Air conditioning units?!

VIRII · 29 Jul 2006 at 09:21

Overlag said:
the heat is still going out the tube at the end like its supposed to, its just not radiating through the tube and heating the room up.

i don't know how this would kill it, it might even help it as the intake is cooler as its not recirculating any hot air through the radiator type things (evaporator's?).

Some heat is still going out the end of the tube, however some heat that used to radiate away from the compressor via the sidewalls of the tube might no longer be able to.
Compressors get very, very hot and are internally lubricated by oil. If the oil gets too hot it can foam and stop lubricating properly.
Does your unit have a fan blowing over the compressor or is it simply using convection to lose the heat?

Even just extending the hose can damage the compressors over time.

phykell · 29 Jul 2006 at 11:13

Try Daikin, they have a good reputation and they have a huge amount of information on their web site about their products for both residential and commercial installations including one-room and whole house solutions:

http://www.daikin.co.uk/airconditioning-products/for_your_home/default.jsp

RJC · 29 Jul 2006 at 11:22

VIRII said:
Some heat is still going out the end of the tube, however some heat that used to radiate away from the compressor via the sidewalls of the tube might no longer be able to.
Compressors get very, very hot and are internally lubricated by oil. If the oil gets too hot it can foam and stop lubricating properly.
Does your unit have a fan blowing over the compressor or is it simply using convection to lose the heat?

Even just extending the hose can damage the compressors over time.

Just to add - the suction gas returning from the evaporator will help cool the oil and compressor.

Also certain external splits have jackets on the compressors to keep them warm and cut down noise.

RJC

Overlag · 29 Jul 2006 at 12:24

VIRII said:
Some heat is still going out the end of the tube, however some heat that used to radiate away from the compressor via the sidewalls of the tube might no longer be able to.
Compressors get very, very hot and are internally lubricated by oil. If the oil gets too hot it can foam and stop lubricating properly.
Does your unit have a fan blowing over the compressor or is it simply using convection to lose the heat?

Even just extending the hose can damage the compressors over time.

so your saying its designed to pump heat into the room via radiation through the tube?

VIRII · 29 Jul 2006 at 14:57

Overlag said:
so your saying its designed to pump heat into the room via radiation through the tube?

No, it is just cheap and cheerful and the hose is not better thermally insulated because that would be more expensive and harder on the compressor as well.
The likelihood is that when these units were tested to see how well they performed that they weren't tested with lagged outlet ducts which will retain the heat around the compressor more than unlagged.
I am sure that you accept that the same heat is being generated, where do you think it is going since you lagged the hose?

RJC said:
Just to add - the suction gas returning from the evaporator will help cool the oil and compressor.

Also certain external splits have jackets on the compressors to keep them warm and cut down noise.

RJC

Absolutely, ice can build up into snowballs on the suction side of a decent size compressor whereas the liquid side can be red hot. Everything in a portable unit is far more cramped and heat expulsion is much more difficult than it is with a split system. As with a fridge or freezer the back of it is hot and getting rid of hot air is not that easy.

Overlag · 29 Jul 2006 at 15:08

VIRII said:
I am sure that you accept that the same heat is being generated, where do you think it is going since you lagged the hose?

out the end of the hose like its suppose to? :confused:

Wren · 29 Jul 2006 at 15:13

I have a 5000 BTU in my bedroom and it does very well.
As far as the BTU goes, it depends on the size of the room you wish to cool.

RJC · 29 Jul 2006 at 15:21

Absolutely, ice can build up into snowballs on the suction side of a decent size compressor whereas the liquid side can be red hot. Everything in a portable unit is far more cramped and heat expulsion is much more difficult than it is with a split system. As with a fridge or freezer the back of it is hot and getting rid of hot air is not that easy.[/QUOTE]

Very few split systems have a large amount of room for the compressor to breath. only larger VRV / smaller water chillers have reasonable amount of room.

On my portable unit the compressor sits at the bottom away from the condenser fan, with small holes in the plastic to allow cool air to enter, lagging the air discharge line in my mind will not course harm, belongs he is not restricting the air flow which will course the discharge to rise and make the compressor work harder.

RJC

VIRII · 29 Jul 2006 at 17:51

RJC said:
On my portable unit the compressor sits at the bottom away from the condenser fan, with small holes in the plastic to allow cool air to enter, lagging the air discharge line in my mind will not course harm, belongs he is not restricting the air flow which will course the discharge to rise and make the compressor work harder.

RJC

So the only route out for the hot air is via convection? There is no forced air over the compressor at all?

The poster was suggesting that heat was entering the room as "leakage" through the sidewalls of the hot air ducting. The heat in the locality builds up, "soaks" the sidewalls and exits through them. If lagged it is going to have a harder time exiting and soaking the sidewalls. As the air is not driven it has only convection to remove it from the compressor.
I would wager that the compressor locality is now quite a lot hotter than it was before, we'd have to tape some thermocouples to the compressor body and try with lagged an unlagged for a decent comparison.
The heat has to go somewhere. If it can't radiate through the walls of the hose because they are now insulated then it will be heating the surrounding area inside the lagging.
It might be more effective to put a fan inline in the hose to drag air over the compressor and expel hot air out the window.

RJC · 29 Jul 2006 at 19:03

VIRII said:
So the only route out for the hot air is via convection? There is no forced air over the compressor at all?

