Manrose MF100T help please!

I have a Manrose MF100T (the run-on timer version) inline extractor fan and I am trying to work out:

1 – does it have a low/high speed setting (Google does not agree on this).
2 – is it currently set on the high speed setting?

I am asking as we have it fitted in a large-ish bathroom and my almost teenage daughters are having increasingly long showers which result in lots of condensation (the ducting length is only about 1 metre so that shouldn’t be an issue) and I can feel air coming out of the vent, but not the loads of steamy air I’d expect given how steamy the bathroom is.

This is how it is currently wired – some Google answers say that if the blue is on S2 then it is high speed which means I will need a bigger extractor 🙁

Or is there anything else I can do to improve extraction?

Hmm.

I have the mf100t and had to set it to the lower setting as was so breezy when turned on! Will the suction hold a sheet of toilet paper against the inlet?

Make sure your ducting is stretched out and therefore smooth on the inside with no sharp corners.

Open a window ! Really. Had this with my son/daughter. The fan on and a window permanently on vent to dry the room out.

Will the suction hold a sheet of toilet paper against the inlet?

Yes it will – there is certainly plenty of suction so I am puzzled as to why the room gets so steamy!

And re the setting – is yours the newer one with a series of pins (like this) or the older one like mine (pictured above)?

We have the same fan, I think. In our case there was a jumper switch that could be set to one of three settings. However, I can’t see it in the photo you shared. If there definitely no jumper switch?

In the end, we settled on the low setting with a longer run time.

This is how it is currently wired – some Google answers say that if the blue is on S2 then it is high speed

My googling would concur with yours.

… it is a good idea to replace the ducting with insulated ducting, particularly if the loft(?) is uninsulated. This will prevent water condensing on the ducting on the way out. However, with only a 1m ducting length it should not be a major issue.

It should definitely be powerful enough, on the high setting it has a much higher output than an inline fan.

Where’s the air to replace the extracted air coming from?

Do you have a suitable gap under your door or other source for the fan to pull fresh air in? Basically, what martinhutch is saying.
If the bathroom is too well sealed no fresh air can be pulled in by the fan, so you end up with no (or very low) actual flow through the room.

Open a window ! Really. Had this with my son/daughter. The fan on and a window permanently on vent to dry the room out.

Yep, we pretty much leave the bathroom window open all day. Have a beefy extractor fan, but it’s not enough. 9″ solid walls….

If there definitely no jumper switch?

No – it is about 7 years old so it is slightly different than the current one.

Where’s the air to replace the extracted air coming from?

From the slightly open door.

We have the identical fan in our en-suite (which is smaller TBF) and it extracts much better (even though it has a longer ducting run) and the door is always closed.

The only other explanation for it is that on the problematic fan the ducting steps down from 4″ diameter to 100m rectangular just before it vents out through the soffit (due to the space restriction).

If you’re getting condensation on walls/mirrors, could those be less well insulated/more exposed than in your ensuite? If the starting temperature of the room is lower, that will make it look more steamy.

We have this problem with one wall in the bathroom in particular, which was clearly missed by the people who did the cavity wall insulation.

Is the fan vent in the right spot?

The only other explanation for it is that on the problematic fan the ducting steps down from 4″ diameter to 100m rectangular

Oh, there you have it then.

Round duct will have about 50% more capacity. Round is also more efficient in terms of air flow, even if the capacity is identical.

Is the fan vent in the right spot?

It’s directly above the shower head.

If you’re getting condensation on walls/mirrors, could those be less well insulated/more exposed than in your ensuite? If the starting temperature of the room is lower, that will make it look more steamy.

They are almost mirrors of each other on the same elevation (and both have two external walls).

Round duct will have about 50% more capacity. Round is also more efficient in terms of air flow, even if the capacity is identical.

Unfortunately there is no other way of venting it unless we had a huge length of ducting to another wall which would negate any benefit of the round ducting. 🙁

You might as well turn it onto the low setting then, save a bit of electric. 🙂

Can you add a second external vent and some form of Y-connector?

Round duct will have about 50% more capacity. Round is also more efficient in terms of air flow, even if the capacity is identical.

That’s broken my head.

