PDA

View Full Version : should I install a TX valve



mak74
03-02-2011, 06:44 AM
Hi All,

Firstly apologies for my lack of correct terminology. I'm not a fridgie, just a sparky after some advice re TX valves.
Here's my story...
We have a "budget" 10 year old reverse cycle ducted system. From what I was told back then approx 8hp cooling capacity. R22
My issue is the unit doesn't get very cold on hot days and struggles during cold winters.
I've been considering replacing the lot but after googling for a while came across TX valves.
And after inspecting found there isn't a TXV on the evaporator. just the orifice.
Is it worthwhile installing a TX valve to such an old unit and would it make any noticeable difference?
The unit still runs fine just always a couple of degrees warmer in summer and cooler in winter than other units I've felt. (with a digi therm)
I always clean the condensor and filters and ensure proper air flow and tried all the other tips and tricks for getting the most from a/c but always assumed that was the best it could do.
I had a fridgie look at it a while back. He put his gauges on the condensor and said it needs a kilo of refrigerant which he put in. That was it.
I didnt know at the time but he didnt check superheat or subcooling or any of those things I keep reading about for setting the unit correctly.
So to cut it short...
Should I try installing the TXV first or bite the bullet and invest in a new one?
Any advice is much appreciated.

taz24
03-02-2011, 03:57 PM
Hi All,

Firstly apologies for my lack of correct terminology. I'm not a fridgie, just a sparky after some advice re TX valves.
Here's my story...
We have a "budget" 10 year old reverse cycle ducted system. From what I was told back then approx 8hp cooling capacity. R22
My issue is the unit doesn't get very cold on hot days and struggles during cold winters.
I've been considering replacing the lot but after googling for a while came across TX valves.
And after inspecting found there isn't a TXV on the evaporator. just the orifice.
Is it worthwhile installing a TX valve to such an old unit and would it make any noticeable difference?
The unit still runs fine just always a couple of degrees warmer in summer and cooler in winter than other units I've felt. (with a digi therm)
I always clean the condensor and filters and ensure proper air flow and tried all the other tips and tricks for getting the most from a/c but always assumed that was the best it could do.
I had a fridgie look at it a while back. He put his gauges on the condensor and said it needs a kilo of refrigerant which he put in. That was it.
I didnt know at the time but he didnt check superheat or subcooling or any of those things I keep reading about for setting the unit correctly.
So to cut it short...
Should I try installing the TXV first or bite the bullet and invest in a new one?
Any advice is much appreciated.
.

To know if changing it will improve it, firstly you need to know how it works.

If it has an orifce plate then there is no control of the refrigerant levels in the evap,
because the system is designed for a fixed amount of refrigerant.

On a TEV (TXV as you call it) the valve tries to maintain more regular
temps out of the evap so it will flood or starve the evap of liquid to do so.

The TEV will give more control and possible beter performance.


But and there is always a BIG BUT....

But why do you think the manufacturer designed it
like that in the first place. Cost mostly, cost of component
parts.

That means that the system is designed to work with
limited amounts of refrigerant and if you go changing a
key component such as the TEV then the whole system
may fail because of it.

Plus its not just a case of fitting a valve you would
need a liquid receiver to store the liquid if you have
a TEV fitted.

Leave it as is or replace the whole lot...
All the best

taz

.

paul_h
03-02-2011, 04:25 PM
Hi All,

Firstly apologies for my lack of correct terminology. I'm not a fridgie, just a sparky after some advice re TX valves.
Here's my story...
We have a "budget" 10 year old reverse cycle ducted system. From what I was told back then approx 8hp cooling capacity. R22
My issue is the unit doesn't get very cold on hot days and struggles during cold winters.
I've been considering replacing the lot but after googling for a while came across TX valves.
And after inspecting found there isn't a TXV on the evaporator. just the orifice.
Is it worthwhile installing a TX valve to such an old unit and would it make any noticeable difference?
The unit still runs fine just always a couple of degrees warmer in summer and cooler in winter than other units I've felt. (with a digi therm)
I always clean the condensor and filters and ensure proper air flow and tried all the other tips and tricks for getting the most from a/c but always assumed that was the best it could do.
I had a fridgie look at it a while back. He put his gauges on the condensor and said it needs a kilo of refrigerant which he put in. That was it.
I didnt know at the time but he didnt check superheat or subcooling or any of those things I keep reading about for setting the unit correctly.
So to cut it short...
Should I try installing the TXV first or bite the bullet and invest in a new one?
Any advice is much appreciated.
No.
Your fridge doesn't have a TXV but performs fine.
Heaps of a/c and refrig doesn't have a TX valve, they use capillaries or orifaces and work just fine.
A TXV is for variable loads and conditions, so it is better, but they also have a liquid receiver to store refrigerant for use. Your system would not have a liquid receiver (holding tank for excess refrigerant) if it never was designed for a TXV.
Systems without a TXV (eg cap or orifice systems) do not have a receiver to store refrigerant, and are charge to hold a precise amount of refrigerant (ie you can not just say it's short of refrigerant and charge some random amount in), but they work perfectly when designed, installed and charged right. If your 10 y/o system isn't working right, or never has, and it's a cheap budget unit, get rid of it.
I'm not a fan of chucking things away generally, and I prefer repairing stuff, but if it's a cheap no name brand without parts/support or people that know how to fix, it's the best option. Learn your lesson and buy a better supported brand so you don't have to throw away a unit in the future

mak74
04-02-2011, 12:50 AM
Thanks for the info guys.
Guess I'll go with the old "if it aint broke don't fix it" policy.
Shouldn't really complain about the unit... we got it for free! plus all the gear. I just had to install it then get a fridgie out to pipe and finish it.
Has served us well till now.
One day we'll have that ice box I've always dreamed of!

nassrifi
04-02-2011, 09:34 AM
Dear friend
I would not advice changing the metering device ( orifice odr cap. system ) to TEV, if the system is designed for fixed load.
As TEV's are used on systems that has a wide range in load verying.
As adviced from our friends above, live with it or change the whole old system.

best regards