Air Source Heat Pumps
Comments
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lomb, unless you know anything about Air to water heat pumps, it is foolish to even make comments like that....an 8kW system is absolutely all you need for a 3 /4 bed house ....I would guess that littletiger82's system might be over spec`d.......an average house with good insulation in the roof and cavity, good double glazing should have a heat load of between 7 and 10kW's.....eerrrm my house is a large four bed and I ripped out an 18kW condensing oil boiler...it now runs on an 8.5kW Ecodan for heating and hot water even with outside temperatures down to 10.2 degrees......There are three types of people in this world...those that can count ...and those that can't!
* The Bitterness of Low Quality is Long Remembered after the Sweetness of Low Price is Forgotten!0 -
littletiger82, is that 463 units just for the heating or is for all of your electric in this time?There are three types of people in this world...those that can count ...and those that can't!
* The Bitterness of Low Quality is Long Remembered after the Sweetness of Low Price is Forgotten!0 -
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Lomb,
The reason why houses have large output gas and oil boilers is to bring cold houses quickly up to temperature - which you can with water at 80+C. Once the house is up to temperature, the boiler modulates and is only giving out a fraction of its maximum output.
The principle of heat pumps is surely to keep the property ticking over at, or just below, the required required temperature. i.e. you don't go away for the weekend and switch on the ASHP on return and expect the house to be up to temperature in 10 minutes.
As said before, if you do need 'fast' heat in a room, stick on a 3kW fan heater for an hour. It will cost an extra 20p.
That said, anyone found any statistics on the power taken by defrost cycles?0 -
WHats annoying me is Lomb that your still saying that the system will some how lose 2kw? An LG system at -5 is still outputting just under 7kw. My system is also a similar output to the ecodan however im sure the ecodan is more efficient and work better in cold weather than my LG equipment.
READ my post below and click the link.richardc1983 wrote: »Ok here it goes:
It takes about 5minutes after the defrost before it is running at full out put again.
Heres capacity tables at different outdoor temps for my multisplit unit:
Page 63 of the pdf reader or page 268 if looking at the bottom of the pages like a book. Use combination of 4 units as then the outdoor will be providing full output with 4 units connected. Numbers in the column that are bold are the design ratings.
http://mylg.co.uk/data%20for%20site/multi%20f%202008%20outdoor.pdf
You can see the unit is rated at 8.5kw output with 1.96kw of input based on ambient temp of 6C and internal temp of 20C.
Follow this across to the left and you can see that at 0C it drops to 7.66kw output with 1.96kw input.
Then -5 is 6.86kw output with 1.97kw input.
Loss is just short of 1kw of output every time the external temp drops 5C.
At -15C the output drops to 4.84kw with 1.97kw input.
Of course 20C isnt that warm to keep a house but even so looking at the internal temp figures of 22C it isnt much different.If you found my post helpful, please remember to press the THANKS button! --->0 -
so about £18.50 per week....at the moment......it is winter you know... OK... some questions
is it a new build
do you cook with electric
how many occupants
how many minutes in the electric shower
what rating is the shower 8, 9, 10 kW
washing machine useage
Tumble dryer?
and then give a minute to answer....There are three types of people in this world...those that can count ...and those that can't!
* The Bitterness of Low Quality is Long Remembered after the Sweetness of Low Price is Forgotten!0 -
Lomb,
The reason why houses have large output gas and oil boilers is to bring cold houses quickly up to temperature - which you can with water at 80+C. Once the house is up to temperature, the boiler modulates and is only giving out a fraction of its maximum output.
The principle of heat pumps is surely to keep the property ticking over at, or just below, the required required temperature. i.e. you don't go away for the weekend and switch on the ASHP on return and expect the house to be up to temperature in 10 minutes.
As said before, if you do need 'fast' heat in a room, stick on a 3kW fan heater for an hour. It will cost an extra 20p.
That said, anyone found any statistics on the power taken by defrost cycles?
Again Cardew, I have a 9kw system for my flat, this would be sufficient to heat the flat on its own and does, better than the central heating system thats also here.
The warm up times are quicker and its quicker to respond than the the GCH. Not sure why we keep covering old ground but 80C is for GCH you dont need 80C flow temp in AIr to Air.If you found my post helpful, please remember to press the THANKS button! --->0 -
littletiger82 wrote: »albyota, that's for all of my electric over the last 2.5 weeks
For a house to be 24/7 at 22C, plus all other electric, I think 463kWh is very good at this time of the year - about £80 a month!0 -
so about £18.50 per week....at the moment......it is winter you know... OK... some questions
is it a new build
do you cook with electric
how many occupants
how many minutes in the electric shower
what rating is the shower 8, 9, 10 kW
washing machine useage
Tumble dryer?
and then give a minute to answer....
Albyota, thanks for all your help, having just bought my first place obviously money is tight and I just want to make sure I'm running it right as I have absolutely no previous experience with ASHP...
Yes, it's a new build
Yes, cooker and everything else is off the electric
Just little old me, but my mum did stay for a couple of weeks
Say 10 minutes per day in the shower? I'm assuming it's an 8kw, can't imagine the builders would have put in anything but the cheapest!
Washing machine on say twice a week, no tumble dryer.
Am I doing the right thing in keeping the heating on 24/7 to keep it at an ambient temp so that it doesn't have to work so hard to get back up to temp? Or should I be using it like a normal central heating system andhave it on and off throughout the day?0 -
richardc1983 wrote: »WHats annoying me is Lomb that your still saying that the system will some how lose 2kw? An LG system at -5 is still outputting just under 7kw. My system is also a similar output to the ecodan however im sure the ecodan is more efficient and work better in cold weather than my LG equipment.
READ my post below and click the link.
After reading your post your system is loosing nearly 2 kw at -5 degrees compared to 6 or 7 degrees. Lets say we round up the manufactuers figures. Bottom line is better too big than too small especially if they can ramp down.0
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