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Appliance Repair Guide

Central Heating Repair Guide

For keeping your rooms warm and your baths hot during the long, cold British winter, you need a reliable and fully-functioning central hearing system. In this article, we look at

Things to consider when having problems with your central heating

Most central heating installers recommend that homeowners replace their boilers every 10 years or so. After 10 years, the chances are that you’ll incur large annual bills on both repairs and maintenance. If you were to purchase a boiler on finance over 5 years, the monthly repayments you make would be significantly covered by the savings you make on your gas and electricity bills.

That’s because the energy efficiency of your boiler goes down over time. A new boiler, depending on the size of your property, may save you up to £300 a year on your utility bills.

Detecting and identifying faults with your central heating

When most central heating systems start to go wrong, there are normally four main issues to look out for:


Either no hot water or no heating

If you’re not getting either hot water or heating, you should check to see that your boiler is still connected to the gas and electricity mains supply. There may also be a fault on your programmer so it’s worth checking that too. The next most likely cause is a seized or faulty pump – if this is the case, it will need replacing or repairing.


No hot water but the heating is fine

If the radiators are working but you’re not getting any hot water, there are likely to be a number of different causes. It could be a faulty programmer or immersion heater – if this is the cause, they will need repairing or replacing.

Your cylinder thermostat switch may be broken meaning that you’ll need to replace the thermostat and test the electrical circuits attached. Your motorised valve may have seized up and if this is so, you’ll need to repair or replace it.

For older types of boiler, an airlock may mean that your cylinder is hot but that you’re getting no hot water to your taps or that your storage tank is empty.


Hissing and rattling from your system

If your system is either hissing or rattling, then you may have a leak in your central heating system. This is a potentially a major fault that will need immediate attention from a professional service engineer.

To discover whether a leak is the cause, you can fill your boiler with water to see how long it takes to drain away. You may also want to check for any water where it should not be in your combi boiler unit itself or by following the drips of water to their source. There may also be excessive air in your radiators causing the system leak.


Poor circulation

A build-up of sludge in your radiators will cause large parts of them to be cold and it will also affect the circulation of water around your central heating system. If you drain your radiator and the water looks dirty, this is an important sign that you will need to take immediate action. It’s more than likely that your entire central heating system will need to have a power flush performed on it by a central heating engineer. Expect to pay between £250 and £450 for a complete system power flush.

These are the types of problem you’re most likely to encounter if you own either a combi boiler or a conventional boiler. A combi boiler, the most popular type in the UK, takes water directly from the mains and it heats the water up within the unit. The second most popular boiler is a conventional boiler – this uses a storage tank which heats up the water which then provides hot water to the rest of the house.


Potential repairs and costs for your central heating

There are four parts of your central heating system, all linked to your boiler, which are more likely to go wrong than the others because of the amount of work they do providing your home with hot water and heat.

Those parts are, together with costs of repair/replacing and labour costs:

  • new heating pump – £170 to £205
  • replacement thermostat – £170 to £220
  • magnetic filter installation – £245 to £355
  • replacement fan – £220 to £270

Because of the expense involved in repairing and replacing boiler parts, many people opt to take out an annual servicing contract – normally between £150 and £250. The price includes cover if your central heating system breaks down so you won’t pay an additional parts or labour charges on top of this amount.

You can also opt for a one-off boiler service – they normally cost between £60 and £110. An engineer will check all parts of your central heating system however if any repairs need carrying out, you will pay extra for that.


Should I repair or replace my central heating?

There are a number of factors you’ll have to weigh up carefully when you’re deciding whether you need to repair or replace your boiler.

Most heating engineers recommend that you have your boiler serviced once a year – even if you think that there’s nothing wrong with it. Because boilers are complicated pieces of technology, it may be that one or more of the parts are not operating as well as they could be. This often leads to much bigger problems later on.

You should think about replacing your boiler every 10 years or so. If you do keep it for longer than that, then the £150-£250 you pay on an annual servicing contract will probably be worth it because there’s a higher chance of your boiler breaking more often.

Please remember too that, as time goes by, safety standards applied to central heating systems improve and it may be that the boiler in your home now would be considered as unsafe by modern standards.

It’s best to get 3-4 tradespeople in to make sure you get the best price if you want to replace your central heating system. If you’re just getting a new boiler put in a 3-bed house, you’ll need a 28-34kW boiler which, including installation and moving pipes, should cost you around £1,900. If you wanted to buy 9 new radiators for your central heating and have them installed, you should expect to pay around £3,500.


What to look out for in when replacing your central heating?

If you’ve decided to replace your central heating, what do you need to be aware of?


Is your boiler the right size?

Different sizes of home require different sizes of boilers. For smaller properties with up to 10 radiators, the power of the boiler you choose (called the “output” by engineers) should be 24-27kW. For medium sized properties with 2 bathrooms and up to 11-15 radiators, an output of 28-34kW will be enough. For the largest homes, ask your installer about a 35kW output boiler.


Flow rate

The higher your flow rate, the more litres of water your boiler can process every minute. If you have a lot of taps around your home, choose a boiler with a higher flow rate.


Energy efficiency

“A”-rated boilers use more than 90% of the power that they draw in heating up your water whereas “B”-rated boilers use 85-90% of the power. The more energy efficient, the better for the environment and the cheaper your utility bills.