Humidity sensor and condensation trap: bathroom fan

[kjmcdow]

I have been reading through the posts on shower extractor fans and I have worked out that I probably need to vent through the roof via the loft space.

My plan is to exit the roof, which is pitched and tiled, using a 4-inch solid duct that will pass vertically through an angled sealing cone and plate and will be capped with a roof cowl. I am thinking of incorporating into the system an in-line fan that will be connected with flexible ducting to the ceiling grill in the bathroom on one side and the roof on the other. I have read that in-line fan systems are much quieter, but this option might be problematic as I want to run primarily via a humidity sensor (see below).

Questions:

Where can I buy a stand-alone humidity sensor that will fit into the ceiling and will control the in-line fan? Is it best to buy an in-line fan and sensor package, if such a thing exists?

Do I need to fit a condensation trap?

If I do, I assume that this must be fitted at the lowest point in the system after the in-line fan? Can you purchase right angled bends (for 4 inch solid ducts) with condensation traps? If you can and a trap is needed, I would fit at end of vertical drop from roof. I assume that the ducts should also be lagged.

Any advice will be appreciated.

 

[jaikaiman]

You can buy bathroom extractor fans usually in 3 flavors.

1. Standard - On or Off
2. Timer - Turns on with the lights and off 5 mins after lights off.
3. Humidistat - Turns on with lights and remains on until humidity is at the level set.

 

[JohnD]

I always prefer a duct through a wall (you can hire a tool to cut a neat round hole to fit) as I think that interfering with a roof is likely to make it leak.

Is there a special reason why you can't go through a wall?

 

[chatsworthRed]

@kjmcdow did you ever find an inline fan with a remote humidity sensor?

 

[kjmcdow]

Thanks for the advice. I went through the wall!