I wonder if ChrisJ is stable yet ?

bob_46

Chris how are you doing ?

ChrisJ

Sadly, nope.

Right now trying to figure out why Goodman used a 6 ton TXV on a 2.5 - 3.5 ton air handler before I try changing it to a 3 ton TXV.

JUGHNE

Bob, I realize now you were talking about his HVAC system......for a minute there.......!!

Any factory rep will tell you that has never happened before.
When they may have had a 10 day run of coils just like yours.

And the sad thing is that many installs would just get some charge added based on oz/ft, get paid and walk away. Not many HO would ever know. Some never had central AC before. Most all would not have gauges.

Harvey Ramer

If you have a 6ton TXV, I'm pretty sure you found your answer. They do have some range, but that's a stretch.

hot_rod

bob said:

Chris how are you doing ?

Did you mean his HVAC system

ChrisJ

Harvey Ramer said:

If you have a 6ton TXV, I'm pretty sure you found your answer. They do have some range, but that's a stretch.

They swear it's the proper valve due to the flow through the evaporator. How that makes sense is beyond me. I thought the flow through the evaporator was determined by the capacity of the system.

Bleh.

bob_46

How did you determine you have a 6 ton valve ? What is the make and model no. ? Have you read Danfoss's literature on MSS (minimum stable superheat) ? Have you tried increasing the superheat adjustment ?

ChrisJ

bob said:

How did you determine you have a 6 ton valve ? What is the make and model no. ? Have you read Danfoss's literature on MSS (minimum stable superheat) ? Have you tried increasing the superheat adjustment ?

Valve is a Parker HCAE-6-KX200 as per the Powerhead.
Also contacted Parker and asked their opinion, they said swap it for a smaller valve.

Goodman's tech support contacted their engineers to confirm whether the valve was correct, because tech support said it seemed odd. The engineers said it's correct.

Superheat is between 6 and 8 degrees I believe, per Goodman's instructions in low stage. From what I recall, Danfoss said 5 degrees was the minimum to expect a TXV to be able to control?

I believe we tried increasing the superheat some. But, how far should I go beyond the MFG's recommendation? We also tried moving the sensing bulb about a foot downstream, no improvement.

I was thinking of pulling the bulb off this weekend and putting it in ice water to see if it stabilizes to prove it's not non-condensables. My concern is, won't pressure variations in the suction line still cause the valve to fluctuate via the equalizer tube, IF, it is the valve?

Sight glass is perfectly clear before the TXV, no signs of gas or anything. Moisture indicator is dark blue suggesting dry.

I was all for swapping in an HCAE-3-KX200 until Goodman's engineers said no, it's the correct valve. Now I really don't know what to think. Parker says swap it, Goodman says don't.

I've attached the pressures etc from Saturday.

EBEBRATT-Ed

There is only one way to size a txv.

Differential pressure across the valve determines correct valve sizing. Find normal suction pressure with a 40 deg coil. Find the discharge pressure @ 95 deg outside air. Subtract the two and that is you diff pressure

pick a valve that will pass the tonnage of your unit at those pressures. If in between sizes pick the smaller valve (usually)The pressure stamped on the valve is only the "nominal" tonnage at air conditioning temperatures.

That's why a 50 ton compressor for an ice rink (freezing) only uses a 35 ton valve.

Is this a one pc valve?? or did they just put the wrong power head on it??

obviously the 6 ton is way oversized and causing your hunting. Did they give you the right coil??

In the "old days" everybody ran 15-20 degree superheat, Copeland, Trane, York, Carrier used to be 10-12 deg. and 15-20 deg subcooling. You won't hurt the compressor with those numbers but efficiency may suffer slightly.

Most of the newer units recommend lower than 15-20 deg superheat.

ChrisJ

EBEBRATT-Ed said:

There is only one way to size a txv.

Differential pressure across the valve determines correct valve sizing. Find normal suction pressure with a 40 deg coil. Find the discharge pressure @ 95 deg outside air. Subtract the two and that is you diff pressure

pick a valve that will pass the tonnage of your unit at those pressures. If in between sizes pick the smaller valve (usually)The pressure stamped on the valve is only the "nominal" tonnage at air conditioning temperatures.

That's why a 50 ton compressor for an ice rink (freezing) only uses a 35 ton valve.

