Small air conditioning units

chickmug

Inactive wrote: »

Absolute rubbish, of course they cool things down, albeit only in a restricted zone.

What Viper means they DO ONLY move the heat from one place to another. In my case from my bedroom moved to outside through the hose in the window. Job done!!!:D

Inactive

Viper_7 wrote: »

Read what I said...

they cool nothing down - just move the heat from one place to another and produce heat in doing so as well as using fossil fuels ( mainly gas/coal powered power stations)
They actually help cause cities to become hotter than they would be without them running.

Oh dear, I guess that you don't use anything that uses fossil fuels then.

No car?..No bus?..No heating? No lighting? etc.:rolleyes:

Viper_7

Of course I do, but there are things that are a necessity, and then there are those like this that are just creature comforts.

richardc1983

VIPER: You could say the same about heating? You heat your house when its cold, the same as the need to be cool, if its hot outside you want your house cool, i know i do. Air con units are actually much more efficient when used in reverse (heat pump) at producing heat than gas etc. FOr every kw of electric you can get upto 4kw back out, wheareas with gas for every kw burnt you get upto 1kw back out in heat. Air con doesnt actually make things cold, it removes heat from the air and moves it elsewhere and in doing so this is what gives the cooling effect as the heat is removed.

Chickmug: Check my posts history lots of useful info on air con, i used to work in the trade so am very knowledgable in this area. Portable units should not need regassing as they are so small there is minimal pipework inside to cause a leak, however if it doesnt appear to be cooling as well, ensure your filters are clean. Also you can conduct a test to see how well it is cooling. Have the unit switched on for about 20minutes, then measure the temperature of the air that is being sucked into the unit to be cooled, now measure the temperature of the air coming out of the cold air vent of the unit, there should be a difference of about 11C, if there is then its working fine if there isnt then the unit has some sort of problem, most likely low in gas. It is probably cheaper to buy a new unit than it is to repair a portable.

A good unit that my parents have been using this year is from b&q and is very powerful & not too expensive is:

http://www.diy.com/diy/jsp/bq/nav/nav.jsp?action=detail&fh_secondid=9372977&fh_view_size=6&fh_eds=%3f&fh_location=%2f%2fcatal!!!1%2fen_GB%2fcategories%3c%7b10096%7d%2fcategories%3c%7b10098%7d%2fspecificationsProductType%3dmobile_air_conditioners&fh_refview=lister&ts=1217628802013&isSearch=false

Any questions please ask.

Inactive

Viper_7 wrote: »

Of course I do, but there are things that are a necessity, and then there are those like this that are just creature comforts.

But what you may consider a " necessity " others may deem a luxury.

It is all about personal needs / choices.

chickmug

richardc1983 wrote: »

Chickmug: Check my posts history lots of useful info on air con, i used to work in the trade so am very knowledgable in this area. Any questions please ask.

Thank you very much for a very useful post and I will try the temperature test later. Meanwhile do you know if the units are quieter these days as it did take some time to get used to the one we have which sounded like a jet engine when we first bought?

richardc1983

No worries, air con is something I have taught myself as well as through personal and business ways.

To be honest portable units are always going to be noisy, the reason being you have got a small engine inside, the type of compressors put into these portables are known as a Rotary compressor which are the noisiest ones about, but are the cheapest to make so manufacturers use these in their machines.

I would say that they are still as noisy as they ever have been you may get the odd one that is quieter depending on how much your going to spend. More expensive units may have insulation around the compressor to silence that horrible noise they make the cheaper units have non.

If your going to get a new unit please message me first and I will tell you what I think of the unit.

Please note though that in the long term your probably best off getting a proper split type air con unit, these have the compressor and the fan outside the house and use better compressors so the noise is almost silent from them. Then again it depends how much your going to pay, either way you can pick up a cheap split system from b&q for the same price as a portable, and it will do a better job, be almost silent in running and you could fit it yourself if its the diy fit type.

I have split systems installed in my flat and it was well worth the money, my portable unit was a 12000btu unit, and yes it blasted lots of cool air but it struggled to cool the room it was in, mainly because the air your cooling a lot of it goes out the hose to the outside meaning there is negative pressure in the room, so where does the air come back into the room to replace this, through the doors and window, warm air. Making your portable a waste of energy really. Now I have split systems installed, also rated at 12000btu i find that the system copes easily on the lowest fan speed and last week on them 30c days we had my flat was a constant 21c throughout and I had the lounge and bedroom units running! Before i was struggling to cool one room with a unit that was supposed to be the same cooling rating whilst eating money and throwing it straight back out the window!

THink about it seriously the ammount of money you spend on the unit and then the ammount your going to be wasting on electric having windows open for the hose, you would be best of getting a split system installed.

