Anyone fitted a pre-charged aircon unit?

[Jeremy Harris]

In the recent hot weather the house has been plenty cool enough downstairs (between 21°C and 22°C) but it's been getting a bit warm upstairs (typically around 24°C to 25°C in the bedroom).  This is with the MVHR running continuously in cooling mode, as that can only provide about 1.4 kW of cooling capacity, split across all the rooms in the house.

 

I've been kicking myself since the house was first built that I didn't allow provision for installing a split aircon unit high up in the central hall, but have now worked out that I can fit one high on our bedroom wall, with the pipes leading through the walk-in wardrobe and out to the service area, from where I can get them out through the wall OK.

 

I've been looking at fitting one of the pre-charged, DIY fit units, as we only need something fairly small (a couple of kW, around 7,000BTU, would be ample).  These are pretty cheap, typically around £500 to £700, so the chances are that professional installation would probably double the cost, which makes me think that a DIY installation might be a better option.  A DIY installation also means that I can make sure the pipes are sealed properly where they go through the wall (I'll probably stick a rigid duct through the wall for them, I think).

 

Has anyone fitted one of these?  Looks easy enough, but I wonder if the fittings on the end of the pre-gassed pipes mean that they need a big hole in the wall to pass through.

[ProDave]

CPC have some, here is there smallest / cheapest one https://cpc.farnell.com/airconditioningcentre/kfr-26yw-x1c-m/black-wall-split-air-con-unit/dp/HG0073606?ost=HG0073606&ddkey=https%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

 

They seem to be inverter driven with a Panasonic compressor.

 

Only has 4 metres of pipe.

 

I have often wondered about these but I assume the units are pre gassed and the connecting pipe either pre gassed as well or evacuated and they must have pre fitted push fit self sealing connectors.  As such I suspect the hole needed will be dictated by the connector size and of course there is no details about that in the data sheet.

 

EDIT: I may be talking BS here, just seen that this unit must be installed by an F Gas engineer so probably not pre charged. Back to the drawing board.

 

This is what ebay throws up https://www.ebay.co.uk/itm/TCL-12000-BTU-WIFI-Smart-A-easy-fit-DC-Inverter-Wall-Split-Air-Condit-iQool12/143003395499?epid=4016472121&hash=item214baaa5ab:g:fTAAAOSw2h9c-oyj

 

Definitely pre charged but still says needs an F gas engineer. Talks about pre flared ends on the pipe so some form of compression fitting? But surely that means the pipes are not evacuated so a small amount of air will get in the system?

[Temp]

We had a small precharged split unit purchased in Belgium 12 years ago. The unit came with instructions on how to separate the two units to allow the pipe to pass through a hole in a wall. As I recall the ends of the pipe had some valves that automatically sealed when disconnected.

[Jeremy Harris]

@Temp, do you recall how big the pipe end fittings were by any chance?

 

It doesn't seem to be something that's included in the spec for any of the units I've looked at, yet it's fairly significant, as I need to get the pipes out through a duct fitted through the wall, and would much rather have as small a hole as possible.

[Jeremy Harris]

1 hour ago, ProDave said:

CPC have some, here is there smallest / cheapest one https://cpc.farnell.com/airconditioningcentre/kfr-26yw-x1c-m/black-wall-split-air-con-unit/dp/HG0073606?ost=HG0073606&ddkey=https%3Aen-CPC%2FCPC_United_Kingdom%2Fsearch

 

They seem to be inverter driven with a Panasonic compressor.

 

Only has 4 metres of pipe.

 

I have often wondered about these but I assume the units are pre gassed and the connecting pipe either pre gassed as well or evacuated and they must have pre fitted push fit self sealing connectors.  As such I suspect the hole needed will be dictated by the connector size and of course there is no details about that in the data sheet.

 

EDIT: I may be talking BS here, just seen that this unit must be installed by an F Gas engineer so probably not pre charged. Back to the drawing board.

