Heat Pump

[Heatcooltech]

I was just wondering if anyone had an Idea of what the suction line temp at the service valve in heatpump mode should be on a 75 degree outdoor ambient with a 75 degree indoor dry bulb

[always learnin]

I would recommend doing superheat check if less than 13seer, or subcool if over

[d_griff]

I was just wondering if anyone had an Idea of what the suction line temp at the service valve in heatpump mode should be on a 75 degree outdoor ambient with a 75 degree indoor dry bulb

whats heatpump mode,you mean a heat pump in heating mode????
it will vary by deasign and manuf..usually you can get a charge chart inside the panel oor have tech support fax it to you,or go online w model and ser. number

[Heatcooltech]

I was just wondering if anyone had an Idea of what the suction line temp at the service valve in heatpump mode should be on a 75 degree outdoor ambient with a 75 degree indoor dry bulb

Did superheat check, No charging chart on unit, Mod and Ser number Sunbaked off the unit. Sorry, yes heatpump in heating mode. Superheat about 12 degrees. Suction temp just continued to climb to an alarming 200 degrees.

[d_griff]

Did superheat check, No charging chart on unit, Mod and Ser number Sunbaked off the unit. Sorry, yes heatpump in heating mode. Superheat about 12 degrees. Suction temp just continued to climb to an alarming 200 degrees.

if you have 75 out and in temp,sometimes i find it easier to flip it to cool and diagnose the charge or problem,have you tried that??you have the temps..
i would try it b/c 75 out and 75 in could just be gettin hot b/c there is plenty of heat outside to pick up at ex..and same temp inside so not much rejection..

[Heatcooltech]

if you have 75 out and in temp,sometimes i find it easier to flip it to cool and diagnose the charge or problem,have you tried that??you have the temps..
i would try it b/c 75 out and 75 in could just be gettin hot b/c there is plenty of heat outside to pick up at ex..and same temp inside so not much rejection..

I also have another intersting phenomenon. I dialed the superheat in to 11 degrees. The temp dropped to 71 degrees at the return however the leaving air temp at the ceiling register never dropped below sixty one. How little attic air could elevate this temp if it were being drawn after the evap coil. I have to do some sealing tomorrow. But its nothing really gaping or anything. Any experience with this for you? And I greatly appreciate your comments.

[BigJon3475]

Whats the humidity like? Do you have a wetbulb or sling psy.?

[d_griff]

I also have another intersting phenomenon. I dialed the superheat in to 11 degrees. The temp dropped to 71 degrees at the return however the leaving air temp at the ceiling register never dropped below sixty one. How little attic air could elevate this temp if it were being drawn after the evap coil. I have to do some sealing tomorrow. But its nothing really gaping or anything. Any experience with this for you? And I greatly appreciate your comments.

ductwok in attic insulated?/
is 11 degrees what the manuf. recommends???

[BigJon3475]

also is that with the system equalized out i think 20 minutes is what is recommended for heat and 15 for cooling. I thought the superheating chart was universal (meaning it doesnt matter what system) for outside drybulb entering the condenser and inside wetbulb entering evaporator.

[Heatcooltech]

Interesting you mention the humidity as I noticed that the condensate drain was not trapped and not producing. I have to say that the humidity was probably about 60%. I was wondering about the condensate buildup in the primary drain being a factor.

[BigJon3475]

Well design conditions should be 95 outside db and 75 inside with 50% RH unless the pros say different this is what I understand to be design conditions. Taking the wb inside temp helps to understand the amount of heat and moisture in the air. Now I'm thinking what d griff was about the ductwork...

[Heatcooltech]

ductwok in attic insulated?/
is 11 degrees what the manuf. recommends???

Yes ductwork is insulated and 12 degrees is what was legible however the chart was not in good condition. I am relatively sure that is close.

[BigJon3475]

http://www.acdirect.com/xcart/images/products/IO-258B.pdf

bottom of page 5 says db of 75 outside and db of 75 inside should be around 17 degrees of superheat i think your overcharged where are you recording superheat at 12 inches from the compressor or as close as possible to that in cooling and is it isolated from the ambient temps sorry if you already know all this just trying to get an idea...

[Heatcooltech]

Interesting you mention the humidity as I noticed that the condensate drain was not trapped and not producing. I have to say that the humidity was probably about 60%. I was wondering about the condensate buildup in the primary drain being a factor.
Anybody have any experience with this?

