Hi-Velocity RPM-E-100 Installation Manual - Page 6

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Hi-Velocity RPM-E-100 Installation Manual

Troubleshooting the TXV

When issues arise that bring the function of the TXV into

question, factors must be looked into before replacement.

Inspect the TXV for signs of damage. This may be from a pinched

equalizer line to a burnt valve. These issues will have an adverse

affect on the operation of the valve. Should the equalizer line be

pinched, the valve will no longer be able to supply the proper

amount of refrigerant to the coil. A burnt valve may have an effect

on the refrigerant charge of the TXV bulb or the seal of the valve.

This may again cause an improper amount of refrigerant to be

metered by the valve or cause the valve head to become seized.

The TXV bulb location and mounting should also be inspected.

The bulb should be securely mounted on the top half of the

suction line. If the bulb is loose or on the lower half of the line, the

bulb will not properly sense the refrigerant temperature and will

not meter the proper amount of refrigerant. Ensure that the bulb

is also properly insulated, as a lack of insulation will expose the

bulb to conditions well outside those of the coil. This will cause an

overfeed of refrigerant to the system.

Should the installation of the valve be proper, and no damage

is evident, inspect the operation of the valve. If the TXV bulb

is removed and held in ones hand, the valve should react

accordingly. This sudden increase in heat will open the valve. This

will cause a rise in suction pressure and a drop in liquid pressure.

Should nothing happen, the valve is likely seized and will need to

be replaced.

Short Cycling

Short cycling is the unnecessary running of the indoor

Specifications

Matching Fan Coil

Part Number

Tons

(1)

Refrigerant Type

TX Cooling MBH

(2)

Latent Cooling MBH

Fin Material

Tubing Material

Type of Fins

Liquid Line (Lq)

Hydronic

Connection

Suction Line (S)

Sizes

Drain Connection

TXV with Built in Check Valve & Bypass

Site Glass

Access Ports

Freeze Stat

Shipping Weight

Module Size (L x W x H)

(1) Minimum of

Minimum of four HE outlets

four HE outlets per ton of cooling needed. (2" Duct = Minimum

per ton of cooling needed. (2" Duct = Minimum eight outlets

(2) Smaller condensers may be matched to the fan coil when needed (match TXV to condenser size)

www.hi-velocity.com

and outdoor unit, on and off. This often takes the form of very

short and frequent on cycles. There are many factors that may

contribute to short cycling of the refrigerant system. These issues

can generally be broken down between airflow related issues,

refrigerant issues, and installation issues.

cycling. As the airflow rate is lowered across the cooling coil, the

coil pressure drops along with it. This lowers the temperature of

the coil and may cause the freeze-stat to trip. As the system settles,

the freeze-stat closes and the cycle begins again, as the unit

does not run long enough for the space to become adequately

conditioned. Ensure that the proper amount of airflow is provided

to the coil. Check for proper air flows and return air practices.

An undercharged system will react much the same as a system

with low airflow. If the charge is low enough, it may trip out on

low pressure. If a system is overcharged, it may trip out on high

head pressure. Ensure that the system charge is within the bounds

described in section "Piping the RPM-E".

Piping practices should be within the bounds described in section

"Piping the RPM-E" and within the realms of the outdoor unit

manufacturer. Extreme and often unnecessary adjustment of

the TXV can create conditions similar to an undercharged coil. A

poorly placed T-stat, such as underneath a vent, can cause short

cycling. This happens due to the T-stat being satisfied very shortly

after the unit has begun to operate.

RPM-E-50

HE-Z/HE-B/HE-50/51

HV-50/51/52

LV-50

20090200050

1.5 - 2.0

(5.3 - 7.0 kW)

R-410A

18-24

(5.3-7.0 kW)

6.8-8.9

(2.0-2.6 kW)

Aluminum

Copper

.006 Al

(0.1524mm)

3/8

(9.5mm)

7/8

(22.3mm)

3/4

M CPVC

(19mm)

Yes

48 lbs

(22kg)

" x 14

" x 18

1 ⁄4

5 ⁄8

1 ⁄2

(489mm x 371mm x 470mm)

eight outlets per ton)

per ton)

-6-

Refrigerant Module Installation

Low airflow rates are one of the most common causes of short

Improperly charged systems run the risk of short cycling as well.

System set-up and installation should be checked as well.

RPM-E-70

HE-Z/HE-B/HE/HV-70/71

LV-70

20090200070

2.5 - 3.0

(8.8 - 10.6 kW)

R-410A

30-36

(8.8-10.6 kW)

11.7-13.7

(3.4-4.0 kW)

Aluminum

Copper

.006 Al

(0.1524mm)

3/8

(9.5mm)

7/8

(22.3mm)

3/4

M CPVC

(19mm)

Yes

59 lbs

(27kg)

1 ⁄4

5 ⁄8

1 ⁄2

" x 14

" x 18

(616mm x 371mm x 470mm)

MBH - Thousand British Thermal Units per Hour

TX - Thermal Expansion

TXV - Thermal Expansion Valve

Module RPM-E

RPM-E-100

HE-Z/HE-B/HE/HV-100/101

20090200100

3.5 - 5.0

(12.3 - 17.6 kW)

R-410A

42-60

(12.3-17.6 kW)

16.0-22.2

(4.7-6.5 kW)

Aluminum

Copper

.006 Al

(0.1524mm)

3/8

(9.5mm)

7/8

(22.3mm)

3/4

M CPVC

(19mm)

Yes

74 lbs

(34kg)

5 ⁄8

1 ⁄2

32" x 14

" x 18

(813mm x 371mm x 470mm)