 

This is what ebay throws up https://www.ebay.co.uk/itm/TCL-12000-BTU-WIFI-Smart-A-easy-fit-DC-Inverter-Wall-Split-Air-Condit-iQool12/143003395499?epid=4016472121&hash=item214baaa5ab:g:fTAAAOSw2h9c-oyj

 

Definitely pre charged but still says needs an F gas engineer. Talks about pre flared ends on the pipe so some form of compression fitting? But surely that means the pipes are not evacuated so a small amount of air will get in the system?

 

One advantage of buying a non-precharged unit may be that I can get away with a smaller duct through the wall for the pipes.  I may hunt around and see how much an F gas person would charge to just connect the pipes, pump the unit out, and fill and test it.  Might be worth going down that route if it means a neater installation with a smaller hole through the wall.

[PeterW]

An insulated pipe at standard fridge spec Armaflex/Insultube is around 35mm in diameter - you could spiral wrap it to reduce a little but I doubt the fittings are anywhere near that diameter as it 9mm pipe usually. 

[PeterW]

@JSHarris I’ve just read the “Chinglese” instructions for installing one of these pre-gassed units ....

 

So basically you have a compressor that is overcharged, and they calculate that 4/6m of pipe and a known evaporator coil has a volume. A quick PVT calculation later, and you can work out the “over gas” weight needed. 

 

The instructions get you to open the T-Valve (usually used to gas the unit) by quarter turn and wait 5 seconds “using a digital clock”... Close the T valve then open the vac valve (Schrader type) by pressing for 3 seconds. And then open the T-Valve and the isolator fully....

 

So in essence, they purge the pipes using refrigerant gas ..!!! Not the most environmentally friendly way, and I bet it’s easy to over vent ..!! 

[Temp]

3 hours ago, JSHarris said:

@Temp, do you recall how big the pipe end fittings were by any chance?

 

It doesn't seem to be something that's included in the spec for any of the units I've looked at, yet it's fairly significant, as I need to get the pipes out through a duct fitted through the wall, and would much rather have as small a hole as possible.

 

Wife reminds me we still have the unit in the garage!

 

The indoor unit is "portable" in that it's on castors but you can't move it around much. The outdoor unit is intended to be hung on an outside wall. Here is a photo of the pipe connections and the instructions on the back of the indoor unit. They are fixed permanently at the outdoor unit. The pipe is oval and has in it.. Flow & return pipes, a condensate tube and an electrical cable. Overall dims of the pipe are about 50mm x 25mm.  The connectors on the end are 24mm (across the flat) but can't be sent through the hole individually. So I think the hole in the wall would need to be at least 50mm and 60mm diameter for comfort. The grey stuff on the cold is foam tape. Underneath it looks similar to the hot connection.

 

 

 

 

 

Edited July 1, 2019 by Temp

[Jeremy Harris]

Many thanks, @Temp, that's perfect, exactly what I was after!

 

I fitted a second MVHR air feed through the wardrobe and up to a terminal on the wall, right where I now want to fit the indoor unit.  To get a neat looking duct run inside the wardrobe I used 110 x 54 PVC rectangular duct, so with luck the pipes will all be able to run inside this.

[Patrick]

I fitted those in  my  previous 3 houses . Easy to do and works brilliantly. A lot cheaper than a pro installed unit. They work perfectly fine for around 1-2 years and then need regassing (sometimes ). But the regassing /topping up should be done for a few quids, rather than full installation costs.

[PeterW]

A good split unit should run for 5-7 years before a gas top up. Nipping up copper fridge lines is an art - too tight and the cones deform. 

[ProDave]

13 minutes ago, Patrick said:

I fitted those in  my  previous 3 houses . Easy to do and works brilliantly. A lot cheaper than a pro installed unit. They work perfectly fine for around 1-2 years and then need regassing (sometimes ). But the regassing /topping up should be done for a few quids, rather than full installation costs.

