Portable A/C doesn't seem to be making the advertised 12,000 BTUs

[CanOfWorms]

I bought this to replace my 8,000 BTU window unit because I thought it would look nicer.
Haier-12-000-BTU-Heat-and-Cool-Portable-Air-Conditioner-with-Dehumidifier-HPC12XHR

I doesn't cool anywhere near as good as the window unit.

I got it cheap because it didn't have the accessory kit, so I rigged up a 5" PVC 90 degree street to a piece of dryer exhaust pipe as the exhaust. This doesn't appear to be leaking, but the exhaust pip gets hot.

I just read online some guy saying that they are inefficient by default as they use indoor air to cool the compressor which is then exhausted outside. This causes hot outside air to come replace it. Try to locate the condenser intake and reroute it outside.

I looked at the unit and this seems to be the case with mine.

If I read him correctly what he is saying is that since the air from inside is being sucked in to cool the compressor and pumped outside, it creates suction that pulls outside air from some other source into the house.

 

[Dana]

That is a fundamental problem with any 1-hose portable AC units. Using room air through the condenser coil and exhausting it depressurizes the room, driving a large parasitic infiltration load. The hotter it is outside, the higher the duty cycle, and the bigger that additional load becomes. The EER efficiency and capacity on the nameplate is somewhat meaningless for single hose units, since the as-used efficiency drops as the duty cycle increases.

Dual-hose units at least take in outdoor air and don't depressurize the room. During high humidity days a single-hose unit might not be able to keep up with the humidity even if it's keeping up with the temperature, due to that parasitic load. Cool but clammy isn't the same as "comfortable".

If you can convert it to 2-hose operation, do it! Even if it's cycling on/off a lot the room will be more comfortable due to the lower humidity, and the as-used efficiency will be higher.

Also, the bigger the parasitic load, the bigger the capacity derating. Even at fairly low latent loads, the sensible load derating with temperature is such that at 85F outdoors a 12,000 BTU/hr unit is only delivering a net ~8000 BTU/hr of cooling, and it drops further as outdoor temperatures rise. This single-hose derating chart was what a dual-hose AC manufacturer calculated for a 70F room.

So when it's edging into the 90s even it's sensible cooling capacity is well below what your 8000 BTU/hr window-shaker was putting out.

BTW: Even an 8000BTU/hr window unit is oversized for most rooms. (The markting "cools xxx square feet" numbers thrown out there are completely bogus.) Bigger is not better, unless the expectation is to have something that can bring the temperature down by 10F quickly. A "right sized" unit will run a 100% duty cycle for the warmest hours of the warmest days, might even lose ground by a degree or two on the worst day, but since it's running constantly the humidity in the room stays low, well under 50% RH. For most office or bedroom sized rooms kept at a constant temp during the day a 5000 BTU/hr unit usually delivers higher comfort & efficiency. (The exceptions being rooms with a LOT of equipment load, not the typical home office.)

Before I had some large trees removed (avoiding a hurricane hazard), I could cool my entire 2400' house with a 5000 BTU/hr window unit in an upstairs bedroom at the local 1% outside design temp. But it would lose ground when temps were 8-10F above that. Now, well... maybe it takes two of them.

 

[Sponsor]

 

[Sylvan]

I bought 2 Works great


LG LP1417GSR 14,000 BTU Graphite Gray Portable Air Conditioner - Rooms up to 500 Sq. Ft

 

[Fitter30]

Measured temperature at filter and supply should between 18-22* difference

 

[Sylvan]

The room I use it for is only 12 x 14 and 10.5 ceilings

My main window unit is
Friedrich Kuhl Series

KCL28A30A
28000 BTU Window Air Conditioner with 10 EER, R410A Refrigerant, 9.3 Pts/Hr Dehumidification, 230V, Wi-F,i Enabled and Auto Restart