Re: Air conditioner cleaning and adding WEB filter

[Guest guest]

Fantastic explination although this brings up yet another question, especially

for those in the southern humid states. How does the information here apply to a

unit that is in the attic, is this even a wise choice of places to put one with

all this in mind. It would seem to me that this would greatly complicate the

issue with humidity always being high, RH always being 50% and above it seems.

Even though the unit is " contained " or whatever would this not make the system

have to work so much harder with more chance of problems to prevail?

 

Chris...

 

 

From: May <jeff@...>

Subject: [] Re: Air conditioner cleaning and adding WEB filter

Date: Sunday, July 20, 2008, 12:56 PM

and Carl and others who have to deal with A/C:

This whole A/C discussion got me interested in dew points. The dew

point is the temperature at which water vapor will start to condense

out of the air; in other words, when the relative humidity is 100%.

[Guest guest]

I agree. " if its not broke dont fix it " send reminisent chills down my acheing

spine. It brings to mind someone driving a car down the road with black clouds

of smoke billowing out the back, the muffler being held on by hangers wraped

around everything under the car and the need to refill every fluid in the engine

at every stoplight. " the damn thing is runnin, Im not touchin it " LOL Funny

funny.

As to the other post about the AC guys. Ya gotta luv em dont ya.......

From: barb1283 <barb1283@...>

Subject: [] Re:Re: Air conditioner cleaning and adding WEB filter

Date: Sunday, July 20, 2008, 1:30 PM

Every year I put a new humidifier pad in my humidifier before

winter and when I do that, I pour some vinegar through the drain line

come from that and it removes some water limestone sediment. I have

not been doing that with a/c simply because I didn't know where the

drain was in there and I didn't see any white lime sediment and used

the old philosophy 'when there isn't anything wrong, don't fix it',

but seems reasonable to me. With new coils and drain pan I may do

that to keep drain line cleaner. I think vinegar might be best since

it should have some cleaning effect as well as remove limestone

deposits which may creat some resistence in drain line or diminish

size of drain line circumference. In any case, I can't see it

hurting anything.

[Guest guest]

Jeff,

Thanks, again, Jeff for a great tutorial. I'm not sure I've seen a

discussion before on the role of the condensate drain line in

relation to blower position and the resulting air pressure

relationships. Because I rarely see an A/C only unit I'll pay close

attention next time. In fact, I'll find out about the one I mentioned

in a previous post. It's scheduled to be inspected and cleaned

later this week.

Carl Grimes

Healthy Habitats LLC

-----

> and Carl and others who have to deal with A/C:

>

> This whole A/C discussion got me interested in dew points. The dew

> point is the temperature at which water vapor will start to condense

> out of the air; in other words, when the relative humidity is 100%. I

> looked on weather.com and they actually have maps of the entire

> country with the current dew point temperatures. It?s quite

> interesting. The dew points varied from 26ºF in Reno, to 32ºF in

> Boise, to 76ºF in Miami (yikes!).

>

> This is relevant to the operation of air conditioning, which is

> designed (in part by adjusting air flows over the coil) to keep the

> cooling coil, which looks like a car radiator, around 40-45ºF. If the

> coil gets too cold, water will freeze up on it and block the airflow.

> You would expect that if the dew point of the outdoor air is below

> 40ºF, not much water would condense out of the air during air

> conditioning, and most of the energy used for the operation of the A/C

> is expended in just cooling the air. (There would be very little water

> in the condensate tray, which every A/C unit must have).

>

> In more humid areas like Miami, most of the energy for ?cooling? goes

> to removing water from the air (since the same amount of energy must

> be removed from air to condense a gram of water vapor into liquid as

> it takes to boil a gram of water and create vapor). That?s why it

> takes so long in a humid climate to cool a room when you first turn on

> an air conditioner.

>

> raised an interesting question about the condensate water, which

> is often quite contaminated with microbial growth (including bacteria,

> yeast and mold). Whether or not this liquid creates its own IAQ

> problem can depend somewhat on the arrangement of the blower with

> respect to the A/C coil, and whether or not there is a condensate

> trap. I hope that I can make this clear, as it is a bit complicated,

> but certainly worth understanding if you have an A/C and mold concerns.