There is no reason they should need re gassing unless there is a leak.

 

Perhaps this is the "problem" with pre gassed units that they can be installed with no professional input and no leak testing?

[Patrick]

No leak testing is most likely the problem

[Jeremy Harris]

Just now, Patrick said:

No leak testing is most likely the problem

 

I'm sure you're right.  Looking at videos of installing these units, it seems that it's pretty important to leak test the joints.  Just spraying them with soapy water seems a reasonable way to check, but, as you mentioned earlier, even paying for someone to come out and regass and seal the system after a year or two is still cheaper than paying for a full professional installation.

[MrMagic]

I have exactly the unit that was linked earlier (CPC) which was 'DIY' fit (and then later serviced by a Fgas engineer) as well as 4 fitted units in the house.

 

The compressor is pre-charged and holds the refrigerant based on a maximum pipe length that can be found in the instructions. The pipes are just normal A/C piping and are reasonably soft so you can bend as required.

 

I would caution, you get what you pay for here... 

1) Strictly speaking this must be installed by an Fgas engineer

2) The purging method is bonkers.. but thats how the chinglish instructions tell you to do it. Vac-pump would be much better and would help confirm the joints are tight

3) My unit is still working but sometimes it seems to have a funny-5-mins. Turning it off and back on again solves this

4) The DIY fit ones take power from the indoor unit - most other systems take power from the outdoor unit

5) The 4 indoor units - pro-fitted Mitsubishi - have worked flawlessly since install

 

I'm sure you have the skills to do the install justice but I'd go for a more recognisable brand (Mitsubishi, Daikin etc). At least then you have some options for servicing/parts in the future. As far as I'm aware a lot of the outdoor units now come pre-charged...

 

Heres some pics of the 'no-name' unit...

 

And the Mitsubishi units..

[Jeremy Harris]

Funnily enough, the unit I've been looking at is a Mitsubishi SRK25ZSP-S

 

From what I can gather it looks like this unit needs a hole about 65mm in diameter for the pipes and cable to pass through, which seems pretty easy to arrange.  I reckon I can probably use a bit of 68mm plastic downpipe as a duct to run through the wall, with a bit of luck, then fill it up with foam to seal it after I've run the pipes through.

[PeterW]

65mm is standard as you need the two refrigerant lines, a 1/2” drain hose, power cable and a control cable. The insulation will squash slightly and the rest can be foamed. 

[Miek]

I've fitted a 2.5kw daikin unit, diy. 

 

The hole in the wall was an offcut of rainwater downpipe which I foamed around. 

 

The copper pipe is soft 1/4" & 3/8" which you need to flare into a cone with a pipe flaring kit. I bought the install kit with the unit to make life easy. This is easy to do IMO. Condensate drain is 20mm flexible pipe. 

 

You can hire the vac pump for £100 a week but I chose not to and just bubble tested the fittings. 

 

Bought the kit from Saturn sales, very helpful and thorough diy instructions supplied, although they explicitly say that if it is not fitted by an Fgas engineer then the warranty is void on the unit. 

 

 

 

 

[MrMagic]

@JSHarris - Exact same units... mine are the 2Kw version (1x standalone, 1x 3 way multi-split) Can't fault them. 

 

They seem very efficient as well - the 2Kw one seems to ramp to about 700w at power on but then settles down and purrs along at about 400w when the compressor is running, and negligible when just circulating.

 

Outdoor units are pretty much silent, theres a 'quiet' mode button on the remote that reduces them even further. The only time they make any noticeable noise is when the compressor stops, the fan ramps for 20 or 30 seconds before shutting off.... but as you already have a ASHP, you'll be used to all this.

Edited July 2, 2019 by MrMagic

[Jeremy Harris]

1 hour ago, Miek said:

I've fitted a 2.5kw daikin unit, diy. 

 

The hole in the wall was an offcut of rainwater downpipe which I foamed around. 

