High humidity with combi boiler. Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[fmck]

I recently finished building a 4mx3m porch after the original small 2 x 1 one was constantly running with damp due to poor build.
It now looks like the comi boiler we have in there produces some amount of moisture and obviously was a big factor in the original porch being so damp. The windows constantly stream with water in cold weather as does any cold area.

Is this normal ? Is there something we can do obviously it worries me venting cold air into the boiler area.

[plastic_man77]

FMCK

I'm concerned that your boiler might be an open flue combi and is not getting rid of the products of combustion properly.

If it is open flue, your new porch should have appropriate permanent ventilation from outside air for combustion. Did your last porch have any?

Seriously, if you believe the moisture could be coming from the boiler, rather than as a result of it just running normally, then stop using it and call a heating engineer to your property asap to get it serviced and checked out. It could even be room sealed and have a poor seal around the combustion chamber??

If it turns out to be a false alarm, at least you can be safe in the knowlege you aren't going to die prematurely from carbon monoxide poisoning.

RJR

[htg engineer]

Is the porch insulated ?
Flat roof ?

It could just be because of the difference between inside and outside temperature

htg

[fmck]

Is the porch insulated ?
Flat roof ?

It could just be because of the difference between inside and outside temperature

htg

Its not open flue and the flue going outside does steam away but inside it still feels like its very humid but no obvious sign of release. Before the porch was just single skin brick and it was running with moisture.

Its now 12m2 with 50mm kingspan insulation top and bottom plus 35mm thermaline board walls all painted with eggshell paint. It is as you say a flat roof and being a porch (building regs) does not have heating etc so you might be right.

Thanks for the replys folks

[Perry525]

The water vapour is coming through or round the front door.
Being warm wet air from indoors, the air cools on entering the porch and condenses on the cold surfaces.
The solution is to provide an opening where the warm wet air can escape to the sky, it means a colder and drier porch.
Or only use the front door during the warmer weather.