Mini split lines frosting up

[Jim Katen]

Mmm. Sichuan rabbit heads . . . 

[John Dirks Jr]

Temp drop across the evap after 5 mins of running.  80 in, 45 out

 

[Marc]

I've never seen a delta T that high...on any sort of AC system.

Edited June 15, 2019 by Marc

[Jim Katen]

That thermometer is worthless for measuring air temperature. Get some probe thermometers for the real numbers. 

[John Dirks Jr]

Jim, I think the thermometer is far from optimal, but not worthless. 

Marc, that is the widest spread I’ve ever gotten with that less than optimal thermometer. 

[Bill Kibbel]

You're not measuring the temperature of the air with that -  just surfaces.  It is worthless.

[John Dirks Jr]

I know it’s surface temp on that tool. Although,  the fireplace remote has a room temp display  on it.  It was reading 81 degrees 4’ off the floor.  So the temp 8’ up the wall above the evap core can’t be lower than that.  I can’t see the evap coil by looking through the louvre on the front of the unit.  That 45 degree reading was off the edge of the blower wheel which is plastic.  So I doubt the air temp at that point is much higher. 

Im not convinced that I’m substantially off the mark with those readings.  But I could be wrong. 

[Marc]

1 hour ago, John Dirks Jr said:

I know it’s surface temp on that tool. Although,  the fireplace remote has a room temp display  on it.  It was reading 81 degrees 4’ off the floor.  So the temp 8’ up the wall above the evap core can’t be lower than that.  I can’t see the evap coil by looking through the louvre on the front of the unit.  That 45 degree reading was off the edge of the blower wheel which is plastic.  So I doubt the air temp at that point is much higher. 

Im not convinced that I’m substantially off the mark with those readings.  But I could be wrong. 

Get a mercury or thermocouple thermometer and check it.  That huge delta T might be a result of sampling the evaporator coil temperature.  What Jim and Bill said.

[John Dirks Jr]

I will get a proper tool for measuring air temp and do it again.  But once more, the evap core is not visible through the front louvre.  That 45 degree measurement is from the plastic blower wheel. 

[John Dirks Jr]

18 degree difference with this probe type thermometer. 

[Jim Katen]

Do I get to say "I told you so"? 

BTW, I love UEI test equipment for cheap things like thermometers. It's hits the perfect point between being affordable and accurate enough for what we do. Plus, they have headquarters 30 minutes away from me. When I have a UEI device that breaks down, I walk into their shop with it and they fix it or replace it for me on the spot. 

[John Dirks Jr]

Don’t count your chickens just yet Jim.  But maybe you can say “I told you so”. We will see but It’s been 10 days since the system was charged.  I just tested with this tool today and the system may still have a leak.  It might be partially leaked out.  It’s still cooling satisfactorily as of now.  I’m not gonna mess with it for now.  But if it has to get charged again, I will test temps immediately after such.  At that point I may be due a full bore “told you so” 

This thing has variable operating modes depending on conditions so it’s not really easy tell exactly what it’s doing at a given time point. .  Not like the standard systems that are either on, or off. 

[Marc]

Since it has no ducts, I'd expect more than 18 degrees differential, unless the condensation flow rate was high.

[Jim Katen]

7 hours ago, John Dirks Jr said:

This thing has variable operating modes depending on conditions so it’s not really easy tell exactly what it’s doing at a given time point. .  Not like the standard systems that are either on, or off. 

With incoming air at 72 degrees dry bulb, and output air at 55 degree dry bulb, that would be a perfect temperature differential if the incoming air was at 62 degrees wet bulb - which I imagine is just about right for Maryland in June. You don't want much more aggressive cooling or you risk poor humidity control. 

[John Dirks Jr]

I sure hope the performance holds.  Otherwise, it’s back to leak hunting. I’ve got my Arlo wireless security cam positioned to remotely monitor the refrigerant lines to see if they freeze up.  There’s an orange ribbon tied to the grill which I can see fluttering on the cam when the unit is running.   Obviously,  it’s not running in this picture. 

[Marc]

Now I gotta have one, an Arlo Wireless!

[John Dirks Jr]

So far I have not caught any human thieves in Arlo.  But I’ve caught deer, squirrel, raccoon, opossum , fox, feral cat, spiders, birds and bats. 

Edited June 26, 2019 by John Dirks Jr

[John Dirks Jr]

Running now.  A little sweat on the line but no ice.  Looks ok from here. 

[John Dirks Jr]

Running now.  A little sweat on the line but no ice.  Looks ok from here. 

[John Dirks Jr]

So, back in June leak sealer was injected into the system and it was topped off with refrigerant.  It’s been running perfect ever since with no leak down.   Just the other day it was 24 degrees outside.   I called for heat at a high demand and the head unit was able to produce 110 degree airflow.  This is without an electric backup coil as this system does not have one. Impressive performance I think.  Here is the actual sealer produce that was used. 
 

https://www.amazon.com/dp/B077Y3CNMW/ref=cm_sw_r_sms_apip_qmXRwt1flUD97

[Marc]

That's great.

[GenderStudy]

There is an objective way to measure cooling. It is necessary to determine the temperature difference at the inlet and outlet of the air conditioner. We measure the temperature of incoming air with thermometer above the indoor unit (we are speaking about wall-mounted split-systems), and the blown-out air - there, where the air flow comes from, near the open curtain. You should not push the thermometer inside, there is a risk to catch it in the fan drum. A temperature difference of 8-12°C or more indicates normal operation, and a smaller temperature difference indicates cooling problems. You can read more information here (advertising link removed) Good luck to you!

[Trent Tarter]

These types of "pre charged" DIY mini splits can be problematic. I would have an HVAC contractor check it out and make sure refrigerant is fully charged and up to specs.