 

The copper pipe is soft 1/4" & 3/8" which you need to flare into a cone with a pipe flaring kit. I bought the install kit with the unit to make life easy. This is easy to do IMO. Condensate drain is 20mm flexible pipe. 

 

You can hire the vac pump for £100 a week but I chose not to and just bubble tested the fittings. 

 

Bought the kit from Saturn sales, very helpful and thorough diy instructions supplied, although they explicitly say that if it is not fitted by an Fgas engineer then the warranty is void on the unit. 

 

 

Thanks.  I have a vacuum pump that I used to de-aerate mixed resin, home made, from an old freezer compressor, but it pulls a pretty good vacuum and has a gauge.  I wonder if I could use that to pump the system out and leak test the pipe connections? 

 

Presumably there's a port on the valve block to allow a vacuum pump to be connected.

 

9 minutes ago, MrMagic said:

@JSHarris - Exact same units... mine are the 2Kw version (1x standalone, 1x 3 way multi-split) Can't fault them. 

 

They seem very efficient as well - the 2Kw one seems to ramp to about 700w at power on but then settles down and purrs along at about 400w when the compressor is running, and negligible when just circulating.

 

Outdoor units are pretty much silent, theres a 'quiet' mode button on the remote that reduces them even further. The only time they make any noticeable noise is when the compressor stops, the fan ramps for 20 or 30 seconds before shutting off.... but as you already have a ASHP, you'll be used to all this.

 

Sounds ideal, especially as it's quiet.  Our ASHP is very quiet, we can't ever hear it inside the house, and it's only barely audible outside - I often have to look in the grill to see if the fan is going around, as at low speeds it's just about inaudible.

 

The plan is to mount the outdoor unit on the rear wall of the house, which faces North, and is hidden by our big retaining wall.  There's a ~1.8m wide gap between the rear of the house and the retaining wall, so it should be OK there, and if the unit runs quietly that's a bonus, as I'm slightly concerned about noise transmission into the wall of the house.  Unfortunately the paved path at the rear of the house is right up against the house wall, so I don't have the option to ground mount the unit.

 

The indoor unit will be in our bedroom, but as I doubt we'll have it on at night (the house stays cool for a long time once it's cooled down) noise shouldn't be a problem.  I think we'll probably run it during the day when the weather's hot (and the PV system is generating) and shut it down over night. and rely on the cool air from the MVHR

[Miek]

6 hours ago, JSHarris said:

 

Presumably there's a port on the valve block to allow a vacuum pump to be connected.

Yes, the port in the LHS in the pic with pink on it. 

 

One other point is that there is a maximum length of pipe run for the pregassed units. Mine was 10 or 15m IIRC. Not usually a problem in the domestic situation. 

[Jeremy Harris]

I've opted for a Toshiba Mirai RAS-10BKVG-E, 2.5 kW, 9,000Btu unit in the end.  Bit of a palaver ordering all the right bits, but the total for everything, including 4m pre-made up pipes, trunking, cable and both a vacuum pump and set of manifold gauges, has come to about £750.  That's £500 less than the price I was quoted for a no-name Chinese unit installed.  The warranty is a problem, as by opting for a DIY install I'll lose the Toshiba warranty, but, on balance, I think that's worth taking a risk on.  If it all goes tits-up I can always get an F gas chap out to re-gas and leak test it for less than £300, so it's still a saving on having it professionally installed.

 

The reasons for opting for the Toshiba, rather than the Mitsubishi were mainly to do with the best deal I could get, plus the much lighter weight of the Toshiba outside unit (23kg).  As I will be wall mounting the outside unit, quite high on the wall, weight was a significant consideration.  Another consideration was the illumination from the inside unit display.  Several systems I looked at had bright displays on the indoor unit, which may have been a nuisance in a bedroom.

