Heat Pump Running Costs

graememk

https://www.boards.ie/discussion/comment/121504597#Comment_121504597

You need to divide by 2 to get kwh

ColemanY2K

https://www.boards.ie/discussion/comment/121504637#Comment_121504637

Brilliant, thanks for confirming.

staples7

here you go,

https://www.boards.ie/discussion/comment/121498494#Comment_121498494

SharkMX

https://www.boards.ie/discussion/comment/121502744#Comment_121502744

Well we are thinking of a heat pump as others might be in the thread, so just trying to add some current comparison to current heat pump running costs.

By the way still havent had to turn on the heating on since i posted that.

So I would be interested in the cost of running a heat pump the last two weeks so i can compare it to the cost of oil.

TimHorton

https://www.boards.ie/discussion/comment/121510502#Comment_121510502

What temp are your bedrooms at night? No heat source is not sustainable if you want rooms to be 19/20 Degrees in December,

SharkMX

https://www.boards.ie/discussion/comment/121510573#Comment_121510573

18 - 19. Havent seen them go below 18 the last few weeks. Its been very mild. Its actually 21 right now in the room im working in and thats probably just from me and my PC. Ive spoken to a few people. The odd person has their heat on for an hour in the morning these days but a good few dont need it on at all. Even today, no sun and the bedrooms are still 18 and 19. I just checked now.

Even the EV is doing summer mileage the last couple of weeks. Nice change from the icy week we had before that.

DC999

https://www.boards.ie/discussion/comment/121510502#Comment_121510502

 

Real world data, go here and you can see installs by location. UK, but weather will be similar and can go further north to get a colder example: HeatpumpMonitor.org

Click into the 'summary' on the right, and can then click on ‘Open Emoncms Heat Pump Dashboard’ on top right to get more detailed data. And can then get a 3 month view showing data energy usage, daily temp, COP….

If you want to dive more into it, look at the Glyn Hudson punter. He’s brill. Has 2 self install videos on YouTube for his own (Samsung) and more recently his parents (Vaillant). His house is small but old and not insulated or airtight. In his home he's running 30C flow temp but he’s added 3 rads in the sitting room to produce the heat (which won’t work for most people of course). But he’s into a very good COP so willing to trade space in the house (in extra rads) for that. His folks are older with a larger home so you'd expect it's running a higher temp so using more energy than his home. either home have UFH. Glyn Hudson - YouTube. One of his vids covers stats on the winter just gone (which had the long cold snap in Dec). Playlist: Heat Pump - YouTube

graememk

https://www.boards.ie/discussion/comment/121510502#Comment_121510502

Every house is different and every person is different too. Some keep a house at 20c, others 18c some like 22!

If you could put a meter on your oil tank, and you'll see how much you use day/week/month

Do you have an old boiler or a new (possibly condensing one, but return temps need to be lowish to actually condense)?

There's 10kwh of heat in a litre of oil, and it's depends on your boiler if your getting 60% or 90+% efficiency!

If your thinking heatpump, that will give you an idea of how much heat energy you will need.

Eleusis

https://www.boards.ie/discussion/comment/121510502#Comment_121510502

Yes it's milder than normal but I'm still surprised you at zero heating. It has still been sub 10 degrees for long periods. For you to not need heat at all your house must be passive or have an alternative heat source. Certainly not enough solar gain this weather. Is it detached? Do you have a stove? Simply HAS to be an alternative heat source your not mentioning. Surly science means this is the case.

Maybe I'm wrong but I honestly don't think we are getting the full context of your set up, which I don't think is helpful in this thread.

graememk

Running some numbers myself.

I'm able to run my heatpump all from batteries. So on load shifted night rate.

I measure about a 20% round trip loss though the batteries. My Night rate inc vat is 14.75c, which makes anything used from batteries cost 17.70c .

For me, cost wise per kwh of heat, is a COP of 4.0 on batteries is the same as a COP of 3.4 on night rate directly. Or a COP of 2.5 on NR is the same as a COP of 3 on batteries.

Night Rate vs Day rate (33.38) costs NR Cop of 2.5 is the same as getting a COP of 5.6 on Day rate.

What I've gathered from this little exercise,

If you can set a schedule for your DHW and depending on how big your tank is, Possibly make sure it runs early in the morning. - even though automation you could even set a higher temperature vs during the day.

for central heating, maybe set a higher than normal temperature in the early morning in the living areas and then setback to a lower temperature until the evening. UFH holds heat for a long time, radiators not so much!

staples7

https://www.boards.ie/discussion/comment/121511618#Comment_121511618

I’m on the same plan as yourself, but not sure in winter months that you could run entire house inc heat pump on batteries. What size battery setup? I would want 20/25kw to achieve that. Not counting Sub zero temps

graememk

https://www.boards.ie/discussion/comment/121512584#Comment_121512584

40! well about 33ish useable.