The poster was suggesting that heat was entering the room as "leakage" through the sidewalls of the hot air ducting. The heat in the locality builds up, "soaks" the sidewalls and exits through them. If lagged it is going to have a harder time exiting and soaking the sidewalls. As the air is not driven it has only convection to remove it from the compressor.
I would wager that the compressor locality is now quite a lot hotter than it was before, we'd have to tape some thermocouples to the compressor body and try with lagged an unlagged for a decent comparison.
The heat has to go somewhere. If it can't radiate through the walls of the hose because they are now insulated then it will be heating the surrounding area inside the lagging.
It might be more effective to put a fan inline in the hose to drag air over the compressor and expel hot air out the window.

Yes air over the compressor is only convection, these compressors are designed for suction gas cooling, and can operate at high ambients.

Installing thermocouples to check the compreesor temperature would make a intresting expreriment to test.

Just re-read your earlier post regards oil foaming, in my expireance oil only foams when liquid comes back to the compressor, oil when hot will just reduce viscosity.

In low very low temperature operations or very high temperature operations we install liquid injection to help cool the oil.

Rob

Overlag · 29 Jul 2006 at 23:28

VIRII said:
So the only route out for the hot air is via convection? There is no forced air over the compressor at all?

The poster was suggesting that heat was entering the room as "leakage" through the sidewalls of the hot air ducting. The heat in the locality builds up, "soaks" the sidewalls and exits through them. If lagged it is going to have a harder time exiting and soaking the sidewalls. As the air is not driven it has only convection to remove it from the compressor.
I would wager that the compressor locality is now quite a lot hotter than it was before, we'd have to tape some thermocouples to the compressor body and try with lagged an unlagged for a decent comparison.
The heat has to go somewhere. If it can't radiate through the walls of the hose because they are now insulated then it will be heating the surrounding area inside the lagging.
It might be more effective to put a fan inline in the hose to drag air over the compressor and expel hot air out the window.

its not leakage, any leakage i had i fixed by making sure the duct was screwed into the fittings as much as possible, I didn't have them screwed in enough before so i had a longer duct, but i ended up with leakage through the duct ends. The problem i had was the thin plastic radiating the heat through, once it warmed up.

it has a fan blowing through the compressor/condenser side then through the said duct. The radiation through the duct itself is a by product of using a flimsy duct that's very fin, it isn't "suppose" to do that, its supposed to blow all heat out the end of the duct.

100% of heat goes into that tube by a blower (or fan, not sure) if 80% comes out the end and 20% radiates through the duct surely that's a bad thing.

Now i probably have 90-95% of heat going straight out the end out the window, and only about 5% into the room again.

I've noticed two things:

the heat behind the unit is cooler (where duct is)
the heat coming out the pipe seems warmer (I'm talking hand feel test)
the cool air coming out the unit is a lot cooler and the room cools faster

Matrix · 30 Jul 2006 at 16:35

I'm looking to getting this one.
Need something for the kitchen/conservatory as it's boling hot in summer and freezing cold in winter.
http://www.diy.com/diy/jsp/bq/nav/n...}&fh_eds=ß&fh_refview=lister&ts=1154273639755

And this one doesn't need another outside unit like some systems need.

RJC · 30 Jul 2006 at 16:53

Looks good, be interesting how quiet it is, as you got all the parts in one box.

RJC

Matrix · 30 Jul 2006 at 22:47

RJC said:
Looks good, be interesting how quiet it is, as you got all the parts in one box.

RJC

It's meant to be quiet and we'll only have it on to warm things up or to keep thing cool when ever we need it.

£100 off till thursday which always help

RJC · 30 Jul 2006 at 23:07

Matrix said:
It's meant to be quiet and we'll only have it on to warm things up or to keep thing cool when ever we need it.

£100 off till thursday which always help

That true £100.00 off is a good deal, just checked delivery time 3 weeks :eek:

.
Least you can test the heating setting

.

Rob

Matrix · 31 Jul 2006 at 09:30

RJC said:
That true £100.00 off is a good deal, just checked delivery time 3 weeks .
Least you can test the heating setting .

Rob

There in stock at my local branch.

Spinal2k2 · 1 Aug 2006 at 21:23

Matrix said:
I'm looking to getting this one.
Need something for the kitchen/conservatory as it's boling hot in summer and freezing cold in winter.
http://www.diy.com/diy/jsp/bq/nav/n...}&fh_eds=ß&fh_refview=lister&ts=1154273639755

And this one doesn't need another outside unit like some systems need.

ive just noticed the optional parts

£79.00 for a longer hose - what planet is that company on because it certainly aint earth

Matrix · 1 Aug 2006 at 21:32

Spinal2k2 said:
ive just noticed the optional parts

£79.00 for a longer hose - what planet is that company on because it certainly aint earth

Yeah i had to laugh at that too.
Picked it up today looks good weighs more than first thought!
Now just got to fit it up get someone to do it as i've got little time at the moment.

RoboCod · 1 Aug 2006 at 21:36

Heat wave is over now though guys, no need to panic, you're not going to die now, you can also save loads of money and not buy one

Matrix · 1 Aug 2006 at 22:10

Captain Planet said:
Heat wave is over now though guys, no need to panic, you're not going to die now, you can also save loads of money and not buy one

The fact that i bought one is that i have a open plan conservatory running into the kitchen and it gets cold in there at winter time.
So i can set this running to keep a nice steady temp which will be nice.