Installing pipework for single split unit

[electro]

Afternoon all

I've finally spent out the money for a Mitsubishi 3.5kw inverter split, I was wondering if you folks had some 'top tips' for installing the copper refrigerant lines.

To outline the plan, I'm an IT consultant, one of my customers is a refrigeration engineer, he needs his website working on, so we're exchanging some labour times between us. I'm going to undertake the hardware installation: mounting indoor unit, outdoor unit, laying in pipework. Qualified electrician is installing the spur needed for the outdoor unit.

Before you all scream the usual "get a professional in!!" - don't worry, I won't be doing the flare joints or vac'ing/gassing, the refrig engineer will do that part.

The pipework run is about 14m, up an outside wall, and inside/over the loft to the other side of the house where the room is. I don't have a pipe bending tool at the moment, although I might be able to borrow one for the job.

I've never worked with this kind of diameter pipeowork before, and I'd definitely like to avoid any ruptures!! Is it reasonably easy to work with?

Cheers!
-Dave


(PS, sorry for the essay )

[Brian_UK]

Hi Dave, you've asked the question but didn't tell us what size the pipework actually is

Anyway, using suitable pipebenders then you shouldn't really have any major problems.

Make sure that the ends of the pipes are always sealed to prevent ANY dirt getting inside while you are pushing/pulling through holes/lofts space etc.

You may need to join the pipework unless you are lucky enough to fit it in one piece so think where a sensible place for the joins to be - ease of access for brazing etc.

We now know what you're doing at weekends now

[taz24]

Afternoon all

I've finally spent out the money for a Mitsubishi 3.5kw inverter split, I was wondering if you folks had some 'top tips' for installing the copper refrigerant lines.

I've never worked with this kind of diameter pipeowork before, and I'd definitely like to avoid any ruptures!! Is it reasonably easy to work with?

Cheers!
-Dave


(PS, sorry for the essay )

Have you got the pipe already ?
The pipes need insulating with refrigeration grade insulation (not plumbing). The insulation needs sealing with specific glue to stop moisture ingress.
What size is the pipe?
Soft drawn coiled fridge pipe is very flexable and easy to install if you know what you are doing.

There are a 101 things that you need to know to do the job correctly and 1001 things that you need to know how not to do it wrong.

I would offer your fridge guy a bit more time on his web system in return for a bit more of his time in installing the pipe.

If he is worth is salt he could do the whole install in 1/2 a day so how much will you save by doing it yourself.
If you do the install wrong will your fridge guy put it right for you for free? I think not.

taz.

[electro]

Thanks Brian 7 Taz for your valued replies, I understand the need to keep the pipes sealed from dust and debris, any crap in the pipes aint gonna do the compressor etc any good at all

I'll be checking all the bends are smooth and round before applying the insulation, I haven't got the pipe and insulation yet but I think it's 3/8" and 1/4" in size.

The trickiest part as far as I can see is going from the outside wall to the inside of the loft, is it easier to pass the pipes up into the loft, or easier to pass the pipes from the loft to outside? (I'll have assistance doing this part)

Cheers!
-Dave

[taz24]

I think it's 3/8" and 1/4" in size.

The trickiest part as far as I can see is going from the outside wall to the inside of the loft, is it easier to pass the pipes up into the loft, or easier to pass the pipes from the loft to outside? (I'll have assistance doing this part)

Cheers!
-Dave

If you have not yet got the pipe you may consider the pre-lagged pipe. It may help you (and hide some minor errors )
3/8 and 1/4 will easily bend and if you are careful you could do them by hand.
It is somtimes easier to pass the pipe from outside to inside but as always its horses for courses.
I would be tempted to put the pipe in some plastic trunking on the out side. That will make it a lot neater and easier for you.
Be carefull when working up that high and dont work from a ladder. For what it costs hire a tower and use it for the high work.