>

> In most furnace applications, the blower is near the floor, the

> furnace/heating portion above that and the A/C coil above that. The

> return air stream enters the blower first, and then is blown into the

> furnace/heating portion and over the A/C coil. Because the air

> pressure is less in the blower cabinet than the basement or mechanical

> closet in which the unit sits, air leaks from the surroundings into

> the blower cabinet. The air pressure is greater in the supply plenum,

> where the A/C coil is usually located, so air leaks from there into

> the basement or mechanical closet. Cold air goes off the coil directly

> into the duct system. In this arrangement, I will refer to the blower

> as being in front of the A/C coil.

>

> In many heat pump and A/C only systems, however, the arrangement is

> the opposite. The A/C coils is located first in the return air stream,

> followed by the fan and blower cabinet, so rather than blown across

> the A/C coil, air is sucked across the coil. This means that the air

> pressure around the cooling coil is less than the air surrounding the

> A/C unit. This is a significant difference, which I will discuss

> below. In this arrangement, I will refer to the blower as being behind

> the A/C coil.

>

> Water drains by gravity from a cooling coil into the condensate tray,

> and again by gravity into the drain line and out of the system, either

> into a condensate pump or a floor drain. In a basement system in which

> the blower is in front of the coil, the water is literally blown out

> of the condensate line, because the pressure of the inside air around

> the coil is greater than the air pressure in the basement. In systems

> in which the blower is behind the coil, the pressure is less inside

> around the coil than out, and room air is sucked into the condensate

> line. Unless there is a water-filled, ?U?-shaped trap in the

> condensate line, the air that is rushing in slows or prevents the

> condensate water from flowing out of the tray. This can cause

> overflowing of water from the condensate tray (and lead to mold

> problems in the insulating liners and leaks from the unit).

>

> In either arrangement, what happens to the air flowing through the

> condensate line? In a system in which the blower is behind the coil,

> air that is sucked in can get contaminated with mold that is growing

> in the condensate line ? even if that airflow is small. In a system in

> which the blower is in front of the coil, there may be no water in the

> trap (or no trap at all), so air from the system is blowing out

> through the moldy condensate line or moldy condensate pump, into the

> mechanical closet or basement. This is particularly true if the A/C is

> part of a heat pump or furnace. Thus the spread of contamination

> happens in either case: within the system itself, or into the area

> surrounding the air-conveyance unit.

>

> Another problem with the arrangement that has the blower behind the

> coil is that the air coming off the coil is at nearly 100% relative

> humidity (RH). Many molds can grow at this high RH, so any dust in the

> blower or on the blower cabinet walls or insulation can get moldy.

> (This arrangement, with the blower behind the cooling coil, is the

> same as the one in all window-A/C units, so the dust in the blowers

> also gets very moldy.)

>

> To prevent mold problems in an A/C system, you must use the highest

> MERV-rated filter you can. In window units, this means about MERV 8,

> and in central systems, about MERV-11. Remember, the purpose of this

> filter is to remove biodegradable particles to prevent mold growth

> within the system. Most biodegradable particles in house air consist

> of skin scales, pet dander, lint, starch (from body powder), and plant

> materials (like pollen and trichomes)all of which are larger than 5

> microns, so a HEPA-rated filter would be overkill. And a filter, no

> matter how efficient, will not ?clean? a system that is already

> contaminated with microbial growth.

>

> In a central system, every condensate line, whether it flows into a

> floor drain, sink or condensate pump, should have a ?U?-shaped trap.

> The best type of trap today is a transparent one so you can see if the

> line is clogging. These traps also come with removable caps so the

> trap and lines can be cleaned. The condensate tray is inaccessible in

> most A/C?s but if accessible, I don?t think that it is a bad idea to

> treat a condensate tray (or condensate pump) every once in a while

> with bleach, but don?t let bleach sit too long on metal components as

> this can accelerate corrosion. The bleach must be rinsed out.