Is this a one pc valve?? or did they just put the wrong power head on it??

obviously the 6 ton is way oversized and causing your hunting. Did they give you the right coil??

In the "old days" everybody ran 15-20 degree superheat, Copeland, Trane, York, Carrier used to be 10-12 deg. and 15-20 deg subcooling. You won't hurt the compressor with those numbers but efficiency may suffer slightly.

Most of the newer units recommend lower than 15-20 deg superheat.

Yep it's the right coil.
I used Sporlan's program to look at different TXVs. For most, a size 2 would work, at lower ambients a size 3 is needed. I have no idea, why they're using a 6.

Looking at the various sizes of the air handler, the 2 - 2 1/2 ton get a size 3. The 2 1/2 to 3 1/2 (mine) gets a 6, the 4 to 5 ton gets an 8!

This is why I'm so confused, especially when their engineering said it's correct. How is that possible!?


For this, Goodman wants 5 to 7 deg subcooling and 7 to 9 deg superheat in low stage.

ratio

Kind of odd that they would specify superheat & subcooling at low stage, as opposed to listing expected numbers, since we're by definition at less than design conditions.

Remember, all mfgr's have least-callbacks as a design goal, and that may not take second place to greatest-efficiency. (It surely wouldn't if I were in charge. No callbacks is my stated goal.)

In any case, if it were Grandma's AC, I'd probably change it to a properly sized TXV & monitor performance carefully, after study of the coil data. If it were my AC, I'd let it ride.

EBEBRATT-Ed

I looked and couldn't find much info on PARKER valves. the info they had was crappy
I would change it to a 3 ton.

My concern with letting it ride would be liquid in the suction line with low superheat washing the oil out and damaging the compressor bearings caused by the valve hunting.

6 ton valve makes no sense to me at all. What size connections are on the valve itself??

Shouldn't have to go through this on a new unit.
Thought things like this only happened on my jobs!!

ChrisJ

EBEBRATT-Ed said:

I looked and couldn't find much info on PARKER valves. the info they had was crappy
I would change it to a 3 ton.

My concern with letting it ride would be liquid in the suction line with low superheat washing the oil out and damaging the compressor bearings caused by the valve hunting.

6 ton valve makes no sense to me at all. What size connections are on the valve itself??

Shouldn't have to go through this on a new unit.
Thought things like this only happened on my jobs!!

I also talked to Parker's tech support which confirmed it is a 6 ton valve. Goodman's tech support also confirmed it, but their engineers said it doesn't matter, it's correct.

Harvey Ramer

> @ChrisJ said:
> If you have a 6ton TXV, I'm pretty sure you found your answer. They do have some range, but that's a stretch.
>
> They swear it's the proper valve due to the flow through the evaporator. How that makes sense is beyond me. I thought the flow through the evaporator was determined by the capacity of the system.
>
> Bleh.

That sounds like a crock to me.

Matt_67

I am curious as to what the SEER rating of your air handler / condensing unit is. I suspect this is a method of increasing the SEER rating of the system - allowing the valve to feed with lower discharge pressures. Do you know if it is a balanced port valve?

ChrisJ

Matt said:

I am curious as to what the SEER rating of your air handler / condensing unit is. I suspect this is a method of increasing the SEER rating of the system - allowing the valve to feed with lower discharge pressures. Do you know if it is a balanced port valve?

Here's the story, as I understand it.
Goodman had a series of air handlers, the AVPTC series. They're variable speed and can be mounted in various ways.

All of them said they were nominal 13 SEER at their specified tonnage.

Recently, maybe 2015? they came out with a slightly modified version identified by 1 number higher, ie *37 for 3 ton instead of 36. These appear to have larger evaporators and maybe even larger blowers running at lower rpms to deliver the same CFM. From what I can tell on mine, they used a blower from a larger model, perhaps 3.5 or 4 ton and have it programmed to run slower.

My specified unit is a *37D and matched to the 2 stage 16 SEER outdoor unit is rated to give 15 SEER. For true 16 SEER I would've needed to go a step higher yet and wasn't willing to do it, primarily because I didn't like the latent vs sensible ratio.

It is a balanced port valve, externally equalized and has a check valve.

I had wondered this (the SEER thing) as well because this series, all have larger valves than the "13 SEER" versions which are common. The 4-5 ton units use an 8 ton rated valve. The 2- 21/2 ton use a 3 ton rated valve. They're all a step higher than you would expect.

