R290 undercharge in 1 ton cap tube split sytem heat pump?

[r290r600]

Another quick note. This unit was fitted to a caravan (trailer) and I tried very hard to find a high pressure fexilble hose solution and could not. went on my trip in july - the pipes failed and out came the gas! could not vac the unit down until I got home 3 weeks later...and only got my flex hose solution installed this month. So the unit has been sitting a while and I thought I will give the regas a go. Only mod to the original setup is a bi directional burnout filter dryer in the liquid line to catch any nasties.
if it doesnt work i will buy another unit , but at least i have learnt someting in the process.

[NiHaoMike]

You'll need to put in R22 TXVs for it to operate correctly.

[jeff5may]

Does the unit use the refrigeration cycle for heating? Or does it use a backup heat source? Most smaller units use heat strips. If this is the case, 150 PSI is not out of range when the refrigerant system is idling.

A make and model # would be helpful here.

[r290r600]

It uses the refrig cycle for heating. the model is Galanz AUS-09C(H)53R150L
looking at the schematic it has 2 cap tubes in series in the liquid line - one has a 'check valve in paralell with it.

[jeff5may]

Is it this line of units?

If so, it's just like the USA mini-splits, like GE/whirlpool. I could tell from the way the manual is written. I can't remember if the OEM was sanyo or samsung exactly, but many have bent these units to suit their needs. As long as the controls work, the rest is easy.

Looking at the manual, your service port is located in the gas line leaving the outdoor unit. As such, it switches sides between heating and cooling mode. During cooling mode, it is before the compressor suction line on the low side. During heating mode, it is after the compressor discharge line on the high side. What this means is that you can only charge the system during cooling mode. During this time, you can take superheat readings.

In heating mode, the gauge will read your high-side pressure. If you ran the unit in heating mode for more than just a short time, this pressure should rise over time. With r410 in the system, this pressure would rise to well above 300 PSI. With r290 in the system, the pressure may need to rise to above 200 PSI to provide much heating effect.

http://virtualmark.net/wx/pressure.htm

[WyrTwister]

I do not know a lot about HP's . Never thought about the service port switching from high pressure to low pressure , when the unit changes from heat to cool ?

Good info .

Thanks , :-)
Wyr
God bless

[jeff5may]

It does if it's in the gas line. The gas line is the larger, the liquid line is the smaller. The thing about it is you never know which line is going to have an accessible service port in it, if any. Some manufacturers have none exposed. In this case, you have to open the cover to find out if they included any or not.

This is one of the most confusing aspects of heat pump operation. On the compressor side of the reversing valve, the ports stay the same, regardless of operating mode: suction is suction, discharge is discharge. But on the other side of the reversing valve, the gas lines switch places, depending on which heat exchanger is being fed superheated gas.

[WyrTwister]

My mini split only has a service port on the large line . To me it is the suction / low pressure line .

Never occurred to me it would become the high pressure line during heat pump mode ?

Of course , when I installed it , I was not concerned about heat . I wanted cool . :-)

God bless
Wyr

[jeff5may]

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[r290r600]

Thats the unit........
So on the heating cycle, what i was reading on the gauge is to be expected.
So much to learn....so little time!
Will post some more detailed information on my A/C adventures soon.