Best inline extractor fan to replace this?

[Andy.T]

Yep we run with an overun of about 25 mins currently as thats what it takes to clear the room of steam and condensation. It's from the lights but it's not a big deal to put them on when we're in there as they are low energy. It's no different to pushing a button to activate the fan really.

As I say the rest of the house is quite dry, no hint of a problem on windows etc. It's just the bathroom where the very hot, very wet air meets the colder ceiling and walls where we have the problem.

The heat recovery systems look great but seem a bit overkill for a normal domestic house. I don't know of anyone who has one of those, but no one I know has the bathroom condensation we seem to get either so there must be other simpler approaches that don't cost a couple of grand.

I've ordered that 5 inch fan which can't hurt, if nothing else it will be quieter and will at least mean the fan is about as good as it gets domestically.

Increasing the insulationin the loft above will help a little I think. Improving the ducting may help a tiny bit too.

If we are still left with a problem after all that I think the next thing to look at might be an additional or better source of heat in the bathroom as raising the temp of the walls and ceiling should help. I don't think adding air supply points to get the air to take different routes is practical due to the house layout.

I'll let you know how we get on.

Thanks again for all the contributions.

 

[Andy.T]

Ok so the new fan has turned up and I'm all set to wire it in tonight.

The current fan is wired from the isolator through a separate overrun timer box seen here...

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• Andy.T
• 7 Jan 2015
• 1

The power comes in to the timer on the left (from the isolator switch), there is what looks to be a little fused earth box and then it goes out (just L and N obviously) to the fan.

The new fan has a built-in timer so I need to get the switched live directly to it from the isolator (bypassing the current timer and making it redundant obviously).

My question is, can I just replace the current timer with a simple junction box (something like this?) and replace the current 2-core + earth that runs from the timer to the fan with 3-core + earth?

Or is that really naughty? Do I need to go right back to the isolator and do a new run of 3-core +earth going directly to the fan?

 

[JohnW2]

My question is, can I just replace the current timer with a simple junction box (something like this?) and replace the current 2-core + earth that runs from the timer to the fan with 3-core + earth? ... Or is that really naughty? Do I need to go right back to the isolator and do a new run of 3-core +earth going directly to the fan?

Although it's always better not to have 'unnecessary joints' in cables (so that replacing all the way back to isolator would be the ideal), in principle, there's nothing wrong with what you suggest. However (a) you would need a 4-terminal junction box for the 3C+E (the one you link to has only 3 terminals) and (b), although a JB like that one would be OK if (as is probably the case) it were going to remain 'accessible', if it were not going to be accessible, you'd have to use a 'maintenance-free' one.

Kind Regards, John

 

[Andy.T]

Thanks for that John, I was going to ask about the earth actually. There's no earth terminal on the new fan...

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• Andy.T
• 7 Jan 2015
• 1

As the bathroom lights and extractor are on an RCD is there still a need to pass the earth through to the fan. And if there is, what would one connect it to at the fan end?

The manual just says "If an earth connection is necessary..." but I'm not sure if that's just because it covers several models.

 

[JohnW2]

Thanks for that John, I was going to ask about the earth actually. There's no earth terminal on the new fan... As the bathroom lights and extractor are on an RCD is there still a need to pass the earth through to the fan. And if there is, what would one connect it to at the fan end?

The regulations,in their wisdom, require that a CPC (Circuit Protective Conductor - aka 'earth') be run to every point in the the installation, and to every 'fitting', even if that fitting does not require an earth. One of the 'explanations' is that the 'fitting' (e.g. fan) may one day be changed to one that does need an earth. It also affords some extra protection - if someone were to put a nail or screw through the cable to your fan, if there were no earth conductor in the cable, then the RCD could not trip as a result - but with the earth conductor, it might trip.

If, as in your case, there is no provision in the fan for terminating theearth conductor, you need to leave it full length (in case it's ever needed), with a but of green/yellow sleeving over it, and terminate it in a little bit of connector block (like that block in the JB you linked to), tucked away safely in some corner of the fan enclosure.

Kind Regards, John

 

[Andy.T]

Thanks again John, you've been really helpful!

I'll get cable and a junction box on my way home and let you know how I get on.

 

[JohnW2]

Thanks again John, you've been really helpful! I'll get cable and a junction box on my way home and let you know how I get on.

You're welcome - and I look forward to hearing the outcome. Don't forget to 'be safe', and make sure that everything is 'well dead' (electricity-wise) before you play with it!

Kind Regards, John

 

[Andy.T]

Extractor went in fine thanks John, comes on with lights and runs on after.

I've not tested it properly (with a nice hot bath) as yet as I've discovered the ducting wasn't properly connected to the roof vent (as it's a funny shape) which won't have been helping! I'll get a steer on that from the guys at the roof forum here with any luck.

 

[JohnW2]

Extractor went in fine thanks John, comes on with lights and runs on after.

Glad to hearthat!

I've not tested it properly (with a nice hot bath) as yet as I've discovered the ducting wasn't properly connected to the roof vent (as it's a funny shape) which won't have been helping! I'll get a steer on that from the guys at the roof forum here with any luck.

Not my territory - I hope you get some help!

Kind Regards, John