Portable A/C question

[ssbtech]

This seems as good a place as any...

I live in an apartment condo (which means I have a 30 car garage ) and I'm re-thinking my A/C strategy here.

My place in the summer hits about 30 degrees (86F) inside and does not cool down much at night so it gets uncomfortable. I've got a portable 8,000 BTU/hr portable AC in the bedroom with the hose that goes out the door. It brings the room down to about 75F on a hot night, but the temperature shoots up as soon as I shut it off.

In the living room, I set a 15,000 BTU/hr window A/C unit in the sliding patio door and block it off above with foam board. It brings the living room down from 86F to a comfortable 71F.

The trouble with that setup is the window A/C is big, noisy, heavy and I have to store it somewhere in the off season.

Now that portable A/C units are up around the 14,000 BTU/hr capacity, I was thinking of using a portable in the living room. I'm a little put off by the portable in the bedroom but it's a small unit.

So my question is this - using my satisfaction with the capacity of the 15,000 window unit, can I expect to get good performance out of the 14,000 portable unit in the same room? It's this one here: http://www.costco.ca/Danby®-Designe...-in-1-Air-Conditioner-.product.100108024.html

It's a single hose design so I'm worried that it might not move as much air as the window unit. I know they're generally not as efficient as the window units.

I have about 700 sq-ft to cool with this one A/C.

Any tips would be great, thanks.

 

[metalTobman]

I would not expect a portable to effectively cool a 700 square foot space, but at least it would be quieter that the average 'window shaker'
Benefits to the 'shaker are that it uses outside air to cool the condenser coil not air from the room, plus condensation automatically drains to the outside, no collection or emptying.
Another thing, the 'shaker is probably a fairly honest 15,000 btu rating whereas the portables probably need ideal laboratory conditions and some optimism to reach their claimed rating. Don't get me wrong, I like the portables, but only in light duty, small area conditions.
Have you tried using a box fan to draw cooler night time air in through a window and push the warmer air out another window or door? This could take some of the load off your a/c units.
Hope this helps.

 

[Rockhead261]

The portable unit with the exhaust hose (spot cooler) uses conditioned air for the intake side of the condensor. The "used" air is then ducted away. This mean the unit is literally using the air it's cooling to cool itself, then removing it from the conditioned space. Since we do not live in vacuums, the displaced air is replaced with free air from the unconditioned space. There's no way around the 100% loss of air going through the condensor. It's much like running the A/C in your car with a window open. While the unit itself can tout decent efficiency, the impact on overall efficiency when you consider the air loss is staggering.

We used those spot coolers in the trade as emergency/temporary problem solvers for data centers with hot spots, temporary cooling during installations of new systems, etc. I'd never recommend one as a permanent solution.

If you don't want to tie up a window I'd go with a mini split or cut in a casement unit if your HOA allows it. Those spot coolers are simply nonsense.

 

[ssbtech]

Thanks for the replies. The portable in the 200 sq-ft bedroom/bath struggles to keep it cool so I know they're not really up to snuff.

My apartment is in a bit of a horseshoe shape with the living room, spare bedroom and master bedroom all with a sliding patio door to the deck. The sliding door is the only ventilation, no other windows open.

The deck is semi-enclosed with window windscreens. It mostly opens up, but with the big A/C blowing the hot air out, it's 107F out on the deck due to poor air circulation.

I considered a mini split but up here in the Great White North I'd be looking at $7-10K for a three-zone installed. I say three zone because I'd need an evaporator in each room as I'd have to remove the baseboard heaters to free up space in the breaker panel.



Do the dual hose portable units offer any better performance than the single hose? It's my understanding that those ones use the exterior air to cool the condenser.

 

[ssbtech]

I think I already know the answer to this question but I'll ask anyway.

If I put in a split system, the idea would be to repurpose a 2 pole breaker from a heater as the heater wiring is already in place near where the system would be installed.

Unfortunately however, the baseboards are only 2-wire. Are there any split systems that don't require neutral?

 

[Ruthless53]

Thanks for the replies. The portable in the 200 sq-ft bedroom/bath struggles to keep it cool so I know they're not really up to snuff.

My apartment is in a bit of a horseshoe shape with the living room, spare bedroom and master bedroom all with a sliding patio door to the deck. The sliding door is the only ventilation, no other windows open.

The deck is semi-enclosed with window windscreens. It mostly opens up, but with the big A/C blowing the hot air out, it's 107F out on the deck due to poor air circulation.

I considered a mini split but up here in the Great White North I'd be looking at $7-10K for a three-zone installed. I say three zone because I'd need an evaporator in each room as I'd have to remove the baseboard heaters to free up space in the breaker panel.



Do the dual hose portable units offer any better performance than the single hose? It's my understanding that those ones use the exterior air to cool the condenser.

I doubled the effectiveness of my portable last night by some ideas I saw on the net and the info I got from here. It was 10 degrees cooler in the garage after running only 2 hours than when I started in the morning and ran it all day. I will take some pictures later today.

