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UPDATED: Air Source Heat Pumps/Air Con - Full Info & Guide, is it cheaper to run than mains gas?

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Comments

  • Thanks Albyota

    I did speak to my installer a while ago regarding the once a week water heating to 65 degrees. I asked if this was something I could change the time of (to come on straight after the water has heated once a week). I was told it was set by the Installers so I didnt pursue it. Would it be more efficient if it was changed?

    There was originally four adults living in our house but now there is only two of us:) (my daughter used to run the shower whilst she got a towel ready, undressed, brushed her teeth, decided what to wear ETC, ETC), so I suppose I am surprised that the heatpump now needs to stay on for the full hour and a half every day when we are using a lot less hot water. In fact my direct debit for Anglian Water has just been reduced to £9.00 a month!!! from £17.00 :j
  • Is your water hot?
    My EcoDans came with DHW cylinders that were supposed to be correct for the units. I was having a similar scenario as you where the ASHP was on for much longer than expected heating them up.
    Long story short is that the cylinder does not meet the spec of Mitsubishi and is not correct for my units.
    Mitsi say for the 14kw unit (mine) that the DHW cylinder coil should have a surface area of 3.0sqm, the ones in my cylinders have a surface area of 0.75sqm. Therefore the ASHP has to run longer to transfer the same amount of heat to the water.

    It may be worth pulling your documents and looking at the spec of your DHW tank.....
    [FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad][FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad]PUHZ-W50VHA - 2sqm - copper[/FONT][/FONT]
    [FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad][FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad]PUHZ-W85VHA - 3sqm - copper[/FONT][/FONT]
    [FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad][FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad]PUHZ-HW140VHA - 3sqm - copper[/FONT][/FONT]
    A pair of 14kw Ecodans & 39 radiators in a big old farm house in the frozen north :cool:
  • albyota
    albyota Posts: 1,106 Forumite
    Yes, mumu29, the times can be changed to suit your lifestyle, you only need heat the amount of water you actually need, in most cases, a hot water cylinder will hold its heat for a good 20 hours, (if not used) so monitor your usage and adjust the timing to suit, this can be done on the programmer. I too have the Ecodan and Solar PV (3kWp) too, so I'd doing the same, heating the hot water during peak times, however I have an extra little gadget (home made) that only allows the heat pump to run if the Solar panels are generating more than say 1kW.
    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!
  • albyota
    albyota Posts: 1,106 Forumite
    TiredGeek wrote: »
    Is your water hot?
    My EcoDans came with DHW cylinders that were supposed to be correct for the units. I was having a similar scenario as you where the ASHP was on for much longer than expected heating them up.
    Long story short is that the cylinder does not meet the spec of Mitsubishi and is not correct for my units.
    Mitsi say for the 14kw unit (mine) that the DHW cylinder coil should have a surface area of 3.0sqm, the ones in my cylinders have a surface area of 0.75sqm. Therefore the ASHP has to run longer to transfer the same amount of heat to the water.

    It may be worth pulling your documents and looking at the spec of your DHW tank.....
    [FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad][FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad]PUHZ-W50VHA - 2sqm - copper[/FONT][/FONT]
    [FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad][FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad]PUHZ-W85VHA - 3sqm - copper[/FONT][/FONT]

    [FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad][FONT=FGYRJ T+ Myriad,FGYRJ T+ Myriad]PUHZ-HW140VHA - 3sqm - copper[/FONT][/FONT]

    TiredGeek, did the systems come direct from Mitsubishi, I suspect not....your installer probably had no idea what tanks to get. Call Mitsubishi, get them replaced, if you need some contacts let me know.
    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!
  • mumu29
    mumu29 Posts: 9 Forumite
    edited 3 September 2011 at 10:06PM
    TiredGeek, I have looked at my paperwork and it says:
    One PUHZ-W8.5VHA2-BS c/w One pre-plumbed M/E-180CP. (McDonald Engineers Powerflow 2000) Yes the water is very very hot.

    Just a thought, even though we are using less hot water, the cylinder is bigger than the old one so I assume it will take longer to heat as there is more water in it.
  • albyota
    albyota Posts: 1,106 Forumite
    edited 3 September 2011 at 10:30PM
    The PowerFlow 2000 is a very good cylinder and if your system was installed by a Mitsi AEI installer, it should be the right one,

    From McDonald Eng' website....


