Mold growth on fan scrolls

[multisync]

Had a customer complain about mold on the indoor unit (4 x Fujitsu 3.5kw) Whatever we try it always comes back.

Now another customer has a similar problem (ironically another Fujitsu 3.5) along with bad smells.Removing and cleaning c/w anti bacteria stuff doesn't cure it. Therefore it must be something airborne or room dependant

I have suggested fresh air fan but has anyone else got any idea's/cures?

Multisync
London

[5H86User]

I'll need a little more information to be able to provide you with a good answer.
What did you clean this with? (i.e, what chemicals?)
What is the device constructed from? (I can't tell from the pictures).
Are there any "seeding agents" in the area (other mold locations?)
Mold likes moisture and darkness. Depending on what kind of mold it is, it may be UV sensitive, so a UV light could keep it at bay.

5H86User

[Abby Normal]

mold requirements

one spore, they are everywhere

food- preference for cellulose, but about anything organic

water to make the food wet, easy to pull water from a coil

generally speaking the same temperatures as humans can survive in.

Fan wheel seems to be getting pretty dirty, perhaps it sucks in air missing the filters and coil.

Perhaps through the hole where the drain and refrigeration lines run.

I would check that it is not sucking in dirty air from a wall cavity or other ways it bypasses the filter, I would check that it drains properly and the system is not pulling water off of the coil.

[Abby Normal]

free chapter from a good book

http://www.masongrant.com/pdf_2008/ASHRAE_HCDG_C7_Mold.pdf

[Abby Normal]

heat pumps smell like hell sometimes after they go into heating mode then revert to cooling.

The Americans call it DSS - Dirty Sock Syndrome, smells like socks

[US Iceman]

On page 116 of the chapter linked to there is a good piece of information that is often overlooked. This is the need to provide adequate drain traps on the cooling coils.

All too often I see no traps, or the shortest trap possible.:rolleyes:

Thanks Abby, that is a good link. BTW, do you have this book? Would you recommend it to others?

[multisync]

We're talking small ductless units here so air ingress is not the source.

However the pictures of from a dentist practice. The other customer is an internal office in a engineering production factory

Multisync
London

[Brian_UK]

Aaah, a dentist. Lots and lots of powder from the drilling of teeth and teeth fillings, powder casts for dentures being ground and filed.

Lots of moisture from the mixing of products and mouth wash equipment; also sweat from very nervous customers.

One of the worst environments I've come across for split systems.

You need to investigate getting the best/finest filters that you can and instigate a rigorous cleaning regime.

The powder dust of course mixes with any moisture and remakes itself into dental cement.

Multi - you're stuffed ;)

[Abby Normal]

On page 116 of the chapter linked to there is a good piece of information that is often overlooked. This is the need to provide adequate drain traps on the cooling coils.

All too often I see no traps, or the shortest trap possible.:rolleyes:

Thanks Abby, that is a good link. BTW, do you have this book? Would you recommend it to others?yes I have the book, I would recommend it. It gets more into controlling humdiity in different types of buildings. The author will be doing a short course or two at the ASHRAE Show in Chicago.

[Abby Normal]

We're talking small ductless units here so air ingress is not the source.

However the pictures of from a dentist practice. The other customer is an internal office in a engineering production factory

Multisync
LondonWhen you figure out how to stop the mold food from collecting on the fan blades you may have solved your problem

dirty fan would move less air, coil will get colder air off coil closer to saturated, tend to get the food wet

[OAT99]

When was your condensate drain cleaned or flushed ?
Do you have open windows or is this a sealed building where your only infiltration is through door cracks? and what is the regions RA (relative Humidity)?
Seems like a number things are happening. It wouldn't:eek: hurt to pay for an air analysis, it could reveal something.








Had a customer complain about mold on the indoor unit (4 x Fujitsu 3.5kw) Whatever we try it always comes back.

Now another customer has a similar problem (ironically another Fujitsu 3.5) along with bad smells.Removing and cleaning c/w anti bacteria stuff doesn't cure it. Therefore it must be something airborne or room dependant

I have suggested fresh air fan but has anyone else got any idea's/cures?

Multisync
London

[back2space]

Sounds silly but have you tried replacing the actual fan, doesnt seem to be mould growing on the coil or casing or anything only on the fan itself.

[paul_h]

How do you normally clean it?
Have you tried completely removing the fan and scrubbing it clean? Treating the fan when it's clean with starsan or iodphor food grade sanatisers might help. Along with spraying the coil and flushing the drain.

Is the drain free flowing and able to empty itself quickly? Where's the outlet, is that in a good clean place?

Do they just run the a/cs flat out on cool all day then just turn it of before they leave, not giving the evap a chance to dry out?
Try telling them to run the fan only for 15-30min before switching it off so the coil dries out at the end of the day, or if the split have coil dry function, get them to use that every day.

Is this problem only in summer?

[Abby Normal]

are they single stage or an inverter?

[Iceman1956]

It's a long time since I have seen one this bad, te last was a large central fan system in a crisp factory. The combination of high humidity and flavourings (Powder) was causing this type of growth. You have two options, a thorough PM plan, with a clean and sanitise on each visit, the second is to have the air sampled and see if the contaminants that are causing this growth can be eradicated. Good Look on this one. Try some of the IDS products such as CLIM they work well at leaving a residue that fights such bacteria and fungal spores.

[Brian_UK]

I know that it will extend the site time but it might be worth getting replacement fan rotors and replacing them on every visit.

The dirty one can then be thoroughly cleaned ready for the next visit.

[multisync]

Ok thank you for the replies.

We do keep spares which we swap out on a regular basis.
we need to introduce fresh air and keep the fans running longer.
Bleach seems to help but unless the whole room is dipped keeping it down is the best we can hope for.

All Fujitsu (hmm a link?) all single stage

Multisync
London

[nike123]

Ok thank you for the replies.

We do keep spares which we swap out on a regular basis.
we need to introduce fresh air and keep the fans running longer.
Bleach seems to help but unless the whole room is dipped keeping it down is the best we can hope for.

All Fujitsu (hmm a link?) all single stage

Multisync
London

In cases like yours, I successfully using next procedure and chemicals.
First, I pump down refrigerant in outdoor unit . Then dismantle indoor unit to constitutive parts and wash them (except motors and electronics) with this chemical (http://www.rectorseal.com/index.php?site_id=1&product_id=67).
Then after thorough washing with water, disinfect them with this chemical (http://www.rectorseal.com/index.php?site_id=1&product_id=317).

Then protect plastics around fan and pan, coil, filter and fan with this chemical. (http://www.rectorseal.com/index.php?site_id=1&product_id=177)

After that protect the drain pan from mold grow puting in it this tablets. (http://www.rectorseal.com/index.php?site_id=1&product_id=182)

Repeat this procedure at first every 3 months (now without pump down, evaporator body and housing back plate removal, but everything else still need to go down) to establish rate of mold grow and treatment frequency.

Good luck.

Disclaimer: I do not advertise these products. I only recommend them because, in my area there is no proper alternative, and because they seem to do the work.;)