Daikin VRV probs PLEASE HELP

[ukcragrat]

1st time I’ve asked a question on here so go easy with me guys, any how we’ve just taken over a new building with a Daikin VRV system, all the staff in the building have complained that the system hasn’t worked correctly for 11 years, which is not the thing you want to hear straight away, the system is made up of one RXY10 KY1 and a RNY10KY1 outdoor units, there are about 12 indoor ducted units and a BL2K control module, the 1st visit showed that the system worked only slightly in heating i.e. temps out of the indoor units to be around 29 to 30 C with strange back pressures on the common suction line on the non inverter unit i.e. around 90 to 100 psi, in cool the temp out of the indoor units was around 22 C so no work being done, again high back pressures, the suction pipe was also warm to hot going back to the comp, on talking to Daikin help desk in Auckland we came to the conclusion that the 4 way valve in one of the outdoor units was maybe not seating correctly, because the suction pipe was a lot hotter on the unit that the other, so after changing the 4 way valve, it was tested again and I was getting between 35 and 45 C out of the indoor units in heat, with very acceptable pressures this time i.e. back pressure of 55 psi and a head of 200psi, by the way it’s running on R22, but when it was tested in cooling I was getting a slight improvement of 18 C off indoor units but nowhere near what it should be and again high back pressures, sorry can’t remember what the head press was. Could it be a problem with the BL2K unit? Just wondered if anyone else has come across the problem? Daikin has really said that there is no one in the country (NZ) who knows about these old systems anymore, so they are no help. Would be interested in any comments. Cheers guys. Alex

[stufus]

Hey Alex
The first thing to do is remove the charge and weigh it ,then calculate the actual required charge.Pressure test and verify system integrity.Pull a deep vacuum and recharge with virgin refrigerant.Until all this is done you will just be chasing your tail.You may have non condensables in the refrigerant or You could have crossed pipes or BS valves passing impossible to say.I'm presuming it's a simultaneous heating and cooling system as im not to hot on Daikin model numbers.
Cheers
Stu

[ukcragrat]

Hi Stu

Thanks for the reply, the thought of removing all the refrigerant is very daunting, the pipe length of the system is going to be very awkward to calculate, I know I could just go by what I take out, but who’s to say it was charged right in the first place, as for new R22, we will have to forgo that one as no one in this area has any new R22 in stock. I’m going back to site tomorrow for another head scratching session.

Alex

[r.bartlett]

Unless you get the charge right you're wasting your time sitting there scratching your head.

Connect a Daikin service checker to the PCB and then F1f2 for a few days and see what readings you get. Failing that get D.NZ to do the same and send it to matey boy in Belgium to have a look at. It is possible you have one indoor unit mis piped..take a day to go round and check the BS boxes and measure the piping at the same time. Where are you taking your pressure/temp readings?

[stufus]

Hi Stu

Thanks for the reply, the thought of removing all the refrigerant is very daunting, the pipe length of the system is going to be very awkward to calculate, I know I could just go by what I take out, but who’s to say it was charged right in the first place, as for new R22, we will have to forgo that one as no one in this area has any new R22 in stock. I’m going back to site tomorrow for another head scratching session.

Alex

The whole idea of weighing the charge out is to find out if it was ever charged right.
Unfortunately it's a necessary evil .Believe me no one likes retracing pipe routes as r.bartlett says you can give the piping and branch selectors the once over as you go.
Failing that you'll be an expert head scratcher by the end of it all.
Cheers
Stu

[ukcragrat]

Not fussed at the moment though guys as we have just had another massive aftershock here in Christchurch. Last thing on our minds is airconditioning at the mo. Cheers for the help. Alex

[jbomba]

The first thing i would have done would be to check all the 4 way valves if they are stuffed you can usually hear them hissing and feel the discharge bypassing directly into the suction line. As for your cooling problem id check your suction pressure transducer against the readings in the service manual. Other than that your gonna have to go through the tedious process of measuring all the lengths & pipe sizes of your liquid line throughout the building and charge the thing properly. do your air offs correlate with your back pressures?