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Author Topic: Sanyo CO2 Eco 9kw ASHP - Help  (Read 35617 times)
StationHouse
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« Reply #60 on: January 01, 2012, 09:32:21 PM »

Hi MacBeagle,
             It's good to see you are experimenting with your system. Every house,heating system and inhabitants are different. Reading between the
lines you seem to have a similar insulation and heating requirements as me. I have experimented over a number of years to optimise efficiency while
maintaining comfort levels. Initially I tried just putting the heating on when required but this meant the fabric of the house was usually cold and
required a higher thermostat setting to feel comfortable(always above 20 C).

I built an extension onto my current house it is now 1/3 of the completed house. I barrowed in the cement for the new "slab" - six tons of it ! So the
whole house slab is probably 18 tons of cement. I carried in the platerboard into the house basically a pile a metre high probably another couple of
tons.The internal walls are solid brick so many more tons of thermal mass. With water pipes furniture crockery kitchen units and much more stuff. This
could easily add up to 50 tons of thermal mass to heat up.

This was brought home to me when I went on holiday for a week in March. No frosts were predicted so I turned off the heating and electricals. Coming
home on a warmish day the house was colder than the outside. The internal temperature was 12 C. Even though we put the heating on the house felt cold.
Everything we touched was chilled cutlery cups etc. It took at least a week before the house felt comfortable. Considering the tonnage of material to
heat this is no surprise. The air temperature was 20 C+ but it just felt cold and draughty.

Although the thermostat is controlled manually I keep the house continuosly between 16 C and 20 C(average 18 C). It feels comfortable and draught
free. Some years ago on the forum there was a discussion about heating continuosly versus heating when required. It was never really decided which was
best for economy. Everyone who maintained an even temperature reckoned it was cheaper.

Over the last year October 2010 to October 2011 my gas heating bill has been 504.66. I use about 40 kWh/day on average With probably the coldest
winter for 20 years included in the year. I am well pleased with this.

Strangely I run my system with a water temperture of about 50 C and maintain the house temperature all the time. This is usually recommended for heat
pumps. You seem to be setting up your system on a timer with fall back temperatures wihch is usually recommended for gas/oil boilers.

Also it is interesting to note that my 40 kWh/day usage is probably at a boiler efficiency of 75% (non condensing boiler) So the actual heat input is
30 kWh/day. If you achieve this with your system it will cost :-

Assume average COP of 2.5. electricity require = 30/2.5 per day = 12 kWh/day
Assuming a cost of 10 p/kWh this equals 12 X 0.1 = 1.20 per day (average)

This is 1.20 x 365 = 438 per year. So assuming gas at 0.035 and electric at 0.10 the heat pump is cheaper to run assuming same output is required.

Out of interest what is your yearly bill ? And do you have a cost for connecting to the gas main ?


Regards Richard

Totally agree with this...^^^

Over on MSE they seem staunchly against this idea but in an older house, as long as it is insulated and draft free, it makes a lot of sense. Perhaps in a small modern box a different approach is required.

Great post  Smiley
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Ladysmeader
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« Reply #61 on: January 05, 2012, 06:02:40 PM »

This has been a very useful thread for me as I'm considering the Sanyo CO2 ASHP for my property. I'd appreciate anyone's comments on my circumstances:-

A remote one off 3 bed-roomed cottage, 400 years old, thick cob walls, no chance of ever getting a mains gas supply. Loft very well insulated with 300mm + insulation, double glazing and well draught proofed. Currently have a 6 year old oil fired programmable rayburn for central heating, hot water and cooking. Also a wood burner which we use most evenings. We keep the temperature at 18 deg C and have the central heating on for 3 hours in the morning , 3 hours in the afternoon/early evening before lighting the wood burner. Have had PV panels installed at 3.96KWp for the last 18 months. We want to get away from oil altogether as eventually it will become prohibitively expensive.

