Re: cleaning mold and replacing HVAC stuff

[Guest guest]

Hi Jolly, welcome. I'll let someone more knowledgeable answer your questions

but I have question. When you say you are adding Merv 11 to return ducts, do

you mean 'cold air returns'? If so, and you have more than one it sounds like,

where are you putting the MERV 11 filters, on wall or floor, where cold air

return registers are, or down in ductwork near furnace unit? You've done a lot

of studying and planning for 8 weeks. Good going!

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> 3.5 New filters in returns (MERV-11) after new system is in.

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[Guest guest]

Another question jolly: When you say 'filter fans', what are you referring to?

Are these free standing fans throughout the house or in windows? Are they

home=made, box fans with filters attached or room air cleaners?

>

During tear out, I will be suited and masked with negative air pressure and

filter-fans going constantly.

[Guest guest]

Thank you Barb for your quick answer!

I have two returns (or intakes?). I have MERV 11's in both of them - both are

also in the wall, not floor. One is 20X 20. The other is 14X14. The

" filter-fans " are 20X20 box fans with MERV 11's taped to the sucking side. I

have six of these running constantly in a little less that 2,000 square feet.

All filters will be replaced - on fans, and in the returns - with the timing of

new system start-up. I do not have filtration in the air handler, but

temporarily placed an ULVL to buy me some time while I had all these decisions

to make.

The new system will be totally outside the house as opposed to a previously

split system with the handler in a dark and difficult to access location --

making it less likely to get a good inspection on a frequent basis, and allowed

gapping and water accumulation to occur, which is BAD with all the saw dust that

got in the system -- THANKS FLOOR GUYS FOR a $25,000 job that junked out my A/C.

In case this did not answer your question from the other post, I will add more

after posting this one.

>

> Hi Jolly, welcome. I'll let someone more knowledgeable answer your questions

but I have question.

[Guest guest]

I hope this solves your problem. It might, or might not. When you look into

any old HVAC system, you will see black. Microorganisms form a biofilm on almost

anything, and begin growing when there is enough humidity and dust (nutrient).

Of course, some surfaces are more hospitable to microorganisms than others. When

contractors install HVAC, many like to tell of the energy savings benefits of

fiberglass ductboard. A side benefit is that it is quieter, and easy to install.

But it is also very microbe friendly, as it easily traps dust and absorbs water.

Cleaning disturbs the inner surface, and makes it more microbe friendly, as well

as releasing fibers into the air. Avoid this material for ducts. Also avoid

ducts with any type insulation inside. Use ducts made of sheet metal. You might

even consider the more expensive AK Steel Agion Technology sheet metal, designed

to retard biofilm formation. Minimize use of flex duct to connectors only, not

as long air carriers. This will be more expensive, but healthier long term. Get

high quality filters, and make sure the filter housing seals well. Think twice

about electronic air filters. Some release ozone, a respiratory irritant.

It sounds like your system is in the crawl space. If so, make sure everything

is well sealed, as any openings can suck crawl space mold into your home. It is

extra important for homes with HVAC in the crawl space to have a dry crawl

space. If you don't have a good vapor barrier over the soil, get one installed

before doing the HVAC. Also, make sure ground water drains away from the home so

liquid water never enters the crawl space. If you have a sump pump, make sure it

is always in working order.

When you start up the system, hopefully it will have no humidifier, as these

are mold friendly. Mold does not form during heating season. But it does form

readily in cooling season, when water is constantly condensed out of the air and

drains down the coil and out the drain line. Operation conditions can minimize

this. First, the unit must be properly leveled so all water readily drains from

the drain pan. When running the AC, leave the fan on continuously. Otherwise,

when cooling shuts down in the cool of the night, the AC chamber warms up, and

residual water in the drain pan evaporates, leading to high relative humidity

inside at the warmer temperature conducive to mold growth. Running the fan

continuously keeps RH no higher than what is in your living space. Newer high

efficiency systems use a variable speed fan which slows considerably when

neither heating nor cooling, minimizing discomfort of a breeze. Always let the

fan run a minimum of 2-3 hours after turning cooling off to dry the system.

But even the best systems will eventually develop some mold. Therefore, insist

that your new system be installed with an access door on the air handler to

allow cleaning of the AC coils. You may find that cleaning 1-2 times per year,

followed by disinfection with dilute chlorine bleach, will keep your system

healthy a long time.

[Guest guest]

Gil, We decided to put in a 16 SEER package unit (all one piece). My

terminology is poor, I apologize. It is completely outside, per specs. It is

visible, uncovered, easily accessible, and NOT full of wood floor sanding dust.

I saw and photographed parts of the air handler before it was taken to the

landfill, and the fins of the coils had the wood dust/mold combo down in between

as far down as half and in between the thousands of fins. I was sick

afterwards!!

Forevermore, October is my family's clean out the A/C system month!

Gotta go wash some holes.

