high head
low suction
19* split
high return temp
high supply temp
after you post superheat and subcooling we will most likely figure out you have clogged dryers!
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2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
Member, IAEI
AOP Forum Rules:
high head
low suction
19* split
high return temp
high supply temp
after you post superheat and subcooling we will most likely figure out you have clogged dryers!
true knowledge exists in knowing that you know nothing.
it is a split coil, one for each circuit.
true knowledge exists in knowing that you know nothing.
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2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
Member, IAEI
AOP Forum Rules:
funny!
molecular sieves, dessicants both silca and alumina gel are not good refrigerants?????????????
most likely once he cleans the condenser coils the head will drop and the suction will drop and the unit will not even stay on line!!!!!
and the evap coils are most likely dirty also!!!!!!!!!!!
true knowledge exists in knowing that you know nothing.
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2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
Member, IAEI
AOP Forum Rules:
It has cool right for the last few years, the building is due for being remodeled in less than a year, from what I've been told McDonalds requires a store to remain at one address for 20 years then can be moved to a newer building. This is the 2nd store that the owners bought.
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Is there a communication or language issue here, or is it just me....?
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2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
Member, IAEI
AOP Forum Rules:
Your head pressures seem very high, what was the out door ambient temperature at the time you took your readings. I was wondering when you checked the refrigerant pressures did you have the access door in place or was it left off.
It is hard to say because there was no outside ambient temp given like alcomech said, but your LS doesn't match HS pressures. You should be seeing more like 90psi LS. 275/90. I would look for blocked return vents or dirty evap because its effecting both stages.
first set of pressures was 86 degrees outside, todays pressures was about 85 at 9am. access door was opened just enough to let the hoses out for the manifolds to be outside the unit.
Checked evap, it was clean and filters were just replaced a few days ago. Didn't find any returns blocked but don't have camera to go thru the ducts up to the unit. I was able to feel air being pulled into the returns.
There's things to look for. If the return panel pulls in really hard you don't have enough return, if you leave return on and take off supply panels and LS psi increases then not enough supply. I've also ran into a situation where both txv power heads were blown on a 10ton split giving me similiar readings.Warm up the bulb with hand or warm rag and check psi. Just a couple of my opinions.. hope it helps.
I know rtu. I would pay attention to possible causes on the LS.
Return panel pulling hard..not enough return
Evap may appear to be clean..might have lacked proper cleaning by others
Filter screens may be blocked in the metering blocks..wrench apart if possible and clean
I would start simple, pm the unit completely and go from there. Clean evap for the hell of it, you may be surprised - surprised me in the past. So this way there is no second guessing
Your HS isn't that far off, but LS is.. I would say even if it were 85 ambient, on a roof more like 90
To put it in perspective, you have a high head pressure and suction pressure does not seem to be a major problem.
However you still have not indicated the super heat and at this point it is critical that you establish the actual sub-cooling, in addition you can indicate the approach.
You say that this unit does not have a TXV, so then it must have orifice nozzles as a metering device. Did you check for frost at the distribution tubes.
Have you verified Factory charge and if so what is it?, and did you weigh in a full charge.
To cover the basics have you checked the run cap and what is the actual MFD. Is the condensing fan motor running both on in the right direction. Did you verify this?
Have you taken a total external static reading on the Evap coil and if so what is the overall reading. What is your return static and what is supply static.
Circuit 1
Suction pressure: 67 psig
Head pressure: 315 psig
Circuit 2
Suction pressure: 65 psig
Head pressure: 250 psig
Yes I verified no frost, there was a leak on circuit 2 that I fixed and replaced filter drier, and weighted in the 7.4 lbs for the circuit that was called for.
Cap was replaced less than a month ago when roof PM was done, fan is running in right direction.
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Suction pressures pretty par for orphis header on the evap, I have never seen 1 run 70#suction or above