>

> I recall being in one, several-story, new condo building with an

> attached parking garage, with spaces at every living level. For some

> idiotic reason, all the condensate from the heat pumps drained onto

> the sloped parking ramps connecting the parking levels. It was quite a

> sight. There were trails of ?bioslime? draining down the concrete

> ramps, all different colored depending on the crud growing in the A/C

> units in the different condos. The architects figured the water would

> evaporate, which it did eventually, but never gave a thought to the

> bioaerosol dust that would be created when cars drove over the dried

> crud. I haven?t been back to the building but I can imagine that they

> have a bit of an IAQ problem in the parking garage.

>

> C. May

> May Indoor Air Investigations LLC

> www.mayindoorair.com

> " Jeff May's Healthy Home tips "

>

> > Re: Air conditioner cleaning and adding WEB filter

> > Posted by: " United States Vet " unitedstatesvet@... unitedstatesvet

> > Date: Thu Jul 17, 2008 7:41 pm ((PDT))

>

> > This brings up a question I had never even given thought to.

> > Especially here >in the southeast what about the drain pipes that

> > drain the condensation from >the unit. Would it not make sense that

> > in time there would be some sort of >growth in the pipes being

> > constantly wet and dark? And if that is the case, >then would it not

> > be recommended to put vinegar or other solutions either in >the pump

> > or through the lines on a regular basis if for no other reason

> > safety >measures??

> > Just a thought.

>

>

>

>

> ------------------------------------

>

> FAIR USE NOTICE:

>

>

[Guest guest]

I don't like the idea of putting A/C equipment in an attic in a humid

climate. In some very humid areas, attic ventilation has to be

minimized to reduce the amount of condensation that occurs on the

ducts and cooling equipment in the attic.

In our new place, we put the upstairs A/C fan coil in a second-floor

closet to keep it accessible and out of the attic heat and humidity.

An alternative is to build an insulated mechanical closet in the attic

for the A/C.

I looked at an A/C in PA that was covered with mold due to high attic

humidity and inadequate insulation.

The metal boots in attics that connect to the ceiling diffusers are

often poorly insulated. Moisture condenses on these and can cause

ceiling stains and mold. Insulation should always completely cover any

part of the A/C air duct system. Insulation can be added to the

exterior of an attic A/C unit that has condensation on the exterior.

Condensation also happens in damp crawl spaces on under-insulated

ducts and where the metal boots under floor registers are inadequately

insulated and exposed. I have heard that in the South, where the kick

space under a bathroom vanity may be used as an ersatz " duct, " water

condenses on the cold bathroom subflooring beneath the vanity and rots

the floor. (The answer to this problem is to seal the crawl space from

the exterior and dehumidify it with a Therma-Stor Advance.)

Since we have two central A/C units (one in the basement and another

at the second floor) in our new place, I am trying an experiment. It

appears that using either A/C provides adequate cooling for the whole

house, so during the day, we only run the second floor A.C since this

is where our offices are. During the day, we operate the basement unit

for the first floor on " fan only " to mix the air. At night, we turn

the basement-unit cooling on and the second-floor unit cooling off but

operate this unit on " fan only. "

This strategy has, I believe, one great advantage. While either unit

is operating on " fan only, " the coil and condensate pan are dried out

completely by the air flow, so the coil in each cooling unit is really

only wet about half the day; I am hoping this will reduce the

likelihood of microbial growth. (Of course, we have an Aprilaire

MERV-11 filter on each unit and Filtrex pre-filters on all the

returns: www.breathgreenair.com)

May

www.mayindoorairt.com

" Jeff May's Healthy Home Tips "

> Re: Air conditioner cleaning and adding WEB filter

> Posted by: " United States Vet " unitedstatesvet@... Date: Sun

> Jul 20, 2008 1:52 pm ((PDT))

> Fantastic explination although this brings up yet another question,

> >especially for those in the southern humid states. How does the

> information >here apply to a unit that is in the attic, is this even

> a wise choice of >places to put one with all this in mind. It would

> seem to me that this would >greatly complicate the issue with

> humidity always being high, RH always being >50% and above it seems.

> Even though the unit is " contained " or whatever would >this not

> make the system have to work so much harder with more chance of

> >problems to prevail?

> Chris...

[Guest guest]

, thanks for explaining that. I thought that myself all along and as you

have said. The consequenses are indeed just as you say. Ive even seen water

dripping out of the vents in part of the house. I will leave it at that but

thanks for clarifying that for me. I agree whol heartedly.