We use 1500 litres of oil at say 50p/l = 750, 8 cu.m of logs at 45/cu.m = 360, and 2000 kwh electric at 14p = 280 (also consumed 1000 kwh of our own generation). This was over the last very cold winter. I think our running costs will be lower this winter as it has been so mild.

Thats a total of nearly 1400 for all heating, HW and cooking. We also made close to 1600 from the FIT in 2011.

We have had two quotes for the installation of the Sanyo ASHP plus thermal store ( not the swedish one mentioned in the thread but a Kingspan job which has been specified by the local sanyo rep to improve the overall COP of the pump. Both installers reckoned we needed 9KWH as we had the backup of the wood burner, and we will at the outset retain the rayburn for cooking which gives us some residual heat for several hours once hot.

The bonus for me is that the Sanyo unit will use up the excess PV electricity we don't use both in the winter and in the summer. In the winter it will go mainly to heating the home, but in summer will keep us topped up with hot water, so that we should not ever need solar thermal panels. We currently export to the grid around 3000KWH which would be better used running the sanyo heat pump. We currently have electric power showers and these will be replaced with a pressured supply from the thermal store.

Thats the theory - anyone have any comments please.

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HalcyonRichard
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« Reply #62 on: January 05, 2012, 06:27:55 PM »

Hi Ladysmeader,
                       If it's cost you are thinking about then you need to calculate how much power you use over a year. Then work out how much power the new system will use. After this you can calculate and compare costs. So using the data given (rough cut ball park figures):-

1/ 1500 litres @ 10 kWh 100 % efficiency = 15,000 kWh
2/ 8 m3 logs say at 500 Kg/m3 @ 4kWh/Kg 100% efficiency = 16,000 kWh
3/ All electricity @100 % efficiency = 3,000 kWh

So yearly heat input = 34,000 kWh (sanity check - my well insulated house last year consumed 14,400 kWh heating)

This figure seems about right to me - it looks in the ball park.

So lets replace all of it with a heat pump with an average COP of 2.5

So electrical input required = 34,000/2.5 = 12,800 kWh electricity to run pump.

Cost of 100% heat from heat pump @ 14 p/kWh = 12,800 * 0.14 = 1,792

So it looks on rough figures the cost is not a big incentive. But you can get cheaper possibly off peak electricity. You may not get all of your heating from the heat pump. You may like the ease of use of the heat pump.

Warning all figures are guesstimates.

Regards Richard
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Laws are for the guidance of wise men and the obeyance of fools - Richard Burton upon Trent
Ladysmeader
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« Reply #63 on: January 05, 2012, 10:43:42 PM »

Thanks Richard. The cost is not the real incentive, its getting away from oil and using as much of the pv generation as possible. Just tweaking your figures a bit. Probably 300l of the oil is used for cooking = 3000KWH and none of electricity is used for heating = 3000KWH. So I would guess 28000KWH goes on heating. We will continue to use the woodburner, perhaps not as much but we like the effect and ambience in our home, so say 8000KWH of the logs can be deducted. This leaves 20,000 KWH. We have 3000KWH PV being exported. If we could use say 2000KWH of this , it reduces the ASHP's requirement to 18,000 kwh at 2.5 COP and 14p/kwh = 1000 cost plus cost of half the logs 180 plus cost of 300 l oil for cooking = 150 Total cost 1330. The cost if the system actually works is very similar to current costs, but is weaning us off the oil . If it does work, we will remove the rayburn altogether in the future. We will never get a payback for the installation costs, but the income from the pv will easily repay both the PV and ASHP installation over 25 years (unless the govt change the FIT tariffs for existing users in the future - not impossible).



