Air vents behind radiators and/or trickle vents

[Spuncho]

I'm putting central heating into a flat which previously had storage heaters. I found evidence of poor ventilation, with black mould build-up most pronounced in the bedrooms. I suspect this is due to a lack of trickle vents in the double glazing. The floor is concrete and the walls are cavity (without insulation). In addition to trickle vents, I'm being advised to install air bricks behind the radiators, under the windows. Everyone I've asked has never heard of air bricks behind rads. Does anyone know if this is a good idea or not?

 

[stem]

I've come across it a few times.

In a room with a gas appliance that was not room sealed and required an air supply. I guess the idea of putting it behind the radiator was for aesthetics, diffusing any draft, and to prevent someone sealing it up.

In a conference room I did some work in. The room had an extraction system in the ceiling and the replacement air came in from air bricks behind every radiator. [They were known as Black Hole Ventilators (See here for website) they had an internal baffle and were supposed to be less susceptible to drafts when it was windy.] The idea was that the air was warmed by the radiators before entering the room. In practice it worked up to a point, but once the room was being used, the radiators went cold because the heat from the occupants turned off the thermostat and then there was a cold draft around the floor and lots of complaints of cold feet and legs. After 5 years the air bricks were filled in and a ventilation system with heat recovery installed.

I would have thought opening the windows would suffice, as they can just be cracked open slightly as and when required, or increase the insulation on the cold surfaces, so that moisture doesn't condense on them in the first place.

Storage heaters are not ideal for bedrooms because of their lack of control can make it too hot, so they tend not to be used, meaning that the fabric of the room doesn't get heated. You may find that once you have radiators installed with proper thermostatic control you won't have the problem. [As long as the radiators aren't used for drying washing]

 

[endecotp]

I'm putting central heating into a flat which previously had storage heaters. I found evidence of poor ventilation, with black mould build-up most pronounced in the bedrooms. I suspect this is due to a lack of trickle vents in the double glazing. The floor is concrete and the walls are cavity (without insulation).

I suspect it's due to a lack of insulation in the floor and walls.
Is there an extractor in the kitchen and bathroom?

 

[^woody^]

Does anyone know if this is a good idea or not?

It's a bad idea.

To get the required air movement to prevent condensation forming on cold walls, air bricks should be sited near to external corners and/or diagonally opposite doors if possible. They should be at high level, 300 mm down from ceilings and 300 in from walls if possible.

But, air bricks themselves are not a magical cure, and unless th new heating drastically alters the internal environment, you will most likely need other remedies and/or chgange the way you do things too.

Apart from that, with an air brick in that location, the radiator will be just be mainly drawing in cold air and heating that up, causing poor heating patterns in the room and inefficient heating of the internal air