Its easier to lag the pipes befor you have fitted them and if I was you I would have someone outside pushing / threading the pipe and someone inside pulling / guiding the pipe.

taz

[Paul@paulrobert]

Hi dave if I was you I would also suggest paying your a/c guy a bit more to install the pipework for you . You would be surprised how many customers I have had who did things themselves and then had to pay for me to do it all again. Hope it all works out well
Paul

[momo]

Barter deals are not always the best deal, it is very easy for one or other to feel done unless you have a good BBQ afterwards ... Discount for customer help when specs. are clear is best option.
Through a loft... unless you're very lucky and clever, I forsee brazing of joints - even 3/8 can constrict on a bad bend (pre-covered pipe is worse, you can't see where it happened); 14m. is a too long for a some domestic units and bends count as lengthening of pipe..., certainly look at the instructions: open the holes (it's your brick dust), check for condensate drainings - and help when he comes, lifting etc ... but coordinate with the guy for the run as much as you can.

[electro]

Any recommendations on the plastic trunking, I've found some but it's not as good as the stuff I've seen used in some offices on the exterior.

Cheers
-Dave

[Brian_UK]

Hi Dave, try here for trunking info...

http://www.ryanairconspares.com/index.php/cPath/324

[electro]

Spot on Brian! That's exactly the stuff I've seen, thanks!!

[electro]

Interesting, their site mentions a 5% VAT level for 'Energy saving materials" - http://www.ryanairconspares.com/info...php?info_id=33

As the system I've ordered is a heatpump system too, might I be eligible for the lower tax rate? - if so, how might one go about getting that relief, I guess you'd have to submit your proof of purchase to the inland revenue or something, I bet there's a minor snag which means I can't get it

Let's get it installed first eh?

[Electrocoolman]

Hi Electro,

If you do a search on this site for VAT then you will pull up lots of info.

Basically, if its a DOMESTIC install, the installer can charge the householder VAT at 5% on the complete cost of the install (Parts and Labour) (assuming he's VAT registered).
If you as an individual are purchasing the bits then I don't see how this will work for you.

[electro]

Just to follow things up, I installed the pipework and armaflex with a friend, everything went nice and smoothly, including the bends in the pipe

The system I have here is a Mitsubishi MSZ-GA25VA, with an outdoor unit of: MUZ-GA25VA.

Technician turned up today, 13m of pipe work, unit pre-charged for 7m, additional charge for 13m is 240g, tech weighed in 320g as I was shouting Stop!! while looking at his scales, whoops...

Pushed the test button on the indoor unit to begin its 30min test sequence, everything seemed great, indoor unit was blowing nice and chilly. The problem begins when the unit leaves test mode, I have a setpoint of 20 while writing this, and the glass thermometer says 23*c, and an RS-232 thermometer says 22*c.

I looked at the outdoor unit and to my amazement the fan wasn't running, but the compressor was still going, after a few minutes of observation, the fan kicks in for a bout 3 seconds, wafts out some hot air, then shuts down for about 1 or 2 mins, repeatidly.

While on the 30 min test, the outdoor unit's fan was on non stop and the indoor unit was blowing perfectly cold.

Heating mode seems to work very well, fan on outdoor unit runs non stop, blowing chilly air, indoor unit churning out hot air, I didn't test heating mode for long as I didn't want to die

I'd be interested in hearing peoples thoughts, I'm un-impressed with the cooling and I'd say there's a problem, it just seems to be holding back with the cooling, whether it's the slight overcharge on the gas, a friend who's an ex fridge tech said that the gas charge is probably within tolerance.

HUGE thanks in advance for peoples help

[taz24]

I looked at the outdoor unit and to my amazement the fan wasn't running, but the compressor was still going, after a few minutes of observation, the fan kicks in for a bout 3 seconds, wafts out some hot air, then shuts down for about 1 or 2 mins, repeatidly.


I'd be interested in hearing peoples thoughts, I'm un-impressed with the cooling and I'd say there's a problem, it just seems to be holding back with the cooling, whether it's the slight overcharge on the gas, a friend who's an ex fridge tech said that the gas charge is probably within tolerance.

