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ProDave

Nuaire Ecosmart (MVHR) "fault"

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ProDave

Got to diagnose and fix a fault with little to go on.

 

As far as I can tell this is an MVHR unit (Mechanical ventilation with heat recovery)  There is a large galvanised steel box in the loft that all the duct work passes through, but I have not yet found any model numbers on it.

 

Downstairs on the wall is a ES-TC time controller, and an ES-UCF controller which amongst other things has a fan speed control knob.

 

The unit is not working, the fan is not running.

 

On the ES-UCF unit a red "fault" light is illuminated.

 

I have searched for a manual, and you can download the manual for both these wall mounted controllers from here: http://www.nuaire.co.uk/downloads/im-manuals/commercial/#2808

 

But the manual for the ES-UCF is about as useful as a chocolate tea pot telling me that when the red light is on it "indicates a fault"  No $h!t shelock.  But gives me absolutely no clue what fault and how to find out.

 

I suspect it might be a clogged filter (I don't think it's been touched for years) and it's sensing insufficiant air flow or something?  when I go back I will open up the box in the loft for a look, which is going to be a pig of a job as it's a very low pitch roof of an industrial unit with not much space, and oh yes, the isolator switch for the loft unit is behind the unit so damn awkward to get to.

Edited by ProDave

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steptoe

I do an apartment block with these in,

There is a plug in controller thingie that usually goes on them,

iirc its about £160 ish

 

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ProDave

What's the betting that is NOT up in the loft.......

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steptoe
17 hours ago, ProDave said:

What's the betting that is NOT up in the loft.......

 

17 hours ago, ProDave said:

What's the betting that is NOT up in the loft.......

It plugs into the bottom/side of the main unit,

Although, yours seems to have the controller remote (now I have read it again)

So it may be a matter of replacing the complete UCS unit,

Give NuAire a ring, I found them to be extremely helpful the first time I came across these systems, they even set me up an account to buy the spares direct from them.

 

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ProDave

I will do that, but first I need to grovel around in the loft to find the model number of the unit up there as that's the first thing they will ask.

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steptoe

If I get a chance o er weekend I'll see if I can dug out any contact info I have, its been a while since I used them, more and more of the occupants are choosing to replace the units with something else, <10yr old and going faulty isn't good. 

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Canoeboy

Dave

 

It may have an airflow sensor - doubtful

It could be the fan is tripped in an internal klixon or bearings seized

 

NuAir fans and speed controllers are one of the worst and cheapest rubbish out there so don't expect it to be anything special. Its just a contraflow heat exchanger - Air/ Air, probably got 4 pipes on it, if you put temperature probes across the ins and outs and do the calcs of the electricity costs of the fan you'll probably find its not efficient at all and costs more to run the fan than you get in recovered heat......

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ProDave

Yes When I first saw it, and looked at the size of the unit in the loft, I though F me. It's only ventilating the gents and ladies loos.  A couple of standard 4" fans would probably give adequate ventilation with a LOT less complication.

 

Not sure when I am going back but I will pick an ovecast day as it gets like an oven inside that small loft with a tin roof if the sun is out.

 

If the unit is terminal and not repairable then I will have to think about an alternative. The unit in the loft is so big it could only possibly have got there before the roof cladding was put on.

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Marvo

If you're not familiar with heat recovery systems maybe just check the condensate drain is clear and clean the filters which should slide out without too much dismantling. If that doesn't clear the alarm tell the customer to get the agents in.

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Canoeboy

@Marvo

 

It probably has no condensate drain and probably has no filters, you could not design it this cheap if your tried....... (in my experience)

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Marvo

@CanoeboyI'm sensing a deep-rooted hatred which probably means you've got bad first-hand experience with them :).  I've never come across that particular make in this area, I've got some experience of Systemair units but maybe these things are different.

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SLIPSHOD & SLAPDASH

I have worked on a few of these and they are very  crude. I know  No other manufacturer that makes a piece of equipment with 2 of everything inside , is it because they know one motor will break so lets build it with 2 & fit a changeover switch to the outside.

Last one i looked at had both motors burnt out and parts so expensive the customer got me a 6" duct fan and asked for that to be bolted inside the Nuair box

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ProDave

Thanks for the comments. I will report back when I have been up in that loft.

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ProDave

Right I have been and had a look.

 

Just as I thought, the original installer did nobody any favours. It's a low pitched roof with little headroom but it's installed on the "wrong" side of the roof space, so that the power input, the isolator and box of elecrtronics that controll it are all on the wrong side.  So get to them, you have to climb over the duct, then crawl along on the low side of the roof on a sloping but not boarded bit of loft (the bottom of a shallow W roof truss).

 

I took the lid off the big unit and inside are two fans and a couple of sensors, not much at all. both fans were okay and both rotate rfeely.  There is also two more boxes on the in and the out of the fan box but both are riveted shut so prusumably fit and forget filters?

 

Anyway having struggled to get to the control box, inside is a PCB and some relays.  There are also some fuses.  BOTH fan 1 and fan 2 fuses were blown, and I didn't have any spares (20mm glass anti surge T1A)

 

Power up and it first tries to start fan 1, which of course doesn't start, it then tries to start fan 2, then both together, then puts the fault light on.

 

I borrowed the fuse from the "damper" output and now fan 1 is working and no fault light. Not sure how it will work without the damper working.

 

So I'll get some fuses and I have to go back and do the contortionist trip once more to replace them and it should be okay.

 

By the way I was being polite to it thinking it was an mvhr unit, it is not. It us just an extract fan system, no heat recovery and no matching input air system, just a great big box and a couple of over sized fans to extract air from the toilets.

 

I couldn't take a picture as my clockwork phone doesn't appear to have a flash, and it was too dark in the loft for it to take a picture.

 

 

Edited by ProDave

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NozSpark

It's always the way,,,, you get to an almost impossible place in an almost impossible position and find that you haven't got the bits that you need :slap

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Marvo

No such thing as 'fit and forget' filters as far as I know. I'd expect any filters to be easily accessible.

 

How badly were the fuses blown? Was the wire just casually separated or was there molten metal bits and large blackened areas visible inside the fuse? Sounds like too much to be a coincidence that both fan fuses would blow together but I'm not sure what would cause it to happen.

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ProDave

I don't think they blew together. Looking at the way it ioperates, it tries fan 1 first, then it tries fan 2, then it tries both, then if flags a fault.  So I am guessing if fan 1 fuse had blown, it would carry on for some time on fan 2 only until that fuse also blew.

 

Nothing drastic looking, just fatigued I am tempted to put 1.5A fuses in where the originals were 1A  I couldn't see a way to get the clamp meter on to actually measure the fan current.

Edited by ProDave

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Andy™

could you not stick a meter between fuse terminals?

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ProDave

It's the sort of fuse holder soldered to a PCB standing upright. You undo a screw and the fuse pulls out of a tube. Nowhere to get meter probes on. the fan wires connect to the back of the pcb so they are not accesible to to get a clamp on.

 

 

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Marvo
23 hours ago, ProDave said:

It's the sort of fuse holder soldered to a PCB standing upright. You undo a screw and the fuse pulls out of a tube. Nowhere to get meter probes on. the fan wires connect to the back of the pcb so they are not accesible to to get a clamp on.

 

 

Sounds like they've covered all bases to make maintenance and fault finding as difficult as possible. I'd just replace the fuses and check the fan motors for slow starting or any other signs that a motor capacitor or one of the windings might be problematic.

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