    Renewable ENERGY
    HotWaterCylinders

    [FONT=DIN,DIN][FONT=DIN,DIN]As well as being one of the [/FONT][/FONT]U[FONT=DIN,DIN][FONT=DIN,DIN]K’s leading manufacturers of hot water cylinders since 1945, McDonald Engineers has been at the forefront of developing cylinders designed to harness renewable energy since the early 1970s. [/FONT]
    [FONT=DIN,DIN]Working initially with solar energy, we have continued to remain one step ahead by anticipating the developments of the energy market and have focused on optimising the heat transfer process for maximum efficiency. [/FONT]
    [/FONT]
    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!
  • albyota
    albyota Posts: 1,106 Forumite
    mumu29 wrote: »
    Just a thought, even though we are using less hot water, the cylinder is bigger than the old one so I assume it will take longer to heat as there is more water in it.

    No, not necessarily, the reason the tank is bigger is that there is a longer coil in the tank, 3m2 surface area, about 15 metres long, so to still get 180 Litre capacity, the tank needs to be taller.

    You could try reducing the time to 1 hour, or even 45 minutes, see if that suits.

    however, when winter comes you will need to put it back to early morning or late at night so as not to interupt its heating cycles, plus, in colder weather, its likely it will need longer, so 1 to 1 &1/2 hours.
    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!
  • Ally74
    Ally74 Posts: 101 Forumite
    I'm wondering if i've had the right cylinder installed? A sticker on it says the following

    Grade 3

    900x450mm

    Capacity; 117Litres - seems a bit small for a 3 bedroom flat in a block of four. 2 adults 2 children in the house.

    Max Working head: 10 metres
    Max Length of immersion heater 700mm
    side entry when applicable 400mm
    surface area of heat pump coil 3.0M2
    Max working pressure of coil 6.0 bar
    35mm foam lagged.

    To heat it from cold from the immersion heater takes a few hours which i'm surprised about considering it's size. I'd say the heat pump takes about 45mins to heat it to 58 degrees.
  • albyota
    albyota Posts: 1,106 Forumite
    Ally74 wrote: »
    I'm wondering if i've had the right cylinder installed? A sticker on it says the following

    Grade 3

    900x450mm

    Capacity; 117Litres - seems a bit small for a 3 bedroom flat in a block of four. 2 adults 2 children in the house.

    Max Working head: 10 metres
    Max Length of immersion heater 700mm
    side entry when applicable 400mm
    surface area of heat pump coil 3.0M2
    Max working pressure of coil 6.0 bar
    35mm foam lagged.

    To heat it from cold from the immersion heater takes a few hours which i'm surprised about considering it's size. I'd say the heat pump takes about 45mins to heat it to 58 degrees.

    Yes Ally, that cylinder is OK.
    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!
  • albyota
    albyota Posts: 1,106 Forumite
    jeepjunkie wrote: »
    To Albyota,

    Despite our EcoDan being cheap to run the wife is keen on being self sufficient energy wise either by solar pv or from our river.

    Say the heat pump is 14kw and the solar pv is 3kw, how does that work?

    Personally I'm not that fussed as our bills are low but if I don't look into it I'll be sent to the naughty step ;) I'd be happy just having a bodge with some solar/river generated outdoor lighting... Though in saying that I think most folk do for the fits return not the small power saving?

    Cheers

    Hi jeepjunkie, anything you can do to reduce running costs / CO2 emmissions all helps, when your heat pump is running, it is pulling power from the grid, if you have solar PV, you can time / control the heat pump to run at such times when the PV is generating at a high rate, then the heat pump would pull say......one or two or three kW (depending on the size of the system) from the panels and the rest from the grid, you are always reliant on the weather, so if you set the heat pump to come on for an hour or so at between 11am and 3pm (say...to heat a tank of water) and pulls 3 to 4kW from the grid and its a cloudy day then you'll get next to nothing from the panels, however, on a bright day, the panels would provide most of the power while using very little from the grid.
    Alternatively, you can get a small solar panel set up from maplins to run some outside LED type lights. If the river is fast flowing, you could try a hydro generator and run it through a PSW inverter for your lighting.
    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!
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