Fitted Air conditioning
Discussion
mikey_b said:
Countdown said:
]I think ours is roughly £1 per hour per room.
I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
That sounds ridiculously high. What sort of system is it? You're not just taking the cooling capacity (which is measured in kW) and taking that as the electricity consumption are you?I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
It says LG Neo Plasma on the cover (2.6kwh I believe). I've also checked my Ovo KWH rate and its not as high as I thought (for some reason I thought it was 40.2ppkwh but it's 26ppkwh)
Countdown said:
I think ours is roughly £1 per hour per room.
I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
Yesterday when it was 35c all day I had the 5kW downstairs MHI split unit running for most of the day to bring the temperature down to 22c on a west facing room in a modern house with French doors and a big window.I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
The consumption increased from an average of 250w to 600w, so it is using about 350w an hour. At current capped rates that is about 10p an hour.
Countdown said:
mikey_b said:
Countdown said:
]I think ours is roughly £1 per hour per room.
I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
That sounds ridiculously high. What sort of system is it? You're not just taking the cooling capacity (which is measured in kW) and taking that as the electricity consumption are you?I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
It says LG Neo Plasma on the cover (2.6kwh I believe). I've also checked my Ovo KWH rate and its not as high as I thought (for some reason I thought it was 40.2ppkwh but it's 26ppkwh)
However, that's running at max power. If you select a sensible temperature - say 22C, and set everything to Auto, then when the room reaches 22C it will throttle back and stop trying to turn your room into a fridge, and just quietly maintain that temp. Probably be more like 10-15p an hour then.
Obviously very approx figures, but you get the idea. It adds up over time of course but they aren't quite the power hogs you're imagining!
mikey_b said:
OK, that will be much cheaper to run than you're thinking. Heat pumps (which is all an AC unit is) give roughly 3-4 the amount of heating/cooling as they consume in power, so take that 2.6kW and divide it by 3.5, and that will be roughly the amount of electricity it uses to run at full power. So when it's running full pelt, it will be pulling about 750W. Not £1 an hour - more like 21p.
However, that's running at max power. If you select a sensible temperature - say 22C, and set everything to Auto, then when the room reaches 22C it will throttle back and stop trying to turn your room into a fridge, and just quietly maintain that temp. Probably be more like 10-15p an hour then.
Obviously very approx figures, but you get the idea. It adds up over time of course but they aren't quite the power hogs you're imagining!
However, that's running at max power. If you select a sensible temperature - say 22C, and set everything to Auto, then when the room reaches 22C it will throttle back and stop trying to turn your room into a fridge, and just quietly maintain that temp. Probably be more like 10-15p an hour then.
Obviously very approx figures, but you get the idea. It adds up over time of course but they aren't quite the power hogs you're imagining!
Using the correct Kwh rating (and the actual usage readings logged on the OVO website) it doesn't look too bad to be honest.
4Q said:
Harry Flashman said:
Thanks for the numbers! We are with Octopus, who i believe are also supposedly all renewable.
I do hope that domestic solar becomes a realistic option one day. When we re-roof this house, i would love to fit it. But at the moment, the payback is just silly.
The payback is around 5 years at the moment, maybe 6 at London prices. I'm tired of arguing with people on here who are anti-solar so I'm not going to get drawn into an argument which is as productive as bashing my head against a wall, but if you want to PM me I can send you a spreadsheet so you can play with your own figures. I do hope that domestic solar becomes a realistic option one day. When we re-roof this house, i would love to fit it. But at the moment, the payback is just silly.
Edited by 4Q on Tuesday 19th July 14:51
Energy Saving Trust’s calculator suggests a 6kWp system would cost £8k.
https://energysavingtrust.org.uk/tool/solar-energy...
On my west facing roof and home all day it suggests a fuel saving of £420 a year (at the current 28p/kWh) and SEG of £95, so £515 a year.
£515 multiplied by your suggested five years is only £2,575 - nowhere near the system cost of £8k, and that is ignoring -
- the maintenance cost over the life of the system of £1,450
- the loss of income from investing the £8k cost
- that electricity remains at current prices over the lifetime of the system - and I haven’t seen any commentator suggest that energy prices will remain at this level for the next 25 years
- and you don’t need to move house, because it isn’t going to add value
And if you are out until 6pm like most households, it suggests a fuel saving of £174 and a SEG of £131, so £305 a year.
Payback over five or six years. Yeh right.
Edited by PF62 on Tuesday 19th July 16:40
GranpaB said:
Is it that important about payback etc though? I don't mind how much it costs if it means i'm comfortable in my home.
The ‘payback’ was in reference to domestic solar - which doesn’t have one as the installation cost is still to high to ever be paid back in energy savings.In relation to domestic aircon, the payback is the first nights decent sleep after it is installed.
mikey_b said:
Countdown said:
mikey_b said:
Countdown said:
]I think ours is roughly £1 per hour per room.
I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
That sounds ridiculously high. What sort of system is it? You're not just taking the cooling capacity (which is measured in kW) and taking that as the electricity consumption are you?I wonder if using it intermittently actually costs more than leaving ot on all the time. However leaving it on means the room is freezing in fairly short order. The thing is as we only use it for a few days of the year I've never bothered working out how to program the damn things.
