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11.2kW Mitsubishi Ecodan replacing LPG boiler

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(@derek-m)
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@peterr 

Let me explain in a little more detail. Because you don't have any electricity meters or a heat meter connected to your FTC controller, then the energy calculations must be made internally. Whilst there are some adjustments that can be made to some of the parameters, to correct for slight inaccuracies in sensor readings, I cannot see how incorrect settings would account for the inaccuracies you are seeing in the energy values.

There is either something I have not discovered, or there is some sort of internal problem that is generating the incorrect readings.


   
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(@batalto)
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@jeff try just buying a cheap electricity meter with a CT clamp and put it round the power for the HP. There are loads of cheap ones with online monitoring. It'll give you an idea of your power use in the short term

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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(@derek-m)
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Hi Peter,

I was just looking at your data again, and what concerns me is that your electrical energy usage does seem to be on the high side. Is there any other equipment that may use a large amount of electrical energy?

Before you had the ASHP installed, how much LPG and electricity did you normally use? Do you have an immersion heater installed and how is it powered? Do you know if your system has a booster heater installed?


   
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(@peterr)
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@derek-m 

Hi Derek,

Our installer has promised me a call back from someone in their technical team within the next 24 hours. Given their previous track record I don't know if this will happen or not! If they can't help I'll get in contact with Mitsubishi.

Regarding our previous usage, I have recorded usage for the last 6 years since our solar PV was installed.  On average in November, we have used 374 kWh. So far this month we have used 714 kWh.  It should be noted that up until last Thursday afternoon we had the system on room temperature mode, with a flow temp of 50C, which may partly explain the high usage.  We do use washing machine and tumble drier regularly, but other than that nothing that would account for high usage.  The tank does have an immersion heater installed, connected to a solar iBoost, but we do not manually use the immersion. It does also have a booster heater, but I have only ever seen this in use once.

I am finding the usage figures a little scary, but, our LPG direct debit used to be £170 per month, which, on our current tariff (20p/kWh) equates to about 850kWh.


   
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(@batalto)
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@peterr you need to consider its November. This month should be approximately 12% of your total heating bill. Given there are 12 months (8% a month) this month should be roughly 1.5x in cost your normal Direct Debit. Your costs in the summer months will be far far lower so you save up the cash buffer for these months.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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(@derek-m)
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@peterr 

Hi Peter,

If my maths are correct, in November you are averaging approximately 20kWh per day to run your ASHP and about 10kWh for everything else. Comparing the size of your home to others, this does not seem too excessive, It averages less than 1kWh per hour.

As Batalto pointed out, November is an higher than average usage month.

Once you get your energy readings corrected, you should then be able to better monitor your usage, and possibly optimise your system.

I would suggest that you unplug the tumble drier and buy your wife a washing line for Christmas. 😋 

 


   
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(@peterr)
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Topic starter  
Posted by: @batalto

@peterr you need to consider its November. This month should be approximately 12% of your total heating bill. Given there are 12 months (8% a month) this month should be roughly 1.5x in cost your normal Direct Debit. Your costs in the summer months will be far far lower so you save up the cash buffer for these months.

Yes, that is true, and when I think rationally the numbers are less scary - I just need to get into the mindset that they represent our entire energy costs, and we're saving a huge chunk on LPG.  Not to mention the RHI will kick in in January 😀 


   
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(@peterr)
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Posted by: @derek-m

I would suggest that you unplug the tumble drier and buy your wife a washing line for Christmas. 😋 

 

You haven't met my wife - that would not be a popular suggestion 🤣 


   
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 RV3
(@rv3)
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@peterr @kev-m just to contribute as a fellow 14kw ecodan user here are my figures for the same period 1-18th Nov. 533kwh heating, 88kwh hot water.

IMG 3368
IMG 3367

(Sorry those graphs look small not sure if they'll be a bit bigger when the post goes up, also it is the consumed energy pls ignore misleading title at bottom of page that's for another graph on melcloud)

 

@peterr we also switched from lpg, our installer also used a Telford tank we also have uponor ufh so some more similarities there.

Our room temp sensor actually in loft as installer said system set to just be dictated to by room thermostats - when they call for heat that's what triggers the ashp so they said it served no use in a room and just put it in the loft.

Energy usage pretty high as previously discussed, certainly compared to some others on here. 224 sq metres bungalow with average insulation but nothing that can easily improve now we've done what we could. Not had chance to have a dabble with the weather comp curve stuff yet. Lots of stuff on the forum to think about - will start to have a tinker.

Main objectives for us are much more basic compared to a lot of the much mor esavvy contributors on here. At the moment our concerns are a) will the ASHP keep us warm enough when temp drops - it's gone pretty cold here in North East last few days but so far seems to be ok b) will it be cheaper or at least no more than LPG which was our previous and c) after that can I get costs down as low as possible / things working at best efficiency.

Interested but also fairly boggled by some of stuff on the forum.

Interested that my COP seems to stay pretty much 2.6-ish throughout both milder periods and in this little cold snap - had thought it would reduce when temps dropped. Astonished to see cops of over 5 being reported elsewhere - though that does seem to be an outlier with most reporting 2.5 to about 3.5 I think? Seems to fall short of manufacturer claims but the forum had warned this would be the case remember an article by Mars on that.

As always thanks to all for various comments and advice in the different threads. Helpful stuff. 

 

 

 

 

 

 

 

 


   
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(@derek-m)
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@rv3 

Hi RV3,

I think that it should be possible for you to get better efficiency, lower energy consumption and a higher COP, if you optimise your system to operate on weather compensation. Do you know how your system is being controlled at the moment? If you can post a closeup photo of your FTC controller, that will probably provide the information>


   
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 RV3
(@rv3)
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Posts: 40
 

@derek-m

IMG 3375

 Hi Derek - happy birthday and is this the RTC? 

 

As always thanks for any help.


   
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(@derek-m)
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@rv3 

Hi RV3,

Thank you for the birthday wishes.

Yes, that is your FTC controller. It would appear to be set for room temperature control rather than weather compensation. Should you wish to change to weather compensation, I can guide you through the process, or you can ask one of the Ecodan owners on the forum, or you can watch the numerous YouTube videos that are available. Please let me know what you decide.


   
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