HELP!!! Sporlan TXV capillary system (power head)

[daveca]

Am working on a heat pump that had low pressure cutout due to low inlet pressure.

A high side Schrader core went 'volcano' in my face and lost the system charge, which was clearly already low due to poor performance.

Fixed that and it heats very well, but no AC. Low pressure cutout.

Found a broken indoor TXV capillary where it enters the bulb. The long cap tube had been improperly coiled and placed and the airflow and vibration broke it.

Sporlan 45 ZGA power assembly, 3 ton heat pump, 410A.

R/R the 'power head' either requires evacuation or losing charge during replacement.
Both options are poor IMO.

I really dont want to have to recover this sytem because thats, in part, embarassing...I ShOULD have caught the failure before recharging the system.

Sporlans tech data, and info on this site, suggest that for 410A, the thermo fluid might be put in a liquid phase by cooling and (mostly) confined to the bulb.

The capillary is 0.110 in. O.D., a common brass compression fitting size.

I have bought two new TXVs for other systems but that have the correct thermostatic assembly (45 ZGA)

Is it possible to freeze the new bulb in a freezer while leaving the head outside and elevated to cause a large delta T, to possibly freeze the bulb in a small block of ice, then take it to the unit, cut the cap tube and bulb from the new unit and connect it to the old power head cap tube (shortened) using a in line brass compression coupler?

Someone PLEASE say "yes"45zga.jpg

[TrevH]

I'd say no Daveca

The power heads are critically charged any loss takes them out of spec not to mention its a blend. Only way I see a solution is a new TEV.

But that being said ..... you could try as if it does work then you've saved time and money ???

Even though it's a heatpump you should still be able to pump down into one of the coils so you don't have to reclaim???

[daveca]

Excellent response. But it wasnt the "Yes" I was hoping for.

But reality. Yes, that bulb charge is critical. Theres not much of it in that bulb system and I dont know the volume above the diaphragm. The purpose of the cap tube is to commute the bulb volume with the volume atop the diaphragm. It may lose a lot of charge. Just because the charge may liquify with low temperature doesnt automatically mean it will also travel to the bulb.

Im getting two new TXVs, could sacrifice one for testing and if it doesnt work, then change out the other in is entirety.

(image)system.jpg


I'd considered suddenly dumping the liquid line charge into a temporary receiver tank, which unloads the right-side port of the TXV, then QUICKLY changing it. Then the TXV only sees the vapour in the indoor coil thru restrictions of the manifold tubes. That is only going to be a pressure loss from the indoor coil as the compressor has a check valve to prevent the rest of the system from also discharging.

General Custer also thought hed "quickly" defeat the Indians and lost.

Could do so at night with cooler ambient, 55F instead of 80, that would reduce system pressures and decrease the losses. That will take 50 psi or so away from equilibrium pressure.

??????

[daveca]

From Parkers Sporlan manual:

"As previously mentioned, the TEV’s sensing bulb transmits
pressure to the top of the diaphragm by a length of capillary
tubing. The thermostatic charge is the substance in the
TEV’s sensing bulb which responds to suction line temperature
to create the bulb pressure, and it is designed to allow the TEV
to operate at a satisfactory level of superheat over
a specific range of evaporating temperatures. The subject of
thermostatic charges is best approached by describing the
categories into which charges are classified.

These categories are the following:
1. Liquid Charge
2. Gas Charge
3. Liquid-Cross Charge
4. Gas-Cross Charge
5. Adsorption Charge

The conventional liquid charge consists of the same refrigerant in the thermostatic element that is used in the refrigeration system, while the liquid-cross charge consists of a
refrigerant mixture. The term cross charge arises from
the fact that the pressure-temperature characteristic of the
refrigerant mixture used within the sensing bulb will cross
the saturation curve of the system refrigerant at some point.
Both the liquid and liquid-cross charges contain sufficient
liquid such that the bulb, capillary tubing, and diaphragm
chamber will contain some liquid under all temperature conditions.

This characteristic prevents charge migration of the
thermostatic charge away from the sensing bulb if the sensing
bulb temperature becomes warmer than other parts of the
thermostatic element. Charge migration will result in loss of
valve control. An additional characteristic of these charges is
their lack of a maximum operating pressure (MOP) feature.