HUGE thanks in advance for peoples help

The fan will cycle with the load and outside ambient temp.
If it was cold when running then the fan cycling may be normal.

IHow long was it running for your room to pull down to 22 / 23degC?

It does take time to pull the room down to temp. Did you have the central heating on by chance?

Let it run and give it a chance.

taz.

[electro]

I think it was on for about 2 hours, the air output temps ranging from 16 to 18*c, room temperatures never really dropped below 21/22*c with setpoints being 20 first, then 16*c later on, it just seems to be in no hurry whatsoever to bring the room temps down closer to your setpoint.

Central heating was not on

Last night I ran it in the test mode again and the output temps were around 9 or 10*c, so it's capable of turfing out some cold air. My main concern is that it's running the compressor to capacity and running in-efficiently.

I don't suppose it could be because it's not warm enough outside?

Cheers!
-Dave

[electro]

I tried it this afternoon when I got back from work, it was hot and stuffy, about 26*c in here so wacked it on.

Left the room, went to look at the outdoor unit, all seemed to be running well there, fan was constant, chucking out slightly warm air. Made a sandwich, went back into the room and the temperature had dramatically fallen, indoor unit chucking out icy cold air, measured at about 7 or 8*c.

After about 20 minutes, the output temperature rose to 21*c, all cooling stopped, went and had a look at the outdoor unit, all silent. After about a minute I heard a relay click in the outdoor unit, compressor started up, slow to begin with, then rising to maximum speed after a few minutes. Fan stayed off for about 5 minutes, then went back to coming on for a few seconds before stopping again, compressor continuing to run.

Indoor cooling stayed measly.

I set the units failure mode recall function, but this didn't seem to produce any error codes for both indoor and outdoor units.

Tech is going to pop around tomorrow and take a look at it

[taz24]

Indoor cooling stayed measly.

I set the units failure mode recall function, but this didn't seem to produce any error codes for both indoor and outdoor units.

Tech is going to pop around tomorrow and take a look at it

If the unit cuts out it means its cycleing ok.
A comfortable temp for a room is about 21degC
set the control to 21 and let it run.
Check the temp of the room in the four corners and then in the middle, see what the temp is.
Set the control to manual cool not auto.
On auto the machine may cycle between heat and cool dependent on the room temp.

Cheers taz.

[electro]

Problem solved - overgassed, my fault for chatting to the tech while he was weighing in the charge!!

[taz24]

Problem solved - overgassed, my fault for chatting to the tech while he was weighing in the charge!!

Good .

Cheers taz.

[Peter_1]

80 grams overcharged??? That's not overcharged and this has nothing to the with the cycle you described.

The cycle you described is normal, let the unit work for some time, fans kicks in controlled by the measurement of different probes. Don't ry to find any logic in it.
That everything runs continuous in test mode , well, that's just the epurpose of the test mode to see if everything runs fine.
But that's not the purpose of an inverter unit.

I can't help this feeling but it seems that you don't have that much confidence in the competence of your tech.

[Brian_UK]

According to the Mitsi data your system is still slightly overcharged.

Your tech calculated an extra charge of 240g which equates to 40g/m. 13m - 7m = 6m * 40g = 240g

Mitsi state the additional charge should be 30g/m therefore 13m - 7m = 6m * 30g = 180g

He added 320g and took out 60g so has added 260g making the overcharge now only 80g.

Base charge on the system is 850g R410a.

[electro]

The main thing is it's working, currently typing this with a setpoint of 22*c and an actual room temp of 22.1*c I'm happy!!

[Brian_UK]

Quick, don't touch it and take a photo

[electro]

and it's Friday 13th !

They could do with a fan only mode on these units, wouldn't be hard to do, saves having to set cooling and set a setpoint of 30*c or something so it just uses the fan.

Excellent forum you have here Brian, keep up the good work

[electro]

You know what? I spoke too soon, I just switched it on and it's playing up again, ahhhh the joys.... last night it was working perfectly!

