Author Topic: HVAC  (Read 7185 times)

General DN 101

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HVAC
« on: August 29, 2015, 08:39:35 pm »
Hey Guys,

Anyone here work in HVAC or have a decent amount of experience working with it?

My House AC runs cool (I wouldn't say cold cold, but enough to where its better than it is outside).
After a few hours of running constantly, it will no longer blow cold air and it seems as if its just blowing room temperature if not hotter.

Google suggests it can be either the condenser, compressor, capacitor or the Freon. Any thoughts?

I've also had pretty low air flow in most of the further rooms, but I believe I also need to replace the ducting as its probably about 10-20 years old.
« Last Edit: August 29, 2015, 08:47:47 pm by DuMnUt 101 »

[T] Bob Loblaw

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Re: HVAC
« Reply #1 on: August 29, 2015, 10:24:24 pm »
over the  phone or over the net surgery sux .. but here we go ..

1. check your air filter . replace if necessary ..
2. are the Freon lines at your furnace or out side at the evaporator iced up ?
get back to me ...
i'D RATHER HAVE A BOTTLE INFRONT OF ME , THAN A FRONTAL LABOTOMY ...

General DN 101

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Re: HVAC
« Reply #2 on: August 29, 2015, 10:35:26 pm »
1.) Changed the Air Filter Recently, Still Seems to be happening (Checked it, its still clean today).
2.) Nothing out there has a freezing feeling, there is a canister that exposed that its cool to touch, but no where near freezing.

[T] Bob Loblaw

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Re: HVAC
« Reply #3 on: August 29, 2015, 11:42:47 pm »
Next step is to check the evap coil .. this is inside the plenum .. this may be a task . after time the coil may become clogged with dust restricting air flow through it , what happens is the the Freon is returned to the compressor as a still cold vapor and this gradually slows down the intended cycle of function . Is there an access door ? 2 sheet metal plates that split ? some way of looking inside to check for a clogged coil . ..
i'D RATHER HAVE A BOTTLE INFRONT OF ME , THAN A FRONTAL LABOTOMY ...

BraveFart

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Re: HVAC
« Reply #4 on: August 30, 2015, 07:41:44 am »
Damn Bob - good to know that you have an abundant wealth of knowledge on this stuff.  I had similar problems with a window air conditioner and the coil was frozen.  Had to let it completely melt and then clean the filter and eventually everything was fine. 

vindisel

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Re: HVAC
« Reply #5 on: August 30, 2015, 05:56:25 pm »
First you need to check outside condenser fan should run when AC is on. Second, you need to take a look at evaporator coil see if it is frozen, if yes your system is low Freon,  it means you have leak somewhere. When you have frozen evap coil, switch you fan position to on, not auto so it can melt the ice at evap coil, then turn ac on, it will cold again, but then it will frozen again because low Freon, but it's ok for you until Monday so you can call HVAC tech
If your out side condenser fan not running, you will see the compressor will run but humming very loud.
Base on your description, I think your ac may low Freon. Chance for clogged air filter is very minimum.
The canister outside that you see called dryer, it is filter to absorb moisture in your system. If your system low Freon, it starts freeze from outside to evap coil, that why to cold to touch.
Let me know if you need more help

General DN 101

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Re: HVAC
« Reply #6 on: August 30, 2015, 07:33:35 pm »
Thanks Bob and Vin.


The fan in the condenser is running. Although it seems like the compressor is a little louder then I remembered, but it could just be me. (Not sure if that matters)

So if I understand correctly, the Evap Coil is inside of that box attached directly to the blower/furnace? Typically requires removing the Foil Tape and removing the panels to gain access to it?
I probably don't want the "Fan" on, so I can shut it off at the thermostat turning everything to an off mode? Do I need to cut the power to it too, before I open it up?
I'm think that my Evap Coil may be dirty, cause I for the first year or 2 I owned the house, I never changed the air filter, because I simply didn't know how often they needed to be changed and I was a new to owning a home. I didn't run my AC much last year few years to even bother with it.

So I appreciate all of your guys' input. I'll take a peak at the evap coil soon. Looks like a pain in the ass to get into since my blower is tucked inside of a tiny closet and up pretty high. Plus I need to get some foil tape to re-seal the unit once I open it.

vindisel

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Re: HVAC
« Reply #7 on: August 30, 2015, 10:07:06 pm »
Everything you said is correct. You can switch your thermostat to off, or just switch inside ac unit breaker to off position. Normally there is an access door to inspect evap coil, it has rectangular or square shape, and less than 12 inches, not too big, you can look for it, some times it's on top or side depend on people who installed it.
Air filter inside should be replaced every 3 months, maybe 4 months if you are not use much
Should have your ac check every year is a good idea and save your cost later on. But in your case I think your system a little low Freon

JD (Stinkfist)

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Re: HVAC
« Reply #8 on: August 31, 2015, 12:24:38 pm »
where do you live?
what kind of unit? heat & a/c?
When you changed filter for first time, was it "sucked in"? letting dirt pass through?
Is it a high efficiency furnace? (there will be 2' or 3' pvc pipes attatched to it)

The secondary heat exchanger may be plugged and limiting air flow. I've had this a few times..

If its low on air flow or low on refrigerant it will ice up. make sure vents are open and unobstructed.



as far as the ducting needing replacement.. you just need to clean the inside or have it cleaned peofessionally, replacement is not necessary.
 
