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View Poll Results: Which route?
Repair existing R-22 13 seer system with new air handler 2 16.67%
New R410a system, 13 seer 2 16.67%
New R410a system, 14 seer 8 66.67%
Other 0 0%
Voters: 12. This poll is closed

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Old 11-10-2012, 02:51 PM   #16
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Installing new R410a system. 14 or 13 seer? Does my plan of attack look legit?


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Yes,

Class III or IV is about as purified as you need...after that the cost becomes probative.

Uncle buys Bone-Dry (classIII) at about $60 for fifty pounds of liquid CO2.

It's advisable to use a flow regulator calibrated in SCFH.
Thanks, that's exactly what I needed to know. I have a flow regulator for welding, what CFM is advisable for 3/8 and 3/4 line? I ordered a nitrogen pressure regulator for doing a triple evac and also leakdown testing, and I might use that instead of a flow regulator if I can somehow convert from psi to cfm becuase it has the proper connector vs my flow regulator which only has a barbed fitting for a hose.

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Old 11-10-2012, 04:04 PM   #17
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Installing new R410a system. 14 or 13 seer? Does my plan of attack look legit?


Make sure you remove the schrader valve cores from the service valves B4 welding and wrap a wet rag around those valves when welding as the seals inside will get damaged or the valves damaged. You need a deep micron vacuum pump to evacuate the system or get the tech who starts it up for you to do it. It can take an hour or more with a used system and you will be paying him by the hour.
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Old 11-10-2012, 07:41 PM   #18
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Installing new R410a system. 14 or 13 seer? Does my plan of attack look legit?


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Make sure you remove the schrader valve cores from the service valves B4 welding and wrap a wet rag around those valves when welding as the seals inside will get damaged or the valves damaged. You need a deep micron vacuum pump to evacuate the system or get the tech who starts it up for you to do it. It can take an hour or more with a used system and you will be paying him by the hour.
Thanks for the tip, sounds like a good excuse to go to harbor freight The cheaper HF vacuum pump is rated to 75 micron, so from what I have read that should be more than adequate. I'm also going to pick up an SMAN3 since it has a built in micron gauge, and it can handle all the refrigerants.
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Old 11-10-2012, 09:01 PM   #19
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Installing new R410a system. 14 or 13 seer? Does my plan of attack look legit?


500 micron is what you are supposed to get/pull on your system and especially when reusing lines. A cheap pump won't do that properly. 500 microns is what we use. You will need a micron gauge accessory to read that also.
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Old 11-10-2012, 09:16 PM   #20
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I was wondering where he read 75 microns is enough. That's enough to destroy his compressor.
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Old 11-11-2012, 04:18 AM   #21
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Installing new R410a system. 14 or 13 seer? Does my plan of attack look legit?


Doubt he'll get his system down to 75 microns.

OP, 500 is low enough.
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Old 11-11-2012, 08:00 AM   #22
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Installing new R410a system. 14 or 13 seer? Does my plan of attack look legit?


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. I'm also going to pick up an SMAN3 since it has a built in micron gauge, and it can handle all the refrigerants.

The SMAN 3 micron gauge is not have the resolution or accuracy to ensure a dry system after pump down.

Too many hose connection when you use a manifold ---just too many chances for a leak that would stop you from hitting your ultimate evacuation requirement.

I use a manifold on small jobs and when the mood strikes me (I have the SMAN 3 and two other Testo manifolds with built in micron gauge). But I also have deep vacuum rated hoses I use along with a commercial thread sealer called Nylog. You can't use off the shelf hoses as they are permeable and will not hold vacuum.

Any of the pros will tell you the same thing (assuming industry standards are being followed).
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Old 11-12-2012, 02:53 PM   #23
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The SMAN 3 micron gauge is not have the resolution or accuracy to ensure a dry system after pump down.
It has a +/- 10% accuracy and 1 micron resolution... that seems pretty good to me, no?