[electro]

Update: (sorry for the repeated posts, this is more like a log file, hehe)
I checked the status LED on the outdoor unit, it's illuminated solid red which suggests no error state.

[Brian_UK]

Right, we need to do some thinking about the positioning of the unit within the room.

I don't think the gas charge difference should make too much difference to the operation although I am ready to be corrected here, anyone?

Does the air being discharged from the unit get recirculated back into the return air path before its cooled the room properly?

Is it bouncing back of walls, bookcases, chimney breasts etc ?

Is it directed straight out of the unit but on low speed, this can sometimes allow the cool air to get sucked back into the unit without travelling far into the room..

I'll have to download the tech manual for this model and see if there are any "tricks" that we don't know about yet.

Don't forget, setting the unit to 16°C doesn't mean that you'll get down to that temperature, they're only numbers

[electro]

Evening Brian

I think it could be influenced by the outdoor temperature, I think yesterdays midnight temp was about 2*c greater than tonights temps.

At the moment its running and it's meeting its setpoint of 21*c, it wasn't as fast to reach the setpoint as it was yesterday when it was working better. But overall, it's definitely working better now than it was the other day!

Output temps on the unit are roughly between 15 and 18*c (I can hear the refrigerant boiling off, this happens in whooshes)

Fan speeds set to 3 (of 4 speeds) - vane is set to point down lowest a the moment as it's a clear path to the floor with a channel for the air to flow along before meeting the opposite wall, I find this circulates the air the best, it won't be like this for long though as I'll be putting the filing cabinet back in its place and this will be right under the unit, I'll stick to horizontal airflow then!

I'll give it a go tomorrow afternoon, get the room nice and hot with the windows closed and see what happens. I did listen to the outdoor unit earlier on and the compressor was running at a lesser speed, so I hope I'm still getting good energy efficiency

I'll get some pics, but beware, the drain hose is work in progress and is going to be done this weekend!

Cheers
-Dave

[Peter_1]

This is the table I use for adding refrigerant, I started in the past with one of R22

[electro]

Well I've given it a good thrashing today, fan running constantly on the outdoor unit with outdoor temps of 18*c ambient.

I set a setpoint of 16*c this afternoon and ran it for 2 hours, it achieved 17*c in the room which suggests it's running perfectly - handy as I was working out by the outdoor unit this afternoon, clearing out the shed, so I could keep an ear on the outdoor unit.

[Peter_1]

You become really obsessed about your Mitsu, I hope it isn't contagious.

[penair]

A very entertaining thread involving your missingbits, sorry..., mitsubishi, since the beginning of your project. Was it really worth the short cuts to spend the extra time scratching your head about a job well done, seems like if you were running a circus you would be an overnight millionaire........

[Craig Flello]

hi dave just a quick one you can buy copper in 30 M lengths just so you know. I always roll my pipework out straight onto the floor with a bit extra length just in case, slip on the lagging glue and tape each joint, then roll out any cables and hose if it`s a pumped condensate onto my pipework. tape it all tohether as one mass makes it a little easyer to work with as this makes it a little rigid and push it in, job done enjoy breathing in that dust.

[stevo]

Would love to see some pic's of this install !!

[electro]

bah! if I post pics you'll prolly laugh

I'll get some pics once I've actually drilled my condensate outlet hole and stuck the cover on the trunking

Next step is to get the IR codes for the Mitsi and get the unit connected up to the home automation system here, which will open it up to full web-based remote monitoring and control.

Have you guys ever done any integration with a/c systems and automation equipment yet?

[electro]

Well you wanted to see it... Brace yourselves




As you can see I tried to panorama the outdoor pics, don't worry, the unit is not that bucked in real life

[Brian_UK]

Looks good, well done.

Does the gate still open or does it smack the condensing unit?

[electro]

Looks good, well done.

Thanks!

Does the gate still open or does it smack the condensing unit?