 

Chris...

[Guest guest]

Carl,

I looked at a heat pump in a home where the mother and daughter were

having allergy symptoms. They had called their HVAC technician to

come repair the heat pummp because water was leaking out and

he " fixed " it.

The blower was behind the cooling coil so the air pressure was less

at the cooling coil than in the basement. There was no trap at all

and the condensate line just went directly into a condensate pump.

Without the trap, air was being sucked into the condensate tray,

which had been overflowing because the water could not flow out fast

enough.

The technician's " fix " was to place a kitchen sponge to block and

soak the splash of the water. The wet sponge and insulation were

covered with Penicillium mold growth.

Jeff May

www.myhouseiskillingme.com

--- In , " Carl E. Grimes " <grimes@...>

wrote:

>

> Jeff,

>

> Thanks, again, Jeff for a great tutorial. I'm not sure I've seen a

> discussion before on the role of the condensate drain line in

> relation to blower position and the resulting air pressure

> relationships. Because I rarely see an A/C only unit I'll pay close

> attention next time. In fact, I'll find out about the one I

mentioned

> in a previous post. It's scheduled to be inspected and cleaned

> later this week.

>

> Carl Grimes

> Healthy Habitats LLC

>

> -----

> > >

> > raised an interesting question about the condensate water,

which

> > is often quite contaminated with microbial growth (including

bacteria,

> > yeast and mold). Whether or not this liquid creates its own IAQ

> > problem can depend somewhat on the arrangement of the blower

with

> > respect to the A/C coil, and whether or not there is a

condensate

> > trap. I hope that I can make this clear, as it is a bit

complicated,

> > but certainly worth understanding if you have an A/C and mold

concerns.

> >

> > In most furnace applications, the blower is near the floor, the

> > furnace/heating portion above that and the A/C coil above that.

The

> > return air stream enters the blower first, and then is blown into

the

> > furnace/heating portion and over the A/C coil. Because the air

> > pressure is less in the blower cabinet than the basement or

mechanical

> > closet in which the unit sits, air leaks from the surroundings

into

> > the blower cabinet. The air pressure is greater in the supply

plenum,

> > where the A/C coil is usually located, so air leaks from there

into

> > the basement or mechanical closet. Cold air goes off the coil

directly

> > into the duct system. In this arrangement, I will refer to the

blower

> > as being in front of the A/C coil.

> >

> > In many heat pump and A/C only systems, however, the arrangement

is

> > the opposite. The A/C coils is located first in the return air

stream,

> > followed by the fan and blower cabinet, so rather than blown

across

> > the A/C coil, air is sucked across the coil. This means that the

air

> > pressure around the cooling coil is less than the air surrounding

the

> > A/C unit. This is a significant difference, which I will discuss

> > below. In this arrangement, I will refer to the blower as being

behind

> > the A/C coil.

> >

> > Water drains by gravity from a cooling coil into the condensate

tray,

> > and again by gravity into the drain line and out of the system,

either

> > into a condensate pump or a floor drain. In a basement system in

which

> > the blower is in front of the coil, the water is literally blown

out

> > of the condensate line, because the pressure of the inside air

around

> > the coil is greater than the air pressure in the basement. In

systems

> > in which the blower is behind the coil, the pressure is less

inside

> > around the coil than out, and room air is sucked into the

condensate

> > line. Unless there is a water-filled, ?U?-shaped trap in the

> > condensate line, the air that is rushing in slows or prevents

the

> > condensate water from flowing out of the tray. This can cause

> > overflowing of water from the condensate tray (and lead to mold

> > problems in the insulating liners and leaks from the unit).

> >Jeff May

> >May Indoor Air Investigations

> >www.mayindoorair.com

[Guest guest]

Jeff,

Will wonders never cease! Stop the symptom but without a

thought to the consequences.

It reminds me of the lower cost flow-through humidifiers that use

a sponge instead of the metal grid. Same exact result - covered

with " stuff " that is then blown throughout the house.

BTW, I've been reading more of the AIHA book. Here is how

Chapter 14, " Remediation: Scope, Roles, and Risk

Communication " begins:

Epidemiologic evidence linking the presence of indoor

dampness with adverse health outcomes justifies

remediation of moisture and mold in buildings.

