I'm thinking of putting a split air con in a room at work, it's been so hot these last few months.
If I understand correctly they can also heat economically, from what I think I know though they work by exchanging heat so on a really cold day surely they would struggle?
I would appreciate any advice on cooling/heating systems as well as recommendations, looking to do this for £100s rather than £1000s.
TIA.
Really cold as in -10 C outside. They do become less efficient when the bit outside, working as an evaporator, ices up. They then have to pump heat out to thaw the ice. This icing generally happens with outside air temps above 0 C up to around 5 C depending on the humidity.
R D S formulated the question :
Some can provide heat as well as cool - the problem is, the colder it gets outside, the more heat you need and obviously the less heat they are able to provide. The last i heard, you can get maybe twice the heat out, for the power you put it so 1.,5Kw in maybe around 3Kw of heat out, subject to weather. As you appraoch zero dgrees outside, the evaporator can freeze up.
Been following these discussions :)
AIUI the weak point on an air-source heat pump is a cold, damp day. The cold end (outside) drops below freezing point and is below the dew point. So you get ice buildup. Then you have to heat it to melt the ice, and your efficiency collapses.
Cold and dry they can manage just fine.
Andy
A COP of 2 is pretty poor, 3 is what is aimed for. So a decent system should be
1.5 kW in 4.5 kW out.Which naggers the COP but once you are below 0 C and dry air the effciency returns. The limit is then how far "up" the heat pump can shove the heat, say it can manage 40 C, room at 20 C, condensor has to be hotter to transfer heat to the room say 30C, so outside can be
-10 C.
I had to put "Naggers the COP" into Google, I thought it might be an old regional expression!
At least I now that COP is Coefficient of performance and I can guess the rest.
Improved insulation on the roof/ceiling might be a better bet. Even a basic fan makes a noticeable difference to perceived temperature - at the risk of having your loose documents flying around the room.
In the UK they would struggle during winter because our high humidity means that the external heat exchanger will ice up pretty quickly for an air source heat pump. You can work around it by periodic thawing cycles but it is nothing like as efficient as in dry cold air.
In dry continental climates then they will work down to something like
-10C external temperature during winter. Supporting a >30C temperature differential their efficiency tails off - they are really very good for
+/- 10C in terms of heat delivered per watt iff you already have one.Nowhere near as good as a gas fire or paraffin heater though.
Passive design adjustments to the building are worth trying first.
Some AC units are reversible, ie pump heat both ways.
Their effictiveness is measured by the Coefficent Of Performannce (the ratio of heat enrgy out divided by electricty in.) Usually around 4 in good conditions.
In "heating mode" they are affected by cold weather. ie work less well when you need them. However. You can now get them filled with propane gas/CO2 that are much improved.
The outside bit can ice up in certain weather coditions on "heat mode" This happens when the outside heat exchanger is undersized, Sometimes an electric de-iceing heater is fitted, sometime the device reverses for a few minutes (all results in energy loss)
But you will only get a piece of shit for a few hundred . Yoii can buy DIY ones with special couplers for the pipework/part which is all pre-charged. But they are again, by and large, pieces of shit.
Or you can get a "through the wall" one that needs no plumbing/messing with refrigerant gas.. Ugly inconvenient things.
Not all will both heat and cool, make sure you get one that will. Others have commented on their general characteristics. An old building used by a company I was associated with fitted them into a number of offices and over the three years I observed them they always produced enough heat to keep the desk workers happy in winter and cooled enough in the summer.
There are a number of pre-filled units on the market where you plumb them in, connect some quick joint couplings and they operate. The copper pipe joining the indoor and outdoor units is both narrow bore and soft so great care must be taken when installing them as it easily kinks. You also need to make a fair hole in the brickwork to allow both the pipes and wiring loom through.
In article , R D S scribeth thus
I've had one here for some 18 years now and by and large it's been fine a Fujitsu unit. Only once was it a problem and that was rather minor.
As other have alluded to there are the odd days when its very cold and wet then it can fall off a bit in efficiency but there're not that often. However their performance has improved in recent times.
Having the outside unit where it can "breathe" and has a good airflow around it helps. I've not dome any serious calculations on it but it does seem to be quite good.
You can these days DIY these thats not too difficult what costs of install is running the pipe work and that sort of thing which is easily do able.
In fact I did phone up a large local firm and their quote for a newer unit was only around the thousand mark which of course cools and heats.
And in the summer when we get those nice humid hot days its a god send:).
Stick to a good known brand like Fujitsu, Dakin or Toshiba and you won't go wrong.
In article , harryagain scribeth thus
Can you be more specific in your reasoning at all then?..
Or is your info and opinion rather out of date?..
The components are cheap, flimsy and don't last long . The couplers often leak.
They will always be ugly and inconvenient. Their only saving grace is you can install them without recourse to gassing them up or dodgy connectors.
Do they?, I'm in and out of office buildings that use Aircon pretty extensively and really there aren't those sort of problems..
Why?.. Thats just an aesthetic opinion.
What's inconvenient?....
You have to knock a huge hole in the wall to install them. Or fit them in a window. Which usually means they have to go somwhere inconvenient. They are also a source of draughts and heat loss through teh cabinet.
Are you totally dim?
It is, to me, pretty obvious that reference was being made to a self-install split unit like this:
Not to a through-the-window type, nor to an "air-pipe-through-the-wall" type.
Nope...
The aircon unit here and a few others that I know of have holes around
1 inch diameter though a wall to take a couple of pipes through to the outside heat exchanger unit and those holes are totally sealed no draughts at all anywhere .. period!...What ever are you thinking about?..
[...]
I think he's thinking that the sort that are precharged and don't need any pipework disconnecting or connecting aren't the same sort that have pipes through small neat holes.
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