Air to water Electricity consumption

Robert Allen

Hello all, I'm having concerns with my Air to water heat pump and looking for advice or opinions before I ring the installer.

I know the Consumption of electricity is going to be high anyway during winter but for the past few weeks our 24hour usage of electricity and heat combined has been in the 40 - 44kw range. It usually is in the 30kwh range.

It seems the Daikin heat pump is using a lot of this perhaps through the defrost cycle. For example, The defrost cycle this morning started at 7ish and ended about 11. It defrosted every 40minutes during these hours and used about 3kwh for every hour - 12kwh for the 4 hours approx.

The heat pump generally does use a lot of energy when it is heating the UFH - which is not very often as the rooms stay around 19 - 21 degrees usually and most stats are set around the 20 degrees. Consumption of / heating hot water doesnt seem a concern as we use very little.

When the ATW sends heat to the Ufh the usage increases about 3kwh. When ufh is not calling for heat the usage for the house drops to 1kwh every hour / couple of hours.

It doesn't seem to be a problem with another appliance or lights eating up electricity as usage spikes when heat is on only. On Friday Dec 18 the combined usage for 24hours was 14kwh - as the weather was slightly warmer that day so the ATW unit wasn't on.

The unit is on a new house, installed 2 years, it is using more than it was last year, it was serviced 2 times / I asked installers to fix noise issues and to put on the quiet mode as the unit is bolted to the wall so the noise is travelling through the cavity and walls.

Insulation wise the house is ok - rooms rarely need heat, when they do they get to desired temp in 1 - 2 hours, and retain the heat for the remainder of the day.

I would like opinions on this as the installers seem secretive when I ask them about it - like I'm being an inconvenience or something. They have the control panel settings locked so I can't view the settings myself. Different workers from the company looked at the machine and ufh set up at different times and they were contradicting each other and complaining the unit wasn't set up right etc etc so it's a bit messy.

I just feel they wont be honest if I ring them about this. I feel like they don't want any issues warranty wise etc so will just say it was set up correctly etc.

Any opinions on how normal or not this ATW / UFH system seems to be in terms of performance would help me greatly. I'm the type of guy who likes to have some info about the system but I was given none to begin with and the Installers wouldnt be overly helpful.

Sorry for the long message - I just don't know anybody personally who can give me an opinion on this and I don't know anyone with a similar set up for comparison.

Thanks lads.

Tefral

Its cold out there it currently -1 degrees C outside and has been over night. Due to the cold your HP should be running continuously for the last week. My own it has not stopped once in that time.


Heres an example:

Calls have started coming in like they do every year. Why is my heat pump costing so much?, im using 55kWhrs of electricity a day at 16c a unit that's €8.80 a day, if I multiply that by 365 days that's €3212 a year. My gas boiler was only €120 a month.

Lets get a few points out of the way, you pay for your energy by direct debit, more in the winter and less during the summer. Alot of companies now allow you to pay an average to cancel or lessen the impact over the winter months.

If you were to average (per month) my consumption over the year, it is up and down every year with the seasons. No one ever rings in July to say " Im saving a fortune, the boiler used to cost €120 a month its now only using 5 units a day which is 75c a day, bargain".

But it gets more complicated than that, your reading is an average over the month, it doesn't show you the peak value per day. Looking at my graph above I should be using 25 units a day this month. Today Ive used 55 units, why?

It was cold last night, below -1C the whole time, im heating the house to 22 degrees C all the time, I have to pay for that. The average December temperature in Clare is 8 degrees C. Next week it will be warmer so the run cost per day will fall.

The biggest issue with electric heating is the meters are too good and too easy to read, I can see what im using right now, this is more difficult with gas so we ignore it.

Don't panic if your run cost is high today, its cold outside, keep an eye on it and take regular readings. Don't look at your direct debit, you need to look at actual use. If you bought your heat pump of someone reputable they would have supplied it with dedicated meters that read just the heat pumps consumption. Im not interested in your house consumption, what you do with your electricity at home is your business. In my house we use 6 kWhrs of electricity every day for lights, cooking internet etc. You could be using a lot more if you have security lights a tumble drier, kids etc.

