R410a Re-charging

[crockfighter]

Hi all.

I'm new to this so please bare with me.

I have a heat pool pump that lost its gas in transit and has been repaired, its is charged with R410a, only i dont think the guy who repaired it knows what he is doing.

I am told by the manufacturer:

"Comment 1"
"To check the charge on the unit, your high pressure gauge should be 30 degrees above the water temperature (sub cooling) and the low pressure should be 15 degrees below the suction line temp (super heat). By temperature it is the saturation section on the gauges" - this is fahrenheit."

My water temperature is 19 degrees C and the guages i have only reflect "bar", not temperature of R410a.

From experience with R22 we normally charge to between 7 - 8 bar in a 40ft refrigerated container requiring a 13 degree C level, and i read on the internet that the charge for R410a is usually double R22. Tha manufactureres have since sent me this:


"Comment 2"
"19.3 celsius (water Temp) is 66.74 fahrenheit, so the high pressure gauge should be 30 fahrenheit above the water temp or 96.74 fahrenheit or 35.96 celsius. If I converted correctly this would be 6.669 bar."

6.669 Bar is the same as i was saying above (around 7 bar for R22). This sounds wrong to me.

Can anybody help me with the bar rate charges per "comment 1"?

I would greatly appreciate this as the unit was bought new in January and it has taken me up to yesterday to get these replys from the manufacturer. As a result the unit currently is charged to 10 bar on the high pressure side and is not meeting the heating specs at all.

Thanks
Kev.

[mad fridgie]

Discharge pressure for R410a, if the manufacturer is correct would be around 21 - 22 Bar

[monkey spanners]

Does the system have a charge weight?

If your water flow rates are different to what the manufacturer use to spec the unit then the corresponding pressure will be different too.

Charging to pressure is more suited to car tyres and such.

Jon :)

[nec0310]

Charge by weight. Over charge may result in compressor damage

[crockfighter]

Thanks

I have been told before to charge the unit until you can feel the cold on the pipe on the other side of the coil, ensuring the evaporator coil is operating efficiently, would this suffice?

[crockfighter]

I appreciate that, thanks.

My gauges reflect R22, R134a, R404a, R407c, bar and in.HG, im just trying to find a comparisson and thought that bar is the only thing in common.

I have asked the manufacturere for a charge weight, however the unit was made in USA and its 8am there in 2.25 hrs, then i have to wait for the reply, if i get one.

[crockfighter]

The begining of the evaporator coil is freezing up, i'm told this is from over charging?

[joe-ice]

http://www.gas2010.com/traditional-hfcs check here for r410 p/t chart may help

[crockfighter]

Hi mad fridgie

I reduced the pressure to what the manufacturers recommend 6.7 bar, and ran it over night. It tripped out on low pressure. so taking your advice i charged to firstly 21 bar, the return on the compressor fromthe evaporator was a little colder, so i took it up to 22 bar and it dropped considereably, helping cool the compressor. All icing dissapeared.
I left this all afternoon and it heated at about double the rate (hooray). However, the temperature of the air leaving evaporator was 9 degree celcius colder than the air outside. I left this overnight and temperatures here dropped to around 9 degrees and maybe a little colder. this morning the evaporator had a band of frosted ice from the input to output side covering a third of the evaporator coil in the middle and the compressor was very hot (no cold refirdgerant returning). i turned off and defrosted asap, and it is cooling the compressor again.

I have read this this morning:
"The operating pressures of R-410A are approximately fifty to seventy percent higher than that of R-22. For example, a normally operating R-22 system will typically have a high side pressure of 260 psig and low side pressure of 76 psig, while a normally operating R-410A system will have a high side pressure of 418 psig and low side pressure of 130 psig." from http://www.gorhamschaffler.com/410A.htm "

Should i take the pressure on the high pressure side up a little more in hope to stop the icing?

[mad fridgie]

No,
I can not be specific, but a few hints.
You pool is still a little cool, so when completly warm head pressure will rise and net refrigeration will drop, which means your evap is less likely to freeze.
Swimming pool heat pumps, normally have big splits bewteen ambient and air temp.
If your unit does not have defrost, then likely 9C ambient is below is normal working envelope.
Just run it during the day when the ambient is above say 12C

[crockfighter]

I need this to run through the night to avoid the water temperature running to low as it is actually heating a fish tank for commecial aquaculture. What could i do to stop the evaporator coil frosting up? the manufacturers said that the unit should easily handle 3 degrees?

[mad fridgie]

Freezing is natural for heat pumps, if the manufactures say it will run at 3C then it must have some for of defrost.
The defrost controller may need setting up