Fan Replacement Issue

EcoTechnologies · Sep 5, 2017

Hello guys

I wonder if anyone can assist me in anyway, was called to a job today to replace 3x extractor fans. Thought it would be a relatively easy job but I was wrong.

The premises is a block of flats with ducting to each bathroom/kitchen above the ceiling for air extraction.

The 2x bathroom fans are PIR grills with a shutter mechanism and the kitchen is a grill with no PIR and no visable switching anywhere. From what I can tell the grills are wired in low voltage cable back to the IP box shown and then all pairs linked together and connected to a single transformer. Then this is linked into the centrifugal fan located above a ceiling void.

The tenants of the flat tell me that the fans have never worked while they have been living there (6 months) and also another tenant in another flat which has been living there for a number of years also has the same problem and they have never worked either...

From what I can figure out the 3 fans are wired in parallel back to the IP rated box to the transformer and I can only assume that when they did work, all 3 grills worked at the same time instead of independently. I have no paperwork or anything usable of the original installation to assist me.

Any help, advice, encounters with something similar would be really appreciated.
Photos to follow

EcoTechnologies · Sep 5, 2017

Photos attatched

[ElectriciansForums.net] Fan Replacement Issue

freddo · Sep 6, 2017

The wiring looks unfinished, I see 12V AC going out but nothing else.

Marvo · Sep 6, 2017

Are the kitchen fans on separate ducting to the toilet fans?

If there's no visible switches or PIR / humidisensor then the kitchen fans may be connected direct to a light supply at a guess....assuming they were ever connected at all......

dmxtothemax · Sep 6, 2017

What exactly do you need to know ?
I would permanently power all three fans from communal power.
Then install local switch's at each location.
Do the motors still function ?

freddo · Sep 6, 2017

Is that red button on the fan some sort of reset? The kitchen grille may be open all the time, the fan also running continuously. Is there power at the fans IEC connector?

dmxtothemax · Sep 6, 2017

How much power does the fans use ?
That tranny is only good for 1.25A.

EcoTechnologies · Sep 6, 2017

Hey guys. Thank you all for your replies.

I was only on the job for about an hour trying to figure what I could out but what I could tell was the 3 fans went into the square ducting box then centrifugal fan sucked all of the air from the box then ported it out on the black outlet duct.

In the kitchen, there was no obvious switching at all and turning the kitchen lights on and off didn't effect the IP rated box terminations at all. I can only assume that maybe when they did work if someone walked into either of the 2 bathrooms it triggered the PIR and opened up the duct, and I assume as it was wired in parallel all ducts would have opened in all 3 fans?

It also seemed like the centrifugal fan (when active) worked 24/7 as there is no obvious switching for that either.

The red light on the black fan is a power light. It still runs but very very weak and when the Spur was turned on next to the IP box the fan made a whirling hum as if it was varying in speed. Seemed like that had packed up also.

Some how I need to rectify this. I'm looking into 3x grills and a new centrifugal fan but trying to understand what the best way of doing this with the cables I have available.

Thanks again.

Wilko · Sep 6, 2017

Maybe that black fan is just full of yuk after the years? I'd dis and open it up ... And publish another pic of course

EcoTechnologies · Sep 8, 2017

Hey guys, slowly getting a bit closer to sorting out this issue. But I'm just curious, what would you guys do?

I have managed to get 2x PIR shutter mechanism grills for the bathrooms, and 1x shutter mechanism on a pull cord for the kitchen(all L/V for the data cable that's been wired). These will all be ducted back to the centrifugal fan which I am also possibly replacing.

Would you guys have the centrifugal fan running 24/7 or try and wire up a contactor to pull in the 3 grills independently and turn the fan on and off?

Many thanks

Lucien Nunes · Sep 8, 2017

I would see if there is an output from each damper grille e.g. a volt-free contact to operate a fan contactor, no point in it running if all the grilles are shut. If the kitchen is currently uncontrolled, make sure that isn't supposed to provide background air changes for the whole flat 24/7 exhausting from each room towards the kitchen.

Fan motor running slow could be stiff bearings or if it is a PSC motor, the cap going low in value. Changing the cap will sometimes restore normal operation if the windings are intact.

Whatever you do, make a better job of the electrical separation to the ELV than whoever put that transformer in. Fuse? Insulation voltage? Not much thought went into that.

Sparkgap · Sep 8, 2017

Daniel Masterton said:
Hey guys, slowly getting a bit closer to sorting out this issue. But I'm just curious, what would you guys do?

I have managed to get 2x PIR shutter mechanism grills for the bathrooms, and 1x shutter mechanism on a pull cord for the kitchen(all L/V for the data cable that's been wired). These will all be ducted back to the centrifugal fan which I am also possibly replacing.

Would you guys have the centrifugal fan running 24/7 or try and wire up a contactor to pull in the 3 grills independently and turn the fan on and off?

Many thanks

Won't do the fan any good having it run 24/7. Best having it brought on by the PIR/shutters. Most flats I've been involved with recently have been MVHR units with almost constant extract/supply rather than plain extract only, and where they have gone for extract only systems it's generally separate fans on PIR/switches for kitchen and bathroom and separate ducts to outside.

Fan Replacement Issue

EcoTechnologies

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EcoTechnologies

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freddo

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Marvo

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dmxtothemax

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freddo

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dmxtothemax

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EcoTechnologies

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Wilko

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EcoTechnologies

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Lucien Nunes

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Sparkgap

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