Basically what I did was sealed a rubber storage tub that was roughly the same size as the intake for the condenser and cut two holes for two 6 inch ducts and ran to the door where my exhaust is vented to pull air in from outside. I then ran a flexible duct from where the cold air comes out of the machine to the intake of a utility fan so it blows the cold air throughout the garage. It's definitely redneck engineered from stuff I already had but it is effective! Should help your portable keep up with that room better

 

[ssbtech]

That sounds interesting. I wonder if that's how the dual hose units effectively do it too.

The deck my A/C vents onto hits 100+ F though, so I wonder what the consequences would be if I cooled the condenser with the hot exterior air.

 

[pseudorealityx]

That sounds interesting. I wonder if that's how the dual hose units effectively do it too.

The deck my A/C vents onto hits 100+ F though, so I wonder what the consequences would be if I cooled the condenser with the hot exterior air.

How do you think any normal A/C condenser works?

 

[Ruthless53]

That sounds interesting. I wonder if that's how the dual hose units effectively do it too.

The deck my A/C vents onto hits 100+ F though, so I wonder what the consequences would be if I cooled the condenser with the hot exterior air.

Here's my cheap fix.

 

[dsimatt]

I've got a 12k btu one and it cools my bedroom quite well, but i tried it once in my living/dining room space and it failed miserable and didn't even keep the heat in check.

My old apt had a good sized wall unit and it took awhile but would cool the whole apt down pretty decent so it looks crappy but might be the way to go.

 

[ssbtech]

How do you think any normal A/C condenser works?

Point taken.

Then again, being a portable unit with the condenser designed to be cooled by the indoor air, cooling it with the hot outside air might be beyond its design parameters.



I've been Googling for window units with an inverter compressor. With the added efficiency and reduced noise, I'm surprised to find that none exist.

Any insight as to why that is?

My 15k unit is loud. I can hear it two floors down at the parking lot. I've been in the suite downstairs with it running and I can hear it in there. I can tolerate the noise but I hate subjecting the neighbours to it. (Probably why they're banned in our bylaws, not that that stops me. )

 

[ssbtech]

Here's my cheap fix.

Thanks, I think I'll give that a try.

Quick question - I've taken the casing off my portable unit to vacuum out all the condenser coils (they were caked in dust) and noticed a temperature sensor clipped to the condenser.

Should I relocate this temp sensor since I'll be changing the intake source for the condenser to exterior air?

 

[Ruthless53]

Thanks, I think I'll give that a try.

Quick question - I've taken the casing off my portable unit to vacuum out all the condenser coils (they were caked in dust) and noticed a temperature sensor clipped to the condenser.

Should I relocate this temp sensor since I'll be changing the intake source for the condenser to exterior air?

I have no idea. I'm new to this ac stuff but I'm guessing the temp sensor on the condenser would be for shutting it down if it gets too hot so probably not. Also my fix is going to cause me an issue for cleaning my filter easily. What I plan on doing is getting a filter and cover to go on the outside of my door that will catch everything before it goes into the ducts and keep me from having to unscrew the Rubbermaid bin everytime I need to clean the filter.

 

[ssbtech]

I have no idea. I'm new to this ac stuff but I'm guessing the temp sensor on the condenser would be for shutting it down if it gets too hot so probably not. Also my fix is going to cause me an issue for cleaning my filter easily. What I plan on doing is getting a filter and cover to go on the outside of my door that will catch everything before it goes into the ducts and keep me from having to unscrew the Rubbermaid bin everytime I need to clean the filter.

I suspect it's the intake air temp sensor so the unit can shut off when the room hits the programmed temperature. If it was a safety sensor, I'd think it would be on the hot side of the condenser.

There are no intake filters on mine except for the evaporator and even then it's a piece of foam. I had to dismantle the cabinet to get direct access to the condenser coils for the vacuum to clean them off. The cabinet grille is a good inch from the coils.

I bought some 4" dryer hose today. I'll make an intake shroud later and run two lengths of hose to the window.

 

[Ruthless53]

I suspect it's the intake air temp sensor so the unit can shut off when the room hits the programmed temperature. If it was a safety sensor, I'd think it would be on the hot side of the condenser.

There are no intake filters on mine except for the evaporator and even then it's a piece of foam. I had to dismantle the cabinet to get direct access to the condenser coils for the vacuum to clean them off. The cabinet grille is a good inch from the coils.

I bought some 4" dryer hose today. I'll make an intake shroud later and run two lengths of hose to the window.

Only reason I have 2 is because my unit has a 12 inch exhaust and you need to match the exhaust hose size to make sure it's getting enough intake air. 12 inch was more expensive than two 6 inch set ups so I went that route.

 

[ssbtech]

I have an 8" exhaust hose, hence the two intakes

 

[ssbtech]

Initial impression is that the A/C now performs better with the above mod, although it isn't as warm here today as it was the past few.

However I noticed it isn't shutting down the compressor when the room temperature hits the set temp and the evaporator appeared to be on the verge of icing up a bit.

I'll have to move that intake temperature sensor. All it is sampling now is the exterior air being drawn into the condenser section.

 

[ssbtech]

Update:

I had this working great for a few days. It was shutting off soon after the room hit the set temp, cooled quite a bit more quickly and was even a bit quieter.

Last night it decided it no longer liked it's own refrigerant and decided to dump it all out the exhaust. 13 years old, I guess a pinhole leak must have developed somewhere.