How can I dehumidify my roof, and prevent condensation dripping down wall cavity?

[ccyounger]

Hi,

I think that the air con pipes/tubes running through my roof cavity, are collecting condensation on especially humid days.  Condensation is then running down the pipe/tubes into the wall cavity, and I'm seeing it drip through downstairs.

The pipe/tubes path cannot be changed, as they sit above the internal unit and so the pipe/tubes are running out of this into the wall, then tracking upwards into the roof and then across the roof to the extractor mounted on a different wall.  As I can't change the path of these pipes/tubes, or put a tray nearby to collect the water, I'm thinking I need to find a way to decrease the humidity in the space.

I was thinking of a whirlybird (mechanical, electric or otherwise,  I'm yet to decide).  But I wondered if anyone else had a similar challenge and what solution they'd adopted.

Thanks in advance

[Jewelleryrescue]

Hi @ccyounger 

A  tricky situation you have there too be sure, 

Not seeing the obsticals you have in person I will try give you my best solution thoughts.

Ok  Your problem begins by the atmosphere touching the cooler pipes, re Condensation.

My first  though is to slide a larger polypipe with a  slit on one side  over the pipe work.  Not a  perfect seal but water will run via surface tension along the insides to an exit/drain  point you make.

Why not try shield insulate the pipes with  Expanding  foam filler as it is waterproof to start with.?

The idea is to insulate the pipes to reduce condensation creation.  So use of lagging to insulate and or re direct water inside the lagging.

A whirly bird may help in open areas but not down a wall.

Down a wall put air  slots in the vertical mortar  joints like you see along brick wall bases.

Hope your problem fixed  soon  you may need an aircon guy to properly lag the  pipes/

[ccyounger]

Thanks, I like the idea of more insulation.

There are a couple of pipes up there, one large diameter and one small. 

I believe the larger one is the 'coolant' line which would carry hot Freon back to the compressor to have heat removed.  I think its ok to leave this one alone.

Apparently the smaller pipe carries the refrigerant that has been cooled and compressed and ready to absorb more heat.

My assumption would be to focus on the smaller pipe, as this theoretically is the cold line which water would condensate onto.

Does this sound correct?

[Jewelleryrescue]

Hi @ccyounger 

I quote this   from the internet I cant validate its accuracy on your system.

Refrigerant lines are two copper lines that connect the outdoor air conditioner or heat pump to the indoor evaporator coil. The larger line typically carries a cool gas and is insulated.

The  cooler gas line will condense water on it.  And its meant to be insulated in theory. 

[EricL]

Hello @ccyounger 

I suggest a combination of both Whirlybird and pipe insulation to make sure that condensation is severely reduced. I suggest having a look at the CSR Bradford WindMaster 300mm Natural Roof Vent to ventilate your roof. 

To insulate your air con pipes, I propose using K-Flex Elastomeric Pipe Insulation along with K-Flex Pipe Adhesive Tape. To lock everything in place, I recommend using Crescent 150 x 3.6mm Black Cable Ties - 25 Pack.

By closing off the any smooth surfaces that condensation can form on, it should reduce the amount of water dripping into your wall.

If you have any other questions we can help with, please let us know.

Eric