[Carry On]

I have had a number of straight HVACs, none of which had an accumulator. Now have a heat pump with one, that was recently replaced (rusted out).

I understand that accumulators are needed in heatpumps to protect the compressor from returning liquid during heating, especially when refrigerant flow rapidly reverses during heat-defrost-heat.

In an automobile AC, an accumulator-dryer is said to provide a reservoir of refrigerant and the system therefore can operate effectively even when some refrigerant leaks out.

Does an accumulator in a heat pump provide a refrigerant reserve that is not available in a straight AC without one? Put another way, can a heat pump sustain a small leak for a longer time because it has an accumulator?

 

[emcoasthvacr]

accumulator less needed with scroll comps

Accumulators are needed to prevent liquid flloodback to the comp (scroll comps are less affected by floodback) -- what annoys techs is they don't understand why they're made out of steel -- neither do I.

Even with multiple comp racks in commercial referigeration, the steel accumulators rust out -- poor engineering.

I have had a number of straight HVACs, none of which had an accumulator. Now have a heat pump with one, that was recently replaced (rusted out).

I understand that accumulators are needed in heatpumps to protect the compressor from returning liquid during heating, especially when refrigerant flow rapidly reverses during heat-defrost-heat.

In an automobile AC, an accumulator-dryer is said to provide a reservoir of refrigerant and the system therefore can operate effectively even when some refrigerant leaks out.

Does an accumulator in a heat pump provide a refrigerant reserve that is not available in a straight AC without one? Put another way, can a heat pump sustain a small leak for a longer time because it has an accumulator?

 

[IFRZAIR]

I have had a number of straight HVACs, none of which had an accumulator. Now have a heat pump with one, that was recently replaced (rusted out).

I understand that accumulators are needed in heatpumps to protect the compressor from returning liquid during heating, especially when refrigerant flow rapidly reverses during heat-defrost-heat.

In an automobile AC, an accumulator-dryer is said to provide a reservoir of refrigerant and the system therefore can operate effectively even when some refrigerant leaks out.

Does an accumulator in a heat pump provide a refrigerant reserve that is not available in a straight AC without one? Put another way, can a heat pump sustain a small leak for a longer time because it has an accumulator?

The part that stores refrigerant is a reciever, totally diff from an accumulater.

 

[AcDOCnTRAINING]

yep

The acumulator is very important part in Heat pump unit, I do I agree that its dumb to make out of corrosive metal, here in beach side florida we paint them with epoxy paint or they be gone in a year ! The acumulator & crank case heater prevents liquid flood back to comp for the simple fact that liquid is uncompresible. As far as a leak NO unit should ever run with a refrigerant leak for LEGAL and mechanical reasons, especialy if the leak has been located.

 

[Carry On]

Accumulator benefit nd preventing rust

I meant "receiver" (sorry), which stores refrigerant since an auto compressor can't, but provides a reserve.

I was not suggesting that a leak should not be fixed but wondering if the same leak, e.g. in the evaporator, would show up more slowly in a HP than a straight AC because of any refrigerant left in the accumulator. For that matter do comparable HPs and ACs (tonnage) differ in the quantity of refrigerant charge in pounds and could such a difference be explained by what is in the accumulator?

On rust, leaned about it too late this time (seven years), but might consider sparying the accumulator with a marine anticorrosion material, such as "Boeshield" which can prevent a piece of steek dropped in salt water from rusting. There are also spray on rust converters. I've used them on auto mufflers successfully and exterior steel containers.

 

[Hrdworkingacguy]

Accumulators store refrigerant...When the load is low it will be full and as the load increases its liquid level goes down...You can add quite a bit of ref. in the summer time to a system with an accumulator and the subcooling wont change much...But then in the winter it will go off on high head pressure...They aren't really a "catch-all" but you have to pay attention charging systems like that...

 

[Carry On]

Accumulators store refrigerant...When the load is low it will be full and as the load increases its liquid level goes down...You can add quite a bit of ref. in the summer time to a system with an accumulator and the subcooling wont change much...But then in the winter it will go off on high head pressure...They aren't really a "catch-all" but you have to pay attention charging systems like that...

So would most pure AC's benefit from one but they are left out to keep the initial cost down?

 

[ambarton]

Accumulators store refrigerant...When the load is low it will be full and as the load increases its liquid level goes down...You can add quite a bit of ref. in the summer time to a system with an accumulator and the subcooling wont change much...But then in the winter it will go off on high head pressure...They aren't really a "catch-all" but you have to pay attention charging systems like that...

what does a accu. have to do with subcooling in the summer?

 

[Hrdworkingacguy]

if you have excess subcooling in the summer time(and no liquid restriction) the accumulator is full and shouldn't be, meaning waaay evercharged..

 

[Hrdworkingacguy]

So would most pure AC's benefit from one but they are left out to keep the initial cost down?

It't not a cost thing...Rheem/Ruud puts them in because they need more total refrigerant charge then just the copper coils/lines can hold...I would assume its the same or similar reason for most manufacturers, that just what I heard directly from the rheem factory...

