View Full Version : Danfoss TXV with MOP

31-10-2007, 07:49 PM
I have a problem in three cases and one frezzer island:
I instaled TXV with MOP in my cases and island but when reach the MOP point close and stay close. If I change those valves for sporland it will be ok., but I want to find out how to handle those?.
I am in Dominican Republic (Caribbean Area). Thanks

01-11-2007, 04:02 PM
Hi there,

The TEV head must be little bit warmer than the bulb, otherwise the valve will close. Somehow you have to create this temperature difference. I had the same problem once and I solved it by wrapping the head with heating element (of course very little wattage).

Hope this helps.


01-11-2007, 05:02 PM
Hey Chap!

A Tev With A Mop(maximum Operation Pressure)is Specifically Installed In Island Freezers And Freezer Installations So That After Defrosts And Other High Load Conditions The Compressor Does Not Overload.keeps The Suction Pressure At A Max.when The Max Is Reached The Valve Closes Off.same As Cpr (crankcase Pressure Regulator).
If You Install A Normal Low Temp Valve With No Means Of Throttling The Suction And Dont Have A Cpr.good Chance The Compressor Will Overload After Defrost Or When Cabinet Is Warm And Probably Cook.

750 Valve
02-11-2007, 11:28 AM
If it shuts off at hi suction pressures and stays shut (with hi pressure still) then this is how it works, drop the suction pressure and it will open up again. If it shuts off at hi suction pressures but will not open back up once suction drops below MOP rating then you have a problem.

02-11-2007, 06:58 PM
I heard a whisper about a certain batch of valves.

Iceman Ian
03-11-2007, 12:22 PM
I heard the same whispers MarkFiddy. But as 750 valve remarks, if the valve remains closed at low suction below MOP, then it will be a faulty TXV. Replace the valve.

05-11-2007, 12:44 AM
I heard a whisper about a certain batch of valves.
Not unheard of ,a MOP valve is made by undercharging the power element and are easy for the factory to make a mistake , I had a sporlan like that I took it back to the supplier who said it wont bed the head , I got him to pull 2 more off the shelf put all 3 bulbs in a glass of cold water then used a straight edge and calipers to measure the diaphram distance , sure enough the one he gave me was a few milimeters short giving the high super heat

07-11-2007, 02:44 AM
One suggestion is to call Danfoss technical support and have pressure readings and such on hand for them to assist in the problem solution. Otherwise stick with what works.

14-11-2007, 10:39 PM
Often MOP with Danfoss might work erracticly since the head is maintained colder because closer outlet(evaporator) connection. With Sporlan, the inlet (higher liquid temperature) will often maintain the head at a higher temperature.