Aircon Pipes Already Installed

[moe666]

Your lines are not grossly oversized, and you should be ok with the smaller unit. Line size matters more when you are using a cap. tube or orifice plate but if the unit has a txv the tube size should be ok. It is the final charging and balancing of the unit that can take out a few of the flaws as long as the flaws are not to big. Good luck, even finding a good a/c mech. in the states is a real pain.

[mdechgan]

Standard industry size for a 18,000 btu unit is usually 3/8" liquid. Some will even use 3/8" pipes for 12,000 units if the lines are long.

The main reason 1/4" pipes are used is because to save costs. So no you are not fixed to 24,000 units. 3/8" pipes for 18,000 unit is fine. All the installers have to do is just weld the 1/4" pipe to the 3/8" pipe that's all.

[bkkbill]

Of course as stated by Naam if anything it would be slightly more efficient using larger piping. Don’t always under estimate Thai refrigeration mechanics some are very good. They will not have any problems with the different pipe sizes. It seem there is a mountain being built out of a mole hill here.

[Naam]

The data sheet does not say the liquid and gas pipes should be the same length. It is often the case in engineering of closed systems, that a ''balance'' is required, to avoid unequal pressure drops.

there is no way that pressure and suction pipes can have different lengths except when making a loop in one. a loop of both pipes is important when the compressor/condenser unit is mounted higher than the evaporator. without the loop the compressort will lose its lubricating oil and clog the evaporator. most thai "engineers" have never heard of this mandatory installation feature.

[Naam]

As the pipes are bigger than needed I would have thought an adaptor was all that is required.

Yes, I would try 2 x 3/8 to 1/4 reducers, installing 1 at either end of the liquid pipe run. You will need to check the max length of pipe run allowed, as you are effectively reducing this by 50% -- by increasing the volume of liquid in the pipe.

what crime did i commit that you two are torturing me?

Sorry Naam, if my comments caused you some pain. Please accept, that they were never intended to cause you any distress.

My suggested solution was an effort to spare the OP from ripping off his wall tiles, and also allow him use the smaller AC unit, if he wished. Other posters have made various comments, but nobody has given a reasonable technical argument, as to why, it will not work.

i hereby certify, swear to an affidavit and state in lieu of an oath that the OP won't have any problems using the existing piping combined with a smaller unit

[Naam]

As the pipes are bigger than needed I would have thought an adaptor was all that is required.

Yes, I would try 2 x 3/8 to 1/4 reducers, installing 1 at either end of the liquid pipe run. You will need to check the max length of pipe run allowed, as you are effectively reducing this by 50% -- by increasing the volume of liquid in the pipe.

what crime did i commit that you two are torturing me?

I cannot speak for jomborn but I thought I would just give you a chance to pontificate Naam.

atta boy!

[Naam]

Unless you've got one wall that is all glass, kilowatts of electrical equipment/lighting & many people in the room, a 3 to 4kW unit should do the job (10k to 15k BTU).

If you don't change the pipework, you're stuck with a 24 000 BTU init (7kW).

i [not so] humbly beg to differ Señor Kangorito. if it was the other way round there'd be a problem. suction and pressure pipe for a 24k unit will work on an 18k or even lower capacity unit as well. in fact in my house i run a number of 13k units on pipes normally used for 18 and 24k because of the distance between inside and outside unit.

perhaps you remember... for aesthetic reasons my outside are lined up left and right of the house, that means some of the units have a pipe distance of 16-20 meters.

Does this mean that I can just install the 18,000 btu unit with the larger piping or do they need the reducers?

YES!

[robblok]

YES!

Naam your a character and i love reading your posts.. you put a smile on my face.

[Lancashirelad]

Well now that that seems to be sorted, i hope the OP doesn't mind if i pop in here and ask another A/C related question which has been on my mind for quite some time:

When the indoor unit senses the air is down to the required temp. it interupts the power supply to the outdoor unit hence switching it off, but the fans of the indoor unit continue to run = noise :-(

Would it possible to change the feed point of the wiring to the fans so that they also stop? = silence & peaceful sleep :-)

No doubt there is a reason why they are made as they are. The above change will i'm sure be possible, but would it do any harm?