Heat Pump Gauge Use.

[hvacrmedic]

I often wondered if these charts where unit specific. So a carrier chart should get me close ona goodman or rheem unit?

You can't use a given Carrier Heating Check Chart on another Carrier, so using it on another brand unit would be foolish. The predicted pressures on the chart will even differ between the tonnages of the same model Carrier unit.

[RoBoTeq]

I was told by a goodman rep you cannot charge a unit accurately in heat mode.

You can at least get the charge close enough that it is not going to adversely affect the equipment in either cooling or heating mode. To really have an accurate charge, it needs to be done on a fairly warm day when the house is already at the comfort level needed.

[Timber]

You can at least get the charge close enough that it is not going to adversely affect the equipment in either cooling or heating mode. To really have an accurate charge, it needs to be done on a fairly warm day when the house is already at the comfort level needed.

Robo, what is that formula you use to give out ? OAT plus 126 ?

[RoBoTeq]

Robo, what is that formula you use to give out ? OAT plus 126 ?

Yes. That was one of Goodman's methods for R22 systems and the basis for Lennox's "approach method" as well as the way York used to teach for troubleshooting heat pumps in the winter. From what I understand, this method also works fairly well for R410a. Actually, what I've heard is ambient plus 110 degrees at the large line service valve, which is the hot gas discharge line after having gone through the reversing valve.

[rwk26164]

The outdoor coil is much larger than indoor coil. In heat mode, the extra refrigerant required in cool mode has to be stored somewhere, and it's the accumulator.

The accumulator also keeps liquid from flooding the compressor.

Except for units that use a txv in the od unit. After the first few years of servicing only bryant equip. the company I was working for started also dealing lennox. I noticed the abscence of accumuator in od unit and when I asked factory rep where the excess refrigerant was stored he said we hide it. Also found out quickly have to use the true suction line port in htg op. Found that one out on my own and then not a week later a newer tech called and said he had a compressor running but not pumping. Yeah use the true suction port for low side in htg insteadof just reversing the hoses. What a miracle the compressor appears to be moving refrigerant now.

[Barrettservices]

Except for units that use a txv in the od unit. After the first few years of servicing only bryant equip. the company I was working for started also dealing lennox. I noticed the abscence of accumuator in od unit and when I asked factory rep where the excess refrigerant was stored he said we hide it. Also found out quickly have to use the true suction line port in htg op. Found that one out on my own and then not a week later a newer tech called and said he had a compressor running but not pumping. Yeah use the true suction port for low side in htg insteadof just reversing the hoses. What a miracle the compressor appears to be moving refrigerant now.

Because of the small or not existant accumulator (to save factory costs imo) in lennox and rheem systems i have found that they are very sensitive to the correct charge. I have gone back on several h/p that were charged properly in the summer and had to remove refer to make them run right in the winter. These system were even charge and airflow verified in the summer by hers raters and still were overcharged in the winter.

[RoBoTeq]

Except for units that use a txv in the od unit. After the first few years of servicing only bryant equip. the company I was working for started also dealing lennox. I noticed the abscence of accumuator in od unit and when I asked factory rep where the excess refrigerant was stored he said we hide it. Also found out quickly have to use the true suction line port in htg op. Found that one out on my own and then not a week later a newer tech called and said he had a compressor running but not pumping. Yeah use the true suction port for low side in htg insteadof just reversing the hoses. What a miracle the compressor appears to be moving refrigerant now.

I may be misunderstanding what you are referring to when you state "just reverse hoses". The small refrigerant line of all split systems other then ductless minisplits is the liquid line whether the system is in the heat or cooling mode. The large line is only a suction line when the system is in cooling mode. In heating mode, the large line is the hot gas discharge line sending hot gas from the compressor to the indoor coil, which is the condensing coil in heat mode.

The point is that brand does not matter as to where we measure our pressures from. In heat mode, we must measure suction pressure from some port that is attached to the suction line which in the heat mode is confined to within the cabinet of the heat pump. There is no such thing as just reversing gauge hoses for heat pump pressure measurement. We must use a "true" suction port to measure suction pressures on a heat pump, and never either of the lineset valve ports.

[RoBoTeq]

Because of the small or not existant accumulator (to save factory costs imo) in lennox and rheem systems i have found that they are very sensitive to the correct charge. I have gone back on several h/p that were charged properly in the summer and had to remove refer to make them run right in the winter. These system were even charge and airflow verified in the summer by hers raters and still were overcharged in the winter.

The amount of refrigerant in a heat pump system must be somewhat correct for both the capacity of the indoor and outdoor coils because these coils swap functions.

TXV metering is more forgiving for heat pump systems because the txv will simply stack more liquid refrigerant in the indoor coil as the ambient temperatures go down. Fixed metering systems need to have somewhere for the additional refrigerant to migrate to, and most systems use some sort of charge compensator. While an accumulator may act like a charge compensator at times, an actual charge compensator will hold or discharge the uneven amount of refrigerant required from cooling to heating modes more accurately.

[allan38]

Amen!
RoBoTeq said it so well that I deleted my extensive post. He said all I had to say and said it better.

[energy star]

Where is this "charge compensator" you speak of on a Trane system?

Accumulator = Compensator

[RoBoTeq]

Where is this "charge compensator" you speak of on a Trane system?

Accumulator = Compensator

If you install Trane equipment, you should be telling us. Maybe Trane doesn't use them. Maybe Trane and other manufacturer's use other methods of adjusting charge from heating to cooling mode.

Your mission is to find out how Trane does this.

[energy star]

Please tell me what manufacturer you use that has a charge compensator on it. I will look up the part number.
Post a pic of a charge compensator from the system you know one to be on. I want to see it.

[clifpaul]

X@. I've seen accumulators, but I've never seen or heard of a charge compensator til now.