Expansion valve issues???

[Delta31]

I am having issues with a Lennox 410a 7.5ton heatpump system. The system has a dual evap coil ran off a single ciruit compressor. My running pressure are way off with my low side at 60 and my high side at 310. I have checked the lineset for any restrictions and could not find any, I have also checked th expansion valve itself to make sure the orifice was clean. I am not a 100% that my valves are sized properly, there are 2 4ton expansion valves on this coil. Is this correct for a 7.5ton condenser and can a singal circuit compressor handle this dual coil??

[ascj]

I am having issues with a Lennox 410a 7.5ton heatpump system. The system has a dual evap coil ran off a single ciruit compressor. My running pressure are way off with my low side at 60 and my high side at 310. I have checked the lineset for any restrictions and could not find any, I have also checked th expansion valve itself to make sure the orifice was clean. I am not a 100% that my valves are sized properly, there are 2 4ton expansion valves on this coil. Is this correct for a 7.5ton condenser and can a singal circuit compressor handle this dual coil??

Can a single compressor handle duel circuit coil?.....sure, it's common practice.

The orifices in the TXV's were clean......please explain that.

Other quesions.....what cfm you moving? What SH and SC you at? You have some models numbers to share?

[Delta31]

I opened up my valves thinking there was a screen but found a fixed orifice instead, it was clean of any obstructions. Not sure on the cfm and have not taken any sh or sc readings yet because I am thrown by my pressure's. It seems as though I have a retriction somewhere.

[prorefco]

what was the outdoor temp?? It could be low on charge...

[ascj]

I opened up my valves thinking there was a screen but found a fixed orifice instead, it was clean of any obstructions. Not sure on the cfm and have not taken any sh or sc readings yet because I am thrown by my pressure's. It seems as though I have a retriction somewhere.

Could it be you have fixed orifices and TXVs installed? I have seen it.

[ascj]

I opened up my valves thinking there was a screen but found a fixed orifice instead, it was clean of any obstructions. Not sure on the cfm and have not taken any sh or sc readings yet because I am thrown by my pressure's. It seems as though I have a retriction somewhere.

Could it be you have fixed orifices and TXVs installed? I have seen it. But not on Lennox, since the have the TXV's with the stem that prevents them being installed with the orifice still in place.

Please explain finding a fixed orifice in a TXV.

[Delta31]

ascj. No the orifice is inside the actual valve. Not sure if that is exactly what it is but it looks like one.
Prorefco. Out door temp was in the low 70's and the charge is not correct I know but when I and refrigerant it just brings up my head pressure.

[prorefco]

Sounds like a restriction alright... Your possibilities are liquid drier, liquid line, metering device (TXV, accurator etc), liquid line service valve, metering device for heating/check valve. What's the temp of the liquid line at the condenser and at the air handler? With a 60 psi suction, you shoud be seeing some frost somewhere....

[Delta31]

ascj. I unscrewed the bottom of the valve where the spring is located and inside where the refrigerant comes in is this Orifice. The best way I can explain it is a small cylinder with 2 small ports at the bottom where the refrigerant comes in and an open end that enters the main valve where the spring is located???

[Delta31]

Proefco. I had just ghanged out the dryer today after seeing my pressure's and the first thing I checked was for some kind of freezing. I could not find anything even at the txv. My line temp pretty much through the system was about 71-72.

[prorefco]

What kind of valve is this? Is it a TXV? (with power element?) What brand? WHat size? Is this a new start-up or an existing system that was working at one time?

[y7turbo]

I opened up my valves thinking there was a screen but found a fixed orifice instead, it was clean of any obstructions. Not sure on the cfm and have not taken any sh or sc readings yet because I am thrown by my pressure's. It seems as though I have a retriction somewhere.

stop guessing and take your subcooling and superheat readings.

We need this basic info to actually help you.

[Delta31]

Tis is a new start up! The valves were sent out with the equipment.... No power element, and I'm not sure on the brand. I'm really questioning the size on them, there both 4ton valves on this dual coil fed by a 7.5ton condenser.

[prorefco]

It sounds like there is a problem with your expansion valves but without more information (make, model, etc) and/or pictures, I'm not so sure we can help much...

[Delta31]

stop guessing and take your subcooling and superheat readings.

We need this basic info to actually help you.

Haven't taken them yet because if I add refrigerant my head just comes up and suction stays at 60

[Delta31]

It sounds like there is a problem with your expansion valves but without more information (make, model, etc) and/or pictures, I'm not so sure we can help much...

Thanks! I appreciate all the help boys! I'll be back at it in the morning... Hpefully will make some progress. Sorry for the lack of info on the valves.

[y7turbo]

Haven't taken them yet because if I add refrigerant my head just comes up and suction stays at 60

dont matter what your pressures do when you add gas, you NEED to take sh and sc readings to find out what the refrigerant is actually doing inside the system.

Are all your condenser fans on while your checking pressures?

[cboe]

is the unit fully charged? got to be fully charged before you can check SH properly.

[lane]

Is the line set the right size for the dual evaporators?

Lane

[VTP99]

Was it in front of a distributor ?