Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-09-2010, 12:15 AM   #31
vdu
Member
 
Join Date: Jun 2009
Posts: 48
Share |
Default

Stop Whining Blower


Yes, currently at 1400 CFM, there is no noise from the machine other than the blowing wind.
From the screen, I measure 67 pixels for the normal pipe, and 45 pixels for the narrowed area. That's not counting the pushed in inside of the curve. I will take a real ruler to measure both location because the image's angle may not give the smallest view of the tube. Take the 2nd images for example, the bended area is barely 50% OD of the original tube.

If using this measurement, this is OD, which means ID probably is off by 1/8" (3/8 - 1/4 = 1/8). Translates into pixel distance, it would be 1/8 * 67 ~= 8.4 pixels. So, the ID in pixels of original tube is 67 - 8.4 = 58.6 => cross section: 2697 pixel square
and the bended tube is 45 - 8.4 = 36.6. With 58.6 * 3.14159 ~= 184 pixel circumference. Approximate the cross section as rectangle, => width = 36.6, length = 184/2 - 36.6 = 55.4 pixels. So, the cross section is: 2027 pixel square. Eclipse is bigger than rectangle for a same circumference. However, since the soft coper get compressed, so the circumference is probably much smaller, so the math is about right (cancel out of each other).

A reduction of 25%. I think that is very sizable. If the output scales with this reduction, I have 0.75 * 3 tons = 2.25 tons system. This is way smaller than it's supposed to be. This is even more important when the house is calculated using Manual J carefully (which is the case here), so it has the lowest possible tonnage. So if it's way lower, it's way undersized.

What I find very odd is that the system document, and online guide asks to calculate charge using superheat and supercool temperature differences, however, the guy only relies on the pressure and temperature alone. In fact, I read somewhere it says for the TXV, superheat and supercool needs to be calculated to make sure the charge is correct. Also R410A values are not the same as R22.
Do I get my information correct?

The guy said he'll stop by later. Should I suggest him to make a T with 1 end of the T capped instead, so that it's better with the flow? My reference here (start at 1:02 into the video):

http://www.youtube.com/watch?v=9YPOD9zHn7Q

In the video, it mentions of how the guy didn't like the restriction on the flow, and make the T himself.

Looked at this page: http://www.plumbingsupply.com/coppertubing.html

The thickness is 1/32 versus 1/16 that I used (which resulted in 1/8 of both sides). I'll measure the real tube, and calculate again later with the 1/32 wall thickness.


Last edited by vdu; 08-09-2010 at 01:04 AM.
vdu is offline   Reply With Quote
Old 08-09-2010, 12:22 AM   #32
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,382
Default

Stop Whining Blower


The charge should be checked by super heat and sub cool. If he is just checking by pressures compared to outside temp. He isn't checking the charge right.

While that ell does look small at its bend. With as close as it is to the coil. Its probably not the cause of your noise.
beenthere is online now   Reply With Quote
Old 08-09-2010, 01:10 AM   #33
vdu
Member
 
Join Date: Jun 2009
Posts: 48
Default

Stop Whining Blower


@Beenthere, the cause of the noise is from the blower, not this. The blower somehow doesn't produce noise at 1400 CFM, but it does at 1200 CFM, 1260 CFM, 1560 CFM and higher. However, at 1400 CFM, my house is not cooling down quick enough. Take 2 days ago for example, outside temperature (at the hottest point) is around 88 degree. It took all days to reach 75 degree when the outside temperature probably already dropped to 75 degree. My effort right now is to keep it at 1400 CFM which is about 470 CFM/ton (a little higher than upper range of 450, but not too much), and keep the house cool.

With respect, from seeing the TXV valve is right before the coil, and its job is just to restrict the flow, I think the position matter greatly how the flow affects the system's performance. But that is just my observation with limited knowledge.

Last edited by vdu; 08-09-2010 at 01:28 AM.
vdu is offline   Reply With Quote
Old 08-09-2010, 01:43 AM   #34
vdu
Member
 
Join Date: Jun 2009
Posts: 48
Default

Stop Whining Blower


I found this video and tool to be very informative: http://www.youtube.com/watch?v=vhrUL...eature=related

It turns out the blower's speed also depends on the super heat/super cool calculation, versus just 400 CFM/ton
vdu is offline   Reply With Quote
Old 08-09-2010, 02:26 AM   #35
Member
 
hvaclover's Avatar
 
Join Date: Oct 2008
Location: Suburbs of Detroit Mi
Posts: 3,704
Default

Stop Whining Blower


Dude...really....call your tech back.
__________________
Just slow, not stupid.
hvaclover is offline   Reply With Quote
Old 08-09-2010, 06:16 AM   #36
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,382
Default

Stop Whining Blower


Quote:
Originally Posted by vdu View Post
I found this video and tool to be very informative: http://www.youtube.com/watch?v=vhrUL...eature=related

It turns out the blower's speed also depends on the super heat/super cool calculation, versus just 400 CFM/ton
You have that backwards.

The SH and SC depends on the indoor blower speed.
beenthere is online now   Reply With Quote
Old 08-09-2010, 08:21 AM   #37
vdu
Member
 
Join Date: Jun 2009
Posts: 48
Default

Stop Whining Blower


Quote:
Originally Posted by hvaclover View Post
Dude...really....call your tech back.
Yes, I did twice already. The 1st time, he came, and said everything is ok, you worry too much. The 2nd time, he's yet to come. But he said over the phone that he can do the super heat/sub cooling calculation, but if his pressure check is good, then the system is fine, and fixing the tube would be double work for him. I said it probably take less than 1 hour to redo that, and it takes longer for him to come over, why not just do it with all the equipment he got.
vdu is offline   Reply With Quote
Old 08-09-2010, 08:25 PM   #38
vdu
Member
 
Join Date: Jun 2009
Posts: 48
Default

Stop Whining Blower


The guy came and replaced the squeezed section. He measured the super heat, but still refuse to calculate the subcooling and insists on the system being run correctly with enough coolant.
Anything can go wrong with this. For example, the TXV valve may not be 100% due to clog. He didn't evacuate the lineset with nitrogen before brazing. I mentioned it, but he said nitrogen is to find leak. All he needs is just to vacuum the system before doing the brazing.
The guy said if I call him again, I have to pay even he gave 6 months warranty because the system is running fine. I probably have to find a person who can do this properly then.

I also brought the print out from the manual for step by step getting the system up (set superheat to 7 to 9 using the TXV valve) and measure the subcooling. Charge more or remove charge as needed. But he just ignores the thing. We got super heat value at 10, and he said that's close enough to 9. Maybe that's right. However, without doing subcooling, I don't know how he knows it's enough charge in there. Also, as I said above, any restriction such as dirty coil or lineset can easily cause issue.

Last edited by vdu; 08-09-2010 at 08:29 PM.
vdu is offline   Reply With Quote
Old 08-09-2010, 09:27 PM   #39
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 24,382
Default

Stop Whining Blower


Sounds like he may be a fast change type guy.

Offers a low price. And moves on to the next job.

beenthere is online now   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Bryant Plus 90 - No Blower Ducaticorse HVAC 11 10-16-2012 08:39 PM
carrier furnace...no heat blower won't stop kevinp HVAC 18 10-27-2011 03:30 PM
Trane Furnace Blower Running Nearly Continuously stephensandlin HVAC 3 01-03-2010 01:21 AM
Carrier 58MXA Wiring Blower Switch 63012753 HVAC 0 10-06-2009 09:09 PM
RPJ2 Blower fan will not stop running number22 HVAC 8 07-19-2009 05:27 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.