Lennox unit head pressure control

[marc5180]

Last year i posted about a lennox unit we had inherited on a maintenance contract.
KVHK48.DVFC

http://www.refrigeration-engineer.co...ghlight=lennox

Since that post we have had so many problems with it it's untrue.
I got called to it the other day and circuit 2 was tripping on HP ( which is controlled by dampers ).
I checked the dampers and they were closed when the pressure was 24 bar. The dampers aren't seized and the actuator does move.

I can't find a service manual anywhere for this model and i tried to contact lennox but got no answer.

Does anyone know the range the dampers are supposed to work between?

Also what controlls it? I noticed a pressure transducer on circuit 1 but nothing on circuit 2.
There is only 1 actuator that controlls the dampers for both circuit 1 and 2.

[Grizzly]

Hi Marc
Logically they would be pressure controlled, obviously what refrigerant you are running on.
Would have huge bearing upon what your head pressure control of the dampers would be!
Like you I cannot find reference to this unit on the Lennox website.
What do you think?
Grizzly

[marc5180]

I managed to find a manual but it isn't much help, the unit is on r407c.
http://www.lennoxeurope.com/transfer..._KVHK-0404.pdf

It doesn't say much about the Condensing pressure control only on page 20
"Based on 2 dampers on the outdoor unit discharge air, which lets you control condensation temperature through air flow
The damper is moving by a servomotor, which receives a proportional signal throughnanpressure detector".

One thing that i noticed is that on page 9 it says minimum on coil temp of the indoor unit is +15C on cooling but the indoor is in the carpark outside and the air is ducted upstairs.

[Brian_UK]

Haven't found a manual yet but found some spec details if you want...

http://pdf.directindustry.com/pdf/le...29175-_34.html

Bottom of page 34/192

edit:
There you go, one Manual..

http://www.lennoxeurope.com/transfer..._KVHK-0404.pdf

[marc5180]

Thanks for that Brian.
The manual doesn't show anything about the head pressure control- what a surprise.

[Brian_UK]

Just says that it is a electric servo motor run off pressure transducers. As you have already said, sorry must read deeper into your posts. DOH!