Water-to-water heat pump rebuild?

[randen]

Bill Sanford

Welcome to the group. After 20 yrs of pump and dump I would suspect the ground loop heat exchanger is packed full. The new scroll compressor would provide you with a lot of heat, if it could source it. Just the fact your not seeing a drop of temp in your water could be your clue. 6lb charge is alot of R22 refrigerant and I doubt low charge is your problem.

Look for a heat-exchanger shell & tube larger than you have you could go almost twice the size and it would make your unit even more efficent with that beautiful scroll compressor.

As far as tools for the trade it can be tough to justify. After you purchase them they seem to just look pretty on the peg board un-less you continue to tinker. A small oxygen and propane torch is indispensable. We have converted mine to propane after years of expensive acetylene use. A manifold gauge set is nessisary but for the recovery I converted an old refrig. compressor that works OK.

Maybe a way to justify the cost of tool, is look at the money you have saved after 20yrs of GSHP heating.

Randen

[Bill Sanford]

Guys,

What kind of brazing rods are the best and easiest to work with? Also, what do I need for flux?

I assume taking apart an existing brazed join is the same as a soldered join, just more heat needed. Heat it up and pull it apart, correct?

Looks like I will end up doing as much of this myself as possible...

Also, any advice on acquiring R22 would be appreciated.

Thanks!

Bill

[Bill Sanford]

Originally Posted by randen

Bill Sanford

Welcome to the group. After 20 yrs of pump and dump I would suspect the ground loop heat exchanger is packed full. The new scroll compressor would provide you with a lot of heat, if it could source it. Just the fact your not seeing a drop of temp in your water could be your clue. 6lb charge is alot of R22 refrigerant and I doubt low charge is your problem.

Look for a heat-exchanger shell & tube larger than you have you could go almost twice the size and it would make your unit even more efficent with that beautiful scroll compressor.

As far as tools for the trade it can be tough to justify. After you purchase them they seem to just look pretty on the peg board un-less you continue to tinker. A small oxygen and propane torch is indispensable. We have converted mine to propane after years of expensive acetylene use. A manifold gauge set is nessisary but for the recovery I converted an old refrig. compressor that works OK.

Maybe a way to justify the cost of tool, is look at the money you have saved after 20yrs of GSHP heating.

Randen

The heat exchanger was acid flushed last year and is clean. I did it myself. The exiting well water and exiting R22 are less than 2 degrees apart. This is with a 10 GPM flow rate with the well water. I can't see how the heat exchanger could do much better than this.

This issue is that the R22 temp is not low enough entering the evaporator. I think this is being caused by two things. #1. I think the charge is low. #2 The TXV valve is not the right one for the job and is not adjustable.

The charge is SUPPOSED to be 6 pounds, but this was with the original compressor. I have no clue what's in it now...

[charlesfl]

If you are willing to study for the epa license you can get one just by taking the test.

EPA 608 Certification

[BradC]

Originally Posted by Bill Sanford

Thanks Brad.

Will the ts8000 be hot enough to braze properly just using propane as a fuel? I thought to braze properly you needed oxygen to get enough heat.

Not with propane it won't. You need propylene (the stuff in the yellow bottles). It has just enough extra oomph to allow you to braze. Personally I use either 15% silver rod for copper to copper or 45% for copper to anything else. I have used 2% silver rods also but always find the 15% to flow a bit better (and it's more ductile so there is less chance of vibration related fracture later on).

Have a squiz at the first post in my "gas and gear" thread to see what I use to braze with. No oxygen, just propylene. I use the double burner as I've been doing a bit of 3/4 & 7/8 where the extra speed is a bonus. I use an old pair of cotton socks saturated in water and wrapped a couple of inches either side of the joint to limit the heat damage to the pipe.

I'm doing what you are, except I'm rejecting heat into the water and rather than "dumping" it I have a re-injection well (keeps the loonies here happy and prevents my house from washing away).

[Bill Sanford]

Originally Posted by BradC

Not with propane it won't. You need propylene (the stuff in the yellow bottles). It has just enough extra oomph to allow you to braze. Personally I use either 15% silver rod for copper to copper or 45% for copper to anything else. I have used 2% silver rods also but always find the 15% to flow a bit better (and it's more ductile so there is less chance of vibration related fracture later on).