My unit is using just on hotwater and heating 42kw on average the last week. My house is A2 rated and 2800sq ft.

ec_pc

This is my first winter with the heat pump installed and am experiencing (expected?) similarities to OP above. I am on a learning curve and the plumber has been excellent in terms of offering advice etc based on his own personal system.

I have an iphone app to control my heat pump so I can easily set up schedules to control hot water and heating. I am making minor changes every few days to determine the optimal settings, but it is very obvious the recent cold snap and negative temperatures do result in longer run times for the heat pump.

Our house is a combination of UFH downstairs and rads upstairs and I can increase the water temperature if needed for more heat in the rads, but this can use a lot of electricity. The plumber took some time to take me through this and it has been beneficial in terms of controlling electricity usage, to reduce water temp by a few degrees on warmer days without impacting UFH or overall comfort of the house. It's just on colder nights upstairs might be about 17/18 degrees so needs a little heat.

Tefral is right, look at this over a full year. My consumption in August was 210 kwh, 803 in November and 1158 in December and 197 so far this month. I do have solar PV installed, but output these days is low, about 22 kwh this month. My House is also A2 rated and 2850 sq feet approx.

Interestingly, I learnt yesterday that Electric Ireland have a heat pump tariff available which offers reductions on existing night and day rates. I have requested a call back from Electric Ireland to avail of this. Maybe this is widely known, but it was news to me yesterday.

Robert Allen

Tefral wrote: »

Its cold out there it currently -1 degrees C outside and has been over night. Due to the cold your HP should be running continuously for the last week. My own it has not stopped once in that time.


Heres an example:


But it gets more complicated than that, your reading is an average over the month, it doesn't show you the peak value per day. Looking at my graph above I should be using 25 units a day this month. Today Ive used 55 units, why?

It was cold last night, below -1C the whole time, im heating the house to 22 degrees C all the time, I have to pay for that. The average December temperature in Clare is 8 degrees C. Next week it will be warmer so the run cost per day will fall.

The biggest issue with electric heating is the meters are too good and too easy to read, I can see what im using right now, this is more difficult with gas so we ignore it.

Don't panic if your run cost is high today, its cold outside, keep an eye on it and take regular readings. Don't look at your direct debit, you need to look at actual use. If you bought your heat pump of someone reputable they would have supplied it with dedicated meters that read just the heat pumps consumption. Im not interested in your house consumption, what you do with your electricity at home is your business. In my house we use 6 kWhrs of electricity every day for lights, cooking internet etc. You could be using a lot more if you have security lights a tumble drier, kids etc.

My unit is using just on hotwater and heating 42kw on average the last week. My house is A2 rated and 2800sq ft.

Thanks for taking the time to reply, I was worried there was a problem with the pump but ill an eye on it. The electricity usage is scaring me 😂

Robert Allen

ec_pc wrote: »

This is my first winter with the heat pump installed and am experiencing (expected?) similarities to OP above. I am on a learning curve and the plumber has been excellent in terms of offering advice etc based on his own personal system.

I have an iphone app to control my heat pump so I can easily set up schedules to control hot water and heating. I am making minor changes every few days to determine the optimal settings, but it is very obvious the recent cold snap and negative temperatures do result in longer run times for the heat pump.

Our house is a combination of UFH downstairs and rads upstairs and I can increase the water temperature if needed for more heat in the rads, but this can use a lot of electricity. The plumber took some time to take me through this and it has been beneficial in terms of controlling electricity usage, to reduce water temp by a few degrees on warmer days without impacting UFH or overall comfort of the house. It's just on colder nights upstairs might be about 17/18 degrees so needs a little heat.

Tefral is right, look at this over a full year. My consumption in August was 210 kwh, 803 in November and 1158 in December and 197 so far this month. I do have solar PV installed, but output these days is low, about 22 kwh this month. My House is also A2 rated and 2850 sq feet approx.

