California Steamin' or R410a or Bust

[hvaChuck]

Hi,
I fall in gray area somewhere between consumer and tech(Prosumer?).
I work on HVAC in my job, but only from a lighter standpoint in that I don't
design,but have some input in what is installed and try to keep
R22 and lithium bromide and ammonia units running without getting too deep,
then I defer the really deep stuff to my a/c contractor.

This is personal,my parents secured a HVAC contractor that did a less than stellar job
installing a Amana 3 ton 2 stage r410a system for a <900 sq ft home.

First, after near a year and several complaints about performance of the A/C
I met a tech and showed him they never connected the 2sd stage wiring and never wired for, or installed a 2 stage thermostat.
They corrected this and the unit started to cool then stopped after 20 minutes.
I base alot of my judgment on cooling on 2 things (please don't ridicule me)
1-does it sweat back to the compressor,(we have enough humid in Ca).it should
2-is there at least 20 degrees diff return air/room and register air,and does it
continue to drop?
That's how I first decided it was not working right.Now they reluctantly came back
and analyzed pressures,low was about 150 and high was 450 @90 degree day.
They saw no sweating and after several hours and phn calls they determined
TXV was bad or wrong.
They replaced valve and now it seems to cool better and though it does sweat it doesn't!
sweat as much as I would like, and cooling/cap stalls at about 74-76 degrees.
Mind you,the occupied space is <900 sq ft with this 3 ton unit (attic insulated-1960 home, single pane windows- no wall insulation).

Now Sept 2 midday I got 130 low side and 320 high side @ approx 105 degrees outside,
no sweat on suction line (ca. has major humidity right now)!
I quickly went to my sisters new home 5 miles away and her carrier 4 ton r410a
for a 2000 sq ft home was sweating big time and pressures were low side 138 and high side
420 @ approx 105 degrees outside,near ideal by what I've read.
I don't see a new dryer after they change TXV and who knows how well they
pumped down, Amana/Goodman requires deep vac or triple evac,since they were in and out in approx 1 hour I have doubts.
I need suggestions,the 320 high side is a good indication somethings a muck,
but I think it's more than undercharge, whaddayathink?

Your Thoughts ,Thanks hvaChuck

[ersham]

check subcooling should be 6-10
if their is a leak you need to repair

[Shophound]

Sweat-back to compressor and temp. split over evap coil are rudimentary indicators at best. Much more preferable is a technician on the job that can gather vital data points such as superheat and subcooling, and understand what that data is telling him. The system you describe needs such a person.

[jinu117]

Yup... for some unforsaken reason this year has been very humid for s. california unlike typical california summer. Sweating would be very common right now even for 2 stage units and R-410a... (first time in many years we are actually turning on A/C at night.. just for humidity control...)
Here are few things I would verify per installation manual. Ambient temp out at condenser, wet/dry bulb temp for evap outlet (or closest distance register from it), some super heat/sub cooling and see if it is what the factory manual specifies at. With some of these information, it might be possible to deduce what might have happened.
It always makes me weary when people change TXV around. Maybe they played around with it bit much and got bulb installed at wrong place or gave it adjustment (which you really shouldn't have to most of time) to make it open too much.
Why don't you schedule time together with contractor next time he comes in so you can be there to ask some intellgent questions and see if the contractor is up on par? Installing 1 stage thermostat on 2 stage unit already is pretty damned big goof off in my book.

[docholiday]

Sweating to the compressor as mentioned is simply just not true. You got bad advice from a mentor somewhere along the lines. Yeah it may be sweating on the neighbors unit but his coil temperature if he's got a 20 degree drop is probably around 25 degrees. A new system, especially if it;s high efficiency enough to be two stage may run a 50 degree coil. Added coil surface and additional run time will make up for the moment by moment humidity removal. You may see as low as 14 degrees drop on some systems and still have the ability to remove all the humidity you have.

Where I come from, if I see sweating back to the compressor and a 20 degree drop, it's time to review the indoor airflow and system charge. Fact is, if the 2nd stage was never hooked up, it cannot possibly be charged correctly. (they must be charged in second stage).

As shophound said, you have a guy guessing his way through his career and need to consider hiring one that actually knows what makes a system work and why it works. Unfortunately your parents saved a couple bucks with this guy on installation but are now paying the price for it.

[hvaChuck]

UPDATE:

Thanks to all your suggestions,

They stiffed me today -One version is their truck broke down the other is
I canceled the call, I set them straight that I am still not satisfied,
and did not cancel the service call and also let them know I verified they
did not change the dryer when they changed the TXV valve.

