Change Leaking Evap Coil and convert to R22a

Problems related to residential installations.

Change Leaking Evap Coil and convert to R22a

Postby steppinthrax » Thu Jan 23, 2014 5:01 pm

I have a Trane XE1000 heat pump (fixed Orifice). The previous owner change the indoor air-handler however, never changed the heat pump and condenser coil. Before selling the house he replaced the compressor on the unit as well. For the last 2 years we've been having to re-charge the system with R-22. Almost every year we lose about 2lbs of refrigerant and when we switch it on to A/C the indoor coil freezes up. The last two technicians indicated that the leak is likely at the coil because there is heavy corrosion on the base of the coil where it makes contact with the pan.

Both technicians tried to do a leak test using a "sniffer" but couldn't find anything. I bought a sniffer and spent hours around the compressor and evap coil and it never went off. I even tried soap water around the connections on the evap coil but got nothing.

Due to money, I was planning to replace the evap coil and recharge the system with R-22a. I took measurements of the Evap coil and I see a few coils on this site *.*/viewcatego ... * that seem to fit OK,with some modification made. to the cabinet panel. I have brazed before and have an idea on the procedure of "pumping down" and cutting out the old evaporator coil. However I have several questions.

1. How do I find the tonnage of the old coil. It's a XE1000 which indicates it should be around 3.5 to 4 tons. But when I look in the specs it list different coil sizes that can go on this unit. When I took the panel off there is no more model numbers to indicate what the coil model was to indicate size.... When I buy a new coil do I have to be exact in the size or is it OK for it to be slightly larger. The coil is a fixed Orifice.

2. When I remove the old coil will it have some leftover oil inside? Also will I have to replace that oil?

3. Are there any online guides regarding recharging a R-22a, I understand you use much less. Also do you have to calculate superheat/supercool. Since this is a fixed orifice should it be easier?

Thanks
steppinthrax
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- Change Leaking Evap Coil and convert to R22a

Postby Freon » Fri Jan 24, 2014 2:44 pm

I would be certain you know where the leak is before doing anything. It could be at the condenser unit. You may go through much effort for naught.

If you look at the data plate of the outdoor condenser you can get the size of the unit (tons or BTU/hr). The model number may also give you an idea. Usually the indoor coil will match the outdoor condenser size. XE 1000, if it's a Trane, usually indicates it's a 10 SEER unit, not the size.

You should read about R22a. I know nothing about it. And to go through all the work you plan for an old system may be less cost effective than buying 2 pounds of R22 before each cooling season.
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- Change Leaking Evap Coil and convert to R22a

Postby steppinthrax » Fri Jan 24, 2014 5:22 pm

Freon -
> I would be certain you know where the leak is before doing anything. It
> could be at the condenser unit. You may go through much effort for naught.
>
> If you look at the data plate of the outdoor condenser you can get the size
> of the unit (tons or BTU/hr). The model number may also give you an idea.
> Usually the indoor coil will match the outdoor condenser size. XE 1000, if
> it's a Trane, usually indicates it's a 10 SEER unit, not the size.
>
> You should read about R22a. I know nothing about it. And to go through all
> the work you plan for an old system may be less cost effective than buying
> 2 pounds of R22 before each cooling season.

Thanks for the reply,

I never thought of looking at the condenser plate. I will look tonight. Yes, you are correct. I don't have a 100% certainty that the leak is coming from the evap. I was thinking of buying some DYE and injecting into the system. However, when I looked up this online I see a kit by Yellow Jacket and I can simply use a UV light to search. Do you know of a simple kit? There seems to be another tool I have to buy that is used to inject the dye?

Also, yes When doing some research on the model number I see that it's roughly a 10 SEER unit based on the white paper.