A thermostatic charge with an MOP feature causes the
TEV to modulate in the closed direction above a predetermined
evaporator pressure, thereby restricting flow to the evaporator
and limiting the maximum evaporator pressure at which the
system can operate.

Similarly, the gas charge consists of the same refrigerant in
the thermostatic element that is used in the refrigeration
system, while the gas-cross charge consists of a refrigerant
mixture. Unlike the liquid type charges, both gas charges are
distinguished by having a vapor charge in the thermostatic
element which condenses to a minute quantity of liquid when
the TEV is in its normal operating range. This characteristic
provides an MOP for the valve at the bulb temperature at
which the liquid component of the charge becomes vapor.
Above this bulb temperature, a temperature increase does
not significantly increase thermostatic charge pressure,
limiting the maximum evaporator pressure at which the system
can operate. A disadvantage of this type of thermostatic
charge is the possibility of charge migration."

This thermostat system is a GA charge, I dont know which type that is.

Ive Emailed Parkers Sporlan Div asking.

[daveca]

From Parkers Sporlan manual:

"As previously mentioned, the TEV’s sensing bulb transmits
pressure to the top of the diaphragm by a length of capillary
tubing. The thermostatic charge is the substance in the
TEV’s sensing bulb which responds to suction line temperature
to create the bulb pressure, and it is designed to allow the TEV
to operate at a satisfactory level of superheat over
a specific range of evaporating temperatures. The subject of
thermostatic charges is best approached by describing the
categories into which charges are classified.

These categories are the following:
1. Liquid Charge
2. Gas Charge
3. Liquid-Cross Charge
4. Gas-Cross Charge
5. Adsorption Charge

The conventional liquid charge consists of the same refrigerant in the thermostatic element that is used in the refrigeration system, while the liquid-cross charge consists of a
refrigerant mixture. The term cross charge arises from
the fact that the pressure-temperature characteristic of the
refrigerant mixture used within the sensing bulb will cross
the saturation curve of the system refrigerant at some point.
Both the liquid and liquid-cross charges contain sufficient
liquid such that the bulb, capillary tubing, and diaphragm
chamber will contain some liquid under all temperature conditions.

This characteristic prevents charge migration of the
thermostatic charge away from the sensing bulb if the sensing
bulb temperature becomes warmer than other parts of the
thermostatic element. Charge migration will result in loss of
valve control. An additional characteristic of these charges is
their lack of a maximum operating pressure (MOP) feature.

A thermostatic charge with an MOP feature causes the
TEV to modulate in the closed direction above a predetermined
evaporator pressure, thereby restricting flow to the evaporator
and limiting the maximum evaporator pressure at which the
system can operate.

Similarly, the gas charge consists of the same refrigerant in
the thermostatic element that is used in the refrigeration
system, while the gas-cross charge consists of a refrigerant
mixture. Unlike the liquid type charges, both gas charges are
distinguished by having a vapor charge in the thermostatic
element which condenses to a minute quantity of liquid when
the TEV is in its normal operating range. This characteristic
provides an MOP for the valve at the bulb temperature at
which the liquid component of the charge becomes vapor.
Above this bulb temperature, a temperature increase does
not significantly increase thermostatic charge pressure,
limiting the maximum evaporator pressure at which the system
can operate. A disadvantage of this type of thermostatic
charge is the possibility of charge migration."

This thermostat system is a GA charge, I dont know which type that is.

[TrevH]

What 'type' of unit is this Daveca?

The reason I ask is that most units types have the facility to 'valve' off parts of the system and then you wouldn't need to use a reclaim cylinder and recovery unit.

Draw yourself a schematic of the pipework and you'll be able to work it out

[daveca]

What 'type' of unit is this Daveca?

The reason I ask is that most units types have the facility to 'valve' off parts of the system and then you wouldn't need to use a reclaim cylinder and recovery unit.

Draw yourself a schematic of the pipework and you'll be able to work it out

Its a residential heat pump package with no isolation valves. Trane XL14.

(sad trombone)

UPDATE- Parker Hannifin tech support says " cannot be done"