LG air to water heat pump via hydro boxes

[chillyblue]

Hi All

I've already written all this once but I think it disappeared so apologies if this is the second one!!

I have a air to water heat pump on a commercial premises supplying hot water at +70deg C
The system consists of two LG V5 series outdoor units feeding 4 x LG hydro boxes feeding water into a buffer tank.
I have a problem with the hydro boxes, on the refrigerant outlet of the hydro boxes (liquid line return to the outdoor units) I have had this freezing down to -13degC which froze the heat sinks on the side of the control boxes of the outdoor units and blew all of the inverter boards.
On the outlet at the hydro box is a eev which I believe should either be open or closed as if it modulates it would cause a pressure/temp drop on the liquid line causing evaporation, the outdoor units have their own eev's which were being starved due to the eev restriction at the hydro boxes, this caused a low load/poor performance at the outdoor units causing the outdoor unit heat exchangers to partially freeze.

I took the eev head off (the eev is the type with the pin Sanhua DPF 0 6.4 they unscrew, not the lift of heads) of the hydro box on the liquid line and the performance was perfect having a 40deg C temp either side of the eev the performance of the system was great no frosting on the outdoor unit heat exchangers and great performance at the hydro boxes, when i tried to get the eev head back on I had a bit of difficulty as both the pins on the head and the valve were fully extended (if anybody has any info on how to get these back together easier that would be great)

I'm assuming that either the eevs have got stuck, got dirt in them and are blocking or are not controlling properly, out of calibration and not opening or shutting properly or I have another problem I'm overlooking, I cant see why you would want the valves to act as a expansion valve when they are feeding eev's in the outdoor units???
I think the valves would be fully open when demand is required and then shut when not required.

Thanks in advance for your help
CB

[Brian_UK]

Do you have the hydrobox model numbers available please?

[chillyblue]

Hi Brian
the 4 hydro boxes are all model number ARNH08GK3A2

[frank]

Not worked on the LG AWHP kit but here is a link to the service manual for the outdoor unit - download the latest edition (date on the right)

The Hydro box details (only model K2A4 unfortunately) are under Multi V Indoor button

https://lghvac.com/resources/

[chillyblue]

Thanks Frank I’ll have a look ����

[frank]

Found the manual for the hydrobox. Page 29 & 30 show the fridge line connections and dip switch settings.

On the size 8, as yours, it says that the hydrobox should be connected to valves 1 & 2 due to the amount of fridge gas flow.

https://www.lg.com/uk/support/manuals

[chillyblue]

Hi Frank
I can’t seem to find it??

[Brian_UK]

Came across this manual, may be of interest.

http://www.google.com/url?sa=t&source=web&rct=j&url=https://www.toshibaclim.com/Portals/0/Documentation/Manuels%2520produits/SM_MuralKRTP-KRT_564804_GB.pdf&ved=2ahUKEwj9ne_InvfpAhXLEcAKHRrACHoQFjADegQIAxAB&usg=AOvVaw2ZaVWTtOHh-5uRhF49qJFF

[frank]

Hi Frank
I can’t seem to find it??

OK

Click on the link and paste your hydrobox model into the first box and click on the spyglass

This will bring your model up into the area below the box. Select it

Next Select the Catagory - Air Conditioning Systems

Next select VRF

Next select Multi Indoor Units

Then select your model number


Simples :D

[chillyblue]

Found the manual for the hydrobox. Page 29 & 30 show the fridge line connections and dip switch settings.

On the size 8, as yours, it says that the hydrobox should be connected to valves 1 & 2 due to the amount of fridge gas flow.

https://www.lg.com/uk/support/manuals

Hi Frank
Found the manual ok just cant find the part your refering too are you refering too page 21, thanks but it's direct feed we don't have any heat recovery boxes its for hot water only.

regaurds
CB

[frank]

page 29 says that size 8 should have 2x fridge lines connected based on gas charge. how is your system piped?

[chillyblue]

I think you’re looking at the wrong model mines a ARNH08GK3A2 I think you’re looking at a 3A4? also that’s for the connections to a heat recovery box!! I haven’t got any heat recovery boxes, it’s a 2 pipe system which is discharge gas and liquid line from the outdoor unit feeding down via refnet joints to each of the 4 hydro boxes

[frank]

My bad

Sounds like either a control setting error, faulty sensor or pcb

Is Function 17 set to ON or OFF?

[chillyblue]

Hi Frank

thanks, that was my thoughts I’m waiting to get the service tool so I can see more of what is happening, re the switch setting I’m not sure I’d would have to check, the 4 hydro boxes are controlled I believe by a bms system controlling capacity, do you know what that mode lock would do or it’s purpose ? LG’s explanation is not the best, I don’t understand the information they give????

[chillyblue]

Hi have you been able to resolve it?