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-   -   R410 Vs R22 Humidity removal (http://www.diychatroom.com/f17/r410-vs-r22-humidity-removal-155328/)

tswatek 08-30-2012 01:22 PM

R410 Vs R22 Humidity removal
 
In June Ď12, I replaced my 10 yr old compressor and handler and always seem to be sweating in my house since the change. I've had the new AC contractor come out 3 times since the install and I just don't understand why I "feel" so hot when all the temp settings are the same as with the old unit. The first two visits, they said the R410 needed to be topped off a little and the 3rd time, they said all refrigerant levels and pressures were right to specs. This is driving me crazy 'cuz I live in FL and even when wearing shorts and a tank top in my house, I'm wiping sweat from my forehead regularly. I keep my 3 zones in the 75-77 range, as I did with my last system. My thermostat reads that the temps are right on, but it just feels like it's not pulling anywhere near the humidity out of the air as the old system did. Here are some specifics:

Old unit: Carrier 5 Ton, 10 SEER, R22, 3-zone, variable speed handler

New unit: Amana 5 Ton, 15 SEER, R410, 3-zone, variable speed handler

Other possibly pertinent info: The unit I replaced is for my downstairs area, which is about 80% of my total living area. I also have a 2 1/2 Ton Carrier system for my upstairs and the downstairs and upstairs handlers sit side by side. The new AC contractor looked at all my duct work for downstairs and said that my downstairs handler wasnít getting enough air supply and he recommended increasing the air flow. He did this by cutting a hole between the supply cavities between the two handlers.

What Iím wondering, though, is if the new 5 Ton unit is now pulling too much air from the supply ducts that used to be just supplying the 2 Ĺ Ton upstairs unit, Iíve definitely noticed that itís a lot more comfortable upstairs since the change, but way less comfortable downstairs. Iím no AC expert, but Iím a pretty intuitive DIY guy and I think this may be the root cause of my humidity issue.

The new AC contractor told me these two things: 1) While the industry officially says theyíre the same, contractors know that R410 systems pull less humidity out of the air than R22 systems; and 2) Just crank the air down an extra 4-5 degrees occasionally to pull out the humidity, then put it back to my normal comfort area. Any thoughts on how to improve my humidity situation?

NitroNate 08-30-2012 02:25 PM

i don't understand the hole between the two returns. if the upstairs unit isn't running, the downstairs unit could pull air from the upstairs registers (reversing airflow through the upstairs system when blower is off), bypassing the filter. this doesn't make any sense if i am understanding you correctly.

i have a similar setup and i do not run my upstairs and downstairs units simultaneously. they are very rarely on at the same time.

tswatek 08-30-2012 04:04 PM

My units are both operating on auto setting so sometimes only one is on and sometimes both are on. I do believe you're understanding the situation correctly. You bring up a good point that I hadn't even considered about my 5 Ton pulling supply air when the 2 1/2 Ton handler is off. I think I'm going to try to seal of the pass-through between the handler supply areas and see if that solves my issue. My old downstairs system operated wonderfully for 10 yrs before the new unit was installed and the pass-through was added to the design.

Doc Holliday 08-30-2012 04:07 PM

How long is the new system running during a cycle (how long does it run until it reaches thermostat set point, how long is it off and how long does it run again before it shuts back off all on it's own) versus the old system? Was the stat changed as well?

I'm betting that it's cooling better, reaching desired set point quicker, thus not given the chance to dehumidify as well. Lower air temp coming from the supply vents, pretty much.

Shut your upstairs system completely off and run only the downstairs and see if that helps. Try that for a day, maybe two.

and time the system's cycling.

tswatek 08-30-2012 04:18 PM

Doc Holliday, I'm not sure on those answers. It doesn't seem like it's running less than the old unit did, though I guess there are longer period where I feel like the air is moving less - or, I should say, longer periods of still air.

By turning off the the upstairs unit, am I trouble-shooting or is that something I'd be doing regularly. Reason I ask is that my office is upstairs and in Florida in August/Sept it would be pretty unlivable upstairs while it's not running.

Doc Holliday 08-30-2012 04:21 PM

Quote:

Originally Posted by tswatek (Post 999883)
The new AC contractor told me these two things: 1) While the industry officially says theyíre the same, contractors know that R410 systems pull less humidity out of the air than R22 systems; and 2) Just crank the air down an extra 4-5 degrees occasionally to pull out the humidity, then put it back to my normal comfort area. Any thoughts on how to improve my humidity situation?

Have you had any work done to the home such as possibly change from single to double pane windows or insulate anything such as the attic? Anything at all which would tighten/seal the home's "envelope" from the elements better?

Doc Holliday 08-30-2012 04:24 PM

I'm not understanding this pass through.

Doc Holliday 08-30-2012 04:28 PM

What I was thinking and getting at since it's a new system and hvac has come a long, long way in ten years, is that what a 5 ton used to be able to handle now can be done by a 4 ton. That would be especially true if you had any work done to the home to aid the system.

You may just need to get yourself a dehumidifier installed onto the new system and be done with it.

techpappy 08-30-2012 04:29 PM

Just wondering...mods aside, is there any way you are now pulling in excess outside "humid" air from somewhere in the downstairs areas. As you say though..I would close off the common return air openings and revert back to the way it was .. likely the answer..but, I am not an AC TECH..still can't imagine reaching set point without squeezing a whole lot of humidity out of the air through that particular unit

tswatek 08-30-2012 04:41 PM

Doc, the pass through was just the idea of the new AC contractor. His reasoning was - after checking all my existing supply ducts - that a 5T handler was capable of drawing more air (he measured the size of all the ducts and showed me calculations that made sense). So the closest additional source of supply was to pull from an existing supply duct upstairs. This was done by creating a pass-through beneath the handlers which (as the theory would go) would allow more supply air to the 5T handler so it can run more efficiently. I haven't done anything else that would change the insulating factors in my house.

tswatek 08-30-2012 04:55 PM

I hope I'm using the right terminology. The new AC guy educated me pretty much on this and said we call the air that is humid and being pulled into the handler the "supply" air and the air that has passed through the coils and is sent out cooler is the "return" air. If that's not the right terminology, then I can see how this would be confusing.

tswatek 08-30-2012 05:10 PM

https://dl.dropbox.com/u/38637500/AC...ustration2.pdf
I'm attempting to insert a diagram.
https://dl.dropbox.com/u/38637500/AC...ustration2.pdf

Doc Holliday 08-30-2012 05:15 PM

Being a zoned system do you have a bypass duct from the return to the supply?

What happens if you drop all three stats about 3-4 degrees?

Doc Holliday 08-30-2012 05:19 PM

This is the first in 12 years I've ever heard of joining two returns and those are cold air returns which are connected. I'd have them close that back up and see what happens. I'm speculating at this point but it's pretty much all one can do.

What I see happening is now the downstair's system is trying to ring out the upstairs system as well.

tswatek 08-30-2012 05:21 PM

Doc, there wasn't a bypass before, but the new AC contractor put one in. He explained that the bypass, which is a duct that has a weighted damper, will open and dump excess return air back into the supply air when the air force would otherwise be too strong for any one zone that was open at once.


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