 

[beenthere]

Your heat pump does not have a receiver, it has an accumilator.

If straight A/C's had receivers. There would just be more A/C's that were over charged.

 

[Carry On]

Your heat pump does not have a receiver, it has an accumilator.

If straight A/C's had receivers. There would just be more A/C's that were over charged.

Why?

 

[beenthere]

Why to which statement?

 

[Carry On]

Why to which statement?

If straight ACs would be overcharged with an accumulator why aren't HP's in AC mode also overcharged? In AC mode both are the same, in essence?

Thanks.

 

[hvacrmedic]

If straight ACs would be overcharged with an accumulator why aren't HP's in AC mode also overcharged? In AC mode both are the same, in essence?

Thanks.

For a moment forget everything posted so far. Some of it is correct, some of it not, and the thread is getting confusing.

An accumulator's sole purpose is to prevent flood back and slugging. When a system doesn't have one, then it was either deemed not necessary by the manufacturer, or it was cheaper to make it without one. If the installation instructions are referred to, then usually there will be some note about flood back prevention on those systems without an accumulator. Long line sets, piston metered coils, excessive vertical rise of the lineset, etc, require special provisions. Some will advise installing a hard shut-off TXV, others a liquid line solenoid (possibly two), an accumulator, etc.,--something to prevent slugging. If the unit doesn't come with an accumulator then it's mostly cheapness, however in some cases the accumulator is deliberately omitted to improve efficiency. In most cases a hard shut-off TXV makes an accumulator redundant.

It's common practice, whether right or wrong, to overcharge systems with accumulators when there is a known slow leak in the system. I think this is what beenthere was referring to.

 

[BigJon3475]

but wondering if the same leak, e.g. in the evaporator, would show up more slowly in a HP than a straight AC because of any refrigerant left in the accumulator.

Plus on heat pumps the heating effect doesn't seem lost with a loss in charge because of the backup heat. Unless the person watches the stat for the backup heat light or watches the heat pump carefully and knows the cycles most regular folks wouldn't know anything is wrong until they either get their bill or it turns to cooling season and now it doesn't work at all or works very poorly and even then sometimes folks just assume the higher bill is because it's winter......only till it get's totally outrageous for some do they research why it's costing them so much.


That's my observation.

 

[hvacrmedic]

Plus on heat pumps the heating effect doesn't seem lost with a loss in charge because of the backup heat. Unless the person watches the stat for the backup heat light or watches the heat pump carefully and knows the cycles most regular folks wouldn't know anything is wrong until they either get their bill or it turns to cooling season and now it doesn't work at all or works very poorly and even then sometimes folks just assume the higher bill is because it's winter......only till it get's totally outrageous for some do they research why it's costing them so much.


That's my observation.

Good observation. And that happens way too often. A seasonal inspection could pay for itself in week or less in some cases because of this very thing. And it's worse than it sounds. If the system is low enough on refrigerant it can actually cost more to run than em heat alone would cost.

 

[Carry On]

For a moment forget everything posted so far. Some of it is correct, some of it not, and the thread is getting confusing.

An accumulator's sole purpose is to prevent flood back and slugging. When a system doesn't have one, then it was either deemed not necessary by the manufacturer, or it was cheaper to make it without one. If the installation instructions are referred to, then usually there will be some note about flood back prevention on those systems without an accumulator. Long line sets, piston metered coils, excessive vertical rise of the lineset, etc, require special provisions. Some will advise installing a hard shut-off TXV, others a liquid line solenoid (possibly two), an accumulator, etc.,--something to prevent slugging. If the unit doesn't come with an accumulator then it's mostly cheapness, however in some cases the accumulator is deliberately omitted to improve efficiency. In most cases a hard shut-off TXV makes an accumulator redundant.

It's common practice, whether right or wrong, to overcharge systems with accumulators when there is a known slow leak in the system. I think this is what beenthere was referring to.

That makes sense and I suspected cost can be a factor.

But would a HP have more refrigerant in the system than an equal AC --both properly charged? How much refrig. is stored as liquid in the accumulator?

My question did not suggest overcharging an HP with a leak but possibly that a HP has a greater amount of refrigerant per ton and therefore the loss of refrigerant would be less noticeable than in an AC with less refrigerant (without an accumulator) because a smaller percentage is lost.

 

[beenthere]

If straight ACs would be overcharged with an accumulator why aren't HP's in AC mode also overcharged? In AC mode both are the same, in essence?

Thanks.

Your confusing an accumilators purpose and a receivers purpose.
They are not the same thing, and do not perform the same function.

An accumilator may or may not have liquid refrigerant in it depending on load conditions at that time. It protects the compressor.
A receiver always has liquid in it. It ensures a liquid feed of refrigerant to the TXV.
(Presuming fully chargfed systems, with no system problems)

Neither is a cure all, and both have been misapplied.

 

[d_griff]

The acumulator & crank case heater prevents liquid flood back to comp for the simple fact that liquid is uncompresible. :

a crankcase heater does not prevent liquid floodback. It prevents liquid on start-up