Longer pipe run splits

[airefresco]

Does anybody know of any 2-3kW split systems or multi-split systems that are good for a 25M piperun?

Trying to keep costs down as our orignal quote was for 3 back to back splits. However the owner of the house has told our client that the outdoor units can't be on an exterior wall or on the roof.

General (Fujitsu) want 3079 euros just for the outdoor unit for there multi-split system, which I'm not really a fan of, but is apparently good for a total of 60M.

Cheers
Paul

[frank]

Hi Paul

The total piperun of 60m is for the TOTAL connected pipe lengths - so you could have 3 indoors connected each 20m from the cond unit.

3079 euros sounds expensive for Fuji.
Have a look at the Daikin 4MKS90D multi split on R410a - 9kw total cooling duty with a maximum pipelength of 70m retails here Trade @ £1317 condensing unit only or the heat pump version 4MXS80D, 8kw cooling 9.6kw heating, same pipelength for £1447

I know you can get Daikin in Spain as I've bought it there - don't know about the islands though.

[dogma]

Can extra charge be added for long runs? I know with 7kw Mitsubishi Inverta, with added charge you can run 35 - 40 meters. Taking into consideration traps and bends.....and height.

[Johnny Rod]

Depending on how much oil the compressor spits out, with long pipe runs and hermetic comps you risk oil starvation as the time taken to return is too long. Dunno if anyone has a suggestion for it though.

[techguy]

Jesus lads
there only splits just install them add a small amount of fridge oil additional refrigerant and walk away. If you really want to be careful fit a few oil traps.
For **** sake just do it
I ve fitted 3.5 kw splits with 50 mtrs on them with a small ammount of capacity drop off but they worked fine.
T

[Brian_UK]

Jesus lads
there only splits just install them add a small amount of fridge oil additional refrigerant and walk away. If you really want to be careful fit a few oil traps.
For **** sake just do it
I ve fitted 3.5 kw splits with 50 mtrs on them with a small ammount of capacity drop off but they worked fine.
T

I've also seen overlong piperuns which have caused the evaporators to start freezing with the resulting water splatter - get the right size units.

[Sir Josiah Sodd]

Jesus lads
there only splits just install them add a small amount of fridge oil additional refrigerant and walk away. If you really want to be careful fit a few oil traps.
For **** sake just do it
I ve fitted 3.5 kw splits with 50 mtrs on them with a small ammount of capacity drop off but they worked fine.
T

Begorra!

Whack in the gas, and scram when you've got the money!

Do you do tarmac as well?

[frank]

Can extra charge be added for long runs? I know with 7kw Mitsubishi Inverta, with added charge you can run 35 - 40 meters. Taking into consideration traps and bends.....and height.

With most 7kw units you will find that the pipelengths are about 50m, depending on the refrigerant.

The pipework lengths are matched to compressor power so if you put long lengths of pipework on small power comps the gas velocities are reduced thereby affecting duty and oil return.

Similar in design to a fan - add too much ducting and the system resistance increases leaving the fan running overloaded doing very little work.

[airefresco]

Cheers lads.

I looked at loads of makes and most of them said a max pipe length of 10-15M.

I quoted for the daikin multi-split that Frank recommended. I think that will be ok for the client needs. I found a company in Madrid that can supply. The price was very reasonable.

Something that does concern me though. The Daikin is almost 2500 euros cheaper than the General (fujitsu) equivelant. Whats wrong with this picture?

If this works out OK, we will never have to touch General again. YEEHA.

[frank]

Good choice.

I think you will be impressed at how the multi works.

The old Daikin VRV II used to tell you if it was under or over charged but the new Daikin VRV III adds the additional gas charge automatically itself to match the installed pipework lengths.

Lots of people call the Japanese but when it comes to electronics they are hard to beat.

[Jez]

Probably a bit late now, but Toshiba do some 25m run high-wall splits (Daiseikai II range) 2.5, 3.5 and 4.5 kW cooling capacity.

[airefresco]

I used to work mainly on Daikin when I lived in England so im happy fitting that.

And Toshiba wash your mouth out.