[Heatcooltech]

http://www.acdirect.com/xcart/images/products/IO-258B.pdf

bottom of page 5 says db of 75 outside and db of 75 inside should be around 17 degrees of superheat i think your overcharged where are you recording superheat at 12 inches from the compressor or as close as possible to that in cooling and is it isolated from the ambient temps sorry if you already know all this just trying to get an idea...
Appreciate the link. And Yes Isolated from the outdoor ambient. Approximately 12 inches from compressor maybe a little further. You know its funny that you bring this up. I had a superheat of about 17 degrees. When savvy home owner says he wants me to try adding some refrigerant as the T-stat at this point had not dropped off of seventy-five and it had been "at least 20 minutes." So I indulged him. I felt overcharged as the suction line was sweating profusely back to Herm. I checked T-stat moments later and was shocked to find temp still setting at 75. However it was enshrouded with indirect sunlight. Tried to explain to the man it was effecting the T-stats ambient temp. He wouldnt have anything to do with that theory. So I placed my $150.00 DT40 probe at the return 10 feet away from the stat and it registered 71 degrees. He raised his eyebrows. This is the kicker. Now he wants to replace the T-stat. I am going to diligently argue we move it. Having fun with this one. Hope hes not on here tonight as I dont want to offend anyone. However the leaving air temp did drop as a result of the added R-22. From 63 to 61. The T-stat dropped to 74 as well.

[BigJon3475]

And the coil is clean and clear and the airflow is the correct amount nothing blocking it fan not clogged? I have seen t stats mounted on outside walls be affected but if both inside and outside are the same shouldnt be an issue. Im assuming this is a fixed bore metering system....I was also under the impression that return air and exit air arent as important as making sure the system is correctly charged. Dont let the HO tell you what to do your the tech. Most people only think the tstat or freon either or nothing else could be wrong. Im still curious as to why there isnt any condesnate in the bottom of the pan. It takes time sometime after everything is said and done I have sat in an apartment for 30 minutes waiting for the temp to go down and it didnt move....I took the humidity level and relized that was why. I let it run for a while to get down to temp and it was fine it just needed to remove the moisture from the air. When its cooler outside like if it dropped a few degrees outside the more it drop the more efficient the condenser is and it starves the evaporator if its a fixed bore system.

[Heatcooltech]

And the coil is clean and clear and the airflow is the correct amount nothing blocking it fan not clogged? I have seen t stats mounted on outside walls be affected but if both inside and outside are the same shouldnt be an issue. Im assuming this is a fixed bore metering system....I was also under the impression that return air and exit air arent as important as making sure the system is correctly charged. Dont let the HO tell you what to do your the tech. Most people only think the tstat or freon either or nothing else could be wrong. Im still curious as to why there isnt any condesnate in the bottom of the pan.Tremendous airflow out of every register I checked. I have to assume that there is condensate in the pan its just not making it outside. There is no trap and it is a negative pressure drain. The condensation on the suction line, the suction pressure, and the suction line temp all suggest to me that the evap is sweating profusely. I dont see how it could not be. I dont think the evap coil is stopped up. Great airflow as I mentioned. New IDBM and clean sqirrell cage. I am wondering if this harbored condensate is going to contribute to leaving air temp elevation that coupled with a little attic air?

[BigJon3475]

And all sections of the suction line you see are well insulated...The suction line really shouldnt be sweating like that suggest an overcharge meaning the suction line is saturated and doesnt have the proper superheat and is colder than it should be. I'm not sure seems as though you know whats going on I think a pro needs to chime in cause I don't know much more at this point. Is it a fixed bore system....or expansion valve obviously it cant be an expansion valve if you adjusted the superheat with the charge...conditions stayed the same temp the whole time? I mean its still 75 inside and 75 outside the whole time? Check subcooling to see whats going on with the charge in the condenser well that would be my next step. If the head pressure and suction pressure coralate to what they should be and nothing seems funny.

[Heatcooltech]

And all sections of the suction line you see are well insulated...The suction line really shouldnt be sweating like that suggest an overcharge meaning the suction line is saturated and doesnt have the proper superheat and is colder than it should be. I'm not sure seems as though you know whats going on I think a pro needs to chime in cause I don't know much more at this point. Is it a fixed bore system....or expansion valve obviously it cant be an expansion valve if you adjusted the superheat with the charge...conditions stayed the same temp the whole time? I mean its still 75 inside and 75 outside the whole time?I totally agree with you The temp was dropping in the house it just was not registering at the stat. Temp at return made it to 71. Thats why I think something is warming the stat or it is faulty. Brand new York digital. HP stat. Yes fixed bore (sorry)