Interestingly, I learnt yesterday that Electric Ireland have a heat pump tariff available which offers reductions on existing night and day rates. I have requested a call back from Electric Ireland to avail of this. Maybe this is widely known, but it was news to me yesterday.

Thanks for that reply.

Can i ask is your solar pv worth it over the year?

It seems your install guy knows what he is at. Maybe ours just give you as little info and access to the unit for fear you will mess up the settings.

Can you tell me what app and set up you have for monitoring the heating? I haven't spent too much time yet looking into this but it seems the 'Nest' set up wont work on our heating system.

I might give the BER guy a ring and see what he could recommend to monitor or control the system.

Thanks a mill for the info. Very helpful.

ec_pc

Robert Allen wrote: »

Thanks for that reply.

Can i ask is your solar pv worth it over the year?

It seems your install guy knows what he is at. Maybe ours just give you as little info and access to the unit for fear you will mess up the settings.

Can you tell me what app and set up you have for monitoring the heating? I haven't spent too much time yet looking into this but it seems the 'Nest' set up wont work on our heating system.

I might give the BER guy a ring and see what he could recommend to monitor or control the system.

Thanks a mill for the info. Very helpful.

We moved from a traditional home setup with solid fuel back boiler and oil central heating and I didn't want this set up after we renovated. I always had concerns over power consumption in this house as we have heat recovery and pumped water in addition to the usual domestic appliances. The solar panels were installed about this time last year and I am only monitoring them since August due to internet issues. It's too early to say if it is worth it in terms of return on investment, but it was also partly a green initiative from my own perspective, plus electricity and energy in general will increase in cost over time.

I think Solar PV is the way forward, I will be expanding my panels and battery in the next few years. I met the ESB meter reader by accident last summer as he read the meter and his comment "what kind of house is this, you are using no electricity" is still ringing in my ears! I am a novice at this, there are others far more suited on this forum to talk about Solar PV.

My heat pump is manufactured by Veissmann, so I bought a Vesissmann internet controller from Amazon and added it myself and this allows interaction with the Veissmann iphone app. I am sure Daiken must have something similar, again there are some other boards members which have Daiken's installed so hopefully they will drop in and advise.

It's very useful to share experiences, as I don't personally know anyone with a heat pump etc to compare notes with.

handpref

Robert Allen wrote: »

Hello all, I'm having concerns with my Air to water heat pump and looking for advice or opinions before I ring the installer.

I know the Consumption of electricity is going to be high anyway during winter but for the past few weeks our 24hour usage of electricity and heat combined has been in the 40 - 44kw range. It usually is in the 30kwh range.

It seems the Daikin heat pump is using a lot of this perhaps through the defrost cycle. For example, The defrost cycle this morning started at 7ish and ended about 11. It defrosted every 40minutes during these hours and used about 3kwh for every hour - 12kwh for the 4 hours approx.

The heat pump generally does use a lot of energy when it is heating the UFH - which is not very often as the rooms stay around 19 - 21 degrees usually and most stats are set around the 20 degrees. Consumption of / heating hot water doesnt seem a concern as we use very little.

When the ATW sends heat to the Ufh the usage increases about 3kwh. When ufh is not calling for heat the usage for the house drops to 1kwh every hour / couple of hours.

It doesn't seem to be a problem with another appliance or lights eating up electricity as usage spikes when heat is on only. On Friday Dec 18 the combined usage for 24hours was 14kwh - as the weather was slightly warmer that day so the ATW unit wasn't on.

The unit is on a new house, installed 2 years, it is using more than it was last year, it was serviced 2 times / I asked installers to fix noise issues and to put on the quiet mode as the unit is bolted to the wall so the noise is travelling through the cavity and walls.

Insulation wise the house is ok - rooms rarely need heat, when they do they get to desired temp in 1 - 2 hours, and retain the heat for the remainder of the day.