 

Assuming all goes well, then when I've finished I'll have a vacuum pump and gauge set available for others to use.  It seems better to use a vacuum pump, both for leak testing and, more importantly, to get any residual water out of the pipework, I think, rather than rely on using a bit of (flammable) R32 to flush the pipes out.

 

The bits should be here by the end of next week, with luck, and I'll update this thread with a progress report.

[MrMagic]

Good luck @JSHarris  I believe most install guides recommend vac’ing out for 15 mins and then holding it for an hour to verify tightness.

 

have a google around and see if you can find the service/install guide for your unit. 

 

 

[scottishjohn]

49 minutes ago, MrMagic said:

Good luck @JSHarris  I believe most install guides recommend vac’ing out for 15 mins and then holding it for an hour to verify tightness.

 

have a google around and see if you can find the service/install guide for your unit. 

 

 

try a local garage --they may have a mobile air con unit- modern ones remove gas then can do vac test and then refill with your same gas and then they only charge for extra weight they put in +  .but i doubt a precharged unit ,unless you are really "ham fisted" , i doubt you will have a problem just connecting up .

your biggest problem would be buying a gas cylinder --from memory you need a gas cert to buy gas now   and not that cheap --had a flyer from local motor factor last week --a small bottle was £150 ,but that will do a lot of systems and most car systems have a lot more gas in them than air con units .

 

what i can say from experience is the usual failure of these systems is leaks ,followed by gather up of water vapour from the air which ends up frozen   in the condenser rad  and  its almost impossible to get it out quickly and easily -and we not talking about a lot ,cos cores are very small.--needs to be degassed and left for a few days then vac and new gas ,and hope its all gone --could take a couple of times --this is why the engineers will tell you it needs replacing --too  much time for them to frig about with it and then ,have to do it again --if first vac +purge does not work --If not in hurry quite sure a DIY could do it taking time and using gas

Edited July 7, 2019 by scottishjohn

[Jeremy Harris]

56 minutes ago, MrMagic said:

Good luck @JSHarris  I believe most install guides recommend vac’ing out for 15 mins and then holding it for an hour to verify tightness.

 

have a google around and see if you can find the service/install guide for your unit. 

 

 

 

I've managed to get hold of the installation manual, which seems pretty straightforward.  The unit is pre-gassed for up to 10m of pipe, and I'll be using 4m, so that's well within limits.  The plan is to connect up the pipework, vac it out using the service port and make sure it holds for 15 to 30 minutes, and, if all is well, open one of the outdoor unit valves to pressurise the pipe work, then close it and leak test all the connections.  If that looks OK I'll then open both outdoor unit valves and finish the commissioning.

 

Main thing to watch seems to be the risk of getting an inadvertent cold burn from leaking refrigerant (I'll wear gloves) and the possible fire risk from leaking refrigerant (pretty low risk outdoors, but I need to ventilate if I get an indoor leak).

 

18 minutes ago, scottishjohn said:

try a local garage --they may have a mobile air con unit- modern ones remove gas then can do vac test and then refill with your same gas and then they only charge for extra weight they put in +  .but i doubt a precharged unit ,unless you are really "ham fisted" , i doubt you will have a problem just connecting up  

 

I've looked at vehicle vac pumps and gauges, but they seem to use different pipe connections to domestic units.  Not sure why, but gauge sets intended for vehicle use come with adapters, so cost more. 

 

I've ended up buying a vacuum pump and set of gauges and hoses for less than £70 delivered, which is way cheaper than the ~£500 to get someone out to install the unit, and less than half the price of just getting someone out to gas and leak test the system.  Seems wasteful to buy kit that may only be used once, but if that's the cheapest way to do it then it makes sense.  May come in handy if I ever have to do any work on the system in future, perhaps.  It seems that cans of refrigerant can be bought for around £30, so now I have the kit it should be possible to re-gas the system if it ever needs it (not strictly legal, as it needs an F gas ticket, but it seems that there are lots of people around who are ignoring this).