Toshiba vrv

[Andy AC]

Hello guys, just been reading the posts about the toshiba mar vrv's, and kind of got the feeling that you guys don't like doing compressor changes on them. I've got one of them go down (inverter side of comp) on one of the sites we look after, we were dreading this day:(
The machine is a MAR F105HTM8-PE (3pipe) on R407c. With the pipes and indoor units the gas charge comes in at just under 36 Kg, and the condenser is up the top end (up several steps) to the end of the garden in an enclosure. From what I've read so far, the compressor is a real brute, so I'm not looking forward to it at all, what are the usual problems changing them? Would I need to get into the left hand side of the unit? (looking from the front) or could it be done from the front or rear only? the unit is very close to the left hand side, and access from the back is a bit limited.
The main thing I am concerned about is how much time to allow for doing the job, I've never had to work on vrv's much so it's pretty new to me, In the past I've just fiited/worked on splits/twins.
Any help/advice greatfully received.

Andy

[The Viking]

Oh dear!

OK,
Good news first, the sides of the unit is only coils, so no access needed there.

BUT.
The top has to come of together with the fans.
The central support bracket has to come off.
The electrical / control panel has to come off (note: can be done with leads attached if careful.)

Then you are ready to shift the compressor, easiest is to cut suction and discharge pipes a bit away from the compressor, where it's easy to get at them, then move the "end bits" between the new and old compressor before lifting the new one in to the unit.

Here's the really bad bit.....
Toshiba san in his wisdom decided that it would be a good idea to put both compressors in the same shell.
As a result the lump is f@@king heavy. Proper lifting gear is essential, manhandling darn near impossible.


Also, remeasure the pipe run and recalculate the total charge. Get rid of the old gas and recharge with fresh.

And before you give a price, make sure the inverter itself is OK.

[superswill]

would it be worth changing the inverter PCB as awell? think they call it the IPDU on these

[The Viking]

Unfortunately, we have changed quite a few of these...

Normally, the inverter electronics are OK.

But if you are doing it on a price it's worth checking first (or make sure it's excluded in the quote, "any other parts found faulty..." but then what will the customer say when the final price is twice the original quote?)

[Andy AC]

Inverter board tested with my edc inverter checker, all seemed fine - first time it's come out of the box, I've had it for more than a year!

Andy

[frank]

Andy.
You can close the service valves and then just recover the outdoor unit gas charge.
When you get the compressor out do an oil acid test. If it's clear then there is no need to recover from the entire pipework and indoor units. Just recharge the amount you took out of the condenser unit.

Saves time and cost :)

Good luck.

[Andy AC]

As a result the lump is f@@king heavy. Proper lifting gear is essential, manhandling darn near impossible.



:eek:You've got me worried now! How heavy is it?

Andy

[The Viking]

@ Frank,

If the compressor failed because it overheated due to a lack of refrigerant.........


@ Andy,

From memory, about 150 kG.....(I might be wrong but it is definitely on the wrong side of 100)

[FreezerGeezer]

I've worked on a few of these type units. I've not had to do a comp. change yet thankfully, but thinking 'what if', I took a good look & frankly I would recommend an a-frame or similar to get the compressor out & new one in. The machine is waaay too tall to be able to lift it in & out by hand, even if it were liftable.

[frank]

Viking
That's a possibility - but would show up as very low suction pressures, frosting and under performance at the fan coils at re-commissioning. At least it would speed up the compressor change if this wasn't a cause of the original compressor failure.

[The Viking]

Sorry Frank,

On this issue we just have to agree that we disagree.

The VRV/VRFs are very good at hiding losses of charge, unless you got the DynaDoctor connected (in the case of Tosh) and can compare to previous recordings, it's very difficult to determine refrigerant losses.

In fact, when you call the manufacturer's engineers out for almost any problem with these machines, their standard greeting phrase is "are you sure the charge is OK, you have reclaimed and checked?"

Sorry but in my mind those extra hours reclaiming is well spent money.

BUT, there is good news.
What I would do is to shut the valves and reclaim the outdoor unit, then reclaim the pipe work / indoor units whilst I change the compressor.

(Oh, one more thing, remember to force the valves in the MC boxes open before you turn the power off to the outdoor unit)

Edit: After the reclaim unit finished with the indoor side, get the vacc-pump working on it...(saves time)

[dannyd]

4-5 days for 2 men + basic brute force- don't go cheap as you have to watch out for recalls after fitting the new compressor. If the DOL side is ok, then charge problems usually not the cause as protection safeguards normally help protect the compressors. We've done several of these units (Comp changes) and were badly stung on one unit with subsequent follow-on probs that even Toshiba threw the towel in trying to solve (Toshiba tech help brilliant in initally supporting us in supplying boards & components to 'trial' & had tech support made available- but eventually diagnosed prob ourselves after 2nd comp change on unit). Biggest problem is what caused the inv side to fail - you usually don't get to know until the comp is changed and you try to recommission the unit.