I would like opinions on this as the installers seem secretive when I ask them about it - like I'm being an inconvenience or something. They have the control panel settings locked so I can't view the settings myself. Different workers from the company looked at the machine and ufh set up at different times and they were contradicting each other and complaining the unit wasn't set up right etc etc so it's a bit messy.

I just feel they wont be honest if I ring them about this. I feel like they don't want any issues warranty wise etc so will just say it was set up correctly etc.

Any opinions on how normal or not this ATW / UFH system seems to be in terms of performance would help me greatly. I'm the type of guy who likes to have some info about the system but I was given none to begin with and the Installers wouldnt be overly helpful.

Sorry for the long message - I just don't know anybody personally who can give me an opinion on this and I don't know anyone with a similar set up for comparison.

Thanks lads.

There are a few things to consider Robert but keeping an eye on consumption is a good way to map what’s going on with the system.

How are you measuring consumption? Does the heat pump have its own meter.

If it’s say running at 300w to a kw it’s just tipping over, the compressor is inverter driven and will ramp up and down accordingly, this is part of the efficiency of the motor so it’s not like an old school machine just banging on and off and hitting maximum amps each time.

Icing up is indicative of a unit that running too hard trying to achieve temperature. Defrost cycles are normal but excessive ice isn’t. How much ice is being created on the outdoor unit?

It seems you have identified the ufh system to be a bigger consumer. You would need to get the delta t of that part of the system- that’s the temp difference of the water in and out of that leg.

It should be 5deg across the manifold inlet and outlet.

I’d start with this- get your flow rates right all round and you system will work more efficiently.

It’s maybe worth asking who commissioned it and what paperwork was produced, if they are iso registered they should have it.
Is it a fridge man looking after the heat pump?
Is it a plumber looking at the flow rates and plumbing pipe work / manifold.
Was a sparks in charge of the control circuit?

Don’t be worried about querying the operation, it needs a methodical approach to setting up a system right, as I mentioned to another boardsie previously there are often 3 trades used in installing these heat pumps, however there is almost no chance of them all being on site when it’s being commissioned.

graememk

ec_pc wrote: »

Interestingly, I learnt yesterday that Electric Ireland have a heat pump tariff available which offers reductions on existing night and day rates. I have requested a call back from Electric Ireland to avail of this. Maybe this is widely known, but it was news to me yesterday.

It's just a discount on their day/night rates.

I'm currently on a lower rate with energia, 7c night 15c day, (36% discount)

My parents signed up later and on a 41% discount.

You have to switch every year to keep the best deals. Some people have just switched the names on the bill.

Gooser14

Don't forget that when you have a day/night meter the day units cost more than with a standard 24 hour meter. To be cost effective your night usage needs to be at least 25% of total consumption. Night rates apply from 11pm to 8am during winter-time and midnight to 9am during summer-time. The standing charge with the day/night meter is also higher.

Robert Allen

handpref wrote: »

There are a few things to consider Robert but keeping an eye on consumption is a good way to map what’s going on with the system.

How are you measuring consumption? Does the heat pump have its own meter.

If it’s say running at 300w to a kw it’s just tipping over, the compressor is inverter driven and will ramp up and down accordingly, this is part of the efficiency of the motor so it’s not like an old school machine just banging on and off and hitting maximum amps each time.

Icing up is indicative of a unit that running too hard trying to achieve temperature. Defrost cycles are normal but excessive ice isn’t. How much ice is being created on the outdoor unit?

It seems you have identified the ufh system to be a bigger consumer. You would need to get the delta t of that part of the system- that’s the temp difference of the water in and out of that leg.

It should be 5deg across the manifold inlet and outlet.

I’d start with this- get your flow rates right all round and you system will work more efficiently.

It’s maybe worth asking who commissioned it and what paperwork was produced, if they are iso registered they should have it.
Is it a fridge man looking after the heat pump?
Is it a plumber looking at the flow rates and plumbing pipe work / manifold.
Was a sparks in charge of the control circuit?

