A/c High Pressures

[freezy]

Was looking at a Panasonic HP 100 split wall mounted system (same as daikin - R407c).

In heat mode after about 5 seconds disharge as read at 3/4 service valve reaches 400 psi and unit trips.pressure is roughly the same at 3/8 service valve and receiver gets warm and solenoid valve seems to work.

In cool mode unit runs with a discharge pressure as read just after 4 way valve of 400 psi, suction line ices all the way to compressor but indoors you would beleive unit was cooling okay, unit does not trip.

There seems to be a restriction in the outdoor pipework somewhere,would it be a good idea to fit a few line tap valves or strip components out. i cant see enough of a difference across any component to find a restriction,is it moving around?

I wish pipes were made of glass.

[frank]

Have you checked the running current?

It may be overcharged.

[chemi-cool]

I'd go also on that, overcharged.

Chemi

[freezy]

Thanks guys,

When I got to the system it had no gas in it so I pressure tested it and it was okay. I then evacuated and charged it with the amount of R407C on the name plate - 3.6Kg. As there was no leak I can only assume someone has already had a look at this system and lost the gas.

I have attached a Daikin piping diagram.

[Brian_UK]

If it is like a Daikin check also that the condenser fans are running at full speed; sometimes they operate on ambient temperature and not system temp/pressure.

This can sometimes throw a high pressure fault. How deep was the vacuum ? Any non-condensibles trapped ? (Not trying to teach you to suck eggs, honest)

[frank]

I've checked the spec for this unit (Panasonic Urban S100K1)and the factory charge of 3600grams is for a pipework length of 70m. The pipework sizes should be 3/8 liquid and 3/4 suction.

How long is your pipework and is is correctly sized?- have you checked the size half way down the run?

Is there any additional filter or sight glass installed? - oil traps are not allowed. Check the whole installation, not just the outdoor unit.

For a single phase unit the FLA = 24.8A
For a three phase unit the FLA = 10.7A

[freezy]

The pipe run is about 5 metres 3/4, 3/8 with no modification, flare nuts used on indoor and outdoor unit. I assumed that this gas charge would be sufficient upto a certain pipe run and knowing Daikin's are usually 30m this was the right charge. Where can you download Panasonic technical info.

[frank]

Where can you download Panasonic technical info.

I don't know anywhere on the net for technical info on Panasonic products. Even the Panasonic home page http://www.panasonic.co.uk/air-condi...home/index.htm for the UK is crap.

As the unit is pre-charged for 70m and your pipe length is only 5m I would suggest that your high pressures are due to overcharge. Remove 0.5kg and see how that affects the head pressures. If you notice a difference you can then either add or remove gas as required.

[bobjob]

Hi Freezy

You need to get some of the gas out of your Panasonic !

Don't know if this is the answer to your head pressure problems but for Daikin Skyair range on R407c the minimum pipe work length is 7.5m

I found this out the hard way by 5 out of 8 compressors haveing to be changed on a site in Warwick.

Pipe run was around 3m for all systems
On the maintenance visit after summer and before winter all ok, After winter 2 compressors not pumping- other 3-had high mechanical noise in body of compressor plus high comp,amps.

Daikin U.K.or Belgium could not at the time make up there minds about the removal of the refrigerant for systems under 7.5m and they had to wait for instruction from Japan.
I could not wait any longer for them so I exstended all refrigerant pipes.

After I did see a memo last year from Daikin that if the run is below 7.5m a certain amount of R407 c should be removed however sorry I can not find the info for you.

regards Bob

[freezy]

Hi bobjob

I have heard that you should take gas out on some systems but never known which ones. The manafacturers give out specifications on systems and should put the full and correct info, I first thought it seemed overcharged but ruled this out as Ive fitted a lot of Daikin kit and never come across this.

Were your comps replaced under warranty as the instructions were wrong?

[bobjob]

Hi freezy

The 8 Daikin units were one of the first installed in the UK using R407.

After the compressor failures and a visit from there top engineers to site. Daikin came forward that the pipe run was to short and that 7.5 m was the minimum, this information apparently is hidden away in the installation manual.

Although i am self employed, i was working for a company that as alway brought Daikin equipment and is a Daikin Business Partner so in the end after some arguments the compressors came under warranty,
(i think one of the director missed out on the Japan trip that year, although he as gone since)

If you look at your Panasonic you will see that it is fitted without any suction accumulator - this is a problem when the pipe run is short.

regard bob

[frosty74]

i have had this problem with panasonic 4kg standard charge for system but pipe run was less than stated reclaimed gas vacumed and charged with 2kg and added to bit by bit to get satisfactory h/p.
ended up running ok with 3kg charge also heard panasonics have had problems with the inline filters.

[freezy]

Thanks for your replies

I will eventually get back to this system to recharge it,etc.

I will keep you posted.

[frank]

Why has everyone decided to exclude internal fractionation?

I think we ought to determine the correct charge first.