Brivis ADD on Cooling Frosting back

[Scottymiles]

Hello, My name is Scott.
I have used this forums many times to solve problems but never have I needed to post.

I have been working on a Brivis ADD on Cooling system 18KW for the last few days with a problems I can't seam to nut out. I'm at a point on this machine that I have no where to turn.

The service call was system Icing back to the compressor, The bozo that works on the machine before me ( Plumber ) Assumed it was short, Pumping it down, pressure testing the field piping finding no leaks ( Amazing :rolleyes::rolleyes: ) At this point he opened the Service valves filling the system with nitro - Destroying the refrigerant. I replaced the refrigerant R22 and the 3/8 LIQ line dryer.

After an hour of running the suction line began to once again freeze up, I added a extra 1KG or so of R22 to make up for the 18M of 1 1/8 Suction line for good measure. Standard Holding is 3.9KG.

Still freezing - Suction Pressure up around 40-50PSI Slowing dropping as the indoor coil freezes.
Replaced TX Valve- Still freezing.
Checked all airflows removing flex from both sides of evap box - and checking heater.

I am absolutely out of idea's, The super heat is within spec - The heater is big enough for the add on cooling Evap Box.

The Coil doesn't seam blocked and it higher then the Condencer ( No oil Blockage )
Frost is developing directly out of the TX Valve.
The LIQ line isn't very warm by the time it's entering the Evap - 2 storey House and uninsulated.

What sort of issues would I see if water was present in the system?
Can I do a oil Check for moisture?

Any help would be fantastic.

Scott Miles

[Brian_UK]

Was there any indication of moisture during your vacuum test?

[Scottymiles]

Thanks for reply.
No I pulled the unit down to 500mic. And put in new Gas.

I'm totally stuck, I think the heater may not be flowing enough air over the coil, But only to the point of 200 or so litters under the spec's, And I'm not sure if that would cause it to ice up so quick.

I'm going to install a sight glass before the TX to get an idea if the coil is getting full LIQ, The TX Bulb is correct and insulated, no blockage on equalizing line either..

[Magoo]

Hi Scott
low air flow over evaporator will give those symptoms, may have been initial problem before the plumber arrived. R22 & 40 >50 psig suction will freeze coil as heat load not balanced with compressor capacity.

[Scottymiles]

Hi,

Thanks for the reply.
I do think airflow also But I'm not 100%.
I will increase the fan speed in the heater to flat out and remove the flew from the out going of the evap box for best testing.

The liquid line is only slightly warm as it leave the condenser, I have lowered the outdoor fan speed to try and build up some heat in the coil and raise he head pressure a touch, But to not much use..

Heading to site with a brivis Tech in the next couple of days, I will let you know what we find.

Scott

[Magoo]

Let us all know the out come of further tests.