Cure condensation and mould. Your heating may be to blame.

Posted on

Does your home have a condensation problem? Do you think it's impossible to cure condensation and mould?

You may be surprised that the way you heat your home can create condensation. But you shouldn't accept condensation as something you have to put up with. There are solutions out there and a little understanding of what's going on means you can probably avoid condensation all together.

cure condensation and mould H2OWhy is condensation something to be avoided? After all, drawing animal shapes or writing messages on steamy windows can be fun!

The trouble is, if left unchecked, condensation promotes mould which ruins your decor and can adversely affect your health. Mould increases the chances you develop respiratory problems, respiratory infections, allergies and asthma, as this NHS article explains. https://www.nhs.uk/common-health-questions/lifestyle/can-damp-and-mould-affect-my-health/

As the article states, mould arises from an excess of moisture. There are many reasons why there may be an excess of moisture in the home, but how to cure condensation and mould is the focus of this blog.

To understand how condensation forms we need to go back to school science lessons. The first lesson is that warm air can hold more moisture than cool air. We learned that when the warm air touches a cold surface, it rapidly cools and deposits some of the moisture it can no longer carry. This appears as condensation on the surface which, in the home, is usually a window or outside wall.

Every home is continuously adding moisture to the air: boiling kettles, running hot taps, drying the washing, and simply the occupants breathing, are all contributing factors. Ventilation helps stop the moisture build-up becoming excessive but condensation will still appear if warm, moist, air contacts a cold surface.

So let's look at the different ways home heating works, and whether condensation is more or less likely to occur depending on the type of heating you choose.

Conventional radiators, fan heaters and convectors

The first thing to understand is that, despite the name, the common wall mounted 'radiator' is mainly a convector. Convectors warm the air and set up circulation currents in the room. Circulation currents are created as the warm air (from the vanes at the back of the 'radiator') rises to the ceiling, gets pushed across the ceiling while cooling, and falls to floor level at the other side of the room.

Similarly, fan-assisted convector heaters and fan heaters heat the air directly and push warm air around the room.

We've seen from the science lesson above that circulating warm air will directly cause condensation when it comes into contact with cold surfaces. Problem areas are un-insulated walls and poorly glazed windows.

And there are other drawbacks. Convection currents mean that the coolest air will be felt as a draught at floor level even if windows and doors are tightly shut. Circulating air will also spread allergy-aggravating dust. See 'Why central heating radiators are bad for you'.

It's easy to see that if you were designing the perfect heating system, there would be no place for conventional radiators, fan heaters and convectors! Of course, most of us are unable to start with a clean sheet of paper and what we need is a simple change that can cure condensation and mould.

Radiant panels, underfloor heating, and on-floor heating

The second science lesson we need to take on board is that heat flows from hot to cold. This can either be by conduction, when 2 bodies are in contact, or radiation, which occurs when the 2 bodies are separated by air or even a vacuum. This is how the Sun warms the Earth from millions of miles away. How strongly it flows from one to the other depends on the difference in temperature, known as the 'temperature gradient'.

You are setting up a temperature gradient when you introduce a warm surface to a room. So long you are able to maintain the temperature of the warm surface, eventually the rest of the room will become just as warm assuming there is no rapid heat loss to the outside .

Most of us will have experienced how comfortable a well set-up underfloor heating system is. The floor is warm, every surface you touch is warm, and even the air is warm.

The heated floor is a 'radiant surface' and continually radiates warmth to the other cooler surfaces. In turn, the air in the room picks up warmth by being in contact with the surfaces. AND, MOST LIKELY, THERE WILL BE NO CONDENSATION.

This is because:

  1. the air is not being artificially circulated
  2. there are no cold surfaces on which condensation would form

This understanding gives us a clue how to avoid condensation: simply eliminate cold surfaces and don't promote warm air movement. Radiant heating from the floor or wall-mounted panels is ideal on both counts.

Radiant heating can cure condensation and mould

Assuming there is no easy way to eliminate the cold surfaces through insulation (if possible, always start with wall insulation, double-glazing etc. for energy efficiency reasons), then radiant heating will usually raise surface temperatures sufficiently so that condensation won't form. It helps if the cold surface has the ability to absorb and hold some warmth. In this respect a wall will be easier to warm than a single-glazed window.

If you don't have underfloor heating there are other effective ways you can introduce a warm radiant surface into a room. For example there are radiant panel heaters that can be fixed on the walls or ceiling, or mounted on castors to be wheeled where needed. Also RugBuddy under-rug heaters count as retro-fit radiant floor heating.

cure condensation and mould trialBeWarmer is running a trial this winter to record how effectively radiant heating is used to cure condensation and mould in a 1950's semi with un-insulated solid walls. Please check back to read about the the trial.