Don’t be worried about querying the operation, it needs a methodical approach to setting up a system right, as I mentioned to another boardsie previously there are often 3 trades used in installing these heat pumps, however there is almost no chance of them all being on site when it’s being commissioned.

Hi,

In fairness I am only reading the ESB meter and noteing figures for consumption when it is on. I haven't researched what meter is available to work with the system - ATW, UFH, MHRV. If you had suggestions of appreciate it as I think it will answer a lot of questions. A night rate set up or change of supplier might help reduce cost.

I'm confused by the system - I put all the stats on in every room Yesterday to call for heat for one hour and this only used 2kwh of electricity. Yet in the past 24hours 64kwh was consumed with about 40kwh of this used from 8 o clock lastnight to 8 this morning when lights were off, no appliances were on etc.

I think I need to put on a monitor with an app to get a better understanding.

I might start another conversation but if there's anyone who has a decent monitor for the above id appreciate it!

Thanks for all the replies,

Rob.

Tefral

Robert Allen wrote: »

Hi,

In fairness I am only reading the ESB meter and noteing figures for consumption when it is on. I haven't researched what meter is available to work with the system - ATW, UFH, MHRV. If you had suggestions of appreciate it as I think it will answer a lot of questions. A night rate set up or change of supplier might help reduce cost.

I'm confused by the system - I put all the stats on in every room Yesterday to call for heat for one hour and this only used 2kwh of electricity. Yet in the past 24hours 64kwh was consumed with about 40kwh of this used from 8 o clock lastnight to 8 this morning when lights were off, no appliances were on etc.

I think I need to put on a monitor with an app to get a better understanding.

I might start another conversation but if there's anyone who has a decent monitor for the above id appreciate it!

Thanks for all the replies,

Rob.

You will be running your heat pump very inefficiently and you will burn out your pump quicker setting it to come on at only certain times. Its designed to be left on all the time.

What you will be doing there is making it work very hard for the hour an then turn off. Heat Pumps modulate so if you set the stats to work on temp only, it will trickle away keeping it at that temp.

You also have the issue where all heat pumps prioritse hot water, so when you have it only on for the hour, it is trying to do both burning up juice.

ec_pc

Huge difference this week with the increased temperatures, back down to about 20 -25 kwh each day. Some good power coming in from solar panels to offset that. Only 17 kwh today for example. Our house is well insulated and the ambient temperature is always in the 20 - 23 degree range.

I got the night meter installed last Monday and configured the inverter to charge from the grid at night rate and then use it during the day. It's only a small saving but it all adds up plus it keeps the battery cycling over too. Apart from charging the battery between 1 -3 AM, I didn't draw from the grid today until 15:30, this was based on using the battery and solar (it was sunny here).

Still learning, but I know a lot more now that I did this time last month!

Robert Allen

ec_pc wrote: »

Huge difference this week with the increased temperatures, back down to about 20 -25 kwh each day. Some good power coming in from solar panels to offset that. Only 17 kwh today for example. Our house is well insulated and the ambient temperature is always in the 20 - 23 degree range.

I got the night meter installed last Monday and configured the inverter to charge from the grid at night rate and then use it during the day. It's only a small saving but it all adds up plus it keeps the battery cycling over too. Apart from charging the battery between 1 -3 AM, I didn't draw from the grid today until 15:30, this was based on using the battery and solar (it was sunny here).

Still learning, but I know a lot more now that I did this time last month!

Thanks for that info. Could i ask is that temp in all rooms inc hall and bedrooms? And is that the temp (20-23 degree) that the rooms would naturally stay at or would the heating kick in to keep it at those temps?

Also if you could give me an idea if you had a similar build to us id appreciate it - ufh, air to water, 150mm pumped bead cavity with insulated slab.

Thanks and sorry for all the questions. Like I said I don't know anyone with a similar spec house so it's nice to get feedback here. Thank a mill.

ec_pc

Robert Allen wrote: »

Thanks for that info. Could i ask is that temp in all rooms inc hall and bedrooms? And is that the temp (20-23 degree) that the rooms would naturally stay at or would the heating kick in to keep it at those temps?