ChrisJ

Harvey Ramer said:

> @ChrisJ said:

> If you have a 6ton TXV, I'm pretty sure you found your answer. They do have some range, but that's a stretch.

>

> They swear it's the proper valve due to the flow through the evaporator. How that makes sense is beyond me. I thought the flow through the evaporator was determined by the capacity of the system.

>

> Bleh.



That sounds like a crock to me.

Does to me too.
The flow through the evap is dictated by the system's capacity, isn't it?

There's a reason they chose those valves though. My feeling is what @Matt is thinking is right. Some how, they cheated and by using too large of a valve it somehow squeaked out higher SEER numbers.

If that's the case, is it actually true in the real world?

I've also got a feeling they haven't sold many of this version of the air handler because even their tech support right off the bat suspected it wasn't matched to the high SEER outdoor unit until he checked.

Harvey Ramer

A higher seer unit, among other things, will have less of a pressure differential between low and high side. This requires a larger orifice or txv to allow the nominal mass flow rate.

Nominal system tonnage is a direct reflection of mass flow rate. The idea that their evap requires a higher flow rate than the system capacity is completely foreign to me.

Matt_67

Would you be able to get the nameplate data off the compressor? I am guessing it is the Copeland 2 stage scroll?

ChrisJ

Matt said:

Would you be able to get the nameplate data off the compressor? I am guessing it is the Copeland 2 stage scroll?

Off the top of my head, it's a ZPS30 K5 series.
Copeland Ultratech 2 stage scroll.

It's sad I remember that.........

I believe the exact and complete model is : ZPS30K5EPFV130

EBEBRATT-Ed

"A higher seer unit, among other things, will have less of a pressure differential between low and high side. This requires a larger orifice or txv to allow the nominal mass flow rate. "

@Harvey Ramer is absolutely correct. They may have oversized the txv to gain efficiency by running less head pressure, lower dp would require a larger valve. I agree with that.

What I disagree with Goodman about is an oversized valve especially running on first stage will be unstable, hunt and have loss of control

Matt_67

I was just interested to see what the actual unit capacity was at those operating points - I attached the performance charts for the compressor. Personally I'd trade good TXV control and better latent capacity for a bit of SEER rating but I live in a cool area where humidity removal is more of an issue. In a hot dry climate I might feel different.

ChrisJ

It sounds like everyone is saying change the valve.

Literally, everyone.

Except Goodman.
If I change the valve, will I have a Greatman?

@Matt
@Harvey Ramer
@EBEBRATT-Ed



So, important questions.
The current valve is an HCAE-6-KX200.
Do I need to use an HCAE-3-KX200 or do I have wiggle room? For example, my understanding is a *ZX200 is generally installed outdoors, will it work fine indoors? Also, do any of those pose any problems running the system when it's cool out? Say, 60 degrees? It looks like a distributor can have up to a 50 PSI drop. Can that become a concern with a smaller valve?


This looks like it'll fit, though the equalizer and cap tube are 10" longer, but I'm sure I can just leave them coiled up.

http://www.ebay.com/itm/NEW-PARKER-THERMOSTATIC-EXPANSION-VALVE-HCAE-3-Kx200-New-In-Box-053-/252328284338


Obviously, if I do this, I assume full responsibility. I'm just trying to get an idea of what everyone's thoughts are on it.

ChrisJ

One more question.....

Can I go to a non-bleed TXV without adding a hard start with this compressor? Or rather, *should* I?

With the unit 20 feet up in an attic, non-bleed seemed like a good idea.

EBEBRATT-Ed

I would install a 3 ton valve...Sporlan. I would stick with the bleed or you may have starting issues pressures need to equalize on the off cycle if you only have a run capacitor

We just did a 20 ton split R410a (2) 10 ton compressors, (2) refrig circuits. I was surprised to find that Sporlan doesn't make a 10 ton valve.

our choice was 8 ton or 12 ton. We went with the 8s and it runs fine.

I was always taught that it's better to undersize rather than oversize and lose control.

ChrisJ

EBEBRATT-Ed said:

I would install a 3 ton valve...Sporlan. I would stick with the bleed or you may have starting issues pressures need to equalize on the off cycle if you only have a run capacitor

We just did a 20 ton split R410a (2) 10 ton compressors, (2) refrig circuits. I was surprised to find that Sporlan doesn't make a 10 ton valve.

our choice was 8 ton or 12 ton. We went with the 8s and it runs fine.

