need?
- What is the difference between a high pressure system and low pressure system?
- My system loses pressure and I have been advised to add a leak sealer. Is this good advice?
- What is mains pressure hot water?
- Should I leave my heating and hot water on all the time; is this more efficient?
- Why has one of my radiators not got a thermostatic valve?
- Do you do service contracts?
- Why does my boiler require ventilation?
- What are the benefits in using accredited installers?
- What makes of boiler do you recommend?
- Why do I need to upgrade my gas pipe or meter?
- How does a thermostatic radiator valve (TRV) work?
Answers
- As of 1st May 2007 all boilers fitted in Scotland have to comply with current Building regulations and must be high efficiency condensing boilers (SEDBUK band A or B).
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- Most people when replacing a boiler ask for a Combi. This type of boiler is normally only suitable depending on personal usage and hot water requirements. The type of existing heating system you are replacing may not be suitable for a combi.
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- A Combi boiler is a boiler which heats hot water on demand. It does this by taking in cold mains water and heating it in the boiler and sends the hot water directly to the tap. Therefore there is no need for a hot water cylinder. A traditional boiler heats water which is stored in a hot water cylinder which you draw from when you run the hot tap. Combi boilers will give you varied amounts of hot water dependent on their size (KW output). A combi boiler will heat the cold water coming into the house by approximately 35 Degrees Celsius at an amount dependent on the boilers size. For example a Worcester 24i Junior (24KW) will heat the temp of you incoming cold water (average temp 10 Degrees Celsius) by 35 Degrees Celsius and deliver this water to your taps, showers etc at 9.8 litres per minute. A Worcester 42 CDI (42KW) will give you the same rise but at 17.1 litres per minute. This can result in bad reports such as it takes 25 minutes to run a bath and the hot tap upstairs goes cold when the washing machine draws water. This is because you are drawing more water than the boiler can provide. Combis should therefore be sized dependent on your hot water usage. The larger KW rating the combi is the more water you get out of it. A Worcester 42CDi will fill a typical bath in 8 – 10 minutes where as a Worcester 24i Junior (24KW) will fill a typical bath in 18 – 20 minutes.
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- We find traditional systems tend to be more reliable. This is due to the hot water use on the Boiler. A combi boiler has more components which go through a cycle every time the hot water is run. This means there is more risk of a component failure. A traditional boiler is connected to a hot water cylinder so when hot water is drawn, the boiler does not fire. It only fires to keep the cylinder hot at the times specified by the customer on their time clock/ programmer. Life expectancy of a combi is approximately 8 – 10years and a traditional boiler is 12 – 15 years.
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- A Powerflush is a machine which you connect to your heating system to clean the system. It does this by pumping water at high pressure through all your radiators, connected pipework and boiler. This breaks up and removes all dirt and sludge in the system which is then collected in a sump and on magnets which is constantly removed until your system is clean. If dirt and sludge are left in your system it can cause serious problems with water flow and damage your new boiler. Manufacturers report that a high percentage of breakdowns and component failures are related to modern high efficiency boilers being connected to dirty systems.
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- CORGI recommends you have all your gas appliances serviced every 12 months. The required service is detailed in the manufacturer’s instructions and should not be confused with an annual boiler check. An annual boiler check/inspection is not a service.
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- Building regulation say you have to have a minimum of a timer/programmer, a room thermostat and if applicable a cylinder thermostat and thermostatic radiator valves. There are many different types of controls available including wireless and intelligent control systems. Our Estimator will go over these issues with you.
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- Radiators will sludge up due to poor system design or system faults. It will also happen if cleaning and rust inhibitor chemicals have not been added to systems when installed.
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- Radiators are sized to heat your room based on a heat loss calculation (how much heat each particular room loses through walls, ceilings and widows etc). This determines the size of radiator required to effectively heat the room. Also taken into this calculation is the size of pipe required to bring the correct amount of hot water for the radiator to effectively output its heat rating. A radiator which has an output up to 1.8 KW can be fitted using 8mm pipe, a radiator up to 2.3KW can be fitted using 10mm pipe and radiators above 2.3KW should be fitted using 15mm pipe. Therefore some radiators need larger pipes than others but this is determined when the system is surveyed.