Also if you could give me an idea if you had a similar build to us id appreciate it - ufh, air to water, 150mm pumped bead cavity with insulated slab.

Thanks and sorry for all the questions. Like I said I don't know anyone with a similar spec house so it's nice to get feedback here. Thank a mill.

No prob, happy to share experiences, like you I don't know anyone with a modern build like ours.

Our house was renovation and extension of old dormer cottage. As a result we have a combination of UFH downstairs and rads upstairs. It just wasn't viable to put concrete floor in upstairs which is the only major thing I would change if I had an unlimited budget. Our build seems very similar - UFH, A2W, pumped 150 mm liquid insulation to downstairs floor with screed on top. Triple glazing, heat recovery and extremely airtight (tested twice once before plastering and then towards end of build).

We have 5 thermostat zones in the house - master in the downstairs hall, 1 in granny flat, 1 in sitting room, 1 in living / kitchen, and 1 on upstairs landing. The hall is in the middle of the house with sitting/living/kitchen all south facing. There is an element of solar gain from those rooms. Typically I have thermostat set to 18 degrees over night and up to 19 or 20 in the morning for a few hours. Floors always warm and I have never seen downstairs themostats read below 20 degrees at any stage. I do adjust water temperature if its a really cold night to get the rads going upstairs. My wife finds the house extremely warm, I am thinking about banning her from opening windows. We tend to leave thermostat upstairs off most of the time, ambient heat from downstairs is enough to heat upstairs.

I monitor the hours the heat pump runs and it varies wildly based on outside temp which is all over the place recently with big outdoor temperature swings from day to day. I also only heat water for 1 hour in morning on night rate and again at about 4:30 pm for 40 minutes. That's it for the day, enough for showers, etc etc. Difference between setting thermostat at 19 or 20 is massive in terms of power consumption in our house.

This week I moved from Electric Ireland to Energia. Electric Ireland had no interest whatsoever in making a decent offer so I swapped provider for the first time ever. I am on the 41% discount with Energia - essentially 14.2 cent day rate and 6.8 cent night rate including VAT. That price can't be beaten and with 45% night rate usage I expect the next bill to be halved.

hero25

this thread may be of use?
https://www.boards.ie/vbulletin/showthread.php?t=2058053474

hero25

and this is a post I posted a while back, may be of use?
********************************************************************************
Ive an A2 house, 320sqm... in it ~4 years. The control unit tells me how many hours its been running and how many hours have been used for heat and how many for hot water. Ive been tracking this for the last ~3 years and have posted a link to usage below.
I think the hours run can be used with the HeatPump Power/KW to determine units used etc, if i was so inclined!
Bottom line is, for all Electricity usage in the house - I've been using ~13,200 units per annum for each of the last 3 years.
Gives me an annual Electricity bill of ~ 2300euro. I'm not sure if it should be lower, but I do have 4 x teenagers and all they bring in terms of energy efficiency....
Overall we're happy with that costs. Hope this helps you get some clarity on your costs....

Gooser14

hero25 wrote:

and this is a post I posted a while back, may be of use? ******************************************************************************** Ive an A2 house, 320sqm... in it ~4 years. The control unit tells me how many hours its been running and how many hours have been used for heat and how many for hot water. Ive been tracking this for the last ~3 years and have posted a link to usage below. I think the hours run can be used with the HeatPump Power/KW to determine units used etc, if i was so inclined! Bottom line is, for all Electricity usage in the house - I've been using ~13,200 units per annum for each of the last 3 years. Gives me an annual Electricity bill of ~ 2300euro. I'm not sure if it should be lower, but I do have 4 x teenagers and all they bring in terms of energy efficiency.... Overall we're happy with that costs. Hope this helps you get some clarity on your costs....

