Choosing a New Heating Boiler
Choosing a new central heating boiler can be a daunting prospect as there are several options to choose from and new ideas are coming on to the market almost every day. The main purpose of a boiler is twofold; it needs to provide hot water to the kitchen and washrooms and to provide heat to the home. It is referred to as central heating because the heat is generated in one place and is then spread via a system of pipes or ducts to the rest of the building.
The principle means of generating that heat is still oil and gas, but there are a number of other systems that are being used to do this. There are still systems around that feed directly off solid fuels, such as coal or wood, but these are not as popular in today’s society where everything works at the touch of a button. Eco-friendly systems are also growing in popularity and perhaps the most well known of the new systems around are solar panels.
Most of us will choose a boiler based on the easiest and cheapest fuel available to us, and we often don’t even ask the plumber which boiler is being used. But it’s worth thinking about that as boilers vary in quality as well as in price and functionality. At the very least we can easily make sure that the central heating boiler we get is a high quality product and it’s worth checking the credentials of any manufacturer we might be interested in before we make a decision.
All boilers now come with an efficiency rating, and gas is no exception. Whether it is natural gas or bottled gas you will a rating in the form of a percentage and the closer to a 100% rating the better and more efficient it is. Gas boilers come as either combination boilers, often referred to as combi boilers or as system boilers. The building regulations state that all new boilers that are installed into domestic homes, whether they are combi or system boilers, must be condensing boilers as they are at least 25% more efficient when compared to non-condensing boilers. Basically, a condensing boiler is completely sealed and takes air from outside the house only, whereas a non-condensing boiler takes air from inside the property, which also means that a condensing boiler is much safer.
A combination boiler will provide instant hot water to the tap and for that reason doesn’t require a storage cylinder for the hot water, whereas a system boiler will produce and store the hot water ready to be used.
Most natural gas boilers can also be obtained as LPG boilers and there are very few differences between the two; the main one being the need to fit different jets to the burners. The biggest difference you will notice is the need to have the gas delivered and stored in a large tank on sited on the property. The possibility of running out of gas before the next delivery is lessened by the installation of a system that monitors the amount of gas in the tank and notifies the supplier automatically when it needs topping up. The only drawback to a new system is the initial cost of installation along with the disruption. The tank can be stored underground but adds to the expense.
Combi versus system
When deciding which system to choose, there are a number of factors that need to be taken into account, as no two households are the same. Combi boilers function by taking the water directly from the mains and heating it immediately before delivering it to the tap. This is great for your pocket as very little hot water is wasted and it can also save desperately needed space as no tank is required to store expensively heated water that then sits in the tank going cold if it’s not used. But it can be a problem if the water pressure to the property is very low as the system relies on that pressure to operate the boiler.
A system boiler, on the other hand, will need to store the water in a cylinder, but works well for a house where there are two or more bathrooms as it doesn’t rely on water pressure for the boiler to work efficiently. A system boiler should be considered for busy households so all of the household can be provided hot water at the same time. The down side is that once the tank of hot water is used up you will have to wait for the boiler to heat it up again. This is fine as long as you plan the system around the household needs.
While an oil boiler works in a similar way to a gas boiler, the main difference is that the oil has to be delivered and stored in a sealed tank. Oil boilers also have the choice of either a combination or system boiler, but the combination oil boiler will have an internal storage tank for hot water rather than instantaneous hot water provided by a gas combi boiler. Oil is a more efficient fuel than gas but both fuels fall in and out of favour depending on how the prices rise and fall.
Oil boilers are also subject to efficiency ratings and must have a minimum efficiency of 86%, and only new oil condensing boilers are able to achieve those figures. Due to advances in technology oil boilers have also been reduced in size and are comparable with gas boilers.
High pressure hot water cylinders
These hot water and heating systems resemble the old hot water storage cylinders. They come in various sizes to suit demand. Heating of the water can be either indirect from a coiled pipe in the cylinder that is heated by the flow of hot water from the boiler, or electrically heated by an immersion heater that is similar to the element found in an electric kettle. As with gas and oil systems these hot water cylinders must be installed by someone who is qualified to carry out the installation. The water is heated up under pressure and because the tank is sealed it needs to have special pressure / heat safety valves fitted that will allow over pressurised water to escape safely if the system over heats. It is essential these valves are installed correctly to ensure that there is no dangerous build-up of pressure with the storage vessel, and as an extra precaution the tank normally has two thermostats as a safety device. The advantages of the system are that no other storage tanks are required, and as the tank is fed directly from the mains it can be located virtually anywhere. Because the water is supplied from the mains the water pressure is much greater than any tank fed system. This has the advantage of greatly increasing the flow rate from the hot water taps.
Problems may arise if the water pressure to the property is too low, and if there is a mains water failure there is no backup from a storage tank. The system can also be quite expensive to install.
There are systems available to help with the problem of insufficient water pressure and they come in various guises depending upon the need. The basic setup is a pump that is activated automatically when a tap is opened, and by storing water in a sump the unit can increase the water pressure to a property on demand. The advantages to water pressure boost systems like these are that they can feed one property or several at a time. If space is at a premium it is possible to install a small pump system in the loft of a property. The pump has its own header tank and can provide between 1 -6 bars of pressure.
