Should I get someone else out here to check the charge?

[CoolIsGood]

Long story short: In the winter, my 5 month old system slowly leaked out r410a because a tech didn't torque down the liquid line nut... So a tech came out and charged the system in the dead of winter while only checking suction line temperature...

Fast forward to 2 weeks ago, I try to cool the house because it's 80F outside and it begins to cool but then the heat pump abruptly shuts off.

..Yep, overcharged. I could see on the technicians gauge that the high pressure was quickly approaching 700psi before he shut the heat pump down...

He pulled out r410a from the high side and then pulled out refrigerant from the low side until his mechanical gauge read 34F (it dropped from 40F). The outdoor ambient temp was 82F.

It seems to me that this guy had no idea what he was doing, seeing as how he didn't even bother calculating subcooling. All he did was evacuate refrigerant until the needle on his gauge dropped down to 34F...

Good enough? Get somebody out to do a subcooling calculation?

[chuckcrj]

It depends what metering device it has......

[CoolIsGood]

It depends what metering device it has......

TXV

It's a model year 2010 Carrier indoor FV4C VS A/H and an outdoor 25HCC 2.5 ton single speed heat pump. r410a.

[chuckcrj]

Yes it certainly needs to be charged by subcooling in the cooling mode.

[chuckcrj]

What were the conditions outside and in? 34° SST sounds a little low.

[CoolIsGood]

What were the conditions outside and in? 34° SST sounds a little low.

(http://img31.imageshack.us/i/ecoreport.jpg/)

Outdoor temp was 83F with 49% humidity.

Indoor temp was 81F with 47% humidity.

[chuckcrj]

Low indoor airflow is a possibility.

[CoolIsGood]

Low indoor airflow is a possibility.

How so? The system was overcharged in the winter (that's why it ran through the winter, but would not run when I tried it this summer. I'm sure you're well aware of Boyle's Law.)

Seeing as how this was installed in a townhouse, the variable speed air handler was set to Hi fan speed. This setting produces an additional 15%(400CFM/ton) airflow over nominal airflow (350CFM/ton). The registers on the upper floors seem to be pushing a good amount of air.

[cuchulain]

if the charge was weighed in for manufacture specs then it shouldn't matter when it was recharged. My recomendation is get someone in there to reclaim the entire system, pull a good vacuum to make sure that there are no additional leaks and weigh the charge in according to specs.

Once it's weighed in to specs then a good subcool/superheat measurement to confirm a manufacture required charge.

[bmathews]

While I have no idea what he did. Maybe he's a buffoon. Maybe you're just angry at him and looking for ammunition? Who knows. But the unit tells you what subcooling to put it too. At any rate. Is there a problem with the unit? Obviously you're not happy with the guy. Call somebody else out to verify or call the company and ask for somebody else to come out.

[CoolIsGood]

While I have no idea what he did. Maybe he's a buffoon. Maybe you're just angry at him and looking for ammunition? Who knows. But the unit tells you what subcooling to put it too. At any rate. Is there a problem with the unit? Obviously you're not happy with the guy. Call somebody else out to verify or call the company and ask for somebody else to come out.

You have no idea what he did?

I'll simplify it for you. The only tools this guy brought to reduce the refrigerant charge was an evacuator, a holding tank, and a manifold set/gauges. He figured the charge was good once he had evacuated enough refrigerant for the needle on the left gauge to line up with 34F.

Do you have an idea now?

I don't want to waste my hard earned money for no reason if somebody here can tell me that this guy can get the correct ballpark charge with just the tools he had. On the other hand, if this method is as sloppy as I suspect it is, then I definitely want to pay a "real" pro to adjust the charge within the proper ballpark.

[bmathews]

You have no idea what he did?

I'll simplify it for you. The only tools this guy brought to reduce the refrigerant charge was an evacuator, a holding tank, and a manifold set/gauges. He figured the charge was good once he had evacuated enough refrigerant for the needle on the left gauge to line up with 34F.

Do you have an idea now?

Nope. I wasn't there and didn't see it. I have found out that there is always 2 sides to a story. He may be an idiot. If you're not comfortable with him. Call somebody else out to check out. I'm really not sure what you want anybody to say.

[chuckcrj]

How so? The system was overcharged in the winter (that's why it ran through the winter, but would not run when I tried it this summer. I'm sure you're well aware of Boyle's Law.)

Seeing as how this was installed in a townhouse, the variable speed air handler was set to Hi fan speed. This setting produces an additional 15%(400CFM/ton) airflow over nominal airflow (350CFM/ton). The registers on the upper floors seem to be pushing a good amount of air.

He was reading 34F on something, or you were reading it wrong.

If he had 34 SLT or SST at 81F inside there is low airflow or low charge or a restriction.....

[CoolIsGood]

He was reading 34F on something, or you were reading it wrong.

If he had 34 SLT or SST at 81F inside there is low airflow or low charge or a restriction.....


This is what I saw when he was outside by the heat pump. The left gauge had the needle lined up at 34F with the heat pump operating in cool mode.

