air quality issue..high particles...high carbon dioxide...high humidity

[robotman2009]

Dear HVAC gurus,

My wife and I moved into a house in January...immediately I started having air quality symptoms. I thought his might have had something to do with the heat pump itself. However, I have been convinced that that wasn't the issue.

Well we had an air quality test done. The results were...outdoor environment B...Chemical pollutants were 820 ug/m3....Particle Allergens were at 27 ug/m3...Carbon dioxde was 771 ppm....Temperature was 70 degrees...all results are given in overall averages....some of the daily and hourly averages were much higher.

So...the air quality guy said to do a blow test or something like that to measure the leakage. Since this is a $$$$ test and our house is only 5 years old, I'm thinking about passing on it. It seems to me we would be really unlikely to be pulling air from outside. Not just that the air quality outside is pretty good...so if I was pulling air in from outside it seems like it would help the indoor air quality. In fact with seconds of going outside my symptoms usually go away.

He also recommended installing an additional return...perhaps one for each bedroom...so +3 more than what we have now. He seem to think this would help the particle count and the humidity. He also said it might be necessary to seal up the vents, canned lights, plugs and switches to keep them from leaking attic air into the house...another hvac guy confirmed this particular thing.

At this point, I have a few questions. Is putting an addtional/additional return/s likely to be effective for the particles and humidity(which would in turn deal with the need to have the thermostat down to 70)? I was thinking of starting with one return at a time to see how it did.

Also, will that deal with the high carbon dioxide levels in the house? If not, would it be possible/adviseable to put a return that sucks air from my patio to pull in fresh air. I got this idea from my dad's house. I have no symptoms at his house...his house is old...has very old vent work but has a return that sucks air from under the house as well as another return sucking air from inside the house. I know my patio isn't as cool as under my dad's house but wouldn't the unit cool and dehumidify the air coming from a patio return?

Any advice about which way to go would be greatly appreciated...I have one more guy coming tomorrow. Just trying to make the best decision I can for my health....my home...and also making this decision with my wife...she thinks a lot of this in my head....and the available funds I have to tackle this issue.

[robotman2009]

Thanks comfortcontrolac...Does the theory of pulling attic air into the house seem valid? If so, any external filter would seem to be useless given that the attic particles are getting sucked from the vents and other receptacles.

[Sleuth]

.

You're describing classic syptoms of a heat pump system that has not been properly installed and/or maintained.

Ask the next tech to visually inspect the evap coil and check for a good functioning p-trap, undersized returns & of course the air filter.

..

[robotman2009]

Thanks superheatsleuth,

I change the filter regularly...regularly. It seems like 3 month filters only last one month or less with this system.

The coils have been inspected and are clean. Don't know what the p-trap is. I do know it has one plenum that feeds all the supply vents..it is a closed plenum. The one supply doesn't have a plenum. It goes straight into the side of the unit.

Could it be that if the return (25x20x1 1600 square foot house) is undersized for the unit, it could be sucking too hard and pulling attic particles into the house?

[robotman2009]

Oh yeah the last hvac guy that came said the system seemed to check out fine when he examined it.

[t527ed]

high Co2 readings would lead me to think the house was too tight, air recovery ventilator would help that.

[robotman2009]

That's what I was thinking too...I didn't know if there was some other variable of which I wasn't aware causing that...perhaps if the system was pulling attic air into the house. Is there a cheaper way to do something like that?...I was thinking of pulling air from outside through an addtional return...I'm really wanting to pay someone to do all this. I just want to make a good decision.

[robotman2009]

How do I determine if my return is too small?

[t527ed]

if the ducts were leaking and sucking in attic air i would expect lower C02 readings.

problem with a straight duct from return to outdoors would be the humid dirty air you would be pulling in.

what part of country are you in?

[robotman2009]

I live in Fort worth TX...the air outside right now is less humid than the air in the house....One day not too long ago I looked and it was about 10% dryer than the air in the house.

[motoguy128]

Maybe the house is very tight and well insulated and a proper load calculation wasn't done or the contractor upsized it "just in case". It also might have the air handler set to the wrong fan speed.

[Six]

Sounds over sized with no make up.

You need to have a qualified technician check it.

[motoguy128]

I live in Fort worth TX...the air outside right now is less humid than the air in the house....One day not too long ago I looked and it was about 10% dryer than the air in the house.

THe relative humidity is probably lower, but the dewpoint (I hope) is mcuh higher outside. Right now its' 95F and 69F dewpoint in Ft .Worth. Indoors, if it was 70F and a dewpoint of 69F, you would have condensation and mold forming inside the home. I'm guessing if it feel "muggy" the RH is around 60% which is a 55F dewpoint.

40% RH is fairly humid... when its' over 90F. Dewpoints in the mid 40's to mid 50's are the most comfortable generally over a wide range of temperatures.

I think you need a good HVAC company to evaluate your system, chekc the blower speed, check how well sealed the ducts are and maye recommendations such as a MERV 11 or 13 media filter and/or an ERV for fresh air.

[robotman2009]

Oh I forgot...the 2nd and 1st guy said that it might be necessary to put glue...then metal tape...then mastic sealant along the edges of the vents to seal them better....to keep them from pulling in particles from attic...along with putting expanding foam in receptacles and plugs. Then do can lights to seal them.

comfortcontrolac...what is that rating in seer instead of ton? I might not be asking that question correctly. Also...what is the name of that fresh air intake? I've looked on websites and can't seem to track down what you are talking about.

[robotman2009]

Motoguy and Six...thanks for the replies.

I thought I did have a good guy come the first time. He looked at the system and didn't make any mention of fan speeds being wrong etc...of course he was the air quality guy not the AC guy...Six...what do you mean when you say oversized with no makeup

I'm not for sure on the walls of the house and the insulation...I can't see them without tearing stuff out.

So...let me do a little stop and check here....It sounds like the no matter what is causing the particles...the CO2 is a clear indication that the house is too tight and not ventilating the way it should...Correct?

Incidentally, our overall humidity was 61%...with a few peaks as high as 65%. That doesn't seem high enough for mold and stuff does it?

As far as the particles, it is possible they are coming from the attic right? Strong possiblility? Weak possibility?

Could those particles be coming from mold?

[beenthere]

comfortcontrolac, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

You can find the rules for posting and qualifications here.


Further infractions may result in loss of posting privileges.

[Six]

Fresh air intake is known as "make up air " in the industry.

A unit that has too much capacity ( over sized ) for a given area wont remove latent heat and will drop specific heat too quickly.

So temp comes down but not humidity. The installer should have done a heat load calculation.

Fan speed is important with humid climates needing usually a little less than 400 cfm per ton.
i
There are guys here that are very knowledgable about make up air per application.

More than I am but 61% RH too high.

[robotman2009]

Six,

So it could be an issue other than too much insulation if the unit is oversized?

[robotman2009]

I'm kinda enjoying the activity of looking stuff up on the Internet.

Here is my system information with model numbers..

Carrier Air handler
fa4cnf042

Comfortmaker Heat pump
n2h336gkb100

According to this post http://hvac-talk.com/vbb/archive/ind.../t-720641.html
my air handler is rated at 3 1/2 tons....trying to find information on the heat pump.

[robotman2009]

On page 7 of this document it says that my unit is 5 ton.

http://www.docs.hvacpartners.com/idc...t/fa4c-5pd.pdf