Whatever boiler you choose always use a properly registered plumber to carry out the installation. One of the best ways of finding a competent tradesman is by recommendation, so tell all of your friends as you can guarantee that one of them will know a good plumber.
Heating Systems – Maintaining and Improving
It is most likely that there is no other system in your house with more working parts than your central heating system, and there are several things that can go wrong with the system. We are going to take a look at what can go wrong and how to prevent or remedy such problems.
Condensate pipe freezing
If the air temperature outside is below freezing it is possible for the discharge pipe from the boiler to become frozen. Moisture from the boilers flue is collected inside and discharge through the condensate pipe. If your boiler is registering a fault and the codes indicate that a frozen pipe could be one of the problems then the first thing to do is to try and restart the boiler. If it fails to restart you may hear a gurgling sound coming from the boiler. Either way, you should check the condensate pipe, this is the plastic pipe which is coloured black, grey or white, and if this pipe is not insulated it is possible that the pipe could be frozen and will need to be thawed.
You may wish to contact your installer or service provider if you have a service contract, as they will offer additional plumbing and heating advice. Otherwise you could attempt to unfreeze the pipe yourself. You will need to exercise extreme caution at all times while carrying out the work and you should only attempt the task if the pipe is at ground level and is easily accessible. One way to unfreeze the pipe is to wrap a hot water bottle around the condensate pipe, or you could use a hair dryer to thaw the pipe. Once you are satisfied that the pipe is no longer frozen you can attempt to reset the boiler. A permanent solution to prevent the pipe from freezing is to wrap insulation around the pipe where it is exposed to the outside air or in a cold environment, such as a loft. It is important to make sure that the condensate pipe has a minimum fall of 3 degrees, which works out to around 1cm every 21cm. If a frozen pipe is a regular occurrence it may be worth thinking about increasing the diameter of the pipe to 32mm where the pipe is fitted externally as most systems will have a 21mm overflow pipe.
Thermostatic radiator valves
Any new heating system that is installed would automatically be fitted with TRV’s, but it is possible to upgrade the old valves on your radiators. There are a couple of things that you would need to check first. If your system is several years old it may have imperial pipe sizes, in which case you would need to make sure that compatible fittings are still available. You also need to look at whether your system has a two pipe layout. This will mean that the radiators have an inlet and outlet connected to separate flow and return pipes. It is important leave at least one radiator with a manual valve, and that will need to be left open permanently to allow water to pump freely through the system.
The next thing to do is to check whether your valves are mounted horizontally or vertically and buy the corresponding TRV’s. Modern TRV’s have some interesting features, such as ceramic discs which are less likely to be affected by hard water. It is also possible to get TRV’s that have a frost setting, which can be handy when you are away from home and temperatures plummet. And some new valves have a remote sensor which can be positioned away from the radiator, giving a more accurate estimate of the room temperature.
Once you have checked out what you require you will need to drain part or all of the central heating system. If you unsure how to do this then consult your manufacturer or supplier for the right plumbing and heating advice. The system will need to be turned off before you begin, and once the system is drained you can then begin to replace the valves. There will be two nuts that need to be undone; one to the radiator tail pipe and the other that connects the valve to the radiator. Unscrew the head and tail from the new valve and wrap the thread of the tail piece with PTFE tape. This is a white tape available from all good DIY stores that ensures a watertight seal.
First connect the valve tail piece to the water inlet pipe and tighten. Then re-connect the valve to the tail pipe. You will need to remove the white cap protecting the valve and replace with the valve head containing the sensor. When it all looks good and you are satisfied there are no leaks you can recheck and tighten the nuts. Once you have refilled the system you will need to bleed the radiators of the air that replaced the water you drained off, making sure at this point that all of the TRV’s are open to allow hot water into the radiators.
You will find a small nipple at the top of the radiator that is designed to do this, but great care must be taken not to loosen the nipple too far so that it comes out; half a turn is usually enough to allow the air to escape. The radiators will have to be bled several times before all of the air is gone at which point you can adjust the thermostatic valves to the desired temperature for that room.
System power flush
The first questions to ask are, what is a power flush, and secondly, how do you know if you need one? Quite simply, a power flush works by attaching a power flushing pump to the circulatory system and then chemicals are passed through to dislodge any rust or sludge. Once this has been done, clean water is forced through the system to push any contaminants out completely. At the end of the flushing process, the system contains only fresh water, and inhibitors are added to this to prevent the build up of rust and sludge in the future.
Most people rely on a plumber or the heating contractor maintaining their system to tell them what is needed to maintain their heating. The downside to this can be companies recommending that you have unnecessary work done to drum up work. So it makes sense to arrange for at least three plumbers to check your heating system to see if they all have the same opinion. Should your heating system need a power flush, it is again worth getting several quotes before you proceed.
It is possible to carry out a power flush yourself as well as adding the inhibitors, and we shall be writing about this in a future article.
There are, of course, things that you can do in the attempt to prevent or limit potential problems with your heating system. Besides adding an inhibitor, you can also add a magnet filter to your system. They are simple to install and require very little servicing, but more importantly, they can save you a large amount of cash. They work by preventing a build-up of iron-oxide and non-magnetic deposits in the system, which can result in a loss of efficiency and fuel wastage.
The central heating system in your home is one of the most important and expensive investments you will make. So it is worth spending some time thinking about how best to protect and maintain it. In the age of the internet, plumbing and heating advice is never too far away.
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