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> I hope this solves your problem. It might, or might not. never dilute

chlorine bleach, will keep your system healthy a long time.

>

[Guest guest]

Jolly,

You should be using Aprilaire MERV-11 pleated media filters at the fan coils,

not at the ceiling or wall grille. You should have cheapo fiberglass filters

(MERV-3) at the reteurn grilles to filter out the big particles and help keep

the return ducts clean.

(Placing MERV-11 filters at the return grilles depressurizes the return ducts

excessively and fosters infiltration of unfiltered air.)

The fan coils should be indoors and accessible.

There should be no fibrous lining material inside the new equipment, only

foil-coated insulation.

The fan coils should not be resting directly on concrete.

Make sure that the condensate traps are deep enough and that the condensate

lines are insulated for a ways as they often get moldy because of condensation

on the outside.

You are correct about floor sanders messing up HVAC systems. In all new

construction, the ducts, coils, etc. are clogged with sawdust- food for mold-

before anyone ever moves in. (The drywall dust doesn't help anyone either.)

Make sure the ducts are clean before they are installed, as I have seen metal

ducts in dusty basements awaiting installation, the ducts already full of

sawdust. (Avoid flexible ducts if you can, and panned-bay returns.)

For more tips, see " Jeff May's Healthy Home Tips. "

Good luck; it's quite a challenge to get this right.

May

www.mayindoorair.com

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> Hi group.

>

> I am new, and have been reading for a few weeks.

>

> I discovered mold in my HVAC system 8 weeks ago, and am finally getting a full

replacement of my downstairs HVAC system.

[Guest guest]

Thanks for the quick response, Jeff, is it?

If I have an outdoor unit - gigantic one piece deal - 4 ton unit, how do I get

filtration into THAT? Is there already a pre-fab location for it? (It is the

American Standard 16 SEER package unit)

Right now, the MERV-11's ARE at the return grills, but the spore count was SO

high a few weeks ago, we had to hit it all hard, filter-fans, the whole bit.

The air is more fresh now. The system will be off until at least Monday.

The problem we almost had was that the flex-duct legs were in place in the crawl

space, but had not been connected to the boots, and were just sitting there in

the SAME space where the old very contaminated junk had just been. ICK! I am

going with flex for now, as I figure they are easily replaced if the get messed

up. A friend of mine just had a bad bad comtamination with a lot of breaks/gaps

in her metal ductwork.

I did have the guys bag up the ends of the ones that were left open, as they had

to stop work for the weekend, and I was NOT gonna let that sit for two days like

that, especially after two days of rain!

Last, I scrubbed out the sixteen holes in the floor/subfloor where the boots

were removed with a recipe of ::

1 quart white vinegar

1 cup boric acid (mine was blue) from the local feed & seed.

1 cup hydrogen peroxide (27.5%) from pool supply store

I had on mask, gloves, and safety goggles. Not too fumey, went well.

They were ALL moldy to one degree or another. Is there anything more I can do

besides scrubbing with the solution above? SHould I consider cutting out the

water damaged parts?

I hope to ozone Monday or Tuesday next week to further disable spores.

I have changed out the HEPA portion of my in-home air filter, and have that

running in the bedroom.

What an adventure!

> Jolly,

>

> You should be using Aprilaire MERV-11 pleated media filters at the fan coils,

not at the ceiling or wall grille. You should have cheapo fiberglass filters

(MERV-3) at the reteurn grilles to filter out the big particles and help keep

the return ducts clean.

> >

[Guest guest]

Jolly,

I could not find an install guide for the AS units, but the typical problems I

have seen with these outdoor units is rain water leaking into the ducts (and you

know what that means!).

Make sure that the exterior is absolutely air and watertight (use a squirt

bottle for testing.). WR Grace " Ice and Water Shield " is self-adhesive rubber

membrane that can be used to cover joints and screw openings that might leak.

Any exposed duct should have a " gable roof " to shed water, otherwise water ponds

and finds a way to get into the duct.

See it there is a filter holder inside the unit that needs maintenance.

The MERV-11s at your grilles are probably only one-inch filters; these can

restrict air flow when dirty, so you have to change them often. (A deeper filter

two or four inch will last longer and give better air flow but you may not be

able to use these if the space is not adequate.)

Cutting up the floor holes is too much trouble. Just seal the wood well (paint

or use epoxy consolidant if you have to.) Make sure that the metal boots are

well insulated (use expanding foam if necessary) becuase any moisture is likely

to condense on exposed cold metal.

See www.crawlspaces.org for what your crawl space should look like. If possible,

its best to dehumidify the space and keep the RH of the air so that water

doesn't condense on any A/C components.

May

www.MayIndoorAir.com

>

> Thanks for the quick response, Jeff, is it?

>

> If I have an outdoor unit - gigantic one piece deal - 4 ton unit, how do I get

filtration into THAT? Is there already a pre-fab location for it? (It is the

American Standard 16 SEER package unit)

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