This Goodman Amana has the dryer in a goddawful place to access
it ,so I understand somewhat but,that's their business.

I really don't trust them, everything from ceiling registers cut crooked and
holes over sized to leaving condensate drain disconnected and leaking in
closet ceiling to the wrong thermostat,disconnected 2sd stage,and
who knows what else I either have yet to discover or can't see.

I'm at the point of contacting BBB or state contractor agency and
getting someone else to get it right and going small claims court
but what a hassle,as it is I've already spent too much time on this
11K install.I need to find someone in the Ontario Ca. area that
can sort it out.

I read up on superheat & sub cool and would really like to see the
effect these measurements would have vs "rule of thumb";I
don't doubt their validity,it would give perspective to see it in
action.

I base alot of what I see in A/C performance on observation, and while our eyes can
deceive us I, there's a reason for expressions like "Common Sense"
"Rule Of Thumb" etc.
I once had a office that had 4 tons and < 1500 sqft.
It was up for a new unit and an engineer showed up to scope it out.
I told him the 4 ton unit never did well and I would want no less than
a 5 ton unit since 400 sq ft /ton was rule of thumb and 1 ton more 4 safety.
He quickly admonished me that it required calcs on load of lighting and
occupants and all kinds of stuff,and 1 ton can do up to 600 sqft under
certain conditions. So when the project went through I
ended up with another 4 ton unit that sucked.
The project manager insisted I use system 1 year and "trend logged"
it with a EMS.The results quickly showed the miserable stats.
I got the 5 ton and it's been fine
One of the things that for sometime got little attention was the load from
all the computers in offices. Thanks You Gates/Jobs!
One thing is true,my folks saved a k or 2 but this has cost more in the Long Run
TBC hvaChuck

[ckone180]

UPDATE:

Thanks to all your suggestions,

They stiffed me today

I really don't trust them

Wow, that takes back the "less than stellar" comment, huh? Maybe change it to something like poor-ass, go for nothing, illegitimate, red-neck, honky, suma***** job. Good luck, I hope you get it taken care of, but I would have a reputable service company take a look-see, who knows, it maybe a tiny issue!

[hvaChuck]

I should have put this in last post but,

Ontario temp today was 100-105 as it was when I read
320-325 psi high side
Now I made intimate contact (not me) but with a digital temp probe and the
high side line line near the high side service valve.
This is one version I've seen about how to check sub cool,
it read 103.5 degrees and 320-325 translates into 100-101 degrees
Now I also read if you take the temp from the outside unit rather
than at the evap you should compensate with about 2-3 degrees
and compensate for extra rise and run if excessive.
So I'm not sure if I add that, to my temp read or the Psi/temp conversion.
Also the name plate calls for a 7 degree sub cool, I've also
read superheat not applicable to TXV situations.
What I don't get is that the air leaving the condenser fan
should reflect heat rejection of both the heat of compression
and conditioned area,therefore at 100-105 degree the high side
psi or even physical air off the fan should read 20-30 degrees higher
than ambient.
Is it a R410a thing? I'm bamboozled, for my R22 and ammonia condensers at work
always have hotter air coming off than the ambient air entering.
hvaChuck

[Shophound]

Ontario temp today was 100-105 as it was when I read
320-325 psi high side
Now I made intimate contact (not me) but with a digital temp probe and the
high side line line near the high side service valve.
This is one version I've seen about how to check sub cool,
it read 103.5 degrees and 320-325 translates into 100-101 degrees

Going by your numbers given above, you have no subcooling occurring.

Now I also read if you take the temp from the outside unit rather
than at the evap you should compensate with about 2-3 degrees
and compensate for extra rise and run if excessive.

Subcooling readings are generally taken on the liquid line as it leaves the condenser on a split system. You are interested in how well the condenser is able to subcool the refrigerant below saturated condensing temperature. If the liquid line temperature is the same as saturated condensing temperature, you have no subcooling occurring. This is often the result of an undercharge; it could also mean the condenser coil is very dirty and should be cleaned.

I've also read superheat not applicable to TXV situations.

That would be incorrect information, or you have misintepreted what that source of info may have been trying to tell you. With a TXV, you do not check for correct charge via superheat, but you do check for proper operation of the TXV by measuring superheat at the evaporator suction outlet. To properly check charge for a system uisng a TXV, the subcooling value is used.

What I don't get is that the air leaving the condenser fan
should reflect heat rejection of both the heat of compression
and conditioned area,therefore at 100-105 degree the high side
psi or even physical air off the fan should read 20-30 degrees higher
than ambient.