You really only need to clean supply side (after filter, between a/c coil and vents) if it's dirty, a light coating of dust is no big deal.
 the return side (before filter) is supposed to be dirty and you will be ok not doing this side. You wont gain much and it will be a mess.
Be positive, love your life!

|CU

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Re: HVAC
« Reply #9 on: September 01, 2015, 08:43:25 am »
One thing we work are told at best in NZ, is do not turn your a/c or heating off ( heat pump ) as it actually creates more work for the system and uses more power, best bet is to keep it at a constant temperature you require, thus creating a consistent environment you require and not putting extra pressure on the system you use.

JD (Stinkfist)

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Re: HVAC
« Reply #10 on: September 01, 2015, 12:58:15 pm »
One thing we work are told at best in NZ, is do not turn your a/c or heating off ( heat pump ) as it actually creates more work for the system and uses more power, best bet is to keep it at a constant temperature you require, thus creating a consistent environment you require and not putting extra pressure on the system you use.
Exactly.
I turn my a/c on in the spring and off in the fall. I have a Aprilaire hepa filter. The" fresh" air may be outside but the clean air is inside.
Not to mention that everything in your home absorbs moisure.
a/c removes moisture / humidity and it takes days to "dry" out your house but once its dry the system barely breaks a sweat keeping up with outdoor ambient temps.

I also recommend an powered attic exhauster with t stat.
Get that hot air out of your attic, your house will be cooler and your roof will last longer. (You basically want to keep your attic temp as close to outdoor temp as possible)
Be positive, love your life!

General DN 101

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Re: HVAC
« Reply #11 on: September 02, 2015, 01:32:47 am »
Thanks for all the input everyone!
I live in Southern California.
Not sure the make and model of the condenser - no indicators on the outside...
The blower/furnace says Payne, but no model number indicated as well.
I can't recall when I had change for the first time that was many years ago. I know it was completely filthy though.
I doubt its high efficiency.
Cool (Not Icey Cold) Air comes out of the top of that PVC pipe, is that normal?

My plan - Clean the Evap Coil ( I have a feeling this might be pretty dirty and don't recall the service tech ever looking at it) Then I can rule it out for a while, without doubt.
AC seems a bit more responsive now that I changed the filter again, but the air is still not Icey Cold. But I don't know that it ever was.
They did install new condenser 4 years ago because the old one died and they couldn't find the right part to fix it. Home warranty covered that for me, but that's really all I recall them looking at.


Quote
The secondary heat exchanger may be plugged and limiting air flow.
Not sure what that is.

I believe when I looked at the ducting the last time I was up there it was withering and its probably 10 or more years old. Its never really had strong air flow in 3 of the bedrooms dining and living rooms. The only one with strong pressure are the master and the 2 bath rooms. Although one of the bedroom is even closer to blower then then either of the bathrooms or master is and they it also has low air flow.
All the vents themselves are opened. I just bought a USB Boresecope that i'm hoping will help me identify whats going on inside the ducts, that'd be nice if I just need to clean them out. (Is there any best approach to do this myself?)

I typically only run it in the summer time.
In the winter, I will turn it on for just an hour before I am scheduled to wake up. Just makes it at little bit easier to get out of bed, but California rarely gets that cold to need the heat (at least I don't think so).
« Last Edit: September 02, 2015, 01:40:29 am by DuMnUt 101 »

[T] Bob Loblaw

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Re: HVAC
« Reply #12 on: September 02, 2015, 08:37:24 am »
That's an old furnace .. no secondary in that , secondary heat exchangers are used in high efficiency units and are located horizontally above the fan compartment . They look just like a regular coil but with way bigger passages in them . All they do is give the exhaust gasses one more go around to get the last bit of heat before being blown outside . Your ducts should be cleaned by professionals . its a shitty job , and they have the right equipment to do it right , besides , shop around , its not that expensive .
any chance of a close up of the fan compartment with service door off ?
 Changed the belt lately ? ( im assuming belt from age of furnace , not likely a direct drive ) . Another idea is to balance your registers . im assuming no basement ? no second story ? partially close off bathrooms and rooms close to furnace with strong pressure so more air flow can get to the registers/rooms that are in need . The air coming from the white pipe is because its open on the top . There should be a trap there , like under a sink . that will fix that .. that is CPVC pipe . Don't glue the second female joint ( for service ) .

consideration for a new furnace may be an idea   ..  :'(
« Last Edit: September 02, 2015, 08:47:49 am by [T] Bob Loblaw »
i'D RATHER HAVE A BOTTLE INFRONT OF ME , THAN A FRONTAL LABOTOMY ...

General DN 101

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Re: HVAC
« Reply #13 on: September 02, 2015, 08:03:59 pm »
Yea, I'm sure its pretty damn old like everything else in this house.. LOL
I haven't ever changed the built but it looks intact.
Not sure what is meant by "Balance Your Registers".
Its a 1 story 4bed/2bath house 1550 sqft.

Yea I was think I need to limit the air flow to the bathrooms, but I believe that's going to have to be done in the attic and isn't quite cool enough for that yet.

I'm some what familiar with the term trap and how its used in plumbing under the sink, but not sure how I would apply that here.

I might consider a new furnace, but I have no idea what size/cost I would need? Is it possible to just add on an additional blower or do I need the whole furnace component.
There term furnace to me means heater, and I don't really use the heater much, but I understand its secondary function is simply moving air about the house.

I'll see if I can get you a picture without the door on..
« Last Edit: September 02, 2015, 08:46:55 pm by DuMnUt 101 »

General DN 101

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Re: HVAC
« Reply #14 on: September 02, 2015, 08:47:53 pm »
More Pictures 2