Battling a similar issue with ours. I’ve bought but haven’t yet fitted solid pipe to replace the corrugated/insulated stuff I used initially. I’ll lag the new pipe to reduce condensation forming.

The supplier I bought from suggested moving down from the high speed setting to the medium, his angle being the tubing and most importantly roof vent can only flow so much, the high speed setting is not increasing the air flow out…

One thing I did notice was the roof vents have quite restrictive gauze over the outlet to stop bugs getting in, maybe have a look at your soffit vents to see if you can derestrict them.

private message sent… one of our forum members designed, tested and implemented that 🙂

medium, his angle being the tubing and most importantly roof vent can only flow so much, the high speed setting is not increasing the air flow out…

Interesting opinion – I wonder if that would actually improve flow though?

One thing I did notice was the roof vents have quite restrictive gauze over the outlet to stop bugs getting in, maybe have a look at your soffit vents to see if you can derestrict them.

Mine doesn’t have the gauze (I know what you mean though).

Our pipe run is around 10m and has three 90 degree turns and goes out through a soffit vent. Even on the low setting it clears the room of condensation within 5 minutes with the door shut. With the door open it does not steam up at all and there is a noticeable breeze.

I would not completely discount that your fan might not be working properly.

Just had a thought – when I installed our (similar) Aventa fan in the loft, the fan body clips into the chassis once the chassis has been screwed in place. Obviously, this has to be put in the correct way round, or it blows in the wrong direction. Are you sure the fan is sucking out & not blowing in? Should be fairly obvious, but from the sounds of it you have two similar set-ups; one which works fine & one which doesn’t with no obvious reason why.
It is starting to sound like either there is a blockage, the fan is faulty or has not been installed correctly.

I installed our Manrose inline. When installing I was advised to go round pipe and make sure the outdoor vent wasn’t ‘fighting the wind’ – so our output is mounted underside of roof verge, pointing downwards, and is ‘open’, not a closing / moving flaps. We’ve a non-return air ‘valve’ at the ceiling extract grill.

After a year of great results (we leave small window cracked open 24/7), it lost effectiveness.

The fan and extract are vertical, but output runs down the underside of roof and out the eaves.

I went into attic to discover that the tied up pipe had undone and ‘drooped’. This was enough that water was condensing and had all but filled the flexi pipe. A quick lift and a few litres of water poured out the output vent…

I also know our tumble drier outdoor ‘flap vent’ regularly sticks.

tldr: check any moving flap vents, check the pipework is clear of water or fluff.

Oh, and I’m a grumpy git should any of the kids choose to have too long a shower, as this is the main issue with steam. Cut the source down? Shorter showers, slow the flow, aerater head?

I think I put the same fan in.

EDIT – actually yours looks different, maybe I’m talking nonsense

There were some jumper settings, bottom of the circuit board in this pic, arranged like a “T”.

Ours still gets condensation when the shower runs, but clears after it’s finished quite quickly. I don’t think any extractor fan can clear all the steam as it’s generated.

Are you sure the fan is sucking out & not blowing in? Should be fairly obvious, but from the sounds of it you have two similar set-ups; one which works fine & one which doesn’t with no obvious reason why.

Yeah I have done a paper test and it gets sucked up.

make sure the outdoor vent wasn’t ‘fighting the wind’ – so our output is mounted underside of roof verge, pointing downwards, and is ‘open’, not a closing / moving flaps. We’ve a non-return air ‘valve’ at the ceiling extract grill.

Yeah it points down and in a sheltered position (although with a converter to the less efficient oblong pipe due to space restriction) – the only other option would be to vent it out through a side wall which means a longer run and it would be ‘fighting the wind’ as you put it.

Idiot question time, but I can’t see a wire on the right side of the S1 connector or the left side of the S2 connector? Probably just the photo?

Idiot question time, but I can’t see a wire on the right side of the S1 connector or the left side of the S2 connector? Probably just the photo?

I have just checked on some other pics I took and yes there is a connection, it just isn’t quite visible on that shot. IIRC it was all pre-wired and all I did was wire up the three connections from the lighting circuit (N, L, LS). Damn, I thought you had it for a second then!

the only other option would be to vent it out through a side wall which means a longer run and it would be ‘fighting the wind’ as you put it.

I had a similar issue and opted to vent through the roof.