Why is suction gauge reading retard during charging?

[acrefconsultant]

Hi all,

A quick question i am currently charging a medium size dorin compressor for a cold stor application. The system was recently vacced. I am in the process of charging the system by weight to its full charge. Due to the fact that the system is R404a i am charging on the liquid side. However whilst i am charging (system is turned off) the suction side gauge on the manifold is going into retard.

Could somone expalin why this is happening and how i can overcome this?

Thanks in advance

[sedgy]

hi there, are you saying thatwhen you started liquid charging the suction gaugue wes showing a vac?

[acrefconsultant]

No i triple vacced the system and the i started charging the system with R404a. As i was charging via the discharge service valve (compressor off) the suction gauge was increasing to the point where the suction gauge reaqds retard basically off the scale.

Why is this and is this a problem?

[Grizzly]

Hi acref.
Like Sedgy confused by your terminology. ( "retarded means backward!")
If on the other hand you mean that this suction gauge is rising and rising.
I suspect that a discharge valve is passing.
Therefore as the high side pressure rises so does the Suction side?

What do you think?
Grizzly

[tbirdtbird]

Low side gauge can only read accurately to 120. Assuming U are charging at room temp say 70*F the hi side s/b reading about 149, which lo side gauge cannot do. So, in other words ignore low side under these conditions. why not charging from both sides?

[monkey spanners]

I had a set of gauges years ago (robinair?) where the last part of the suction range was of a different scale so the needle would move less for a given pressure increase and this section was labeled 'retard' i guess it is to cope with high standing pressures and heatpumps.
I think this is what acrefconsultant was on about.

Jon

[Shibhrac]

If you mean the low side gauge read the maximum while you were charging the refrigerant in the liquid phase from the discharge line and the compressor was not running .for me that means either the solidnoid valve is passing, fully oppen ,not existing in the system . Or compressor valve is passing and assuming all that when your gauge was properly fitted.

[taz24]

Hi all,

A quick question i am currently charging a medium size dorin compressor for a cold stor application. The system was recently vacced. I am in the process of charging the system by weight to its full charge. Due to the fact that the system is R404a i am charging on the liquid side. However whilst i am charging (system is turned off) the suction side gauge on the manifold is going into retard.

Could somone expalin why this is happening and how i can overcome this?

Thanks in advance


Hi There.

The retard on the suction just means the suction gauge is at the limit of its range and the retard just means lower the pressure to the gauge, or retard the pressure.

The reason why it happened could vary.

one reason could be you had the suction valve on the gauge manifold open so the liquid went into the comp suction as well as the receiver.

another reason is it would be normal if there was no solenoid valve fitted into the liquid line or the mag valve is faulty and passing.

It could be normal dependant on the system.
Let us know the type of system and we will be able to offer more advice.

Cheers taz.

[HallsEngineer]

Possibly the TEV was open and you had left lifting magnet on from evac?

[acrefconsultant]

The system has a solenoid valve on the liquid line prior to the TXV. It did occur to me that the solenoid valve was open and letting by. However after further investigation i found that the remote condenser had a pinhole leak on the coil which was very dfficult to spot.

And before anyone comments i did pressure leak test the system to 1xPs before i vacced. However the dam leak was on the enlarged section of pipework entering the condenser. Basically the section that links all the condenser coils into one manifold.

Anyway will attempt the process again once the leak is fixed and see if the issue is not persisting.

Thanks again for all your help and comments.

[paddyaircon]

a leak on condensor wouldnt cause low gauge to read high on charging- suspect ur low gauge is either on high side or possibly on reciever?