But firstly check your filters and do the temperature test. Make sure that the compressor has been running though for 20mins before you carry out the test.

REgards
Richard.

chickmug

richardc1983 wrote: »

But firstly check your filters and do the temperature test. Make sure that the compressor has been running though for 20mins before you carry out the test. REgards Richard.

Richard - Just done as you suggested. Outside temp is 19 degrees. Bedroom started at 25 degrees. After cleaning filters and running for 20 minutes it is 15 degrees so I guess that is not bad?

What spoilt me is being in a friends BMW on which the air con made it feel like the inside of a freezer and very quickly.

richardc1983

Hey Chickmug

Yes your portable is working as it should, the cold air the unit throws out is soon sucked away back out the hose and blown back outside, its a viscious circle so the units can never bring the room temperature down unless the temperature outside the room, or air coming into the room from other areas be it outside or from other rooms in your house is lower than the actual room temperature the air con unit is in, once however the room temp has leveled out to the air coming into the room the portable unit can do no more as it is going to be like having your central heating on but with your window open. My split units make the house like a freezer if I want to but thats because they are proper air con systems much as your friends BMW the air con system in that car is not sucking air out, all the air being put into the car is refrigerated by the a/c system.

I will also bet that you got a portable unit under 12000btu (3.5kw), you will find with portables that if you oversize the unit (get a larger capacity unit) than you need that the extra capacity the unit has will overcome the air that it is sucking out of the room.... meaning that it produces more cold air than is being sucked out the room!

A quick way of looking at this is imagine a plastic cup with a hole in the bottom, the interior of the cup being your room and the hole in the cup being your doorway or window of your room or any other areas where cool air will be lost (the heat gains in the room such as people, electrical appliances, areas of heat/cooling loss, walls, ceilings, floors,) if you fill the cup with water from the tap (the tap being your air portable air con unit or source of cooling) you have to put water into the cup quicker than the rate the water leaks out of the hole in order to fill the level of water in the cup otherwise its just going to leak out quicker than you put it in. So therefore if you put more water in than is leaking out you are achieving something by filling the cup up. THe principle with air con is exactly the same in order to achieve cooling (lowering of room temp) you have to put more in than you need to compensate for the heat gains and cooling loss, but with portables this is magnified by the fact the normal heat gains does not take into account the fact a lot of the cool air put into the room leaves back up the pipe so you have to oversize the unit to still get the required level of cooling!

In air con terms the explanation would be this. Your room might only need 2.5kw (9000btu) of cooling but because 1.5kw of that is going straight out the hose your really not doing anything with the remaining 1.0kw, its acting more as a spot cooler (cool if your sat literally on top of it) but not actually reducing the room temperature. TO reduce the room temperature you have to ensure that if your room needs 2.5kw of cooling that you are getting the 2.5kw of cooling so if your buying a portable you need to get one that is higher powered than that as most of the cooling it produces goes back out the hose (approx 1.5kw). So for instance if you get a 3.5kw unit (12000btu) you are making up for the 1.5kw that goes back out the hose as its putting in an extra 3.5kw of cooling. But please be aware that your going to be burning more electricity to achieve lower room temperatures and even then it will struggle on warm days

Comparing this next to a split system where the unit recirculates the air. YOur getting full usage of your 2.5kw of cooling as non of it is leaving the room apart from normal methods, through walls and any internal doors you leave your not actually creating negative pressures where air must rush back into the room to replace the air that has gone up the hose. With a split system if you put more capacity in than needed, for this case 3.5kw, your unit will achieve the lower room temperature very quickly indeed but wont actually condition the air, that means humidity in the air is not reduced as the unit isnt on long enough to remove moisture as you have more capacity than you need.

Bear in mind though the above is just an example, your room may need more or less cooling.

When I had portable units I made my unit more efficient by making the unit a 2 hose system, I got a spare hose and made a type of air inlet funnel type thing over the bottom half of the unit (the condenser section) air inlets and the hose was at the end, I made the funnel out of a very strong plastic and used duct tape to secure. I then had a hose coming out of the end of the funnel, this hose was placed out the window, so instead of the unit creating negative pressure due to sucking air out of the room to cool the condenser section the 2nd hose used outside air to cool it. My unit worked a lot better and I did achieve cooling within the room, however this is a fiddly thing to do and is really a lot of messing about etc and you still have an open window unless you want to put 2 hoses through your wall, but then you might as well just have split systems!!

Hope I made sense and didnt waffle on.

chickmug

Richard
Thank you so much for the obvious time you have taken to give me a really excellent bit of help. I tend to help folks out on the housing board (I am an EA) and know how long it can take to give a full reply.