charging heat pump in heat mode

[kc0ovt]

hey all im fairly new into the industry and been seeking the answer to this question and have been unable to come up with it.

What is the proper charge rules for a heat pump operating in heat mode? How do you go about charging in heat mode if the unit is low?
-brian

[1972torino]

Most will have the procedure on the control access panel.

[amickracing]

There really is no correct answer for how to charge a heat pump in heat mode. In the panel they might have a "getcha close guide", but it won't be dead on. You will have to come back in the summer to get it perfect.

[monkeyman#1]

Ya wanna do it right? Recover, find and repair leak, evacuate, weigh in charge!

[ARPA]

And,

Why is the OP asking this in an open forum, and not even a pro member? Didn't you read the rules of the site?

[kc0ovt]

I read the rules didnt seem to far off from the ability to seek advice in the forum from the rules i read.

And,

Why is the OP asking this in an open forum, and not even a pro member? Didn't you read the rules of the site?

[ARPA]

I read the rules didnt seem to far off from the ability to seek advice in the forum from the rules i read.

Hmm..

Feel free to ask any question relating to HVAC, or other topics of general interest except DIY.

2. Do-It-Yourselfers - not here.

This site is for industry professionals and folks seeking HVAC/R advice and knowledge. Please do not ask for step by step instructions on purchasing, installing or repairing your own HVAC equipment, that is our job and our livelihood. We are generous, but not to a fault.

[Johnny Law]

There really is no correct answer for how to charge a heat pump in heat mode. In the panel they might have a "getcha close guide", but it won't be dead on. You will have to come back in the summer to get it perfect.

I think you have that backwards. A system can tolerate a over charge in cooling but it won't in heating. I would rather charge in the heating mode. I put a thermometer under the insulation and slowly add freon and watch the temp rise while also adhering to the charging chart on the unit. You better just about be dead on with these new high seer units with no accumulator.

[ARPA]

If you are in the industry, get your required number of posts and apply for the pro forum.

In the pro tech forum, you won't even have to ask this question, as it is explained.

[snewman24]

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You better just about be dead on with these new high seer units with no accumulator.

I was under the impression that all heat pumps have accumulators. Which manufacturers are not designing one into their units?

[Johnny Law]

I was under the impression that all heat pumps have accumulators. Which manufacturers are not designing one into their units?

For years some Lennox units didn't and may still don't and new Rheem units don't have them

[docholiday]

Accumulators were required when pistons are used. They were the last protection from sending liquid back to the compressor. With TXV's you control the superheat and will not be sending liquid back. With pistons, the mfg had to do something to protect compressors from overcharge. The vast majority of systems out there are overcharged and with a piston system, that means slugging. If a little is good, then a lot must be better attitude.

Accumulators as we know also carry liabilities in oil return and rust. Since there is no real advantage to having one on a TXV system, why take on the liabilities?

Accumulators were the sole reason you could not accurately charge a HP in the cold winter months because as a tech, you could not know how much liquid was sitting in the accumulator. It had nothing to do with charge balance. That is the role of a reciever or charge compensator. The accumulator is not a storage tank. Its a place for liquid to boil off before entering the compressor.

[amickracing]

I think you have that backwards. A system can tolerate a over charge in cooling but it won't in heating. I would rather charge in the heating mode. I put a thermometer under the insulation and slowly add freon and watch the temp rise while also adhering to the charging chart on the unit. You better just about be dead on with these new high seer units with no accumulator.

Every unit I've worked on has said on that paper to charge in cooling mode. I know you can charge it in heating mode, but I've never seen or heard of a 100% sure fire way to get it right on.... like you can in cooling.

But, before this gets too in depth we should likely wait to finish this debate off in the pro forum vs here.