Split Air con

Yup I think so. Apologies if I did not explain it in the most efficient way :D I am in the middle of decorating my kitchen wood work atm.

Just remember, it'll no doubt be very inefficient if your external unit can power all your internal units at 100%, as the majority of the time the internal units will be ticking over to maintain temp and wont need to run 100% (Unless maybe you leave your windows open and set it to 16c ;)).

Once all 3 of my 2.5kw internal units reach temperature, my 5.5kw external unit can cope with them all no problems. It goes very quiet at that point too so I doubt its stretching its legs at the moment either. Maybe things will be a bit different when the temperature hits 30c outside.
 
HungryHippos said:
Ah think I got it, so I could realistically have 3 x 2kwh units inside, with an outdoor unit at say 5 or 6kwh (20.8A or 25A respectively) instead, which would give a bit of leeway for other devices running off the sockets to operate without exceeding the 32A limit?

Wouldn't give much headroom at 6kwh but that would only be used if all 3 internal units were running flat out at the same time.
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You are quoting cooling capacity not power draw from the wall.

Each indoor unit runs a 4 core flex to the outdoor unit, the compressor outdoors is the thing which uses the real power, the indoor units power draw is minimal.

I would not wire an AC system to the ringmain unless it was a low power system, you need a dedicated feed from the consumer unit, mine will be on 32amp dedicated circuit but power draw will be something like 20amp.
 
Yes I was just going to say - the cooling power isn’t the same as the power input. They would be insanely expensive to run if that was the case!

On my 3.5kw cooling/4kw heating unit the input peak power is c.1kw.

You wouldn’t want to pull more than 2.4kw from a domestic socket for a long period (10A).
 
That makes a lot more sense actually, and as the units are about 300% efficient the power input must be way less than the heating/cooling.

So for an external 6kw unit, the actual draw on that would be much closer to 2kw, possibly slightly under, at peak?
 
If you check the manufacturers product page for the condenser it shows what is the recommended fuse rating is, I need a 5kw and hoping to modify an external socket to run this.
 
HungryHippos said:
That makes a lot more sense actually, and as the units are about 300% efficient the power input must be way less than the heating/cooling.

So for an external 6kw unit, the actual draw on that would be much closer to 2kw, possibly slightly under, at peak?
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Broadly, yes. Efficiencies very a lot between manufacturers and models however.
 
External Ambient air will also play a factor in the efficiency and power draw of the unit and sometimes better sited away from direct sunlight and shaded area.
 
RJC said:
External Ambient air will also play a factor in the efficiency and power draw of the unit and sometimes better sited away from direct sunlight and shaded area.
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Depending on if you want to use it predominantly for heating or cooling. I've purposely sited mine in a sunny location so it's more efficient in winter as it's more likely to get outside it's cold envelope (-15 C on my machine) than it's hot (+45 C).
 
Matthew.M said:
Depending on if you want to use it predominantly for heating or cooling. I've purposely sited mine in a sunny location so it's more efficient in winter as it's more likely to get outside it's cold envelope (-15 C on my machine) than it's hot (+45 C).
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Ideally you need it on flexible pipe work and rails - sunny area in the winter and shaded cooler area for the summer.

But for a normal house hold once its taken hold of a room it sits there ticking over unless you have a mass of people and PC's running, I tend to use mine in the hallway at night and since getting a bigger floor fan it direct the cool air in to my room better.
 
Yeah, it's just important to remember the heating aspect, if you plan on using it at all, as it's more likely to ice up in winter (and then it stops heating the room as it reverses to de-ice the condenser) than it is to be interrupted in summer.
 
Probably get more use out if it in the hot weather, for heating I'd use it but maybe more where I am locally rather than all the units heating the house. I still have central heating after all with the rads, and unfortunately can't entirely replace my gas supply as I need the combi for hot water.
 
I had fun and games in the past testing our (chiller) heatpumps defrost termination time and setpoints before it turned into one ice cube.

One style of unit we had issues with the 3 way getting stuck and had use a club hammer and piece of wood to free it up.
 
Had a good long think about things. For internal aesthetics I think I was basically sold on the Mitsubishi Electric units MSZ-LN series, just looked the part better than the cheaper MHI or similarly priced Daikin units.

My installer, based on this, has quoted:

£3950 ex 5% VAT (£4,147.50)
1 x MXZ-3F54VF outdoor condensing unit
3 x MSZ-LN18VGV-E1 indoor units

The final idea then would be to site the outdoor unit like in one of my original pics (spoiler image below), with the lounge and study as shown as well, using the vertical guttering to try and mask the pipework climbing the side of the house as much as possible.

For the 3rd unit in the master bedroom, the current idea is that the vertical run there carries on until it gets into the loft space, then the master bedroom unit is run via an "up and over" approach instead of external. This gives me one vertical climb up the external wall.

