Looking for SH and SC guidelines

[kbm]

Hi I am new to this field.
I am familiar with charging a system using superheat and subcool levels based on manufacturer's performance chart.

What do you guys do when the chart is missing or ruined by age/water/bugs.
I am talking about residential units less than 5T.

Is there safe, general rules to use for SH and SC?

How about TXV vs. cap tube systems?

Would the levels be different for R-22 vs. R-410A?

I know it is not the best way to ball-park it, but if in a jam it'd be good to know a safe level to start.

Thanks for your help.

[iraqveteran]

Hi I am new to this field.
I am familiar with charging a system using superheat and subcool levels based on manufacturer's performance chart.

What do you guys do when the chart is missing or ruined by age/water/bugs.
I am talking about residential units less than 5T.

Is there safe, general rules to use for SH and SC?

How about TXV vs. cap tube systems?

Would the levels be different for R-22 vs. R-410A?

I know it is not the best way to ball-park it, but if in a jam it'd be good to know a safe level to start.

Thanks for your help.




#1. you gotta get 15 posts and apply for pro membership. We can help you out a great deal there.


#2. Its called tech support. Don't be afraid to call tech support to get this vital information. A truely honest tech won't hesitate to call when he/she is unshure of information.


There isn't really a rule of thumb. I hate rule of thumb. It will only get you into trouble. You've got a phone, use it. You gotta let the system run anyhow to balance out. So spend that time on the phone with tech support.

Another idea......write it all down. If you start now, you should have a nice little reference guide by summers end.


Good luck. Have fun. Get to pro. And then we'll have a lot of fun

[iraqveteran]

oh yeah....

1 more thing.

You can get superheat/subcooling calculators from a lot of supply stores. Exactcharge also has one that can be loaded onto a PDA.

[kbm]

Is this calculator that will give you a estimated SH, SC based on size and rating of the equipment?

No doubt calling the support folks to get right info for unit is best way. But sometimes, say late night or special locations or old stuff, it may not be possible.

Just checking with you guys that are doing it.
I know people that don't even use SC/SH.

[iraqveteran]

no. The calculators that I have.....

you use a slide calculator. First two are....

indoor ambient temp (DB/WB)
outdoor ambient temp (DB/WB)

with these in line, you will be able to read target superheat.

then you slide arrow of target superheat to calculated number and then start looking at temps and pipe temps. It even tells you when to add or remove refrigerant.


Subcooling is always based off man. specs.




But remember, all the pressures, temps, and SH/SC in the world won't help you one bit if the airflow is the problem.

[castillo7411]

Carrier and most other dealers have these slide calculators available either for free or for a small fee I have found as i am sure most of the experienced techs have come to find that superheat based on indoor return wet bulb and outdoor dry bulb for both 22 and 410 a to be the same and whn looking for the subcooling as long as what you are looking for then the only thing that has changed is the pressure/temp readings

[iraqveteran]

http://www.exactcharge.com/

check it out. I have the software and its worked out really well for me. I mainly use the pressure/temp charts.

[Twilly]

Twilli says thermostat

[iraqveteran]

Twilli says thermostat

Don't mind Twilli.........

hes very consistent with the random words coming out of his keyboard:D

[castillo7411]

But remember, all the pressures, temps, and SH/SC in the world won't help you one bit if the airflow is the problem.

Good point, We have a new guy who just began getting comfortable charging 410a units and he called me up asking questions and based on what he was telling me i told him he was still undercharged and because he was adjusting the charge on a 5 ton system that had 1 1/8 line 60 foot run it would take a while 2 hours later and he said it didnt look right so i went out there and found the fan was running very low airflow across the coil, even though his subcooling would seem right his superheat and suction pressures were showing a restiction across the coil, something that is more or less learned and th charts dont really tell you!

[iraqveteran]

Good point, We have a new guy who just began getting comfortable charging 410a units and he called me up asking questions and based on what he was telling me i told him he was still undercharged and because he was adjusting the charge on a 5 ton system that had 1 1/8 line 60 foot run it would take a while 2 hours later and he said it didnt look right so i went out there and found the fan was running very low airflow across the coil, even though his subcooling would seem right his superheat and suction pressures were showing a restiction across the coil, something that is more or less learned and th charts dont really tell you!

EVERYTHING IS LEARNED.

What you need to tell the new guy is to leave his guages in the truck. Once he has looked at EVERYTHING........then he is allowed to check pressures and SH/SC to verify the system is running properly.

[kbm]

http://www.exactcharge.com/

check it out. I have the software and its worked out really well for me. I mainly use the pressure/temp charts.

I like this. Will check it out. Thanks for sharing.
When I googled it, it is around $74 for the software.

[iraqveteran]

I like this. Will check it out. Thanks for sharing.
When I googled it, it is around $74 for the software.

There is a gentleman on this site that I believe is the creator of the software. If you speak with him......he may give you the software free.

I talked with him and got it free. All I did was sent him an email. He said get the PDA and let him know. I bought a used PDA of Ebay and he sent me software free.

[iraqveteran]

try this link

http://www.hvac-talk.com/vbb/showthread.php?t=167594&highlight=exactcharge

Post #8. Thats the man you wanna speak with.


If it don't work. Just contact Exactcharge through their website. Be sure to tell them you heard of them from this website. You may get lucky.

[skwsproul]

try this link

http://www.hvac-talk.com/vbb/showthread.php?t=167594&highlight=exactcharge

Post #8. Thats the man you wanna speak with.


If it don't work. Just contact Exactcharge through their website. Be sure to tell them you heard of them from this website. You may get lucky.He gave that to you as a way to say thanks for serving our country. Either way

THANKS

I too full support the war on terrorism and again THANKS

[kbm]

try this link

http://www.hvac-talk.com/vbb/showthread.php?t=167594&highlight=exactcharge

Post #8. Thats the man you wanna speak with.


If it don't work. Just contact Exactcharge through their website. Be sure to tell them you heard of them from this website. You may get lucky.

I appreciate your help. Will give it a try.

[Twilly]

Twilli meant to invent that.

[kbm]

Twilli meant to invent that.

Where there's a 'TWilli' there's a way.

Joking aside.
Exactcharge does not works with Blackberry, I think.
Am not buying a new pda just for it.
The other SW mentioned was Verified RCA.
If one believe half their claims on energy savings possible, there is a lot of watts burning up out there.
With oil at $140/barrel, electricity cost is next shoe to drop on Joe Public.