Lennox chiller exv replace

[W.Miller]

Has anyone ever replaced a tq55 expansion valve on a Lennox lch chiller with success?? Would interested in this as I'm looking for a fix for a lch range chiller. I've fitted new valve and driver, just can't get chiller to recognise it.

[install monkey]

if its carel controlled- u need to address the driver- on the white box-flip off the lid and theres a tiny row of dipswitches

[W.Miller]

The driver I fitted was an ekc 316a, along with an ets 50b, pressure transmitter and sensors. The Lennox control has a 0-10v signal going to the original bored. I'm confused as to what to do with this 0-10v output. The new kit is 24v. If you could answer this would be a great help @install monkey

The only dip switches are on the controller bored I think. I will check manual again.

[W.Miller]

Its a Danfoss expansion valve and driver

[HVACRsaurus]

Hi Mr Miller,

I am thinking the 0-10v signal would become redundant - just terminate it individually in some connectors or spare terminals.

The 316A/ETS50B should be happy to do its own thing - it has it's own pressure / temperature sensors as you've mentioned - but it does need an "Enable" digital input (terminals 1 + 2). This enable is often connected to something like a compressor run auxiliary or even just bridged out depending on the application.

I doubt the Lennox controller will have the smarts to realise the original TQ valve is no longer there, if it does just connect all the original kit up again - but just leave the TQ laying about inside the package as a dummy.

[W.Miller]

The problem with leaving the old tq valve in place is the chiller is seeing a faulty valve so it is alarmed out on expansion opening fault. So with out letting the chiller control this the chiller won't tell the compressor to come on. This is the issue I've got. Unless I'm over looking something?

[HVACRsaurus]

What is the controller for the TQ, is a Lennox module or Danfoss controller?

The 0-10 volt, is it going to or from the "chiller" controller?

[W.Miller]

It's the Lennox module VOPT the 0-10v comes from the kp04 to the opto board and activates 24v signal to tq55 valve, but it's looking for it opening and I think also a temp as tq had sensor in built.

[HVACRsaurus]

Hi,

I'm sure you understand - its a matter of figuring out how to provide the necessary circuit to make the controller happy, but first of all, identifying which circuit it is making the alarm.

Consider the four kinds of input / output & their ability to activate an alarm within the controller

Digital input - Yes
Digital output - No
Analog input - Yes
Analog output - Generally No.

The other consideration is Communications, but probably not applicable in this instance.

So, yes the alarm might be temperature feed back from the TQ head - unfortunately I do not know what kind of signal this is. Measurements could be taken from a serviceable TQ, or enquiry could be made through Danfoss.

However, chances are it some sort of resistive device that changes with temperature (as most temperature sensors are) & chances are it could be a Pt1000 ohm as often used by danfoss controllers.

I'd suggest acquiring a Pt1000 sensor & connecting it to your wiring in place of the TQ feedback sensor (terminal 35? + 36? in TQ head). It may be necessary to "warm" the sensor up in some hot water (to simulate a "warm" TQ head). If this happens to work its a matter of measuring the temperature of the water (with a thermometer) that keeps the controller happy, then referring to Pt1000 temperature / resistance charts, identifying the equivalent resistance & then installing a fixed resistor in the circuit for continued operation.

Getting a bit long winded now but....

Further clarification of TQ temperature sensor could be made by connecting Pt1000 to terminal 17 + 18 of Danfoss AKC315A & referring to service parameter u04.

Further again, if the chiller package happened to be available with different TX valve options from the factory - say conventional TXV versus Electronic XV - there may be a parameter in the chiller controller to alter this selection & then the controller would stop checking for this alarm condition.

Happy hunting.

[W.Miller]

As chiller is looking for a resistance due to tq valve warming up. I've removed the sensor and put in a 10k potentimeter that's adjustable and set the resistance as per needed. The circuit ran :) Just gonna continue to test it and tweak settings.

[W.Miller]

Thank you for your time and help HVAC

[HVACRsaurus]

Good work!