Paphos Life

As the weather has been pretty awful today, I decided to do an experiment to see how many kwh our invertor aircon units used to heat the whole house. We have a 5kw photovoltaic system so our electricity costs are 5 cents net metering charge and other addons, including VAT, per kwh. Neighbours who do not have a photovoltaic system paid 26.3 cents per kwh on their last November bill.
Last night was the coldest night of the year so far, down to 9c. Our uninsulated house had lost 3c during the night, from 21c down to 18c overnight. Unoccupied bedrooms were down to 16c. We live in a bungalow, with open plan areas of a kitchen, dining room and lounge, plus a corridor to the bedrooms.

I ran all 5 of our aircon units, set on heat at 21c and the fan setting on 2. Our main aircon unit is 2400btu. Secondary one 1800btu and 3 bedroom units, each 1200btu. All were on for 5 hours. In the 5 hour period we used 8.1 kwh through the meter and 4.26kwh solar units, totalling 12.36 kwh. Our cost for the electricity would be €0.405. Without net metering the cost would be €3.25. However, even without net metering we got the whole of the house to above 20c in the five hours at a reasonable cost.
For the rest of the day, I turned the bedroom units off. We usually do not run them anyway, but just air the bedrooms during the day with the large main unit in our open plan dining room.
The two large units, 2400btu and 1800btu, during the remaining 4 hours, used 2.7kwh through the meter and 2.3kwh solar. The cost to us, for 4 hours of heat maintaining a temperature of 21c in all our living areas, would be €0.135 or, without photovoltaic and net metering, €1.315.
Our aircon units are all new LG, with a 10 year guarantee from LG on the invertor.

Very interesting figures John. Even with that unusual low temperatures, which will change anyhow tomorrow, the consumption of your air-con heating is very low. I was going to post an article these days about air to water heat-pumps for central heating instead of gas/diesel. After your post on air-con heating,(which works similar), I won't, as you explained everything perfectly. As soon as the temperature goes back to normal at daytime (18c) the consumption will be even more reduced as both systems are using the warm air of the environment to heat up the premises. It is the future for heating specially in warm countries like Cyprus. If we had better insulated houses here (also windows) one could wait after the night until outdoor temperatures reaching 15c or so and start then running the air-cons/or heat pumps.

Max

Today was the shortest of the year in terms of daylight. After my experiment yesterday, the house was at a liveable in 21c in the dining and lounge areas, kitchen area and hallway. We just ran the 1800btu aircon unit in the lounge last night, and ended up turning that off for the last hour before bed. During the night we lost 2c, so the temperature was 19c this morning, again on a cold night when the temperature fell to around 9c.

We have been doing jobs today, both inside and outside, so have not needed any heat. Our inside temperature fell to 18c by 5pm, when we put our main aircon unit on.

Last nights and todays total consumption is as follows. This is from 6pm when I concluded the experimentof running two aircon units. We have produced in total 12.99 kwh and used in total 12.49kwh. 10kwh have gone through the meter costing us 50cents.

Max is right about using the aircon for heating and heat pumps when the air temperature is higher. During the last cold spell, I ran our swimming pool heat pump for 6 hours in the evening, when the air temperature was 13c and I used 33.8kwh in totaland only raised the water temperature by 1c. During the same day, when the temperature was 19c, the heat pump was on for 9 hours and used 33kwh, raising the temperature by 3c.

I think that if we upgraded our oil fired underfloor heating system, which we do not use because of the expense, we would use it like the old storage heaters, heating the floor during the day and turning it off at night in order to get the best economy out of the heat pump.

Keep warm and safe.

Ideally, it would be possible to heat the water for underfloor heating using the aircons. Unfortunately, I was told that´s not possible.

I doubt that a drop of air temperature from 19°C to 13°C would decrease the efficacy of an air-to-water heat pump as much as you observed. There must have other factors been at play, too (like e.g. wind).

We read a similar post on FB about this a few days ago. We use our LG aircon units fitted by Green Air for heating and they are very economical. We don't have net metering but, nonetheless, our heating bills are much lower than before we had them installed. We run ours in a low fan setting and after 20 minutes or so our uninsulated bungalow is nice and warm throughout. They've definitely been a good investment for us.

Anarita John wrote: ↑Tue Dec 21, 2021 5:35 pm Today was the shortest of the year in terms of daylight. After my experiment yesterday, the house was at a liveable in 21c in the dining and lounge areas, kitchen area and hallway. We just ran the 1800btu aircon unit in the lounge last night, and ended up turning that off for the last hour before bed. During the night we lost 2c, so the temperature was 19c this morning, again on a cold night when the temperature fell to around 9c.