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dhaslam
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« Reply #64 on: January 06, 2012, 01:14:25 AM »

Would it be possible to insulate the walls  outside and  get  the outside  finish back to the same as it was? 
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
knighty
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« Reply #65 on: January 06, 2012, 02:20:00 AM »

Ladysmeader

if you're going to a have a thermal store, then it seams almost crazy not to have solar thermal, you'd get a hell of a lot of heat for the cost of the panels and a bit of pipe (if you're already buying the thermal store etc... then that's the big stuff already paid for)


I don't know much about there availability, only there existence, but can you install a heat pump which can run at lower power (an inverter controlled one) - I can't remember the proper name for these...

the idea being it would make better use of the power you generate if the heat pump runs at 3kw for 12hours instead of 9kw for 4hours ?
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Ladysmeader
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« Reply #66 on: January 06, 2012, 04:32:16 PM »

Thanks for the answers so far. Our house walls are cob and as such they have to be "breathable". Any external wall insulation, or internal for that matter has to allow the walls to breathe. We have looked into this, products are available  but the cost is astronomical, like 25,000 to externally insulate our cottage.

We have space to put solar thermal panels on our roof and the thermal store will have the capability to take the heat from them as a future project.

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StationHouse
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« Reply #67 on: January 09, 2012, 11:38:48 AM »

Hi

Looking at Dimplex Smartrads as an alternative to the old slimline radiators to make the most of the ASHP.

This is a question for StationHouse really but feel free to chip in. In one of his posts he said "we went for the white glass fronted Dimplex SmartRads. Size them at the lowest fan speed to the room so they run at their quietest." How did you do that?

Cheers and a Happy New Year to you all





Hi,

Have you seen the sizing chart in this PDF?

If you like send me your room sizes and will compare to mine to double check?

Cheers
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MacBeagle
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« Reply #68 on: January 12, 2012, 12:25:25 PM »

Hi

"Have you seen the sizing chart in this PDF?" Not sure what PDF you mean. I did use the Dimplex heat loss calculator on their website to work out rad sizes - how does this correlate to fan speeds?

The relevant rooms sizes are:
Hall - 4mL x 2.9mW x 2.37mH - Dimplex suggests 1.26 kW DuoHeat Radiator
Living Room - 4.8mL x 3.8mW x 2.37H - Dimplex suggests 2.35 kW DuoHeat Radiator
Dining Room - 6.7mL x 3.8mW x 2.37H - Dimplex suggests 3.14 kW DuoHeat Radiator

I reverted back to the original installation settings and we are now getting temperatures through the rads of 54-58 without any increase in costs. A blitz on all the draughts and not letting the house fall below 15 at night has shown a big improvement, but there again outside temperatures of 7-10 degrees have helped.

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SpeedEvil
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« Reply #69 on: November 01, 2012, 11:45:30 AM »


Also it is interesting to note that my 40 kWh/day usage is probably at a boiler efficiency of 75% (non condensing boiler) So the actual heat input is
30 kWh/day. If you achieve this with your system it will cost :-

Assume average COP of 2.5. electricity require = 30/2.5 per day = 12 kWh/day
Assuming a cost of 10 p/kWh this equals 12 X 0.1 = 1.20 per day (average)

This is 1.20 x 365 = 438 per year. So assuming gas at 0.035 and electric at 0.10 the heat pump is cheaper to run assuming same output is required.

Sorry to necro the thread, came across it after finding a reference to the OP's heat pump.
However, am I missing something, or is there an error above?
I agree that to provide 30kWh/day with 10p/kWh and a COP 2.5 pump would be 438/year.

But, 10/2.5 =4p/kWh, And the gas boiler will hit 4.11p, assuming 80% efficiency, And needs to hit 87% before parity.

Are you really basing the 'cheaper' claim on 12 quiddish savings a year?
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brackwell
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« Reply #70 on: November 01, 2012, 02:08:54 PM »

That thinking has to be based on wrong premise.

There is no way one can talk about a "average" COP as it is highly variable from say 1.0 in the depths of winter to perhaps 5.0

Further the COP can be significantly changed by output temps and usage patterns which dont really affect the gas boiler efficiency that much.

The real life efficiency of a gas boiler supplying DHW only is nearer 50%

Suggested reading http://www.heatpumps.co.uk/DHW.htm

Ken
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