Have a squiz at the first post in my "gas and gear" thread to see what I use to braze with. No oxygen, just propylene. I use the double burner as I've been doing a bit of 3/4 & 7/8 where the extra speed is a bonus. I use an old pair of cotton socks saturated in water and wrapped a couple of inches either side of the joint to limit the heat damage to the pipe.

I'm doing what you are, except I'm rejecting heat into the water and rather than "dumping" it I have a re-injection well (keeps the loonies here happy and prevents my house from washing away).

Thanks Brad.

The gas and gear thread is a very interesting and is mostly nothing related to the thread name! The controller project looks very cool. Sounds like you're really into this stuff neck deep!

Bill

[AC_Hacker]

Originally Posted by Bill Sanford

...This issue is that the R22 temp is not low enough entering the evaporator. I think this is being caused by two things. #1. I think the charge is low. #2 The TXV valve is not the right one for the job and is not adjustable.

The charge is SUPPOSED to be 6 pounds, but this was with the original compressor. I have no clue what's in it now...

The refrigerant weight spec assumes that the original configuration of the machine has not been changed. If you change the compressor, the volume of the system is likely to be different. The same holds if you employ a different HX, or different line-set length or tube diameter, etc.

The unit should also have a High-Side pressure and a Low-Side pressure spec that would still apply, if modifications have been made (assuming you have not gone to a different type of refrigerant).

The tools to check pressure aren't so expensive and the procedure is straightforward.

Yes, you may have too little refrigerant. On the other hand, too much refrigerant will also result in abysmal performance.

You won't know until you check pressure.

Best,

-AC

[Bill Sanford]

Originally Posted by AC_Hacker

The refrigerant weight spec assumes that the original configuration of the machine has not been changed. If you change the compressor, the volume of the system is likely to be different. The same holds if you employ a different HX, or different line-set length or tube diameter, etc.

The unit should also have a High-Side pressure and a Low-Side pressure spec that would still apply, if modifications have been made (assuming you have not gone to a different type of refrigerant).

The tools to check pressure aren't so expensive and the procedure is straightforward.

Yes, you may have too little refrigerant. On the other hand, too much refrigerant will also result in abysmal performance.

You won't know until you check pressure.

Best,

-AC

Hi AC,

Post #1 in this thread listed the pressures and temps as follows:

High R22 pressure 240 PSI
Suction R22 pressure 54 PSI
R22 line temp entering the evaporator 43.7 degrees
R22 line temp leaving the evaporator 44 degrees
Source water temp entering the evaporator 49.9 degrees
Source water temp leaving the evaporator 45.5 degrees

The pressures are very close to the original system specs. I don't have a PT chart here, but seem to recall that for 54 PSI, the phase change temp is around 30 degrees F. With a R22 measured temp of 44 degrees leaving the evaporator, the superheat is 14 degrees, correct? The measured temp of the R22 line leaving the TXV is 43.7 degrees.

Wouldn't this indicate a low charge? Also my thoughts are that the TXV may be opening too much, but I certainly could be wrong!

Thoughts?

[Mikesolar]

Bill,

A couple of things.

1] The yellow bottles are MAPP gas, don't ask anyone for propylene, they won't know what you are talking about. MAPP gas is a mix of propane and acetylene IIRC. I do most of my brazing in the field with a MAPP tank and a Turbotorch unless you are doing 7/8" and bigger piping.

2] Don't look at the system and say it is short on gas yet. By the looks of of it you have a burnout filter on the system and the way to tell of it is plugged is to measure the temp on either side of the filter. If there is any real difference, you have a plugged filter. Try this first.

3] I still don't think you should start changing components until you look at the the filter first and then adjust the pumping in and out.

[BradC]

Originally Posted by Mikesolar

1] The yellow bottles are MAPP gas, don't ask anyone for propylene, they won't know what you are talking about.

The "new" fuel is known as Map/Pro and is greater than >95% propylene. Mapp has not been produced since 2008. Still a yellow bottle though.