The lounge and study units can use the guttering there as the escape route for the water removal. The master bedroom unit would need a condensate pump in the loft space to use the same return channel, so the installer has instead suggested feeding that separately to the guttering on the other side of the house, with only the electrical/refrigerant lines using the loft space.

Overall thoughts on whether this plan is good/these units will be happy with that external one etc?

Reminder that the gallery of pics of the back garden is here: https://imgur.com/a/6iH4Crv

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Our system is being installed as we speak... looks good so far - the unit in the kitchen/family room is in; they've actually ended up going for a 3.3kw there (instead of 2.5kw) purely due to availability of parts (and amazingly at no extra charge to me!) Currently on a lunch break and will be moving onto the upstairs unit this afternoon
 
uncle_rufus said:
Our system is being installed as we speak... looks good so far - the unit in the kitchen/family room is in; they've actually ended up going for a 3.3kw there (instead of 2.5kw) purely due to availability of parts (and amazingly at no extra charge to me!) Currently on a lunch break and will be moving onto the upstairs unit this afternoon
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pics when it's up? good result on the bigger unit!
 
HungryHippos said:
Overall thoughts on whether this plan is good/these units will be happy with that external one etc?
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Sounds good to me. If you are dead keen on avoiding minimal trunking on the outside then the condense pump makes sense for your install. I think you would be kicking yourself in the next few weeks if the temperatures start creeping up and you only went for the office/lounge. That or you will be will attempting to sleep on the sofa! Your cooling capacity of that external unit looks almost identical to my setup. I doubt the AC installers would under sell you a product too!

P.S your cost is about £150 more than mine, considering its now warm weather I think that is pretty good (and your units are a bit more powerful than mine overall).
 
Just trying to work out if that external unit will be happy on the outdoor socket already present.

The answer I have concluded is "maybe?". I'd like to be a bit more certain though.

Wonder if anyone who knows electrics a bit better than me can take a gander at the specs and advise if that will be happy on the standard outdoor socket that has been spurred off the existing downstairs lounge sockets?

From a bit of a look into this with a very limited understanding of how this works, the value under RUNNING CURRENT (A) for Heating/Cooling [MAX] is 7A for heating, and 5.9A for cooling. So the unit needs more power to max out heating than cooling, but in either case it shouldn't use more than 7A at any one time?

I doubt I would be running all 3 units at full capacity very often, so that 7A draw would probably be much lower most of the time as the units shut off/go into eco mode or whatever once temps are reached.

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I'd like to add a proper external supply on a rotary isolator but my consumer unit is quite far away, so I'd have to run the power along the external wall of the house most likely then through to the unit. Not impossible, but it's an added expense and if it's not necessary, I'd prefer to use that as a backup if the existing socket doesn't work.

The other negative of using that socket is that presumably the overall draw matters from other devices on the same thing? for example my TV and it's speakers will be effectively having to share the larger overall capacity.

@fobose regarding the condensate pump for the loft, think the plan is to avoid adding it. If the unit in the master bedroom can drain freely through a different channel then I can just keep the power/coolant lines going through the loft space, and not have the drainage return using that.

5.4kwh external unit fits perfectly into 3 x 1.8kwh internal units, so I should actually be able to run them all reasonably flat out if I wanted to, which is a nice bonus :)

For the pricing, I think they cost a bit more due to being slightly fancier units, but performance wise I reckon nothing in it really. For a shade over £4k getting 3 rooms done and dusted means I will have aircon basically everywhere it's needed!
 
HungryHippos said:
From a bit of a look into this with a very limited understanding of how this works, the value under RUNNING CURRENT (A) for Heating/Cooling [MAX] is 7A for heating, and 5.9A for cooling. So the unit needs more power to max out heating than cooling, but in either case it shouldn't use more than 7A at any one time?
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That is how I read the spec too but probably best to wait for someone with a bit more knowledge to confirm ;) With regards to the rotary isolator, my installer mentioned that it is quite common for installers to install one but it is unnecessary in most cases. Mine just has an isolation switch behind an external socket cover which looks better IMO.

HungryHippos said:
@fobose regarding the condensate pump for the loft, think the plan is to avoid adding it. If the unit in the master bedroom can drain freely through a different channel then I can just keep the power/coolant lines going through the loft space, and not have the drainage return using that.

5.4kwh external unit fits perfectly into 3 x 1.8kwh internal units, so I should actually be able to run them all reasonably flat out if I wanted to, which is a nice bonus :)
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Ah, I must be blind. I missed your new quote with the 3x 1.8kw units and the fact you mentioned the condense for the master bedroom being routed in to the guttering. That will give you a nice neat install.

I did think the external unit was meant to be underspec'd for the best efficiency but I have no idea how true that is or if there is much saving in doing that. I bet on a really hot day/week you would rather be able to cool the rooms a lot quicker.

The all most important question.... when can they do it? :D

*edit* I've just checked my external unit, mine is the exact same model number.
 
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