I should mention that the heat pump appears to be cooling the house fine thus far in these 85 degree temps (also getting good dehumidification) . I just want to make sure that I am operating within the ballpark of manufacturer specifications.

http://img191.imageshack.us/img191/4852/lx1001aw.jpg (http://img191.imageshack.us/i/lx1001aw.jpg/)

[chuckcrj]

[QUOTE=CoolIsGood;10060972] I just want to make sure that I am operating within the ballpark of manufacturer specifications.



Impossible to tell from behind a keyboard. Like someone said, get an hvac tech you can trust.

[CoolIsGood]

Why can't you give me a straight answer? Is it possible to REASONABLY adjust the charge with only a gauge set. This is what his gauge looked like under the conditions that I listed:

As you can see in the graph that I posted, the house was cooled quickly and dehumidified well. I have not had any issues, the air blows out very cold and without any unexpected interruptions. I just want some reassurance...

http://img171.imageshack.us/img171/1880/gm4103.jpg (http://img171.imageshack.us/i/gm4103.jpg/)

[cuchulain]

if the tech is familiar wit hthe system, has some experience under his/her belt then yes it is possible to get within the ball park with just a set of gauges. I'm NOT saying it will be correct and what is required for your system, but it could very well be in the ball park. But then again a ball park is a pretty big place esp if it's the outfield.

[chuckcrj]

No you can't reasonably check charge with only a gauge set.

[bmathews]

No you can't reasonably check charge with only a gauge set.

I can get pretty darned close. Even within manufacturers specs 90% of the time. I still check myself. But any tech with experience at all can do the same thing. You still need to check yourself. Hell who knows. Nobody on here can give you an answer without being there and looking at everything. They would be a fool to do that.

[CoolIsGood]

I can get pretty darned close. Even within manufacturers specs 90% of the time. I still check myself. But any tech with experience at all can do the same thing. You still need to check yourself. Hell who knows. Nobody on here can give you an answer without being there and looking at everything. They would be a fool to do that.

So what do you think? The cooling seems to be working great after he reduced the charge. No icing over (this never happened before anyways), air coming out of the vents is COLD, heat pump doesn't cut out abruptly like it did before the adjustment.

Do I bother burning away at minimum $100 of my hard earned money if cooling seems to be ok?

[bmathews]

Don't know dude without being there. Pay $100 to have it checked or however much more in 3 years for a blown compressor. Pay now or pay later.

[cuchulain]

it may seem "OK" at the moment, but if it isn't charged to specs, then the unit isn't doing what it is designed to. And if it's a new"er" unit and it's not doing what it's designed for then why even bother buying it. You'll reduce the life of the unit, increase your electric bill, decrease your comfort level over the long haul.

[badboyheel]

Does this company warranty their work for the first year? If so, call them back and kindly ask them to send another tech. Explain your concerns to them and they'll probably be glad to come out and take care of the situation....if there is one.

[CoolIsGood]

Sigh...

Any recommendations on who to call in Montgomery County, Maryland?

[CoolIsGood]

Does this company warranty their work for the first year? If so, call them back and kindly ask them to send another tech. Explain your concerns to them and they'll probably be glad to come out and take care of the situation....if there is one.

I spoke with the owner of the company, who also seems to think that nothing else other than a set of gauges are needed to "sufficiently" adjust the charge on a unit in warm weather...

[chuckcrj]

I spoke with the owner of the company, who also seems to think that nothing else other than a set of gauges are needed to "sufficiently" adjust the charge on a unit in warm weather...

Sounds like another "beer can cold" type.

[chuckcrj]

I can get pretty darned close. Even within manufacturers specs 90% of the time. I still check myself. But any tech with experience at all can do the same thing. You still need to check yourself. Hell who knows. Nobody on here can give you an answer without being there and looking at everything. They would be a fool to do that.

How do you tell whether or not you have 100% liquid feeding the txv with pressure only?

I know what you mean though, beer can cold is close enough.

[ewwilt]

I spoke with the owner of the company, who also seems to think that nothing else other than a set of gauges are needed to "sufficiently" adjust the charge on a unit in warm weather...

That is definately the wrong answer. All that tech did was adjust the charge according to the temperature conditions at that time. Even though I say a 34 deg evaporator is too low for those conditions. And another thought, if he did happen to get the charge 90% right, you could possibly be running at least10% inefficient. Being a heat pump, that you run year round, the extra cost of running it will add up.

[gravity]

goto yellowpages.com and search for hvac contractors in montgomery county. my company is local to you.

[CoolIsGood]

How many labor hours am I looking at to get a subcooling measurement done and potentially having the charge adjusted (it should be pretty close now, but who knows since it was only done using gauges)

[Roadhouse]

How many labor hours am I looking at to get a subcooling measurement done and potentially having the charge adjusted (it should be pretty close now, but who knows since it was only done using gauges)

Proper charge includes verification of proper air flow. A simple static pressure test done with a manometer by the hvac technician you choose to use will give evidence of proper air flow. Proper air flow goes hand in hand with both evaporator AND condenser coils being as clean as per design specific when new. No if, ands or behinds about not having clean coils to check charge.