I was always taught that it's better to undersize rather than oversize and lose control.

I like Sporlan, but my fear is I don't know how to cross to it from Parker. I know that HCAE-3-KX200 fits, and has the proper charge.

Harvey Ramer

Sporlan and Parker are the same company, if I'm correct.

What @EBEBRATT-Ed said.

ChrisJ

Harvey Ramer said:

Sporlan and Parker are the same company, if I'm correct.



What @EBEBRATT-Ed said.

Yep, you're correct.
What I don't know, is if Sporlan makes higher end products vs Parker? Or if they're the same thing with slightly modified part numbers etc.

Interesting note in the help section of Sporlan's program.

"An flag will be displayed beside low values of loading to serve as a warning the valve is oversized for the application. Please note, however, certain refrigeration applications requiring fast pulldown will actually benefit from having the expansion valve oversized. For these applications, the system designer should use his or her best judgment as to the amount of valve oversizing that can be tolerated by the system.

"

Faster pull down sounds like something that could help increase SEER numbers, no?

ChrisJ

A 3 ton non-bleed TXV will be here Wednesday along with a new C-163-S-HH dryer. I may change the dryer, I may not depending on how I feel things go. If I can flow nitrogen good and keep all air out of the system I'll likely leave it. Funny enough, the TXV I ordered is the one Goodman recommends for my outdoor unit.

I also ordered a 5-2-1 hard start, I've been considering one for months just because I think it's easier on things.

hvacfreak2

Question : Sorry if I missed it if it has been mentioned , does the outdoor unit have a suction line accumulator ?

ChrisJ

> @hvacfreak2 said:
> Question : Sorry if I missed it if it has been mentioned , does the outdoor unit have a suction line accumulator ?

Nope

EBEBRATT-Ed

Don't know much about Parker. Everything used to be Sporlan or Alco. Sporlan always seemed to be the most popular. Parker bought Sporlan and I think Emerson bought Alco.

I didn't like Alco driers. Had one break down once. All the little beads came out of the drier and plugged up the liquid line.

I keep trying to think of an application where an oversized txv is used. Can't think of one.

I think you will get that changed out and it will run like a top.

hvacfreak2

I am thinking about the Bryant / Carrier FK series years ago
( R-22 ). They used the same indoor unit for like 2-5 tons. You had to select the outdoor unit capacity on the board so the ecm fan motor would control to the correct speed , but the outdoor units all had accumulators. I never measured the superheat on the new installs , just the subcooling stated on the nameplate and on to the next one.

So , you have a matched system that was designed by a team who sat in a lab and watched this combination work. The guys from Parker were not there , and no one on this board was present either I'm guessing. Is the system cooling ? Are you chasing
" a number " , for the purpose of perfection ? Concerned with floodback ? Maybe the larger valve allows for higher latent capacity early in the cycle ? If this is an ecm motor is the fan speed setting correct or you may need to move to the next higher setting ? I am not familiar with the brand but I do see some other brands doing some wacky things to meet the efficiency standards. If it is cooling well you might be better off going with an accumulator and let the superheat do what it wants.

ChrisJ

hvacfreak2 said:

I am thinking about the Bryant / Carrier FK series years ago
( R-22 ). They used the same indoor unit for like 2-5 tons. You had to select the outdoor unit capacity on the board so the ecm fan motor would control to the correct speed , but the outdoor units all had accumulators. I never measured the superheat on the new installs , just the subcooling stated on the nameplate and on to the next one.

So , you have a matched system that was designed by a team who sat in a lab and watched this combination work. The guys from Parker were not there , and no one on this board was present either I'm guessing. Is the system cooling ? Are you chasing
" a number " , for the purpose of perfection ? Concerned with floodback ? Maybe the larger valve allows for higher latent capacity early in the cycle ? If this is an ecm motor is the fan speed setting correct or you may need to move to the next higher setting ? I am not familiar with the brand but I do see some other brands doing some wacky things to meet the efficiency standards. If it is cooling well you might be better off going with an accumulator and let the superheat do what it wants.

Thank you for taking the time to read the thread and respond. I appreciate it.

