Ecodan ASHP Help...BILLS!!!

sunnychad

Hi All,

I have recently moved into a newly built house. 5 bedrooms and quite spacious. The developer has specified a Mitsi Ecodan HW140 single phase unit for the house. It has been coupled with a Manco cylinder, underfloor heating with stats in each room, rads upstairs with a central stat, hot water runs for 1.5 hours a day and 300 mm insulation in the walls and loft.

Apparently it is very well insulated and ticks all the boxes. Lighting is mainly energy savers and there are low voltage spots in bathrooms, kitchen, master bedroom and hall, though in the bedroom and hall we use energy saver lamps. Immersion heater for legionella runs daily for 1 hour (I might run this once a week for 30 mins from now on)

Meter read on completion 5 March 2010 - 5647 (we moved in on 11 March 2010)
Meter read on 20 March 2010 - 6706 (it had been left on boost by installer!!!)
Meter read on 17 April 2010 - 7810

All in all we are using about 40 kwh a day now. When I speak to electricity company they say it is ridiculously high. Settings are as per Mitsi reccommendations so any ideas, feedback and suggestions will be highly appreciated.

Cardew

40kWh a day(say £4) for a spacious 5 bed house for all electricity, including heating and hot water is not particularly high, let alone ridiculously high, at this time of year.

albyota

£4 per Day.....????!!!

Report back if it really becomes ridiculously high, also report back when it is unbelievably LOW......like it will be!!! as mine is!!

Underfloor heating has to be run correctly....with night set back controls, you don't control it like a normal system.

sunnychad

Thanks for the reply. As gas consumption will be really low (hob only) the overall bill will probably similar to my 7 old 3 bed flat where I spent approx £1260 Jan 09-10 on gas an electric combined (stupidly I didnt do direct debit and all the other discounts). I felt £4 a day for ALL my energy needs fairly reasonable just the guys at Eon were super bemused. Have applied to move to NPower as of this AM and they understood the setup real well!!!

sunnychad

@albyota - So that are the best ways to set up the system? The installer hasn't given me much info sadly. Look forward to your experienced opinion.

Thanks

albyota

Unfortunately, on new builds there is not the time or inclination for an engineer to set up the whole system correctly, (also being difficult in an empty dwelling) i.e. balancing the systems radiators and setting the blending valve and flow rate of the UFH. I suppose it will be down to you to get all this optimised. Correctly setting the radiators TRV's is an important factor and when set must be left alone. As for the hot water, the setting of one hour per day for thermal disinfection can be changed to once per week but MUST be for at least an hour, or for such a length of time to enable the cylinder to get to 65 degrees, usually this is done by our engineers and set to operate directly after the heat pump has lifted the water to 55 degrees, therfore only requiring the element to further heat another 10 degrees and should cost between 14 -18 pence to do that.

My total fuel bill for a large well insulated four bedroom house with UFH similar to yours, has cost £840 for Jan 09 - Dec 09.

HeatSpecific_Ltd

Greetings

I new here but just thought i would add something to the topic.

I installed a 8.5kw Ecodan unit in February and on average it has been costing on average £1.50 to £2.50 a day for heating and hot water.

It is in a 4 bed bungalow(1970 built) with K2 radiators (11 Rads), bathroom with underfloor and a 210L water cylinder. So far we are very happy with how the unit is performing. Hot water is programmed to come on at night during off peak electricty. Heating is on a main room stat and eco setting within the FTC Unit.

With spring around the corner our 3m2 solar thermal is now satisfying most of the hot water demand, with a little boost fromthe heat pump. So far our old oil boiler has not been used since the addition of the heat pump.

The difference in running costs maybe to do with the Power Input (kW) an 8.5kW unit draws 2.88kW on start up, a 14kW unit draws 5.21kW. So at 12p kwhr that will be costing 60p an hour to run where as the smaller unit will be 34p. We have a energy monitor on the heat pump so we know exactly what it is using, perhaps you should consider that too.

If anyone has any questions i would be happy to answer them..

G

paceinternet

How many hours a day have you been using it, as those costs do not indicate many hours running?
And can you justify using an E7 tariff, or do you have a lot of other electrical use during the E7 period?
Thanks

Cardew

HeatSpecific_Ltd wrote: »

Greetings

The difference in running costs maybe to do with the Power Input (kW) an 8.5kW unit draws 2.88kW on start up, a 14kW unit draws 5.21kW. So at 12p kwhr that will be costing 60p an hour to run where as the smaller unit will be 34p. We have a energy monitor on the heat pump so we know exactly what it is using, perhaps you should consider that too.

Those figures are straight from the tech spec of the Ecodan and only apply to one set of conditions(A2/W35) with water at 30C inlet 35C outlet with the outside temp at 1C(humid) or 2C(Dry)

How will you cope with 35C water in existing K2 radiators in winter in a 1970s bungalow?

It is interesting to note that under those conditions the COP for the 8.5kW model is higher at 2.95 than the 14kW model at 2.69 - not very impressive for a temperature above freezing??.

At the other quoted set of conditions(A7/35) - same water temp at 35C - but outside temp of 7C or 6C the 14kW model has a considerably better COP of 4.19 to 3.85.

I wonder what the COP would be with water at 45C or 50C which surely must be the minimum in winter?

paceinternet

From the other thread:

Ambient air degC, COP @ water in 30 out 35, COP @ water in 40 out 45, COP @ water in 50 out 55
-15, 1.77,1.41, ?
-10, ?, ?, 1.37
-7, 2.41,1.89,1.46
2, 2.97, 2.27, 1.81
7, 3.96, 3.05, 2.28