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Author Topic: 12kw Heat pump.  (Read 10870 times)
biff
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« on: May 11, 2013, 10:28:06 AM »

I got a visit from a friend yesterday,
                                  His house is over 4,000sq feet and his lecky bill is in excess of 3,000euros per annum.He says that 1800euros of this is running the heatpump which he says is 12 kw.I was wondering if there is any way that such a setup could be run of a much smaller pump,?.
       I recall some years ago our vacuum cleaner was in excess of 2kw and just too hard to run.We bought a dyson 600watt job and it turned out to be the best vacuum cleaner we ever had.Maybe there is a similar move as regards the heat pump motor,?
                                                                                                 Biff
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brackwell
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« Reply #1 on: May 11, 2013, 10:40:28 AM »

Does a smaller compressor motor not just mean you have a smaller capacity HP ?

Your friend needs to read this http://www.heatpumps.co.uk/viability.htm and more on this site.   

As i see it the problem is not the heat pump, but the lack of training/education/understanding that is the downfall of many systems where people use them like they would use a gas/oil boiler which is probably close to being the worst thing one can do.

As a friend of yours he must have done the insulation?

Ken
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biff
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« Reply #2 on: May 11, 2013, 11:02:03 AM »

Yes,the place is insulated to the hilt.
                    He would not be very clued up on heatpumps,neither am I but I knew enough to avoid them and wood pellet boilers as well whistlie.
         I will have a read of the link and hopefully learn a little more. Thanks
                                                                 Biff
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Bodidly
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« Reply #3 on: May 11, 2013, 11:22:33 AM »

I think the guts of heat pumps are much the same for efficiency unless undersized and using direct electric to keep output temperatures up.
The gains are to be had through raising inlet temperatures and lowering outlet temperatures.
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HalcyonRichard
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« Reply #4 on: May 11, 2013, 12:08:55 PM »

Hi,
    If it's an old installation his COP could be lower than the modern Heat Pumps. But is it Air source or Ground source ? This also has implications for efficiency/weather conditions. My House is about 120 m2(bungalow) insulated to current standards. Heating cost for gas is 12,000 kWh @ about 5 p = 600/year. As a rough approximation if he used the same amount of heat into the house had a COP of three his bill electricity should be about 600. So does he have something wrong with the set up ? Or does he run a hot house ? People and lifestyle are probably the largest influence on bills.

Richard
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knighty
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« Reply #5 on: May 11, 2013, 02:36:10 PM »

as above, need to know if it's air source or ground source


I'm thinking maybe he has it hot tap water temperature set too high, so it's working flat out trying to reach that high temperature

numbers will be different for each setup, but 50'C should be easy to reach, 60'C will take longer... 70'C will take bloody forever



if he needs lot of hot water, he could add another hot water tank, so instead of 200litres at 70'C he could have 400litres at 50'C... lots more hot water, and it should take a lot less power to reach that temperature :-)
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baker
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« Reply #6 on: February 12, 2015, 02:56:52 PM »

biff
their is nothing wrong with heat pumps , / wood pellet well I agree
its the way you install and use them
their is something wrong ,bet it s the ( shame) old storey
a diy job /installer with no exp,
best thing to do is get a experienced engineer to check and resolve the problem
has it got bad with time? or like it from the start

one of many things to think about
if a heat pump is undercharged it will run 24 /7 and little heat, and guess what   comes in the post
1800 bill hysteria
whats the make /model
f gas? r407 or 134a or 410a



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dhaslam
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« Reply #7 on: February 13, 2015, 11:03:52 AM »

If there isn't   an immersion attached the  cost would be almost the equivalent of running the heat pump  for 24 hours every day and if that happens the ground loop can  be cooled too much.  They are generally rated for ten hours per day  or less in  winter,  that allows the  ground around the pipe to regain heat.   If the ground is dry  heat recovery would be much slower.           
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Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
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