House and farmyard, Barley crusher can eat the power too. If I'm running short on battery, I can light a fire.

staples7

https://www.boards.ie/discussion/comment/121512640#Comment_121512640

ah nice, DIY or off the shelf? Have TAMS in at the moment for 50 panels any advice greatly appreciated.

graememk

https://www.boards.ie/discussion/comment/121513086#Comment_121513086

DIY battery, cost about 5k,

house/yard is the one connection. We just went the domestic grant as it was a lot simpler.

When I was doing it 3 yes ago, the higher tams wasnt there, and it wasn't worth the bother. Possibly could have cost me more. Drystock so farm use isn't huge.

dbas

https://www.boards.ie/discussion/comment/121507728#Comment_121507728

Hi there,

Cool graph. Would you mind explaining it to me please.

Hot water load looks consistent over the year, which makes sense as we generally use same amounts of water over the year, but the COP of the heat pump will change according to outside temperature- more efficient on hot days. I would have expected more of a drop off in energy for hot water generation in summer compared to winter, due to the cop increasing

ColemanY2K

new build house. the heat pump has been up and running since 11am last friday. the data pulled off from esbn website is interesting which i've manipulated (into a very rough and ready excel sheet) to work out the units the house has used and corresponding cost. its early days yet with sundays figures in particular skewed by the fact we had a 2.5kW electric heater running for several hours.

looking at friday and saturdays data i estimate the heat pump is using somewhere around 25kWh each day getting the house up to temperature (21C). annoyingly esbn data for yesterday is yet to be made available which was when the house hit 20C.

The screen on the heat pump only gives you the number of hours it has been running (heat & hot water). yesterday i was youtubing shelly EM and reckon i will look to buy one of these to monitor the HP.

i am curious to see how this weeks data (monday to friday) compares to next week as the first 200mm layer of mineral wool insulation will be fitted between the joists at the weekend. this should have a significant effect on the HP and would i imagine significantly lower next weeks daily kWh figure.

Eleusis

https://www.boards.ie/discussion/comment/121513738#Comment_121513738

When heat pumps are turned on for the first time and it's during winter they will use alot at first to get the fabric of the building up to temps. After that they take much less to keep it there. Especially if you have good insulation.

2nd week should have more accurate results. Doesn't your heat pump and in a built in energy monitor?

ColemanY2K

https://www.boards.ie/discussion/comment/121515762#Comment_121515762

The built in energy monitor appears to be a web based accessory. I might pay for it to unlock the feature.

Although having said that I prefer what a Shelly EM combined with Home Assistant can do.

riccol1966

Daikin 11Kw installed in Sep 2023, 230L DHW tank, on radiators only, no underfloor. House is 23years old but insulated quite well. Heat pump commissioned late Oct 2023, so I wanted to wait until a complete month before posting. I was talking to someone about their Daikin heat pump stats and they didn't believe the energy figures on their heat pump, as their actual energy bills were significantly higher than expected. When I compared mine I agree: the energy figs shown on my heat pump display are a lot lower than what my Shelly clamps are recording. I trust the Shellys. I have 2 clamps, one on the main heat pump MCB and the other on the backup heat pump MCB. The backup heater is used in very cold temps and I can see it being used for the weekly legionella disinfection. In Home Assistant I combine these two into 1 figure. I also changed the DHW setting on the heat pump from "Schedule+Reheat" to "Schedule Only", as I was finding it annoying to lose temp in the rads just because someone has taken a shower. Heat pumps are not great at double jobbing, its either DHW or Heat! I time the DHW main heatup overnight on cheap rate and then boost it for 1.5hrs at midday. Still tweaking and testing.. Debating whether to leave HP on all day or to continue with times slot operation.. that's another story.

Here's the HA Energy tab for Nov:

So 394 / 30 = 13Kwh per day, €4.27 per day. Before I moved to a heat pump I was on oil, and I estimated, based on cost of oil fills per year, that if I was under €5 per day on a heat pump I would be more or less saving a little. Buy it's early days. And of course we are at a wierd time in terms of electricity prices, so I expect that to normalise somewhat next year (hopefully!).

DC999

https://www.boards.ie/discussion/comment/121517460#Comment_121517460

Good details and helpful, ta

Latro

The heat pump only registers energy consumed by the compressor. It does not account for electricity used for fan, water pump and electronics.