It says LG Neo Plasma on the cover (2.6kwh I believe). I've also checked my Ovo KWH rate and its not as high as I thought (for some reason I thought it was 40.2ppkwh but it's 26ppkwh)
However, that's running at max power. If you select a sensible temperature - say 22C, and set everything to Auto, then when the room reaches 22C it will throttle back and stop trying to turn your room into a fridge, and just quietly maintain that temp. Probably be more like 10-15p an hour then.
Obviously very approx figures, but you get the idea. It adds up over time of course but they aren't quite the power hogs you're imagining!
I should know as i previously had a mitsubishi split system in a conservatory in our old house, however that was in the days of electric being about 4p kWh
GranpaB said:
Apparently, any room that has a split unit fitted should have the radiator turned off as they are much more efficient at heating the room than the rads?
More efficient, yes. More economical, depends on what's fueling the boiler. With a decent modern natural gas boiler, there's not much in it. m3jappa said:
With regard to the heating do they consume the same amount of power as cooling would?
It's dependant on room temperature and outdoor air temperature but the theoretical output in heating is slightly higher than in cooling due to the heat gained at the compression stage of the refrigerant (needs to be rejected to outside in cooling mode but will contribute to the heat going into the air or water when in heating mode). So in theory with everything else being like for like, then slightly cheaper to run in heating but not in a measurable waykambites said:
GranpaB said:
Apparently, any room that has a split unit fitted should have the radiator turned off as they are much more efficient at heating the room than the rads?
More efficient, yes. More economical, depends on what's fueling the boiler. With a decent modern natural gas boiler, there's not much in it. Jakg said:
When I did the sums I made a split about 50% more expensive than oil at heating - but oil and electricity have nearly doubled since then.
A COP of say 3.7 when heating with an ASHP aircon and a gas boiler at say 95% efficiency would mean that gas would need to be less than 1/4 the price of electricity to be cheaper.With electricity at 28p/kWh and gas at 7p the difference is insignificant, but if gas increases significantly in price more than electricity in October then they might be cheaper than gas to heat.
PF62 said:
Jakg said:
When I did the sums I made a split about 50% more expensive than oil at heating - but oil and electricity have nearly doubled since then.
A COP of say 3.7 when heating with an ASHP aircon and a gas boiler at say 95% efficiency would mean that gas would need to be less than 1/4 the price of electricity to be cheaper.With electricity at 28p/kWh and gas at 7p the difference is insignificant, but if gas increases significantly in price more than electricity in October then they might be cheaper than gas to heat.
My A/C basically has a remote control and an app, if you forget to turn it off, it will happily heat the room all day long at whatever the last set temperature was...
On a separate note, I have to say that I consider my A/C system to have "paid for itself" in terms of increased comfort in the 15 months I've had it.
Blue Oval84 said:
PF62 said:
Jakg said:
When I did the sums I made a split about 50% more expensive than oil at heating - but oil and electricity have nearly doubled since then.
A COP of say 3.7 when heating with an ASHP aircon and a gas boiler at say 95% efficiency would mean that gas would need to be less than 1/4 the price of electricity to be cheaper.With electricity at 28p/kWh and gas at 7p the difference is insignificant, but if gas increases significantly in price more than electricity in October then they might be cheaper than gas to heat.
My A/C basically has a remote control and an app, if you forget to turn it off, it will happily heat the room all day long at whatever the last set temperature was...
If you were to use the AC system as the main heating system you could make it ‘smart’ for a relatively trivial cost or would have bought a ‘smart’ system in the first place.
Blue Oval84 said:
On a separate note, I have to say that I consider my A/C system to have "paid for itself" in terms of increased comfort in the 15 months I've had it.
This is something all those without AC don’t seem to get. The cost of AC is low in comparison to many other things that they spend money on.
I have a Panasonic TZ for my garden office, above shows estimated usage yesterday. Garden office was custom built and so is well insulated (80mm in the frame and 25mm over the top, well air sealed), but I still think this is a good result. Approx 7.5p / hr ish. So don’t think 10p is far off.
Considering AC for loft conversion and at the same time kitchen / diner which gets very hot. Also good as backup heating.
Harry Flashman said:
For those curious about bills, we are running 4 units continually at the moment in the heat, as kids nurseries have closed so we need more rooms cooled than normal in hot weather.
2 splits (one running two indoor units) and two integrated wall mount units. 3 big rooms (5x5 and 8x5) and two small ones (3x4 and 4x4) are at a constant 20C. Yesterday's smart meter reading for this was £7.52. So probably £4-5 worth of extra electricity
Modern inverter units seem pretty decent, and i will oay this money quite happily. One day, if it ever becomes cheap and London has Barcelona's climate, i'd like solar to help run it all. Will make me feel a bit less guilty...
£15.32 for the week so far at 9am this morning, so is tracking consistently. This is on a Victorian home with poor insulation - you notice that it heats up fast whem you turn a unit off as the thick walls are like radiators having absorbed heat. 2 splits (one running two indoor units) and two integrated wall mount units. 3 big rooms (5x5 and 8x5) and two small ones (3x4 and 4x4) are at a constant 20C. Yesterday's smart meter reading for this was £7.52. So probably £4-5 worth of extra electricity
Modern inverter units seem pretty decent, and i will oay this money quite happily. One day, if it ever becomes cheap and London has Barcelona's climate, i'd like solar to help run it all. Will make me feel a bit less guilty...
Edited by Harry Flashman on Tuesday 19th July 10:24
This is absolutely worth it to me! Modern inverter units, and budget brands (TCL and ElectriQ, which use Panasonic compressors).
Alexa voice control of them is a nice touch and very user friendly.
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