Need Advice for charging R410A splits

[asmaircon]

Hi I would like to know when you install a split system with a pre charged pipe run of 10m and say the run you need is only 5 metres do you actually recover some refrigerant out of the condensor or leave the remainder in there, will it run fine with the excess refrigerant? if you take it out how much do you take out? also what should be the right running bar pressure of r410a split systems

Many Thanks

[Tayters]

Shouldn't need to recover the excess unless the installation manual says to which will be unlikely.
Should run at a saturated evaporating temperature about 5*C, a comparator will give you a pressure reading.

Cheers,
Andy.

[Brian_UK]

If installing new equipment - read the installation instructions.

[install monkey]

or to be on the safe side run an extra 5 mtrs of pipework and u dont need to refer to the manual

[Tayters]

or to be on the safe side run an extra 5 mtrs of pipework and u dont need to refer to the manual

Ahh good one, unless the manual had the details of maximum pipe run then it'd be a catch 22.
Flares wellied up until yer sacks twinge, gas and go, then off to the faulty central heating job. Vac attack optional. ;-)

[monkey spanners]

Hi I would like to know when you install a split system with a pre charged pipe run of 10m and say the run you need is only 5 metres do you actually recover some refrigerant out of the condensor or leave the remainder in there, will it run fine with the excess refrigerant? if you take it out how much do you take out? also what should be the right running bar pressure of r410a split systems

Many Thanks

Depends if its under the minimum allowable pipe run, often something like 3meters, have a word with the manufacturers tech dept and see what they say about your specifc proposed install.

If it needs 30g a meter over the precharged length then it will likely need -30g a meter under the minimum length, good luck with measuring that though as its about a gauge line full!

[MikeHolm]

" Flares wellied up until yer sacks twinge, gas and go, then off to the faulty central heating job. Vac attack optional. "

WTF....sounds like greek to me....I need a translation

[mikeref]

[QUOTE=MikeHolm;244426]" Flares wellied up until yer sacks twinge, gas and go, then off to the faulty central heating job. Vac attack optional. "

About 830Kpa, or 120 Psi low side pressure. Changes with compressor speed. Don't know what Tayters had to drink today !!

[Tayters]

Flares wellied up until yer sacks twinge,

Do the flares up untill the effort exerted on the spanners produces enough downwards force through the stomach and lower intestines causing discomfort in the scrotum. If unlucky it'll cause a hernia - it did to me once, only I was lifting a car wheel up at the time!!

gas and go

Charge the system and make haste to the next job.

then off to the faulty central heating job

Suspect posters main job isn't in AC due to the question. Possibly a plumber. Could be wrong though.

Vac attack optional.

Subject pipework internals to negative pressure via a vaccuum pump to give some credence to a job well done. If not bothered, a swift purge during the 'gas and go' stage.

Drink had nothing to with it - just high on life!!

Cheers,
Andy.

[spoon man]

Ac normally has a big enough reciever to cope. If not you running pressures will let you know

[asmaircon]

Thanks for all the replies guys, another question, how many of you other engineers actually connect a ofn bottle to purge through the pipes while brazing? In the real world and the contractors iv worked with not many of them do, also what are your pro's and con's of brazing with or without OFN

Thanks

[Brian_UK]

<snip> also what are your pro's and con's of brazing with or without OFN

Thanks

No OFN means a bad job , no warranty, short life span.

[MikeHolm]

Do the flares up untill the effort exerted on the spanners produces enough downwards force through the stomach and lower intestines causing discomfort in the scrotum. If unlucky it'll cause a hernia - it did to me once, only I was lifting a car wheel up at the time!!

Andy.

I guess i won't lend you my 4 foot steel pipe wrench

[mikeref]

Could use an 18" shifter Andy. Saves on dislodged shoulders and straining other muscles.

[Makeit go Right]

"what are your pro's and con's of brazing with or without OFN"

There's a YouTube display of all the dirt left inside a braze due to oxidizing inside the pipe, when you do not use a nitrogen bleed through the pipeline, which is a shocker.

I was talking with an engineer the other day (not one of mine) and he explained about a VRV system he helped install without nitrogen. The whole system (something like 30-odd room units with BSV boxes and all the brazes around them too..... all without nitrogen. Almost finished and the builder is not paying until the pipe is fully installed. Not sure if he has said he wants to see it commissioned before letting some of the payments go out. Probably not, I guess.

It is very sad. You can see how this is going to go.
The customer will have some cash yet to pay the builder on the job -- more than the value of the aircon install..... the builder will be holding back the bulk of the aircon invoices, like he normally does (while the installer squirms to cover his supplier/labour costs, hoping that the builder will pay when it is fully piped.

The installer does not (did not) realise there will be a problem, or he would push for the bulk before he commissions. Because the commissioning is going to be a disaster.

As soon as the cat is out of the bag, and the fan goes brown, the Customer will not pay anything more. Builder will not pay subby. Subby goes broke, owing suppliers and labour, and all his engineers are promptly looking for work elsewhere. The manufacturer checks out the system/compressor and explains the bad news about the system and the equipment warranty. The customer says he wants the whole thing ripped out and a new system+kit installed. Subby is unavailable, believed living in another country. The builder looks for a new contractor to a) rip it all out and b) install all of the system a second time, properly. New rip+install cost is more than double what he thought he was paying. (The new contractors should be on high guard that they will not get paid from this job. Some shy away from it.) Project is in megger delay and liquidated damages are flying around. Other contractors claiming extensions of time. The customer cannot move into the building with aircon engineers ripping down ceilings and braising in new pipework system, craning in new condensers. Builder is having cash flow problems and the other subbies on the site are not getting paid. Some subbies go broke or stop work and loose what they have spent on the job. Builder eventually goes broke, owing several subbies and suppliers lots of cash. Some directors loose their houses, which were security for business loans.

All for a few bottles of nitrogen and a little extra time during the install. Pennies on that kind of install.

<b>Pros?</b> None really, except for the fly-by-night labour who gets paid up by the week, and is long gone when they see the problem brewing.

[MikeHolm]

Wow, nice "play by play"

[Tayters]

Thanks for all the replies guys, another question, how many of you other engineers actually connect a ofn bottle to purge through the pipes while brazing? In the real world and the contractors iv worked with not many of them do, also what are your pro's and con's of brazing with or without OFN

Thanks

Ahh sorry mate, there's me hinting you were a plumber. Looks like the joke's on me then!

From my experience brazing without OFN is widespread. I did as the rest before I wised up.

Once you're all set up it doesn't take much longer. Gonna need OFN for pressure testing anyway so not like it's much more work really. Remember many AC systems don't have a filter as such, just strainers by the EEV. I think their capacity is generous but wouldn't like to find out how much they can take!

Also it shows a degree of professionalism. If the tech doesn't purge then what else gets missed? If a tech does purge then there's a fair chance he/she will do the rest of the job correctly.
When all else fails and the system still wont work at least you'll be confident it's not down to any muck stuck where it shouldn't be - unless you were to generous with the brazing rod!

Cheers,
Andy.