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Old 07-10-2012, 01:28 PM   #46
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70 degree Supply Air


Quote:
Originally Posted by ryanxo View Post
I don't want to hire an actual HVAC tech...hence being a member of a DIY forum
Agree with gregzoll - you have obviously reached the limit of your afterhours tech's experience (or desire to help) and now have decisions to make.

You can buy gauges, thermometers, etc etc, and read up on the matter of subcooing and superheat, airflow, duct design, etc etc ... and continue in the DIY vein. You'll very likely end up with a LOT of money and time invested, and be no further ahead of the game.

Or you can hire a competent local HVAC company with the tools, knowledge and experience to diagnose your system.

As greggzoll said, you must know when it's time to draw the line. I think that time is now for you.

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Old 07-10-2012, 05:44 PM   #47
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70 degree Supply Air


Quote:
Originally Posted by ryanxo View Post
I don't want to hire an actual HVAC tech...hence being a member of a DIY forum

Understandable. However without actual readings of the pressure and temps we can't really give you any advice to help you. Sort of a catch 22. Does that charging chart specify if its for a piston or TXV system.
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Old 07-10-2012, 08:30 PM   #48
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70 degree Supply Air


Quote:
Originally Posted by scottmcd9999 View Post
Agree with gregzoll - you have obviously reached the limit of your afterhours tech's experience (or desire to help) and now have decisions to make.

You can buy gauges, thermometers, etc etc, and read up on the matter of subcooing and superheat, airflow, duct design, etc etc ... and continue in the DIY vein. You'll very likely end up with a LOT of money and time invested, and be no further ahead of the game.

Or you can hire a competent local HVAC company with the tools, knowledge and experience to diagnose your system.

As greggzoll said, you must know when it's time to draw the line. I think that time is now for you.
heck, let 'em dive in nose first...what's the worst that can happen?
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Old 07-10-2012, 09:55 PM   #49
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70 degree Supply Air


Quote:
Originally Posted by beenthere View Post
Understandable. However without actual readings of the pressure and temps we can't really give you any advice to help you. Sort of a catch 22. Does that charging chart specify if its for a piston or TXV system.
I took pics of the service manual. I can't get them to resize in this forum but they are named manual1, manual2, manual3, and manual4

I just uploaded them to my site.
http://ryantwilkins.com/AC/

If you cant read them... only thing i could find that mentioned expansion valve was:
Refrigerant Control: Expansion Valve under outdoor coil

And im guessing the worst that can happen is what I'm about to do anyway... get a new one.

If you get bored and wanna go look at pics of my ductwork and AC and give me tips they are all at that address
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Last edited by ryanxo; 07-10-2012 at 10:04 PM.
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Old 07-10-2012, 10:03 PM   #50
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Ok, it has a charging chart for an indoor coil with a TXV. Shows how to check for proper charge. Now all you nee is someone to check it by those instructions. It also has the FCCV/piston charging chart. determine for sure which type metering device you have. And check the charge to the appropriate instructions. A piston/FCCV system charged by TXV instructions won't cool well. A TXV system charged by FCCV/piston instructions won't cool well.
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Old 07-10-2012, 10:10 PM   #51
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Quote:
Originally Posted by beenthere View Post
Ok, it has a charging chart for an indoor coil with a TXV. Shows how to check for proper charge. Now all you nee is someone to check it by those instructions. It also has the FCCV/piston charging chart. determine for sure which type metering device you have. And check the charge to the appropriate instructions. A piston/FCCV system charged by TXV instructions won't cool well. A TXV system charged by FCCV/piston instructions won't cool well.
OK i'll see what i can do. It's not super hot so the AC appears to be working correctly. I'll wait for it to get hotter than hades again so the tech can see that not all is peachy in ACLand
In the meantime I'm gonna see if i can insulate the plenum some more and I bought solar gable fan that I'm going to install.

Also have insulation tech coming friday to give me a recommendation/estimate/plan of attack. If he is cheap enough I'll just let him do it.

Is it bad to wrap the air handler in duct wrap? What about the plenum?
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Last edited by ryanxo; 07-10-2012 at 10:21 PM.
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Old 07-10-2012, 10:51 PM   #52
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Wrapping the air handler won't harm anything. Adding insulation to the plenum is ok if its lined.

