Heat Controller R410A manual R410a Application and Service Guide, Th

R410a Application and Service Guide

An overcharged TXV unit can be identified by:

•High subcooling

•High head pressures

Even though R410a has a very small fractionation po- tential it cannot be ignored completely when charging. To avoid fractionation, charging a system with R410a should be done with LIQUID from the tank to maintain optimum system performance. To ensure the proper blend of refrigerant is used, it is important that liquid only be removed from the storage tank. Some cylinders use dip tubes which allow liquid to be extracted from the cylinder. These can be identified as recovery tanks with yellow tops and gray bottom and have a dual liquid and vapor valve assembly. Storage tanks without dip tubes will need to be tipped upside down in order for liquid to be removed. Once the liquid is removed from the storage cylinder, it can be charged into the system in the vapor state as long as all of the refrigerant is used from the charging cylinder. Liquid charging can be accomplished by using:

Figure 3. Th

•A throttling valve (Figure 3) to ensure the liquid vaporizes as it enters the suction line of the unit.

•Τhe gauge set valve as a throttling device to restrict liquid from flooding the compressor during charging.

Recharging should always be accomplished by using the nameplate charge. When this is not possible, charging us- ing the subcooling method can be done using the follow- ing procedure. This method requires accurate gauges and a digital strap-on temperature meter.

1.Operate system for 10 minutes to stabilize.

2.Ensure that the unit has proper water and air flow and the air filter is clean.

3.Attach gauges to discharge port and record the saturation temperature at this pressure using a pressure/temperature chart for R410a.

4.Measure the liquid line (LL) temperature (between aircoil and TXV in heating and between coax and TXV in cooling).

5.Subtract the LL temperature from the saturation pressure to find the subcooling. Consult Table 4 for appropriate values.

6.If the subcooling is too low add 2-4 oz.; if too

high, remove 2-4 oz. Typical values are shown in Table 4.

Superheat can be calculated similarly. This method also requires accurate gauges and digital strap-on thermometer.

1.Operate system for 10 minutes to stabilize.

2.Ensure that the unit has proper water and air flow and the air filter is clean.

3.Attach gauges to suction port and record the satura- tion temperature at this pressure using a pressure/ temperature chart for R410a.

Table 4. Typical Pressure and Temperatures (HTV060 Shown)

HTV060			Full Load Cooling - without HWG active						Full Load Heating - without HWG active
Entering	Water	Suction	Discharge	Super-	Sub-	Water	Air Temp	Suction	Discharge	Super-	Sub-	Water	Air Temp
Water		Pressure	Pressure			Temp Rise		Pressure	Pressure			Temp Drop
TempºF	Flow GPM	PSIG	PSIG		cooling	ºF	DropºF DB	PSIG	PSIG		cooling	ºF	RiseºF DB
	7.5	1 17-127	170-190	27-32	15-20	18.2-20.2	17-23	66-76	282-302	10-16	9-14	8-10	19-25
30	1 1.3	1 16-126	143-163	28-33	13-18	12.6-14.6	17-23	69-79	285-305	10-16	9-14	6-8	19-25
	15.0	1 15-125	135-155	29-34	12-17	7-9	17-23	72-82	289-309	10-16	10-15	4-6	20-26
	7.5	128-138	238-258	16-21	14-19	20.5-22.5	21-27	90-100	310-330	1 1-17	12-17	1 1.3-13.3	24-30
50	1 1.3	126-136	222-242	21-26	13-18	14.9-16.9	21-27	95-105	313-333	1 1-17	12-17	8.5-10.5	25-31
	15.0	125-135	205-225	26-31	12-17	9.2-1 1.2	21-27	99-109	316-336	1 1-17	12-17	5.7-7.7	26-32
	7.5	135-145	315-335	10-15	14-19	21-23	22-28	1 15-125	337-357	12-18	14-19	14-16	28-35
70	1 1.3	134-144	296-316	12-17	13-18	15.5-17.5	22-28	120-130	341-361	12-18	14-19	10.6-12.6	29-36
	15.0	133-143	276-296	15-20	1 1-16	10-12	22-28	126-136	345-365	12-18	15-20	7.3-9.3	30-37
	7.5	139-149	408-428	10-15	15-20	20.1-22.1	21-27	157-167	390-410	15-20	14-19	18.2-20.2	37-45
90	1 1.3	138-148	386-406	10-15	13-18	14.8-16.8	21-27	161-171	394-414	15-20	14-19	13.9-15.9	38-46
	15.0	138-148	364-384	10-15	1 1-16	9.5-1 1.5	21-27	166-176	398-418	15-20	15-20	9.6-1 1.6	39-47
11 0	7.5	144-154	515-535	8-13	14-19	19-21	20-26
	1 1.3	143-153	493-513	8-13	13-18	14-16	20-26
	15.0	142-152	469-489	8-13	12-17	9-1 1	20-26

HWG should be disabled for accurate chart comparison

*Based on Nominal 400 cfm per ton airflow and 70° F EAT htg and 80/67° F EAT cooling **Cooling air and water numbers can vary greatly with changes in humidity Subcooling is based upon the head pressure at compressor service port

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