We have been doing jobs today, both inside and outside, so have not needed any heat. Our inside temperature fell to 18c by 5pm, when we put our main aircon unit on.

Last nights and todays total consumption is as follows. This is from 6pm when I concluded the experimentof running two aircon units. We have produced in total 12.99 kwh and used in total 12.49kwh. 10kwh have gone through the meter costing us 50cents.

Max is right about using the aircon for heating and heat pumps when the air temperature is higher. During the last cold spell, I ran our swimming pool heat pump for 6 hours in the evening, when the air temperature was 13c and I used 33.8kwh in totaland only raised the water temperature by 1c. During the same day, when the temperature was 19c, the heat pump was on for 9 hours and used 33kwh, raising the temperature by 3c.

I think that if we upgraded our oil fired underfloor heating system, which we do not use because of the expense, we would use it like the old storage heaters, heating the floor during the day and turning it off at night in order to get the best economy out of the heat pump.

Keep warm and safe.

I really like it when people like you John, testing their equipment and making notes from the result. This could make you proud that with your investment you did something for the environment AND save money. Further it proves what YOUR installation is doing and not what one can find in the many stats on Google. In the last 30 years, since I am interested in PV I did a lot of experiments also with wind power to find out that a lot of published information was wrong.

Keep posting about your systems John and perhaps you install also a heat pump for your underfloor heating and led us know how it works...

Max

Thanks Max, I will continue to monitor all of our system. Jeba, the night I put the swimming pool heater on was very humid, so with a high dew point. The unit was covered in condensation and the elements inside,(or whatever they are called) must have iced up as the unit periodically went into de-ice mode. This is one of the problems with units in the UK. When this process of de icing first happened, we thought something was wrong and called out Green Air, who sent out Ken, who had fitted our heater to check it out. He explained what had happened.

I´m currently thinking about how to heat a house which is still to be built in Polemi. I thought I could use the aircons for heating and install only a weak electric heating system, just enough to warm up the floor (as I hate cold feet). If aircons are really that inefficient in winter, I´ll either have to have a bigger PV system or an additional source of heat. I wonder whether it would make economic sense to have a water-based underfloor heating system in connection with vacuum tube thermal collectors. And thoughts on that anyone?

Jeba, I was talking about our swimming pool heater. Also, in the higher electric consumption, I did not account for appliances running in the house and also I was using our mains pool pump, so probably the consumption figure was around 4kw per hour, not 5. Aircon units are very efficient for heating, most getting an A+ or A++ rating. Today, when I monitored just our 2400btu aircon unit for two hours this morning, when the outside temperature was only 10c, our average consumption was 1.75kw per hour and our inside temperature rose from 17c to 20c.

If we were building from new, we would still have underfloor heating installed, powered by a heat pump. However, I would ensure that sufficient runs of piping were put in and there was an easy way to control the heat in each room.

Have had a ground source heat pump with underfloor heating for the last 11 years, consistently reliable and economical to run .....
Also use LG a/C's as a back up.......
Total running cost for a 3 bed bungalow villa,(170 covered) including local taxes is around €500 a year ...since installing a PV system..and insulation.

jeba wrote: ↑Wed Dec 22, 2021 1:10 pm I´m currently thinking about how to heat a house which is still to be built in Polemi. I thought I could use the aircons for heating and install only a weak electric heating system, just enough to warm up the floor (as I hate cold feet). If aircons are really that inefficient in winter, I´ll either have to have a bigger PV system or an additional source of heat. I wonder whether it would make economic sense to have a water-based underfloor heating system in connection with vacuum tube thermal collectors. And thoughts on that anyone?

No, it make no sense to install a water-based underfloor heating while the source is only from vacuum tube thermal collectors. The idea of a underfloor heating is perfect, but it has to be connected with a secure hot water supply, for example a air-to-water heat pump. Solar thermal works only when you have plenty of sunshine daily,( which won't happen at Polemi in Winter), together with an huge storage warm water tank and electric back up coil.

I suggest you get a quotation from Green Air Paphos for installing underfloor heating in combination with a 12 KW heat pump. (for ca 100 m2 area) If you enlarge your PV system a bit (you need 3-phase) then your electricity bill in future will be very low and your house cosy warm. Perhaps your PV inverter can take some more modules (Just ask also Green Air)

Max