Incorrect. The 30 degree above ambient is very old school, and the higher SEER systems are eroding away the 20 degrees above ambient guidepost as well. There should be a temperature rise across the condenser coil of the air moving over it, yes. If it's not much of a rise, then yes, you're not dumping much heat. If the system is undercharged, it not only is not picking up a lot of heat from the evaporator, it's also going to have a lower heat of compression, right? The compressor itself will run hotter due to the motor windings not being sufficiently cooled by the returning refrigerant vapor from the evaporator, but heat generated by compression will be less because there's less volume of refrigerant being compressed.

Is it a R410a thing? I'm bamboozled, for my R22 and ammonia condensers at work always have hotter air coming off than the ambient air entering.
hvaChuck

When you checked your neighbor's R410A system, did it also have hotter air coming off the coil vs. the one you're concerned about? Not that such tells you a great deal...throwing your neighbor's unit into the mix is only fogging up your analysis of the system you are otherwise to be focused on, IMO. In troubleshooting, it is always best to first understand how all components of the system interact, and then systematically evaluate what is the source of the malfunction. If you do not understand how the system is supposed to work, you will always be frustrated by your attempts to troubleshoot it.

[hvaChuck]

Everything I've been taught is that the condenser removes the
heat from the system,all the stuff I work with behave with that
concept,however r22 units will see a 20-30 degree difference
in the entering air and the leaving air or high side pressure
and so do my r717 units and Lithium bromide seem closer in concept
to this sub cool thing.
Water enters the condenser at approx 84 and leaves at 94
so a 10 degree split in in out water is indicative of the heat being
removed from the conditioned space and the heat of absorption.
The skin temp of the condenser and the water is ideally 13 degrees
difference,both temps confirm the rejection of heat.

So today the Owner/tech looked at the unit and was not convinced
there was any problem,he took high side pressure and ambient air
they were almost identical so he was satisfied.

I asked him did they check the sub cool and showed him the manual
value of 7 degrees.He said they don't check sub cool as if it was
a unimportant value.
After over an hour watching the unit he said indoor split was
19 degrees and that it was doing fine the amount of heat gained
from windows and uninsulated walls may exceed capacity and my
expectation was too high.
I countered that they selected the size and 1 hour to drop 2 degrees
(76 to 74 [outside 92]) was not what I would consider efficient;Again
3 tons for a <900 sq ft home is fairly generous capacity.
I said the condenser temp. must reflect some heat rejection
and the amp draw was 9.2 amps vs. the name plate was 16.5 RLA.
And it never sweat the whole time he was there,even with Ca.humidity.
He finally agreed to send another tech to set sub cool value
as if he tacitly acknowledged it's validity.
TBC hvaChuck

[cmajerus]

Everything I've been taught is that the condenser removes the
heat from the system,all the stuff I work with behave with that
concept,however r22 units will see a 20-30 degree difference
in the entering air and the leaving air or high side pressure
and so do my r717 units and Lithium bromide seem closer in concept
to this sub cool thing.
Water enters the condenser at approx 84 and leaves at 94
so a 10 degree split in in out water is indicative of the heat being
removed from the conditioned space and the heat of absorption.
The skin temp of the condenser and the water is ideally 13 degrees
difference,both temps confirm the rejection of heat.

So today the Owner/tech looked at the unit and was not convinced
there was any problem,he took high side pressure and ambient air
they were almost identical so he was satisfied.

I asked him did they check the sub cool and showed him the manual
value of 7 degrees.He said they don't check sub cool as if it was
a unimportant value.
After over an hour watching the unit he said indoor split was
19 degrees and that it was doing fine the amount of heat gained
from windows and uninsulated walls may exceed capacity and my
expectation was too high.
I countered that they selected the size and 1 hour to drop 2 degrees
(76 to 74 [outside 92]) was not what I would consider efficient;Again
3 tons for a <900 sq ft home is fairly generous capacity.
I said the condenser temp. must reflect some heat rejection
and the amp draw was 9.2 amps vs. the name plate was 16.5 RLA.
And it never sweat the whole time he was there,even with Ca.humidity.
He finally agreed to send another tech to set sub cool value
as if he tacitly acknowledged it's validity.
TBC hvaChuck

quit wasting your time with idiots, and find a cotractor that can charge this system (in 2nd stage) properly! Which would be with subcooling, forget the sweating suction line, yes it will sweat but not necessarily at all times. depends on what stage and indoor/outdoor temps.