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HVAC Forums => Technical Information => Topic started by: walker on July 24, 2015, 11:32:40 AM

Title: Piston Orifice Sizing
Post by: walker on July 24, 2015, 11:32:40 AM
Does the SEER rating of an A/C make a difference with what orifice size should be used on a A/C? ie would a 10 or 13 or 14 seer use a different size?
Title: Re: Piston Orifice Sizing
Post by: Admin on July 24, 2015, 12:28:41 PM
I believe the indoor coil and tonnage of the system would dictate the piston size.

Download the Goodman Piston Chart - Here (http://www.hvactechgroup.com/files/Goodman%20Piston%20Chart.pdf)

If you look at the chart the piston size seems to be the same on some 13 and 14 seer systems, but changes with tonnage or coil type.
Title: Re: Piston Orifice Sizing
Post by: walker on July 24, 2015, 03:29:34 PM
Ah OK thanks.  Been doing a lot of piston changes from txv on all these Rheem units with the stuck txv issue and have been getting some funny readings in some of them.
Title: Re: Piston Orifice Sizing
Post by: slo-115 on July 27, 2015, 12:11:38 PM
Last year i had a nightmare with adp coils with tx valves, some slammed right shut on start up, other failed several weeks later. Im still afraid of icp coils after constant micro leaks, i see they have gone to a all aluminium "N" coil. Ive always been a believer in the best and most efficient equipment , its sad that a cheap aspen piston coil seems the most reliable. For the extra 1 seer im on the page that the tx valve isnt worth it
Title: Re: Piston Orifice Sizing
Post by: walker on July 27, 2015, 02:10:14 PM
We've been instructed to remove the txv and change it to a piston.  Replace the filter drier and add in the A/C renew. 
Title: Re: Piston Orifice Sizing
Post by: Admin on July 27, 2015, 05:35:31 PM
I was under the impression this recent TXV problem was caused by a rust inhibitor that Copeland was adding to their compressors.  I believe Rheem uses Copeland compressors.  I found the Lennox C-15-03 TXV Update Bulletin - Here (http://www.hvactechgroup.com/files/Lennox%20TXV%20Bulletin.pdf)

I wonder how many 15 seer systems that qualified for the OPA rebate will now be turned into 13 or 14 seer systems by switching from a TXV to piston.  That will mess with someone's experiment  :-X
Title: Re: Piston Orifice Sizing
Post by: walker on August 02, 2015, 06:46:22 PM
well I changed about 15 of them in the last 2 weeks.  customers already received there rebate so they're aren't really to worried about it, they're just happy to have a properly working A/C finally.