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- A low pressure system is normally one which is connected to a small tank (expansion or header tank) in the attic. The only pressure in the system is the weight of the water in the tank. This will normally run at around 0.1 to 0.5 bar. A high pressure system is one which is filled up by mains water and has an expansion vessel connected. This will normally run at 1.0 to 3.0 bar. A traditional boiler can be run on low or high pressure where as combis are mainly on high pressure. Care should be taken when changing systems from low to high pressure as this can cause problems with leaks resulting in excessive topping up of boilers, which in the long term causes damage to the boiler, pipe-work and radiators.
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- Before any chemicals such as leak sealers are added to your system all efforts should be made to find and repair the leak. Leak sealer should only be put in as a last resort. You should also seek expert advice before adding this to your system as it can seriously damage certain types of boilers especially combis.
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- Mains pressure hot water is hot water at the same pressure as water from the water main enters your house. This is done achieved by connecting your hot water cylinder to the cold water main in your house. This then pushes the hot water out of the cylinder at mains pressure. This requires a mains pressure tank and a few other control devices. Most manufactures have now got tanks that can run at 3.5bar which will deliver your hot water at that pressure.
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- This was always a difficult question to answer because the only way to determine this is to try it and compare bills. This however does not take into consideration changing gas prices and weather conditions. There was a survey completed under test conditions by Corgi which was documented in the Gas Installer magazine. They concluded that you should only heat your house and water when required. However they also said it was more efficient to not let your house drop below 15 Degrees Celsius. This is why more and more heating controls have a night setback module built in which brings the heating on at a low rate should the house drop bellow 15 Degrees Celsius. Your first point of call when looking to save on heating bills is the insulation of your house and the efficiency of your heating system.
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- This is what is commonly called a bypass or heat loss radiator. This is so that when all the other radiators have shut off, the boiler still has somewhere to pump the heat away to that has built up in the boiler when it has been running for long periods. It is normally fitted in the same room as the room thermostat so there is always a heat source to activate the room thermostat.
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- Yes we do service contracts. Information can be obtained from the office.
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- Certain types of boilers, mainly older open flued boilers, require purpose provided vents. There are two reasons for having vents. One is to provide a fresh supply of oxygen so that the boiler burns correctly. If a boiler is starved of oxygen it can burn incorrectly and produce carbon monoxide which can be lethal if inhaled. The other vents are normally for cooling purposes. If your boiler is in a cupboard then high and low vents are normally cut in the door to stop the cupboard that the boiler is in from overheating. Corgi has recently changed their ruling on ventilation and recently a lot of customers have had to upgrade vents which no longer meet the correct standards.
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- If you were to use an accredited installer you should be getting an organisation that has a more in depth knowledge of the products they are supplying and fitting in your home. This knowledge is obtained by the manufacturer requiring its accredited installers / engineers to attend technical courses on the products they are installing and keep its accredited installers up to date with products changes, technical issues etc with mail shots and e- mail etc. The benefits to the customer are often better advice, installations, extended warranties, proper maintenance and repairs of your appliance which can lead to fewer breakdowns, longer life expectancy and less inconvenience.
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- There are many types and makes of boiler on the market, in our experience of maintaining and installing them, we would recommend either Worcester Bosch or Valliant. This recommendation is based on build quality, reliability, good variation of boiler choice over the range and excellent engineering. Both of these manufacturers also provide an excellent after sales service.
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- As the size of houses increase as well as the amount of heat and hot water people want in their houses so does the size of the boiler. This means that at peak demand times the boiler will require more gas. Therefore larger gas pipes and larger meters are required to allow more gas to pass through them to the boiler. This is often the case when fitting a new or replacement high efficiency combi boiler. If the boiler gas supply is about 10 metres or more a 28mm gas pipe will be required more often than not.
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- A thermostatic radiator valve opens and closes depending on the air temperature in the room. It is like having a thermostat on every radiator so that when the room gets cold it opens and the radiator heats. When the room comes up to temperature it closes and the radiator cools. This means you can have temperature control in every room in the house. It also means that once set, the radiators should keep the room air temperature stable.
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