Check to see what kind of metering deice you have now, before it gets real hot outside.
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Old 07-10-2012, 11:08 PM   #53
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Where do I find this metering device? Air handler? Compressor?

I don't know if my plenum is lined or not. It's just fiberboard. Shiny outside and fiberglass inside
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Old 07-10-2012, 11:13 PM   #54
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It will be in or just outside of the air handler at the coil. Bubble wrap is ok to use on duct board.
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Old 07-15-2012, 10:18 PM   #55
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I checked. There was no TXV when i looked so i grabbed the installer guide and it mentions a FCCV(flow control check valve) so that would be what i have i suppose.

I put some radiant barrier(shiny bubble wrap from Lowes) around the air handler and got the top of the plenum covered and it didn't make a difference.

The higher the outside temp goes the higher the temp the AC puts out even though the air in the house only goes up by 2 degrees or so.

I give up on the DIY. It's not worth it. I've called 2 duct work/insulation guys and 2 HVAC guys who are coming out to do estimates this week. Luckily I think I know enough from reading so much on here that they won't be able to BS me. I'm assuming the HVAC guys will say its working fine and that it's my insulation aka I'm not going to pay them a dime and the insulation guys will say ok lets put 400 inches of insulation in your attic
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Old 07-16-2012, 06:35 AM   #56
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Forgive me if I'm wrong, but it looks to me as if you have a standard heat pump air handler AND some sort of evap coil installed as well. Unless the coil in the air handler has been removed, then you've got two coils in the system, which can rob your system of performance quickly. That also means that you can't really go by the service manual (unless that coil is mated to the unit), and you'll have to go by subcooling/superheat to correctly charge the unit.

If you open the top portion of that TWE air handler (where the PVC pipe goes in) do you also see a coil? I see a drain line running out of there, but of course can't see any refrigerant lines (the pictures don't show that section of the air handler).

Last edited by scottmcd9999; 07-16-2012 at 06:37 AM. Reason: mods re: service manual
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Old 07-16-2012, 07:20 AM   #57
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scott,

There is an A coil in the air handler but I'm pretty sure that is standard. The 2 copper lines run from the outdoor unit up into the attic and then into the air handler. The PVC pipe is just the drain line where all the condensation drains out.
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Old 07-16-2012, 07:36 AM   #58
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Okay ... scratch that last one ... the pictures were just a little confusing. You do have the evap coil installed in the air/handler, and that is correct. This pictuure (http://ryantwilkins.com/AC/DSCF0576.JPG) was confusing, until I realized that it's a picture of the return duct, and needed to be rotated to be viewed correctly.

Never been a big fan of flat-panning the bottom of an airhandler to attach the return. They should have added a plenum, or a square-to-round. It's probably not worth changing at this point, but I bet if you could take temp readings on various areas of the coil, you'd find that you weren't getting good saturation of the return air across that coil. Far better to have a plenum or S2R on there which allows for some mixing of the air just before it hits that coil.
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Old 07-17-2012, 01:11 PM   #59
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scott would that make a big difference? Like the temps I am seeing now?

At night my temps coming out the air handler are 57 or 58. In the afternoon when it's hot my air right out of the air handler is 67 or 68. Could there be anything on this crazy Trane unit that changes the temperature drop or is it just purely that my attic is hot?

At this point none of the techs say anything is wrong. I guess I'll run it like it is this summer and replace the stupid thing in the winter when it's not 105 degrees
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Old 07-17-2012, 01:19 PM   #60
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I'm not sure it would make a difference, and it certainly wouldn't make a 10 degree difference - it's just not right.

Did you ever have a tech out to check subcooling and superheat? I know you used the chart, but in cases like this you'd want to be sure and check everything.

FWIW, we don't use ductboard in my area so I don't know how much heat that ductboard would pick up, but somewhere along the way your system is picking up a LOT of heat.

My only other comment would be this: Given that your system seems to work well when the load is off the house (i.e. at night), then my guess would be that either (a) your system is undersized or has a mechanical problem or (b) you have insufficient insulation and/or ventilation in the attic. I know some don't think active roof ventilation is needed, but in my 20+ years in the field I can tell you that I would MUCH rather work in an attic with powered roof vents than in attics with passive vents. Especially given your very low roof line, active vents would be much preferred - at least in my opinion.

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