Condensation remained

[Allsorted]

We have a detached bungalow with loft conversion which has been suffering from condensation and had a PIV system installed which included a roof vent for the air intake as the reduced loft space due to the loft conversion was deemed to be inadequate,diffusers were installed on the upstairs hallway and one in the entrance hall ceiling, after a period of three months the system failed to make any impact on the problem.The front elevation of the house faces Westerly and gets the cold wind mostly from that direction,the double glazing was not up to current spec so at an additional expense the glazed units were replaced (£1100) in the hope that condensation would now not form,sadly it made only reduced but still present condensation 1cm water droplets along the bottom edge of the windows.
The installers have now removed the system and refunded.a dehumidifier is now in use and humidity levels have dropped from 60°+ to low 50°s and no more condensation even at low outside temps.
My analysis is the house is to airtight for a PIV system to work.
Full up to current spec D/Glazing
No open fireplace/chimney
Insulation between ceiling and upper floor.
Kingspan isulation to upstairs ceiling and walls.
A continuous fan is installed in the downstairs toilet/ shower room.

 

[Allsorted]

The problem

 

[IT Minion]

Do you dry clothes in the house?

 

[Allsorted]

Condensing dryer.That is not a cause as we were away from the house for two weeks in January the central heating was left to run as normal and the PIV was in operation. On our return to the house at 09:30 there was considerable condensation present.

 

[Ivor Windybottom]

You've got a water source somewhere. You need to find and eliminate it, otherwise you're wasting your own and everyone else's time and money trying to cure the symptoms rather than the cause.

Do you have a ground floor suspended wooden floor? If so look under it in various rooms. In our previous house we had what's called a "perched" water table. Basically when the ground water gets up above the foundations it floods in through the inevitable holes in the brickwork then remains trapped inside, under the floor. It doesn't leave as readily as it enters so can sit there for days or weeks after rain. Basically your foundations are an empty container waiting to fill. This is exactly the issue we had with our previous house. I took various steps to drain it and reduce it but concluded it was pretty much incurable. Obviously check all downpipes and replace drains with new soakaways well away from the building and preferably downhill. You can investigate running it into a sewer but this is not encouraged these days. Whatever the solution, this is a big task.

Also buy some decent humidity meters, place them in a number of rooms. You need to aim for 60%. We often got 80% in our previous house that had water under the floor.

Approach with an open mind. You may have a leaking water supply pipe, absolutely anything is possible. Don't rule out anything until you've ruled it out.

 

[Allsorted]

As I mention in my post, at present we no longer have the problem the humidity levels were 60,+ with the PIV system currently it is 50° with the dehumidifier in operation on low setting.
Perhaps the PIV was actually introducing humid air being as the outside readings were higher than inside.

 

[pcaouolte]

Outside readings of RELATIVE humidity are almost always higher than inside due to the lower temperature outside. There is still usually less moisture in the outside air than inside.

As an example the outside relative humidity at my home is currently showing 85% (at 7 degrees C) whilst in the lounge I have 57.5% RH (at 19.1 degrees C). In absolute terms there are 6.8 grams of water per cubic metre of outside air but 9.4 grams per cubic metre in the lounge. A PIV moving that outside air inside will reduce the humidity in the house.