Who can't understand that? Those that create the moisture and

mold by putting sponges in the condensate tray!

Carl Grimes

Healthy Habitats LLC

-----

> Carl,

>

> I looked at a heat pump in a home where the mother and daughter were

> having allergy symptoms. They had called their HVAC technician to

> come repair the heat pummp because water was leaking out and

> he " fixed " it.

>

> The blower was behind the cooling coil so the air pressure was less

> at the cooling coil than in the basement. There was no trap at all

> and the condensate line just went directly into a condensate pump.

>

> Without the trap, air was being sucked into the condensate tray,

> which had been overflowing because the water could not flow out fast

> enough.

>

> The technician's " fix " was to place a kitchen sponge to block and

> soak the splash of the water. The wet sponge and insulation were

> covered with Penicillium mold growth.

>

> Jeff May

> www.myhouseiskillingme.com

>

>

> >

> > Jeff,

> >

> > Thanks, again, Jeff for a great tutorial. I'm not sure I've seen a

> > discussion before on the role of the condensate drain line in

> > relation to blower position and the resulting air pressure

> > relationships. Because I rarely see an A/C only unit I'll pay close

> > attention next time. In fact, I'll find out about the one I

> mentioned

> > in a previous post. It's scheduled to be inspected and cleaned

> > later this week.

> >

> > Carl Grimes

> > Healthy Habitats LLC

> >

> > -----

> > > >

> > > raised an interesting question about the condensate water,

> which

> > > is often quite contaminated with microbial growth (including

> bacteria,

> > > yeast and mold). Whether or not this liquid creates its own IAQ

> > > problem can depend somewhat on the arrangement of the blower

> with

> > > respect to the A/C coil, and whether or not there is a

> condensate

> > > trap. I hope that I can make this clear, as it is a bit

> complicated,

> > > but certainly worth understanding if you have an A/C and mold

> concerns.

> > >

> > > In most furnace applications, the blower is near the floor, the

> > > furnace/heating portion above that and the A/C coil above that.

> The

> > > return air stream enters the blower first, and then is blown into

> the

> > > furnace/heating portion and over the A/C coil. Because the air

> > > pressure is less in the blower cabinet than the basement or

> mechanical

> > > closet in which the unit sits, air leaks from the surroundings

> into

> > > the blower cabinet. The air pressure is greater in the supply

> plenum,

> > > where the A/C coil is usually located, so air leaks from there

> into

> > > the basement or mechanical closet. Cold air goes off the coil

> directly

> > > into the duct system. In this arrangement, I will refer to the

> blower

> > > as being in front of the A/C coil.

> > >

> > > In many heat pump and A/C only systems, however, the arrangement

> is

> > > the opposite. The A/C coils is located first in the return air

> stream,

> > > followed by the fan and blower cabinet, so rather than blown

> across

> > > the A/C coil, air is sucked across the coil. This means that the

> air

> > > pressure around the cooling coil is less than the air surrounding

> the

> > > A/C unit. This is a significant difference, which I will discuss

> > > below. In this arrangement, I will refer to the blower as being

> behind

> > > the A/C coil.

> > >

> > > Water drains by gravity from a cooling coil into the condensate

> tray,

> > > and again by gravity into the drain line and out of the system,

> either

> > > into a condensate pump or a floor drain. In a basement system in

> which

> > > the blower is in front of the coil, the water is literally blown

> out

> > > of the condensate line, because the pressure of the inside air

> around

> > > the coil is greater than the air pressure in the basement. In

> systems

> > > in which the blower is behind the coil, the pressure is less

> inside

> > > around the coil than out, and room air is sucked into the

> condensate

> > > line. Unless there is a water-filled, ?U?-shaped trap in the

> > > condensate line, the air that is rushing in slows or prevents

> the

> > > condensate water from flowing out of the tray. This can cause

> > > overflowing of water from the condensate tray (and lead to mold

> > > problems in the insulating liners and leaks from the unit).

>

> > >Jeff May

> > >May Indoor Air Investigations

> > >www.mayindoorair.com

>

>

>

> ------------------------------------

>

> FAIR USE NOTICE:

>

>