At least displace the oxygen with nitrogen prior to brazing if not willing to maintain an active purge while brazing.

Unfortunately resi systems lack an oil level sight glass

I agree about the flaking copper oxides. Always best to be on the safe side. One of my previous jobs was in a ASME code weld shop. We back purged just about everything. The specialty gas truck was rolling in everyday to delivery.

I will do my best to see if they can apply some sort of N2 purge. If I am lucky, they will roll in and just pull out the N2 as they get set to braze. I guess I will find out next week. As a homeowner, asking for things that are not "normal" for the contractor are usually viewed in not the best light, so to speak. These guys seem easy to work with, so I will ask if I don't see it.

I was worried about the oil. No way to tell I guess. I would assume most of the oil would kind of reside down in the compressor, but maybe it spreads out evenly all through the system? So I assume they add "some" and hope its in the ballpark.

Does anyone know if Climatemaster specs how much oil and what type to add during a coil R&R? I assume it's all POE oil of some certain spec.

Is the range of allowed oil volume wide enough that the compressor longevity and system efficiency will not suffer? Or is it really important to get it near perfect?

Any tips or comments are very much appreciated. Thanks again for the expert advice.

Chris

I might let slide failure to N2 purge a cheap and dirty part swap on a 10+ year old code sub-minimum R22 system at a hunting camp or similar out-building.

No way on a premium R410a geo system...no purge = hit the road.

Curt,
Likely, they will purge, but if not, I will attempt my best to insist that it be done. Thanks for your tips. Great info.

Anyone, have any idea about how much POE oil (if any) and what brand/type needs to be added to my Climatemaster TT049 when they change the coil? Anyone? I want to try my best to be informed as to what is normal for one of these jobs. I want to get as much life out of this unit as possible as these are very costly to repair oncetheir out of warranty.

Thanks in advance for any replies.

Chris

Anyone with experience on a coil replace job and have any insight on whether oil needs to be added during the repair? I would very much appreciate comments/advice.

The service guy added a pound of 410A last Friday and got the DAT up to about 90F. The unit was performing pretty good for while. This morning it was down to 85F. Should I shut down the compressor and just use Aux Heat until the repair comes next Tuesday. I dont want to run Aux too much, but if i need to to prevent compressor damage, I will do so. I am using the wood stove a bunch to help reduce run time. Any advice appreciated.

Thanks,
Chris

Chris, If your unit has loss a considerable amount of oil then yes oil needs to be added.I would after removing coil purge old coil with nitrogen and collect any oil that comes out. I would not reuse this oil but could gage how much oil was entrapped in the coil.As far as your concerns about running unit, this model has a low pressure cutout switch for low refrigerant charge, error code 3 . When a coil leaks refrigerant, oil usually escapes with it and that is why you visually saw the oil traces. Unless there is a significant amount of oil that is all over the coil or has run down and formed a puddle, there is no need to panic about loss of lubrication to the compressor.

acwiz- thanks for the info on the oil.

I have set the stat to 60F and to just run Emergency heat until the repairs are done. I am heating with the wood stove mostly for now. It can keep the downstairs at 70 and upstairs at 64 if I feed it well.

I hope the repairs go as planned.

Update- coil and filter/dryer replaced by vendor yesteday. Pulled down to 250 microns for a good while and weighed in new charge per nameplate (81 oz.). No oil was added. Nitrogen back purged used on most connections. I missed the first connections, oh well.

They installed a tin plated (silver color) coil in lieu of the e-coated(black) original. Anyone know if that is a new change for the better, or did I get slipped a mickey here by Climatemaster?

Compressor made a couple of noises on start-up, but smoothed right out. Ran in AC mode first, then to heat 2nd stage. Subcool was at 11 deg, compr discharge was around 161 F, 360 psi. Incoming water was 50 F. DAT at mid 90's measured with his Fluke. No additional freon added. Finished right after lunch. All looked good.

I noticed the watts from the TED was around 4,025 watts while we rain it 2nd stage (this includes both 26-99 circ pumps). Used to usually run about 3,700 - 3,800 watts. I thought this was a little off, but nothing special, so I went to work.

Got home from work and ran unit in 2nd stage. DAT was now 90 (measured with my meter, not his) and watts was only 3,750. Inlet Air and Water temps all measured the same. It seems like the heat output and consumed watts went down some.

Is it normal after a recharge to see watts and heat output to settle down some? Could the TXV be adjusting or something?

Nitrogen back purged used on most connections. I missed the first connection

Guess that means you had to ask them to do this?

Steady state wattage is quite dependent upon both loop temp and interior air temp. Since you started with a loop that had a few weeks off, there was above average available heat to be extracted. With more heat available on the low side, refrigerant enters compressor warmer and at higher pressure than normal, making compressor work a bit harder.

If when you get home from work system is recovering the house from a cooler than normal occupied setpoint, then the system has an easier time rejecting heat into house air, so refrigerant discharge pressure is lower, reducing compressor shaft torque, amps, and power. You don't mention EWT on day two, but I'm betting it was below 50 now that the loop is back at work. That reduces power, too.

Curt,
I agree with what you say. But conditions were the same for both tests.

The house was 68 when we first started it up. I was running the wood stove and had the house nice and comfy. So, IAT was the same both times. The inlet water temp was 50 degrees during both tests as well. There was not much load yet between the tests, so the loop stayed at 50. That is why I was so puzzled by the lower DAT and less watts on the second test.

I just remembered we did turn off the Dsuperheater pump for the initial testing and it was on for the second test. The buffer tank was very cold, so that likely pulled the DAT down a few degrees.

I will do some more testing to try and get the total heat capacity and report back. The house is nice and comfy now and seems to back to normal.

Any idea about the coil being just tin plated now?

Thanks,
Chris

Desuper could well have made the difference, especially with a chilly buffer tank.

Desuper pump and coax puts cold water in close proximity to hot refrigerant gas right as it leaves the compressor. That is an additional path for heat rejection, so every thing else being equal as you advised, discharge saturation temperature and associated pressure falls, dropping compressor torque, current and power, easily 10% as you observed.

This is why system charge checks are conducted with desuper pump off, so as to remove that variable from the field.