pury250fmfb problem

[refaircon]

as title
ground floor system was short of gas, decant p/test find leak. re test and finally vac.#
no additional charge details, locate pipe work and measure liquids and calculate charge. all ok upto now
add the charge to system run it up, low side 40 psi, high side at 145 psi, taken from the valve connections
typical air on between 18 and 20, air off 10 to 18
un even temps around the coil,
any ideas?
condensor fan seems to be running very quick for my liking

now just to add to this there is a second system on the 1st floor same as above after i repaired a leaketc etc. calculated the charge and get the same results as above

once again any pointers

r22 systems

[philjd26]

check controllers are in cool or heat mode... when in mix mode you might get strange readings

rgrds phil

[refaircon]

the system is a 2 pipe system, all on heat or all on cool, no bs box or anything like that

rob

[Saturated]

g'day refaircon. I'd be checking your superheat and condensor subcooling first off. Can you get a temperature from the suction line leaving the evap and the liquid line leaving the condensor. Once you've got those you'll have a bit better idea to whether it's still S.O.G

[The Viking]

g'day refaircon. I'd be checking your superheat and condensor subcooling first off. Can you get a temperature from the suction line leaving the evap and the liquid line leaving the condensor. Once you've got those you'll have a bit better idea to whether it's still S.O.G

Sorry M8,

But these VRF systems are cleaver, they will modulate valves/open bypass valves/inject liquid, just to hide that they are short of refrigerant.

The only way to know for sure if you got the correct charge in a VRF/VRV system is to measure the piperun, calculate the correct charge and then reclaim the whole charge and weigh it.
:cool:

[Thermatech]

It must be a PUHY 250 YMF-B heat pump model.
These units I think still had one outdoor coil circuit although 2 coils arranged in V bank configuration 100% outdoor coil open to circuit all the time.
These units tended to have poor high pressure control & overcondensing problems.
The next model YMF-C split the two outdoor coils 50/50 with solenoid valve so HP control was much improved.

I know it was it bit cooler today but less than 10 bar is overcondensing big time.
45 psi suction is alot less than zero deg C so the indoor units will be going into coil frost prevention as the coil temp will be alot less than +1 deg C.

As you are sure the refrigerant charge is good I would suggest put the front panel over the outdoor fan & to make the air short circuit & or blank of some of the air inlet to the outdoor coil.
If no other problem with the system you will see the discharge presssure improve & also the suction pressure improve with it.
Aim for 225 discharge at this you should get the suction temp above zero & the system should be working much better & good performance at the indoor units with no coil frost prevention.
You can then make an accurate judgment of the refrigerant charge by looking at suction SH & discharge SH. You should get consistant AL1 liquid level at the suction accumulator ( SW1 dip & led display )

The system is possibly at least 7 years old & typically indoor units have LEV valve failure , locked fully open or fully closed. So turn off indoor units one by one with outdoor unit running in cooling & check for refrigerant bypass at indoor units switched off to confirm that the lev valve at each indoor unit does completely shut.

If the outdoor unit absolutly must provide cooling below about 20 deg C outside ambient then you will need to consider alternative low ambient fan speed control to prevent overcondensing.

[refaircon]

It must be a PUHY 250 YMF-B heat pump model.
These units I think still had one outdoor coil circuit although 2 coils arranged in V bank configuration 100% outdoor coil open to circuit all the time.
These units tended to have poor high pressure control & overcondensing problems.
The next model YMF-C split the two outdoor coils 50/50 with solenoid valve so HP control was much improved.

I know it was it bit cooler today but less than 10 bar is overcondensing big time.
45 psi suction is alot less than zero deg C so the indoor units will be going into coil frost prevention as the coil temp will be alot less than +1 deg C.

As you are sure the refrigerant charge is good I would suggest put the front panel over the outdoor fan & to make the air short circuit & or blank of some of the air inlet to the outdoor coil.
If no other problem with the system you will see the discharge presssure improve & also the suction pressure improve with it.
Aim for 225 discharge at this you should get the suction temp above zero & the system should be working much better & good performance at the indoor units with no coil frost prevention.
You can then make an accurate judgment of the refrigerant charge by looking at suction SH & discharge SH. You should get consistant AL1 liquid level at the suction accumulator ( SW1 dip & led display )

The system is possibly at least 7 years old & typically indoor units have LEV valve failure , locked fully open or fully closed. So turn off indoor units one by one with outdoor unit running in cooling & check for refrigerant bypass at indoor units switched off to confirm that the lev valve at each indoor unit does completely shut.

If the outdoor unit absolutly must provide cooling below about 20 deg C outside ambient then you will need to consider alternative low ambient fan speed control to prevent overcondensing.

i agree with the above, i reset all the lev heads, i removed the fan power and got a hell of alot better running pressures. may look at replacing the ambient sensor and then take it from there, or at least measure its resistance

rob

[refaircon]

I can't agree that there is no BC box.Please find it check all the hatches designated for a service of the system.Rememer when we found a leak on a old R22 system most of the flare nuts were cracked due to the age of the system constantly cooling /heating (shrinking /expanding)and this process makes the nut to crack . :cool:

i must say that you are completely wrong there is no bc box at all, this is a simple 2 pipe system with refnets on the mains branching off to each unit
condensor model is a mitsi puhy250ymfb
r22
i have gained acces to 99 percent of the pipework. so i know quite a bit of where the pipes etc go

[jteixiera]

you must becarfull with the puhy unit due to the capacity control on the condenser. basically you have a few solenoid valves on the condenser depending on the load then these valves will open up to diffrent sections of the coil. now you said yuo get strange reading in the mixed mode if this is the case yuo musy have a BC box somewere. a 2 pipi system cannot do mixed mode without a bc box. so i doont understand where yuo are running in mixed mode and if it is a heatrecovery unit it must ahve a bc box if that is the case please let me know as i cracked my brain on lots of old PURY 250 YMF units. i can point you in the right direction

[sinewave]

OP never mentioned a Mix Mode that was the first reply viewpoint.


Plenty of old R22 VRF's about without BC boxes

[refaircon]

you must becarfull with the puhy unit due to the capacity control on the condenser. basically you have a few solenoid valves on the condenser depending on the load then these valves will open up to diffrent sections of the coil. now you said yuo get strange reading in the mixed mode if this is the case yuo musy have a BC box somewere. a 2 pipi system cannot do mixed mode without a bc box. so i doont understand where yuo are running in mixed mode and if it is a heatrecovery unit it must ahve a bc box if that is the case please let me know as i cracked my brain on lots of old PURY 250 YMF units. i can point you in the right direction

i am running in cooling only mode, the 'mix' mode is not available due to it only being a 2 pipe refnet system!

does nobody read properly?
r22
2 pipes refnet
lev on each unit

[refaircon]

If the system is PURY...... IS HEAT RECOVERY if it is PUHY then it is heat pump.

Go get a good hunt and find the BC box.

the condensor is a condensor model is a mitsi puhy250ymfb

my mistake on the title