It is intended design, to fairly compare this energy source to other. Oil, coal, pellet etc. These do not account for electricity used for fans, pumps and electronics either.

getoutadodge

https://www.boards.ie/discussion/comment/121517460#Comment_121517460

Thanks for this. Fiver per day...so 180 Per month. Seems high. How well insulated is your house (BER rating) and what size it in m2.. if u don't mind me asking.

riccol1966

https://www.boards.ie/discussion/comment/121525370#Comment_121525370

Well it's €128 for Nov, could be that I'm tinkering a bit too much with it.. Anyway house is quite well insulated, 180m2, split level, brick and block with cavity bead insulation, passive ventilation, 35mm insulated plasterboard on all external walls, extra 55mm insulated plasterboard added to ceilings, 300mm fibreglass + extra 150mm rockwool in attic. Internorm triple glazed windows and doors. Heating by radiators only. Current BER is B2, before heat pump and PV have been assessed, so I expect it to be A when new BER is issued. I think I have insulated as much as possible, with the exception of the floor which would be of standard insulation used when built. Don't want to take up all the wooden floors, I think that's a step too far for a limited gain. A few rads were changed out for the heat pump to make them larger. Considering MHRV as a future option. I've been very careful to identify all air gaps etc and seal up. Although I have passive vents the vents are "smart" : I have a HA routine to open and close them i.e. upstairs vents will close in daytime as bedrooms are unoccupied, and downstairs vents will close at nighttime. I have a wind monitor which triggers all vents to close when windspeed goes over 26KPH, which is great as it stops the heat escaping when the wind is strong. Open to suggestions as to how heat pump costs can be lowered. As I mentioned I'm wondering if moving to "all day" heat would be better than the on-off timed heat.

jasgrif11

What vents are you using that have HA integration capability?

riccol1966

The vents are Econet controls EV-100 vents, they are Z-wave but I don't think they're available anymore. I had these years ago, before HA became popular. So last year I integrated them into HA using a Z-wave stick. They are originally intended as hot air vent controllers for US houses with ducting to deliver heat to rooms, and I thought they'd make a good substitute for the standard plastic air vent covers we have in Irish homes.

getoutadodge

https://www.boards.ie/discussion/comment/121529203#Comment_121529203

Thanks for this. So an A2 house of 180m. Considering moving to a new build to get the A rating. 120 plus per month in Nov? Let's say a thousand per annum for electricity. Maybe the hoped for savings are not so great after all? Not sure what I was hoping for. I thought maybe 600 euro all in for the year for a 120 m house. The again currently I use gas for hot water only (no heating) and that alone costs circa 600 per annum.

Eleusis

https://www.boards.ie/discussion/comment/121532715#Comment_121532715

I don't think you should guestimate a years heating to be €1000 from one month measured in Nov. There is plenty better info on this thread if you read back. I have a 220m2 house A3 and I used 1150 units (heating only) in a year which is approx €350

Every house is different and personally I don't think BER is very accurate. I'd put more emphasis on actual build quality/design and attention to detail when insulating. BER doesn't measure this.

Also airtightness in combination with heat recovery ventilation makes a massive difference to actual heat retention but makes little difference to BER rating.

graememk

https://www.boards.ie/discussion/comment/121534166#Comment_121534166

Even having a heatpump or not greatly skews the BER, solar can do it too.

Talking the default basic value for a heatpump gives a 2.5x efficiency (reduces the energy requirement of the house, increasing the ber rating) Vs the same house having a condensing boiler has only like a 0.9x efficiency (it's in the DEAP manual)

Heating is the biggest end of the energy requirement of a house.

riccol1966

Yeah the BER for anyone retrofitting is just a tick in the box really, it's no indication of how much energy a house will use. No BER assessor is going to wait for a windy day, then get down on their knees and check for air ingress at your house. Homeowners know their houses best. If I were to rebuild the house and do underfloor and MHRV and pay attention to building design and fabric from the start I would be fairly sure to have some really low running costs. Other might be lucky and still get very low running costs when retrofitting. But we wanted to move away from oil, do our bit etc. And we've spent a pretty penny getting to this point. I do wonder whether the heat pump will last as long as the old oil boiler which we had for 22yrs, considering the base cost of a heat pump is say, 3-4 times that of an oil boiler. Will I regret it.. hard to say.

dominatinMC

Just reviewed the performance of my heat pump last year. I live in a 5 bed dormer, 245m2 approx. with one large open plan area utilising UFH and the rest of the house served by rads. I used 3718 kWh, or 15kWh/m2, last year in total. On the face of it, I'm happy enough with that figure, but would be interested to hear from others on their annual performance. TIA