R-22a is a drop-in replacement for R-22. It is quite literally propane. I did some research on this and from what I understand it's used throughout the industry anyway as propane. I read the risk is quite low considering it has be leak in a confined space and it has it has to come in contact with something quite hot. Pretty much the only way it can be dangerous if there is a "perfect world" situation to occur. I would also put a label there indicate a conversion. Also this is a heat pump (no nat gas).
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- Change Leaking Evap Coil and convert to R22a

Postby Freon » Sat Jan 25, 2014 12:21 pm

The dye kit will work assuming you can see every part of the system piping. Condenser coils are tricky. I would look first at each connection and see if you notice and oil stains. The refrigerant oil will leak out with the R22 and leaves a nice clue. Check the condenser unit also. Look for places the copper tubing is touching any other metal surface. The vibration of the compressor will sometimes cause a chafing hole to form in the tubing. Look for oil.

Regarding oil, be very certain the current oil that's in your R22 system is compatible with the R22a refrigerant. If it's not you may have to clean out the old oil. Check the age of the condenser. The manufacture date will be on the data plate also. If this system is old, you may be pouring good money into a losing proposition. Nursing the system along for another few years and replacing it all with a R410 system may be more cost effective.
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- Change Leaking Evap Coil and convert to R22a

Postby steppinthrax » Sat Jan 25, 2014 2:30 pm

I"m seeing this as an option.

**/qfsjx9b

It looks like 4 oz of UV reactive dye? How much should be used in a system like this? The dye injectors seem to need some sort of back pressure.

I did look at the plate on the outside unit. However it just list the model and serial and gives info regarding maximum refrigerant capacity. When I search the model and serial I get the white paper giving multiple coil options for the unit.
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- Change Leaking Evap Coil and convert to R22a

Postby Freon » Sat Jan 25, 2014 3:40 pm

Post the make and model of the condenser. Many times the size of the unit is in the model number.

I have never used the dye. The directions should explain how much to use. I would make sure it's safe to use with R22.
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- Change Leaking Evap Coil and convert to R22a

Postby steppinthrax » Sat Jan 25, 2014 7:15 pm

Sure

TRANE XE1000

TWR042C100B2

I believe it's 42K BTU/HR or 3.5tons, not sure?
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- Change Leaking Evap Coil and convert to R22a

Postby Freon » Sun Jan 26, 2014 11:47 am

You are correct... 3.5 tons, 42,000 BTU/hr. So you will need a 3.5 ton coil, if that is really where the leak is.
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- Change Leaking Evap Coil and convert to R22a

Postby steppinthrax » Sun Jan 26, 2014 12:12 pm

Thanks,

A few more questions before I go off diagnosing.

Assuming it's the coil---->

1. Can I re-use the orifice from the old coil (should I match the orifice size?). Based on a website I found a 3.5 ton unit is supposed to use a 0.080 orifice?
2. Would there be any benefit to use a TXV, it's more work for me, but the unit is only 10 SEER, I was reading there is no advantage unless you are at 14 seer.
3. When you replace the coil do you have to add any oil to the system? Where does the oil stay when the system is cut off? I imagine there will be some residual oil in the coil?
4. I'm looking at a 3 - 3.5 ton aluminum Goodman coil. Why is it listed 3 - 3.5 and not just 3.5?

Thanks
steppinthrax
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- Change Leaking Evap Coil and convert to R22a

Postby Freon » Sun Jan 26, 2014 2:34 pm

1. Can I re-use the orifice from the old coil (should I match the orifice size?). Based on a website I found a 3.5 ton unit is supposed to use a 0.080 orifice?
The coil you buy will come with its own orifice. Be sure it is appropriate for R22a.

2. Would there be any benefit to use a TXV, it's more work for me, but the unit is only 10 SEER, I was reading there is no advantage unless you are at 14 seer.
I wouldn't use a TXV for the system you're playing with. Again, R22a is an unknown quantity to me.

3. When you replace the coil do you have to add any oil to the system? Where does the oil stay when the system is cut off? I imagine there will be some residual oil in the coil?
Depends on if R22a can tolerate the R22 oil. The old oil will be in all the tubing. If you pump-down the condenser more oil will be in the condenser. Oil type is very important because with improper oil the compressor will be toast soon.

4. I'm looking at a 3 - 3.5 ton aluminum Goodman coil. Why is it listed 3 - 3.5 and not just 3.5?
Coils can be sized a little smaller (good for humidity control). So 3 to 3.5 tons for a coil size is understandable. Again, make sure the coil is designed for R22a.
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