Heat Pump Running Costs

are they part of the rads or are added seperately?

An overview of my own homes performance for 2025.

(These €€ figures include all Standing Charges & PSO Levies)

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Personal Insights:

Air2Water System - Mitsubishi Ecodan R32 6KW

• Heating
  • Home temperature set to 20.5°C for upstairs and downstairs all year round.
  • April - September no home heating is produced by the system due to good home insulation levels & mild outside temperatures.
    • For anyone with a Mitsubishi Ecodan system please note it has a known flaw of over-reporting kWh consumed for heating particularly during summer months due to rounding errors in the systems standby power measurement within its own reporting interface. This issue mostly relates to days where no heating power has been called for by the system. E.g during summer it often reports 2 kWh daily heating consumed when in reality it has only used roughly 500 watts for standby power and no heating had been requested or produced by the system. (Not including hot water heating which is measured separately).

• Hot Water
  • Heated to 52°C most nights.
  • Runs during EV rate window - Averages 1.5 kWh per run.
  • 2 showers taken in the household per day on average.
    • The water cylinder is located in the utility room in the middle of the house so minimal heat loss throughout the day.
    • Having tested the water cylinders heat retention performance - if no showers have been taken on the first day then the tank retains enough hot water for a shower 48 hours after that heating cycle has taken place and as such I have automated the system to not reheat the water cylinder unless it has dropped below a 44°C threshold before the next scheduled heating cycle reducing unnecessary power consumption when enough hot water is available for the next day’s use.

Air2Water Power Consumption & Delivery for 2025:

*Excluding standby power for months with no heating requirements.

Appliances/Devices

• Dishwasher
  • Runs on average 4 times weekly.
  • Run during EV rate window - Average 1 kWh per run.
• Dehumidifier
  • Runs for 6 hours during night & EV rate window - Average 1.2 kWh per run (Only recently purchased)
• Home Server
  • Runs 24/7
• Boiling Water Tap
  • Runs 24/7

Device Power Consumption:

(Smart plugs have been placed on larger devices to understand power consumption over 12 months)

Always On Devices:

• American style fridge/freezer
• Boiling water tap
• Home server
• Raspberry Pi (mini computer)
• Modem, router, fibre ONT & WiFi mesh plug
• 20 Smart lights
• 4 Alexa speakers
• 2 Air purifiers (small)
• 4 Smoke alarms (wired)
• 6 Room thermostats (wired)
• Video doorbell

Home Electrical Base Load: 300 Watts (average)

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Thats nothing too mad…if thats for two months then that ok really…the main thing with HPs is just keep an eye on them I check my graphs once a day almost during the winter. (checking to see when and how long durng the day it was on for) The last thing you want to find out is its being running flat out for 2 or 3 weeks because one of the kids decided to set the room temp to 25degs…

I sometimes myself forget that its actually winter and thats what happens in winter the heating needs to come on so your bills are going to be higher. If you have a smart meter schedule your DHW to one of those "EV" rates 2am to 5am also pump up the heating at this time also to build up thermal mass in the house (I know you have rads so a bit harder to do) but these super cheap rates are ideal for HPs

I think the ev rates can be good but I think it depends on circumstances. Solar and batteries are a must unless you have an ev I guess maybe then it still makes since but would need to look at the numbers. Even with solar and batteries energypal has the ev windows down the list for me and still had day/night/peak being the best fit though as I’ve said on another thread it’s not a great year to judge only having lived in the house 4 months but having base load only and solar exporting like crazy all summer.

I think one most suitable one with an ev window is the night boost from electric Ireland as it’s still got a good night rate too but the standing change plus no switching bonus puts it at about 120 euro higher before 1kwh is used. My gut feeling is over a year I will make that back and more by shifting a lot of what I do at random in night rate to this window but even moving numbers a bit in energypal it’s still giving me the electric Ireland day/night/peak with the low standing charge as the best fit though I’m inclined to go for the flogs day/night/peak which as a lower night rate and a higher standing charge but I think one that can be overcome and bettered with their lower rate. Need to think more on it between the flo gas and electric Ireland.

The ev windows just seem too short, in 3 hours I would maybe get to 70% on my batteries but at 100% I can just above get from 8am to 11pm on some days in winter. I would end up using a lot of expensive day rate I feel with an ev rate, having an ev of course changes that too as an ev window is more beneficial then to overall but you are fighting your max draw from the grid then trying to so everything in that window.

That's insane, my bedrooms are 19 and I would have them lower only for herself. But each to their own.

Thanks a million.

I wonder if/when the V2H or V2G will become commonplace. The theory is that rather than buy a battery you charge your EV using the night rate and then use the car to power the house during the day, so that your Heat Pump running costs, and other electricity costs reduce. I know there's a whole load of questions that this raises such as a) new EV birdirectional chargers b) cars needs appropriate logic c) cable sizes from charger to fuseboard may need increasing d) reliability / feasibility of constantly using the car inverter e) managing the EV range. With this concept you would make your car with its 125Kwh battery "work" for you rather than sitting idle outside when you're not driving it. Just some thoughts… I'd really like to pay less for running my heat pump.

Yeah agreed battery prices are reducing and not only that in time they'll become much smaller and more compact whilst giving the same or greater Kw output, but it seems a little daft to have one large battery doing nothing for most of the day the car is at home (for those to whom this applies) and then you create another battery pack inside your home! I do like the concept of V2H and it would also mean you have backup power etc to manage electricity outages.

Very interesting, while googling this I also found out about this home energy loan scheme which i had not come across before

https://sbci.gov.ie/products/home-energy-upgrade-loan-scheme