Stop Whining Blower - HVAC - Page 3 - DIY Chatroom Home Improvement Forum

 DIY Chatroom Home Improvement Forum > HVAC Stop Whining Blower
 Register Blogs Articles Rewards Search Today's Posts Mark Forums Read

08-09-2010, 12:15 AM   #31
Member

Join Date: Jun 2009
Posts: 48
Rewards Points: 25

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):

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

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.

 08-09-2010, 12:22 AM #32 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,406 Rewards Points: 7,802 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.
 08-09-2010, 01:10 AM #33 Member   Join Date: Jun 2009 Posts: 48 Rewards Points: 25 @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.

 08-09-2010, 01:43 AM #34 Member   Join Date: Jun 2009 Posts: 48 Rewards Points: 25 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
 08-09-2010, 02:26 AM #35 Member   Join Date: Oct 2008 Location: Suburbs of Detroit Mi Posts: 3,704 Rewards Points: 2,000 Dude...really....call your tech back.
08-09-2010, 06:16 AM   #36

Join Date: Oct 2008
Location: Somewhere
Posts: 34,406
Rewards Points: 7,802

Quote:
 Originally Posted by vdu 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.

08-09-2010, 08:21 AM   #37
Member

Join Date: Jun 2009
Posts: 48
Rewards Points: 25

Quote:
 Originally Posted by hvaclover 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.

 08-09-2010, 08:25 PM #38 Member   Join Date: Jun 2009 Posts: 48 Rewards Points: 25 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.
08-09-2010, 09:27 PM   #39

Join Date: Oct 2008
Location: Somewhere
Posts: 34,406
Rewards Points: 7,802

Sounds like he may be a fast change type guy.

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

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Ducaticorse HVAC 13 01-03-2015 04:39 PM kevinp HVAC 19 11-13-2014 10:37 PM stephensandlin HVAC 3 01-03-2010 01:21 AM 63012753 HVAC 0 10-06-2009 09:09 PM number22 HVAC 8 07-19-2009 05:27 PM

Top of Page | View New Posts