I will run some tests on the manifold itself while I am pulling vaccum to see what the rate of permeation is on the manifold and charging hoses in isolation. The way I see it, as long as the rate of evacuation by the vacuum pump is higher than the rate of permeation by the connections to the system, then the system will be able to be pulled to an adequate vacuum. Of course, the rate of permeation will be greater as vacuum increases so the test will only be valid for a single high vacuum point, but should in any case be a worst-case scenario.
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Old 11-12-2012, 03:45 PM   #24
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There is more to pulling a correct vacuum than hooking a hose and vacuum pump.

No offense, but knowledge is no substitute for experience. Vacuum technology is Rocket Science. And yes, the deeper the evacuation the higher the permeation rate. Non rated hoses will collapse during evacuation.
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Old 11-12-2012, 03:50 PM   #25
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I forgot to mention that when ever I use a SMAN 3 or a Testo digital set, I use a dedicated BlueVac micron gauge. I just use the on board micron gauge as a novelty.
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Old 11-26-2012, 09:53 AM   #26
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The install went well, I'll post some pics later but wanted to post a summary of some of the things that went well and things that went awry, along with a couple of remaining questions that I need to iron out:

- The system works well, and seems to heat more efficiently than my old R-22 system!
- I got a single stage robinair vacuum pump rated to 75 micron and it pulled down to 600 micron in about an hour through the SMAN3 gauge including YJ hoses, and with schraders still installed. From what I have read about pulling a vac through hoses I think that's pretty good. After last pull the vacuum rose to about 1050 after approx. 5 minutes so I think I got the lines pretty well prepped.
- I notice that the new goodman heat pump is smaller than the old unit, and the low side charging port is at a 45degree angle... it looks like goodman is continuing to improve their products which is a good sign

- My brazing on the 3/4 line wasn't terribly clean because I only have a size 0 tip -- ordered a couple of larger sizes for the future
- I noticed that the previous install used shur-tape SF-686 which looked like a butyl surfaced, foil backed tape. I used butyl lining that I had left over from installing new windows (protecto-wrap) as it is rated to 340 degrees flash point. I ordered some of the SF-686 in case I need to redo it in the future but I think it shoudl hold and seal well
- I realized after brazing that the LL is actually 5/16" with several feet of 3/8" coupled to the ends, probably from the prev. install. Had I noticed this before I woudl not have reused the lineset but from what I have read it shouldn't be a problem given that the low side is properly sized
- Tapes are really expensive for HVAC -- UV tape, foil backed butyl tape etc.... I hope my kids never find my tape stash and go crazy with it.

And some questions:

- The drain ports on the new air handler are lower than the old, and this causes the p-trap outlet to actually come out lower than the drain pipe outlet coming out of the crawlspace (it is pitched back slightly). I know this will cause the line to hold too much water. What is the right way to compensate for that? If I use a running trap the pitch would be ok, but I read those are no good. I can't lower the outlet because it is already at ground level outside, and I don't want to bury it.
- I set the blower (variable) CFM based on the install manual, but it blows way harder than my other pre-existing system. I set it at 840CFM using the suggested 400CFM per ton (2 ton system), and am using a ramping profile that does a 30%/80%/100%/80% CFM cycle or something like that. Is there a reference that I can learn about to manually calculate the actual correct CFM for my system, including duct sizing?

Pics to come!
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Old 11-26-2012, 10:37 AM   #27
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Old 11-26-2012, 04:32 PM   #28
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Set the blower speed lower. Knock of 10%.
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Old 11-27-2012, 01:51 PM   #29
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Set the blower speed lower. Knock of 10%.
It is set to 840CFM right now so that would make it about 760CFM. I'll try it and give it the ear test. I'd still like to know how to calculate the "optimal" CFM though... I'm sure if I continue reading my 1000 page HVAC book I'll come across it eventually.
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Old 11-27-2012, 03:44 PM   #30
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Technically for heat pumps in heating mode 450 CFM per ton(900CFM on a 2 ton) is best efficiency. Not always best comfort though.

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