I'm chasing a number, and I want it to function properly.
Having the lowside pressure swing up and down isn't helping my latent capacity at all. I'd much rather it pull the evap down, and stay down. It may, some how cause it to score higher in SEER ratings, I don't know. But it's scoring pretty low in my book right now.

I am concerned about floodback as well.

You're correct, the people at Sporlan/ Parker weren't there nor was anyone on this forum. However, they all know the signs of an oversized valve that isn't working properly.

I'll take a properly working system over a fake SEER number any day.

That said, I've considered an accumulator as well, just because it seems like something all systems should have. But, I probably won't add one at this point.

bob_46

Do you have some kind of anti-short cycle timer ? I wouldn't chase Goodmans superheat number, I would look for the lowest stable superheat.

ChrisJ

bob said:

Do you have some kind of anti-short cycle timer ? I wouldn't chase Goodmans superheat number, I would look for the lowest stable superheat.

Actually, I have 3 right now.
The thermostat has one, the outdoor unit has one built into the PCB and I added one, which I may remove now that I know the outdoor unit has one.

Why do you ask?

bob_46

Sounds good. Just a hunch but you just might possibly be a thermostat twiddler *~<;-)

hvacfreak2

ok , I wasn't clear on the suction pressure hunting. If the bulb is tight and insulated than it could be a bad power head. I would replace it with a new warranty exchange and pull the charge and weigh new. The 6 ton valve was selected for a reason , I don't believe the problem that you are having is due to the valve sizing just a bad valve.

You know what's weird , back in the old days it was a rare occasion to find a bad TXV on a new machine ( my experience at least ). Nowdays it is like 50/50 , man even on larger machines it has become business as usual to find a new valve that doesn't work.

Probably old news but stainless hose clamps work well for bulb mounting. Just watch it because you can get too much torque , but the bulb has to be tight enough that it will not move at all. The brass straps are the best to use , but you have to align the holes with the one that barely lines up. Cork tape is the only way to insulate these also. Oh and sand the tube and the bulb if they are oxidized before hand. Silicone caulk distributer tubes on larger machines as to separate them. secure the extra bulb lines with zip ties or electrical tape and isolate from other components.

Next year it's time to do that accumulator , a RAWAL kit , dehumidification control sequence , and a DDC control system lol.
Good luck with the system brother !!!

ChrisJ

hvacfreak2 said:

ok , I wasn't clear on the suction pressure hunting. If the bulb is tight and insulated than it could be a bad power head. I would replace it with a new warranty exchange and pull the charge and weigh new. The 6 ton valve was selected for a reason , I don't believe the problem that you are having is due to the valve sizing just a bad valve.

You know what's weird , back in the old days it was a rare occasion to find a bad TXV on a new machine ( my experience at least ). Nowdays it is like 50/50 , man even on larger machines it has become business as usual to find a new valve that doesn't work.

Probably old news but stainless hose clamps work well for bulb mounting. Just watch it because you can get too much torque , but the bulb has to be tight enough that it will not move at all. The brass straps are the best to use , but you have to align the holes with the one that barely lines up. Cork tape is the only way to insulate these also. Oh and sand the tube and the bulb if they are oxidized before hand. Silicone caulk distributer tubes on larger machines as to separate them. secure the extra bulb lines with zip ties or electrical tape and isolate from other components.

Next year it's time to do that accumulator , a RAWAL kit , dehumidification control sequence , and a DDC control system lol.
Good luck with the system brother !!!

So far, we pulled the original charge, vacuumed down and refilled with fresh 410A. Problem persisted. We pulled the charge again, installed new TXV right from Goodman, installed Sporlan solid core HH drier up before TXV and removed the pellet style from the outdoor unit, refilled with fresh 410A again, problem persists. We moved the bulb a foot down the suction line, problem is still there.

I have a hard time believing it's non-condensables at this point, and I can't imagine two brand new TXVs bad out of the box. Blower speed is set for 400 cfm per ton, and static pressure confirms. Outdoor fan is running steady and compressor amperage is steady.

Kinda running out of things to check.

hvacfreak2

Sorry I missed that as well.

Time to write Goodman a warranty bill. But yeah , sounds like you don't have a choice other than to go with a different selection. Good grief.

ChrisJ

hvacfreak2 said:

Sorry I missed that as well.

Time to write Goodman a warranty bill. But yeah , sounds like you don't have a choice other than to go with a different selection. Good grief.

Amazing, isn't it?