Bosch IDS 2.0 A/C System Homeowner needs help with must/mildew

CFJonnyHomeOwner

Homeowner here, have a Bosch IDS 2.0 A/C system installed in central Florida since 2022. Enjoying the efficiency and quietness of this system but we are now getting a very strong mildew/must smell out of the vents, especially when it kicks on. The air handler is a BVA-48WN1-M20 and it's using an Ecobee 3 stat. Upon taking the front cover off of the front of the air handler there is a thin layer of moldy looking stuff accumulating inside the top area where the wires are. I would like some assistance in making sure all of the dip switches and thermostat settings are correct.

We usually keep the A/C set to 76 and the humidity stays around 55% according to the stat.

The unit seems to satisfy temperature but I am concerned about the mildew smell and wondering what is causing that. My family is starting to sneeze and sometimes we get itchy eyes and I want to make sure this A/C isn't blowing bad stuff out of the ducts.

Thank you.

pecmsg

55% is a little high.

4-Tons how many Sq Ft?

New construction or older?

Did it work well 2 years ago?

Jamie Hall

Start off by having the units thoroughly cleaned — new filters, everything cleaned both in the air path and outside it. Including the duct work. Hard to say what's growing in there — but whatever it is, you don't want it.

GW

I wonder if the ahu was set up to run two stages. It's one of those 'details' that gets dropped here and there

4 tons———how big is the home?

AC too large is a common problem

CFJonnyHomeOwner

https://forum.heatinghelp.com/discussion/comment/1808504#Comment_1808504

The square footage this A/C covers is ~ 2,500 sq ft, 2 story. There are 2 other A/C units for the rest of the house. Total under air is ~ 5,500 sq ft. The house was built in 1987. The unit did work well for the 2 years. This smell started before the summer. I have cleaned the drain out, changed the filter and made sure there isn't a water leak or roof leak anywhere. Yesterday the cover of the air handler was taken off and there's definitely something growing on the inside of the insulated board inside the air handler.

CFJonnyHomeOwner

https://forum.heatinghelp.com/discussion/comment/1808529#Comment_1808529

I do believe it runs in two stages. The thermostat will say mode 1 or mode 2 and you can hear the air handler much more when it's in stage 2. The air space this unit is responsible for is about 2,500 sq ft, 2 story.

Jamie Hall

As I say, if there's something growing — or even dirt present — CLEAN IT.

GW

I'm a northeast guy (less AC loads here), yet the ac seems kinda large at face value. So I'm just winging opinions (like everyone else who isn't on site). Too big = shorter run times, and that means poor dehum attributes.

pecmsg

https://forum.heatinghelp.com/discussion/comment/1808530#Comment_1808530

Condationed space above, below?

Based on that…….Oversized equipment!

CFJonnyHomeOwner

What is the typical cold temperature I would expect with a digital thermometer right inside the air plenum ?

CFJonnyHomeOwner

I'd like to check the dip switches to make sure they are in the correct positions. There is no telling how this a/c was originally set up. Is there a link to the manual somewhere?

Yesterday we had the installers check the system out after notifying them about the smell. They said the air was blowing too cold at 55° and they added gas to bring it up to 59°. They squirted some anti mildew inside the unit and I am supposed to let them know how it goes. I don't think they are very familiar with the inverter systems and definitely not familiar with the ecobee stats. I'm hoping I can get some help here direct from you guys.

pecmsg

https://forum.heatinghelp.com/discussion/comment/1808563#Comment_1808563

start looking for a more knowledgeable tech.

pedmec

They added gas because the air was too cold??? you need another company to come out. You don' t overcharge a system to increase supply air temperature. adding refrigerant to a properly charged system can cause you slug your compressor causing compressor damage, increase head pressure causing the compressor to over work, and cause tev valve hunting, to name a few things.

Ironman

You need to find a competent tech who can confirm that the sizing, the refrigerant charge and the airflow are correct.

As mentioned, you don’t add refrigerant to bring up the discharge air temperature. And 59* is too high to properly dehumidify.

GW

I’m assuming it’s a 5 ton outdoor unit (he said 4 ton indoor unit)

The system may be a bit large—-stating that it’s a “portion of the home”. Meaning, some of this structure is not gaining heat at all.

I once wasted several hours trying to nail the sub cool on a smaller 2 ton system (3 ton Bosch). The inverters have a mind of their own.

colder coil means better dehum. I think your ac co sent the beginner crew

Someone needs to get eyes on the set up. Condensate water lying around?

That system has a dehum setting too- maybe get a better stat with dehum

PRR

humidity stays around 55% according to the stat.

Humidity meters are erratic. Don't trust a built-in one too far. Get another. Also take it walkabout: I have significant room to room variation unless I have a circulating fan.

This is a real cheap piece of work, and does not look as good as the picture, but you can get two, cross-check, walk to different areas. Also logs max/min in case it has midnight wetness.

https://www.amazon.com/dp/B09N9G7L2M