Paul

[rbartlett]

does that mean you won't be coming round to do my drive??

cheers

richard

[Johnny Rod]

Good grief, it's turning into one of those threads. Who needs Marc for some random aggro?

[phil68]

Blimey. For God's sake don't anybody mention anything about lepracorns

[Lancer]

Just go to the next size vapor return pipe, this will reduce the extra friction load on the compressor, and stop your liquid line icing up all the way to the evaporator.
I have seen a few installs of long run splits (20 - 30 mtrs) that have this problem.

[hybridjunction]

Hi Lancer. Can you elaborate further?

[frank]

Just go to the next size vapor return pipe, this will reduce the extra friction load on the compressor, and stop your liquid line icing up all the way to the evaporator.

And reduce the vapour velocity and reduce oil recovery

[Lazarus]

Decrease pipe size on the risers to increase velocity and therefore oil return.... Increase pipe size on the horizontals to decrease friction losses..... Both suction and liquid lines as its an heat pump....
But could you utilise both and to what extent.... where would you meet the limit.....
How far on average could you increase the pipe runs...
If you are using non-standard pipe size can you still use the g/m extra refrigerant guide....

what a tangled web we weave.............. A bit tongue in cheek i admit

[Lancer]

Hi Lancer. Can you elaborate further?

hybridjunction,
hi hows things?, in my experiences I have found that most split have a metering device (capillary tube) at the compressor end before the liquid line service valve, so depending on the system balance (liquid/vapor) when the delivery head is to high, there is a tendency for the suction pressure to drop to low across the evaporator/distributor causing the liquid to boil off back down the line. Depending on the charge (to some degree) I have seen units with the armaflex on the liquid line sweating from the head to the compressor, I can only assume that armaflex has been pushed past its insulation value (-10 deg C) by the excessive run length and insufficient gas.

And reduce the vapor velocity and reduce oil recovery

Frank hi,
your point is very valid and should always be taken into consideration when working with installs where the head is located below the compressor, most manufactures recommend P traps in this situation. In the other case where the compressor is below the head I have found that gravity is sufficient to return enough oil for the compressor to operation normally.

I am interested in the views of others upon this subject because I am frequently confronted with installs where the client wants the condenser positioned past the recommend pipe length.

On an other point, how many guys look at the super heats across the evaporator; or just use the sub cooled vapor pressure, to determine correct charge? I have often wondered how may splits have had there efficiency affected by under or overcharge condition caused by pipe length.

Please forgive me if this subject has been bashed about this forum before, I must admit it is a pretty obvious problem with pre-charged units.

Lance.

[hybridjunction]

Hi Lancer. Things are good u?

By increasing suction pipe size does this not "raise" evap pressure giving better efficency? Assuming the pipe lenght is the same as it would have been with the smaller dia.

[Lancer]

hybridjunction

By increasing suction pipe size does this not "raise" evap pressure giving better efficiency? Assuming the pipe length is the same as it would have been with the smaller dia.

Yes my thoughts exactly, I have use this principal successfully on many installs.

Lance

[airefresco]

It's a bit late now because I no longer need a unit capable for a long, but I found one!!

The Toshiba R410A Daiseikai Inverter Split system are good for 25M. They come pre-charged for 15M.

Just thought I'd post this for future reference.

Paul..

[Jez]

It's a bit late now because I no longer need a unit capable for a long, but I found one!!

The Toshiba R410A Daiseikai Inverter Split system are good for 25M. They come pre-charged for 15M.

Just thought I'd post this for future reference.

Paul..

Errr, didn't I mention that on page 2 of this thread?

You told me to wash my mouth out, which I did.

[airefresco]

oh yeah. Errrm. I'll go and find the soap. Sorry.

Actually I'm thinking about giving Toshiba another go. I used to look after a site in Bradford that had loads of Toshiba splits and VRF's and they were always breaking. We use to get a couple of call outs a week there, hence why I dislike Toshiba. However, from what I have read recently, it might not actually be bad kit.

I need to find someone who does a decent cassette, single blow and ducted system. I'm fed up with installing General.

So, if Toshiba ever get back to me and tell where I can buy it, I might give it a go. Alternatively im also looking at Hitachi and Mitsi-elec.

Regards (and sorry, again)

Paul..