[philjd26]

hi,

have done a few of these poxy things...more or less have take main control board out ofthe unit...think you remove mains supply and the thing shifts when snip a few cable ties..........there is a swage connection on the suction before it goes inti compressor(sweat this out)....and sweat discharges

when your done that,look at the compressor feet and notice the tray that it is sitting on...this tray slides out with compressor on it so you can lift iton outside unit...

make sureyou have plenty of silver solder n flux for de suction as its copper to metal...

rgrds phil

[Andy AC]

(Oh, one more thing, remember to force the valves in the MC boxes open before you turn the power off to the outdoor unit)
How do I do this then? is it just a case of asking all the air handlers to run in the same mode? or do I have to physically do something to the multi boxes?, I don't have any info on this system, it looks far to complicated for its own good.

Andy

[The Viking]

You have to open the control section of the MC box, set the rotary dial to a certain value and shorten out 2 pins..
Then turn the power off within a minute....

I will check if I can find the official description somewhere, otherwise the guys at Toshiba technical are good at describing it over the phone.

[The Viking]

Found it!
(But that text was too short to post)

[Andy AC]

Cheers Viking

Andy

[Loops]

Hi Andy,

See you are from IOW - I was over there on Sat visiting my sister. Chance to give the bike a run out.

Viking has it mostly correct and pointed out the important thing to open the PMVs in the multi boxes before recovering the charge.

But he said to take off the fans and central support which is not necessary for the F105 model. The F105 design should allow the commressor to be removed on a tray from the rear.

Viking you were thinking of the earlier models with two fans.

Some other useful pointer is to evacuate from liquid and discharge ports (don't evacuate just from suction) - all three is fine.

Pressure test by putting OFN in the suction port.

If you've got outputs from the IPDU board then there's no need to change it.

Compressor weighs 120kg - it's one shell with two compressors inside 1 x inverter & 1 x fixed speed hence it's weight.

I reckon two men for lifting\sliding compressor and two days to do job thoroughly.

Highly recommend you measure pipe work and calculate additional gas charge independant of any information written on site. What else are you going to do during pressure test or evacuation?? May as well measure the pipework.

Cheers

Loops

[Andy AC]

The F105 design should allow the commressor to be removed on a tray from the rear.


Does it have to go in and out from the rear? I haven't got much room to play with. I'd rather slide it in and out from the front but the 1 1/8 pipe looks like its going to get in the way.
I spent most of the day getting the rest of the gas out of it and stripping out the electrics. It was 1kg short of what it was originally calculated to be, so possibly not enough to cause it too much of a problem. Most of the time it only ran 5 out of the 10 indoor units connected, never works hard, maybe works hard for 1 week a year. The gas didn't smell either, which is a good sign but I will do an acid test when I get the old one out.
Just had a thought, when the original installer came back to sort out some problems, they moved one of the indoor units by about 8m. Can you pump these down like you would a normal split system? or would all the gas need to be recovered to extend the pipework. There was no mention of the extra pipe on the calcs. I bet they didn't add any more gas.
Before I get any deeper into this is there anything else I can check? or are these compressors just a bit on the unreliable side?

Andy

[TRASH101]

there is a swage connection on the suction before it goes inti compressor(sweat this out)....and sweat discharges



sorry philljd

It is, in my opinion, bad practice to apply brazing/ soldering temperatures to fridge line that potentially has oil in it. Im sure you know what I mean because oil fires aside the fumes are noxious and toxic and you dont want that muck left in your pipes.

[TRASH101]

Andy,

If its not to late, could you not factor into your price provision for setting up a F gas log including initial pressure test. If your working on a system with an unknown volume of gas its down to you to mark up the system for the new charge and you cant prove it wasnt leaking before you attended site if the original installers didnt mark up the original charge. So after the acid test I would treat the system as a new install and fully re commission. This extra provision might subsidise the repair if things go amiss.

good luck:D

[Andy AC]

It's in, and it works:D, has been for nearly a couple of weeks. Fortunatley I missed the carrying of the compressor up the steps to the garden,( convenient, well timed marstair cellar cooling breakdown on the other side of island:)) but tragically I am going to have to remove the old one from the garden at some point:(
Anyway thanks all for the crash course in vrv's:)

Andy

[Rotax100uk]

Andy.
You can close the service valves and then just recover the outdoor unit gas charge.
When you get the compressor out do an oil acid test. If it's clear then there is no need to recover from the entire pipework and indoor units. Just recharge the amount you took out of the condenser unit.

Saves time and cost

Thought with R407 ya couldnt "top-up" once charged?

[nike123]

Thought with R407 ya couldnt "top-up" once charged?
If you recover that in empty tank, and then charge back to system, that is not "topping-up".

And R407C could be topped up if that topped amount is not higher than 10% (some sources say 20%, but I prefer to be at safe side) of total charge.

[Rotax100uk]

i was told its something to do with the refrigerant splitting as to why it couldnt be "topped up" do you know of this?

[paddyaircon]

i did one of these compressors on a town hall roof just - not a pleasant experience- carried compressor thru a window as only access to condensor- total nightmare- right to open pmvs for reclaim and vacc-

[Air Bear]

I have done loads of these and they are a piece of p**s. All the bits come out in lumps, inverter/control box etc, cut the suction where it is out of the way to remove the comp but where easy enough to re-join. Cut the discharge pipes close the the comp then un-braize the stubs after the pot is out.
The comp can be took out the front or back (97Kg). 1 day 2 men to recover all gas, replace the comp and stick on vac, 1 day 1 man to re-charge and re-commission. Acid test/treatment and a liquid drier are a good idea, you don't want to do this job again under warranty.

[paddyaircon]

no pressure test then air bear?????