hi all
we're looking to install a new air-con unit in a small apt, so need a bit of advice. the original has been wreecked, thanks to some friends that spent the week there in august, in the hottest week of the year. there appears to have been some problem with it not coping, so they decided to keep tripping the leccy to get it back working. now the innards are burnt out, we've had a couple of engineers out, both saying its billy rucked.
ok, so any advice on what to get? firstly, i am not made of cash, it must be as much under a grand as possible, secondly we only use the apt occassionally, but its let out to friends and family most of the summer, and the apt is quite small (about 55m2).
the original was an 'inverter' which i am told is 'the only one to buy' is this correct? i've seen inverters at about €600-700 plus fitting. i assume the cheap standard ones you see in the diy stores are kaka (and maybe eat the leccy?), but i honestly dont know, as we dont have any aircons in the villa, just good old fresh air and fans.......
cheers in advance
dd

inverters are better (there was a thread about how they convert the leccy a while back), more economical and usually quieter than the cheapies. As far as Im concerned you get what you pay for

I have seen quality units (LG, Panasonic) in Master Cadena for around 700€ incl installation so worth shopping around

If you buy a unit yourself you can find people to fit them for around 200€

Are you fiiting 1 unit to cool the whole appt ?

yes, one unit was more than adequate before, it seems to get to the bedrooms too.
€700 for an inverter inc. fitting sounds good to me, the best i've got so far was €600 for unit + installation at €200 + iva which i thought a bit ott.
must find that thread.......

We had inverters fitted and they cost a ot less than €1000 inc fitting, you need to shop around, you should be able to get a decent one for less than €700 inc fitting, and they are much more efficient.

My 5p for what its worth,
Aircon with inverters is without a doubt both cheaper to run and gives better temperature control, as it controls the air better, it is also much quieter.
LG are not the best on the Market (I have one at its not patch on the Panasonic or Mitsibushi we have)
I would look for a unit with a heat pump also so that you can have it as a heater in the winter as it is the cheapest form of direct heating ( IE about 20% the cost of an equivalent electric convector heater to run!!),

But as you only intend to use it as a holiday apartment, is the extra cost justified, given that you will save on an inverter about 50% on running costs, say three weeks @ 10 hours a day = (8KWh per day VS a non inverter at about 15KWh per day))about 7/12€'s per year? vs the difference in price???
of say 250 to 400€,,, ??
I just bought a unit from Vial for 199€, fitted myself no special tools required, used it thru Aug for about 6 hours a day, and cost was less than a euro a day

hi, well we do use the apt in the winter too, so either way, we want one that heats as well, but as you say, are the savings that great from a standard unit against an inverter for an apartment that isnt lived in all year round?

Where do you get that figure from?

Even the most wildly optimistic claims from resellers only claim up to 40% and I have never seen that claim tested for accuracy!

As far as I am aware, the main advantage of an inverter unit is that the motors run continuously at a variable speed thus avoiding the extra start up loads when a non inverter unit is cycling on and off.

Sorry Fred you are right on a strictly aircon basis,I just reread my note and yes I didnt make it clear but take into account heatpump efficiency on heating and the saving is significantly higher but not only down to the inverter technology. IE the unit is only using about 25/30% electric power to produce the the equivalent direct electical output of heat so on an annualised basis the savings are a lot better. and 50% is then quite conservative.
But the point I was making (and badly so it seems) is that the inverter is not necessarily a good buy if you take the running savings vs the extra cost to purchase (which you have made even stronger!!)

so fred, whats your view on the minimum type i should get? and that does BTU stand for?

It's a bit more complicated than that, especially as inverters - when dragging up an AC motor on start - can induce quite high demands on the supply due to power factor and harmonics. Start-up loads can be reduced vs DoL with a soft-start - but that's not strictly a feature of having an inverter. I'll try not to go into too much detail, though - it's just that this was my final year dissertation subject!

The main advantage is that you operate the entire system at a combined thermal / mechanical / electrical efficiency which is higher by running the compressor at a variable speed.

The best analogy is a car... Air-con with 'on' and 'off' settings only is like driving a car at either full-throttle or no-throttle. Hardly an efficient way to drive a car if you only want a bit of power. An inverter air-con gives you all the bits in the middle - so starts off at full power, but as demand drops the power input reduces.

You get some mechanical and electrical efficiency savings as you back off input power, but the big saving if I recall correctly is in thermal efficiency of the heat pump, as the CoP of the system decreases with increasing delta-T. Less input power = reduced delta T = higher CoP = less running cost.

Clearly, if you add in reverse-cycle heat pumps - i.e. the sort that can heat as well as cool - then you get even greater savings - mainly because thermal losses in the compressor circuit actually contribute to the CoP (help to heat the parts that that are supposed to be getting hot).

Here endeth the thermodynamics / electrical engineering lessons of the day!

I would agree with that entirely.

There is no doubt that the efficiency of a heat pump is quite amazing compared to conventional heating or cooling - in fact on the most efficient systems you can produce almost times as much output as you consume - it sounds impossible but is perfectly true.

Inverter units can be more efficient for a number of reasons but I really do doubt that the claims made will be achieved in a real world environment. In fact if you have both types of unit running flat out there is virtually no difference. I think a realistic figure in normal use might be 10% for an inverter unit over a conventional unit but I have yet to see an independent evaluation of the savings.

As for the claim that they are quieter - that really applies only to the outside compressor unit so it depends on where you have located them. The inside units have the same fan system as a normal unit and the fan speed is user variable anyway so I don't think that makes any difference at all.

A few years ago the cost of inverter units was very much higher than conventional units but now the gap has closed a lot and that makes them a more affordable option - in fact some manufacturers only seem to offer inverter units.

Thanks for the lesson! I agree with everything you say - my problem is that I do not believe the gain in efficiency is anything like as high, in normal use, as that claimed by the manufacturers.

Well, since you are replacing an existing unit and assuming that the old one was adequate, just get a replacement of the same size.

BTU is a "British Thermal Unit". Normally A/C units are quoted in Kcal/hr. A typical bedroom sized unit would be about 2000 Kcal/hr which equates to about 8000 BTU. In Spain the units are often rated in "Frigorificos" which are actually Kcal/hr.

The ratings on a particular unit are different for heating and cooling - the heating rate is usually marginally higher than the cooling rate by about 10%.

HI Fred, yes, when you look into the detail of the manufacturer's claims on efficiency you find that it is under extremely controlled and defined conditions,

for example it will be in a room with Insulation factor xxx , the condensor in a controlled ambient enviroment xxx, voltage regulated at xxx. and so on, not reflecting the real world variation. (Charlie turning up with 5 mates after a curry night!!) All designed to produce optimum figures for marketing!


PS Twytub, you didnt discuss "specific enthalpy" vs "Enthalpy flow"

ok, so to not beat about the bush any longer,as all this thermo nuclear power versus a good old a-bomb doesnt really make alot of sense to me........

55m2 apt, one unit wanted to mainly cool/heat living room/kitchen area but to help the bedrooms, was originally an inverter unit, do i get an inverter again at, say €700-800 fitted, or go for a decent non-inverter unit for quite possibly half that ammount?
bear in mind the apt is pretty much used throughout the summer by us,family or friends, and in the winter, probably only used at weekends at most (but therefore needng to heat too).

answers on a postcard.....