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Heating

Advice on boilers, radiators, central heating systems and keeping your home warm and energy efficient.

Heating

Focus on Damp Part Two: Condensation

It’s that time of year when the heating goes on and the windows are closed. It is also possibly that time of year where you notice the odd damp patch or spot of mould on walls or ceilings.

It’s that time of year when the heating goes on and the windows are closed. It is also possibly that time of year where you notice the odd damp patch or spot of mould on walls or ceilings.

Discovering that you have got damp is a headache, but the sooner you get a damp specialist in to take a look, the easier it is to deal with. Last week, we talked about rising damp, the signs, causes and prevention. This week, our attention turns to one of the sneakiest of damps: condensation. Here’s what you need to know.

All about condensation

You don’t need to be a science genius to know that when warmer air cools rapidly, water particles in the air condense, forming droplets of water. It happens on an ice-cold class of drink, in cars and, of course, in homes. Condensation is more of a problem when the difference between the air inside and the air outside is very pronounced, for example, when it is 1⁰ outside and 20⁰ inside. During winter, the warm, moist air inside your home reaches a cold window or wall, the water in that air becomes water on your windows or walls.

Condensation is made worse if you have poor ventilation in your home, especially in Kitchens and bathrooms where you are creating a lot of steam that doesn’t have anywhere to go.

Identifying condensation

Condensation is fairly easy to identify; look out for droplets of water on walls and windows, a damp smell, or dark mould patches.

Dealing with condensation

If you notice a damp or mouldy patch, don’t panic! At the point of noticing, condensation is fairly easy to deal with; it is only if you leave it unchecked that it can cause serious damage. Here are some easy ways to treat condensation:

  • Dramatic changes in temperature make condensation much worse. Instead of having the heating go on and off, keep it on low all of the time. It’s cheaper and easier on your boiler, too.
  • Ventilate, ventilate, ventilate! If you are in the shower or bath and you don’t have an extractor fan, shut the door and open the windows to let the steam go out. In other rooms (particularly if you notice mould or water droplets), you can use a dehumidifier to remove some of the moisture from the air, or invest in proper ventilation.
  • Make small changes – don’t dry washing on the radiator (you are just adding more water to the air!); put a lid on pans of water while they are boiling.
  • Clean the mould. Mould can be harmful to your health, so once you have sorted your condensation problem, it is a good idea to clean off the mould. There are good antifungal sprays available, but hot, soapy water might do the trick.
  • Ask a professional. If the problem is persistent or you are concerned, call a damp specialist.

Next week, we turn our attention to penetrating damp. For more information and advice, follow us on Facebook or Twitter.

Looking for more heating advice?

Find clear, practical answers to common heating questions, helping homeowners understand everyday issues, know what checks they can carry out safely, and when it is best to contact a qualified professional.

  • What is the difference between a combi boiler and a system boiler?

    A combi heats water straight from the mains on demand - no cylinder needed, which makes it compact and ideal for smaller homes or flats. A system boiler works with a hot water cylinder, storing a ready supply that can serve multiple taps or showers at once without the pressure dropping - better for larger homes with more bathrooms. There's also the conventional boiler, which needs both a cylinder and a cold water tank in the loft - common in older properties. A heating engineer can help you figure out which suits your home best.

  • Is an air source heat pump right for my home?

    Heat pumps pull warmth from the outside air (even when it's cold) and use it to heat your home and hot water. They work best in well-insulated homes, ideally with underfloor heating or larger radiators that work well at lower temperatures. In draughty or poorly insulated properties, the benefits are more limited. The Boiler Upgrade Scheme currently offers a grant of up to £7,500 towards installation, so it's worth getting a professional assessment to see whether your home is a good fit before committing.

  • How often should a boiler be serviced?

    Once a year, by a Gas Safe registered engineer. It keeps the boiler running safely, catches small issues before they become expensive, and is usually a condition of the manufacturer's warranty. Some home insurance policies require proof of regular servicing too. If you're not sure when yours was last done, book one before winter - better to find out before you're sitting in a cold house!

  • Why is my radiator cold at the top but warm at the bottom?

    This issue is almost always trapped air. Bleeding the radiator - using a radiator key to release the air - usually sorts it, and it's one of the few heating jobs you can safely do yourself. If bleeding it doesn't work, or if several radiators are having the same problem, it might be a pressure or pump issue. Worth getting a heating engineer in to have a look.

  • What are the signs my boiler needs replacing?

    Keep an eye out for: frequent breakdowns, energy bills going up without using more heat, unusual noises (banging, kettling, or whistling), a flame that's yellow or orange instead of blue, and any visible leaks or rust around the unit. If your boiler is over fifteen years old and ticking any of those boxes, replacing it is usually the more economical choice - modern boilers are significantly more efficient.

  • Is underfloor heating worth it and do I need a professional to install it?

    For a new build or a big renovation, underfloor heating is often a great investment - it heats rooms more evenly than radiators and can be more efficient, especially alongside a heat pump. Retrofitting in an existing home is more of a job, and how worthwhile it is depends on your floor types and how much disruption you're happy to deal with. Either way - wet or electric - it has to be installed by a qualified professional.

  • Why does my boiler keep losing pressure?

    Some pressure drop over time is normal, but if you're topping it up regularly there's usually a cause: a small leak in the system (which isn't always easy to spot), a pressure relief valve that's releasing water, or air in the system after bleeding radiators. Topping it up via the filling loop is fine as a short-term fix, but if you're doing it more than a couple of times a year, it's worth getting an engineer to look into why it keeps happening.

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