Doh! I knew I had to do something wrong, hehe
Correct, the gate will not open fully, but what's just out of shot to the right of the unit is a garden shed (parked on the driveway) - so there's only a 1m space to walk past, so no need to open both of the gates.

[taz24]

Well you wanted to see it... Brace yourselves




As you can see I tried to panorama the outdoor pics, don't worry, the unit is not that bucked in real life

Good job but your office / bedroom is a mess .

All the best.

Cheers taz.

[TRASH101]

How big is your room and how big is your window and how many heat dissipating gadgets have you got in there!! The summertime may prove a prove a fitting test for little'ol 3.5 Kw in sunny Devon

[TRASH101]

P.S. the Condenser is mighty close to that wall

[electro]

How big is your room and how big is your window and how many heat dissipating gadgets have you got in there!! The summertime may prove a prove a fitting test for little'ol 3.5 Kw in sunny Devon

Well when it behaves, it puts this room on ice, so far I've seen the room go from 23*c to 18*c in about 30 or 40 minutes

From calling Mitsi tech support, they've said that the threshold temperature for the fan running on the outdoor unit is 17*c ambient outside, I asked if reduced cooling is normal and they said yes. I've found that if you run the unit to capacity in this state, it achieves no cooling at all, if you set the setpoint closer to the room temp, the compressor then slows down and the indoor unit blows a minimal amount of cold air, still enough to hold the temperature in the room.

What rattles my cage is the fact that you can hit the emergency operation switch on the indoor unit, which runs a flat out test for 30 mins, and the unit cools perfectly, albeit with no temperature control. If its capable of cooling with a low outside temperature then why have they designed it to behave poorly it would seem? - it's got me

Condenser close to the wall? nope - it appears so because of the panorama's warping of the picture, and the fact that the brackets are overkill in their size accommodation, there's a good 20cm of clearance behind the unit

[electro]

A small update...

I've been e-mailing a tech at Mitsubishi who gave me a modification to make to the outdoor unit, a simple one, disconnect a solenoid valve which short cycles the outdoor unit, reduces head pressure and keeps fan noise to a minimum as a result, I'm not exactly sure what the purpose of this valve is for as the tech says it only energises when the outside ambient is < 17*c.

In his words:

Effectively the valve is an unloader and causes the the system to run short cycle around the outdoor unit.

I carried out the modification and it's working perfectly as I type, pinning the room temperature at the setpoint.

Result!

[Makanic]

P.S. the Condenser is mighty close to that wall

I would Have to agree there ,Restricted air flow,Not a good thing when the weather gets hotter

[electro]

Don't make me get a ruler out and take a photo showing the distance!

The brackets are overkillingly long for the unit, so gives the appearance that it's pushed up against the wall.

[MikeT]

Thanks for the thread electo, made quite a nice read.

I have a Fuji split 18k btu and an LG split 13k btu here that I have to install and get an AC guy I know to come do the flaring and gassing on once they are ready, lets hope I dont have your sort of problem.
I have a Fuji 18k btu through the window type rattler in my workshop/office that I fitted some months ago and apart from the really high (40 odd amps) start current on the compressor I am really pleased with that.

[Sid Jones]

Hi there dave
The pipe work in its self is not too demanding. The 14 Metre straight up pipe run is something else again, unless you are an alpinest? I would suggest you run the pipe work and the power supply in uv friendly P.V.C. ducting. Like the man said be sure that your insulation is sealed from moisture. Oh and take your hand off your heart and get the job done professionally, in the long run it will prove to be cheaper and a lot safer.

Good luck.
Sid

[rickysmithrs]

good luck!!!

[bebad]

hmm, nice trunking in your room. did u ask for that? y not go out the back? = zero trunking.

[Boet]

You should remove all the goodies below the unit. When changing to heating, the goodies will cause short cycling as the warm air should be aimed at the floor at a slight angle to the wall. Leaving it in the horizontal will also cause short cycling. Think and enjoy!