Then and only then can the difference in subtracted heat from the heated liquid refrigerant be calculated with the use of a thermometer and gauges for optimal charge, directly accompanied to total and accurate system performance.

Good luck.

[CoolIsGood]

Proper charge includes verification of proper air flow. A simple static pressure test done with a manometer by the hvac technician you choose to use will give evidence of proper air flow. Proper air flow goes hand in hand with both evaporator AND condenser coils being as clean as per design specific when new. No if, ands or behinds about not having clean coils to check charge.

Then and only then can the difference in subtracted heat from the heated liquid refrigerant be calculated with the use of a thermometer and gauges for optimal charge, directly accompanied to total and accurate system performance.

Good luck.

So what is the estimated labor hours that I'm looking at?

This system isn't even a year old yet. The coils are clean and I would be surprised if my variable speed blower isn't maintaining a minimum of 350CFM/ton seeing as how it's currently set to 400CFM/ton.

[gravity]

approx. .5-1.5 hours if everything is clean.

[Roadhouse]

So what is the estimated labor hours that I'm looking at?

This system isn't even a year old yet. The coils are clean and I would be surprised if my variable speed blower isn't maintaining a minimum of 350CFM/ton seeing as how it's currently set to 400CFM/ton.

Let me ask you, how many times have you NEEDED to replace your return air filters and what are your living conditions which coincide with how dirty they may get as in do you have pets or do the filters just become abnormally dirty for no apparent reason if they do get dirty for no apparent reason?

What I'm getting at, something I left out previously, is are we certain that there are no air leaks in your duct system..? I know I'm getting technical but if you want to be certain then hvac is an absolute science and all aspects are relevant. Dirty filters would suggest a leak in the return air which would mirror a dirty evaporator coil but you are saying it's clean just because it's one year old. So, your filter situation, good or bad?

And how many times has the grass been cut next to your condenser? Any trees next to it, dirt?

If all of this is checked and verified clean and no air leaks than you may be looking at, as gravity has already said, one half hour to one and a half hours dependant upon who is there and what tools they have.

I have a digital subcool and superheat meter that reads real time temperatures and thus calculates proper sc and/or sh johnny on the spot so if I were to come out and verify all of the applications which make for a complete and optimal hvac system and then hook up my meter, I could be out of there within 45 minutes max on a day I'm not feeling good and sluggish but you'd be charged a full hour service call minimum plus refrigerant as needed, no if ands or butts about that either.

[CoolIsGood]

Let me ask you, how many times have you NEEDED to replace your return air filters and what are your living conditions which coincide with how dirty they may get as in do you have pets or do the filters just become abnormally dirty for no apparent reason if they do get dirty for no apparent reason?

What I'm getting at, something I left out previously, is are we certain that there are no air leaks in your duct system..? I know I'm getting technical but if you want to be certain then hvac is an absolute science and all aspects are relevant. Dirty filters would suggest a leak in the return air which would mirror a dirty evaporator coil but you are saying it's clean just because it's one year old. So, your filter situation, good or bad?

And how many times has the grass been cut next to your condenser? Any trees next to it, dirt?

If all of this is checked and verified clean and no air leaks than you may be looking at, as gravity has already said, one half hour to one and a half hours dependant upon who is there and what tools they have.

I have a digital subcool and superheat meter that reads real time temperatures and thus calculates proper sc and/or sh johnny on the spot so if I were to come out and verify all of the applications which make up a complte and optimal hvac system and then hook up my meter, I could be out of there within 45 minutes max on a day I'm not feeling good and sluggish but you'd be charged a full hour service call minimum plus refrigerant as needed, no if ands or butts about that either.

I replace the filter every 3 months. It's not excessively dirty either, especially since I have continuous fan going. I have no pets. The heat pump is in a gravel area, there are no trees and no grass near it to be cut.

[Roadhouse]

I replace the filter every 3 months. It's not excessively dirty either, especially since I have continuous fan going. I have no pets. The heat pump is in a gravel area, there are no trees and no grass near it to be cut.

Heat pumps need to charge in cooling mode. Make certain the system has been running and cycling so the technician does not need to wait for the system to stabilize so leave it on as normal.

You should be good with an hour service call plus refrigerant if needed but make certain whomever you call and ask to come out at the very least agrees to verify that the coils, both inside and out, are clean and is prepared to clean them if they need it.

And be prepared to pay for those services, if they're needed.

[CoolIsGood]

It was 2 pounds undercharged. 1F subcooling. The last moron that came out here took too much refrigerant out. Now I'm sitting at 11F subcooling.

[Roadhouse]

It was 2 pounds undercharged. 1F subcooling. The last moron that came out here took too much refrigerant out. Now I'm sitting at 11F subcooling.

Cool, pun intended.