Are you on day/night metering or just straight 24 hour metering? Who is your current power supplier & do you change supplier annually?

macgabhs

Gooser14 wrote: »

Are you on day/night metering or just straight 24 hour metering? Who is your current power supplier & do you change supplier annually?

I find it best to change supplier annually to get the best deal. I’m in my house since 2016. 270m2 with A2W. UFH downstairs rads upstairs. Decent air tightness and MHRV. Downstairs stats at 21 upstairs at 18/19. Been tracking elec usage since I moved in using an open energy monitor. Averaging around 8200 units per annum for all electricity usage. It’s a 60/40 split day and night and I have the day night meter. Depending on the provider that works out about €1350 per annum.

hero25

RE "Are you on day/night metering or just straight 24 hour metering? Who is your current power supplier & do you change supplier annually?"

I'm on flat rate, always have been. I havent looked into it hugely, but the heat pump comes on and off whenever appropriate in the 24hrs, hence why i didnt think going day/night rate would be of any benefit.
currently with Energia, with discounted rate of 0.124per uni & yes, change supplier annually.

@macgabhs: great value there in running a house for a year for €1350- well done. do you mind me asking, are there many living in the house?

macgabhs

hero25 wrote: »

RE

@macgabhs: great value there in running a house for a year for €1350- well done. do you mind me asking, are there many living in the house?

Yes I’m happy with it. There are two adults two small kids. like the OP I was fairly apprehensive of what the costs might be like as I had no experience of A2W. I also moved in during the winter and remember watching the meter carefully for the first few months. The key in my mind is to sign up for the level pay option to spread the costs equally across the year. No doubt if I was to do the traditional bi-monthly billing cycle my winter bills would be huge relative to summer.

KCross

hero25 wrote: »

RE "Are you on day/night metering or just straight 24 hour metering? Who is your current power supplier & do you change supplier annually?"

I'm on flat rate, always have been. I havent looked into it hugely, but the heat pump comes on and off whenever appropriate in the 24hrs, hence why i didnt think going day/night rate would be of any benefit.
currently with Energia, with discounted rate of 0.124per uni & yes, change supplier annually.

If you have a heat pump you should be on a night rate.
You'll pay ~1c/unit more by day but you'll pay half price at night. A slightly increased standing charge (~€45/year) also but it will still pay for itself.

Easiest way to convince yourself of that is to check how many units your house consumes during night rate by reading your meter at 11pm and again at 8am and if its anything more than ~3 units you should be on the night rate.

Latro

KCross wrote: »

If you have a heat pump you should be on a night rate.
You'll pay ~1c/unit more by day but you'll pay half price at night. A slightly increased standing charge (~€45/year) also but it will still pay for itself.

This is debatable, and it is impossible to tell if the OP would benefit from switching to the night rate without knowing more details.
I doubt he would.
3kWh of night usage would not be anywhere close to justify switching. 3kWh x 0.13 x 30days would cost only about 12 euro per month on Energia discounted rate.

320sqm is a big house, on top of that there are at least 6 people living in it. 13,200 units of usage per year, heating included is a reasonable in my opinion.

KCross

Latro wrote: »

This is debatable, and it is impossible to tell if the OP would benefit from switching to the night rate.

Did you not read the 2nd paragraph?

The heat pump will be heating his domestic hot water everyday so that should be timed for night rate. There is the background load of the house which will also be there. Uness he has an odd usage profile and uses huge amounts by day that he cant shift to night it will pay to have night rate.... and, as I said, check his usage by taking some readings and he wont be long finding out.

1874

Tefral wrote: »

You will be running your heat pump very inefficiently and you will burn out your pump quicker setting it to come on at only certain times. Its designed to be left on all the time.

What you will be doing there is making it work very hard for the hour an then turn off. Heat Pumps modulate so if you set the stats to work on temp only, it will trickle away keeping it at that temp.

You also have the issue where all heat pumps prioritse hot water, so when you have it only on for the hour, it is trying to do both burning up juice.

What this guy says,
Was reading through the thread, waiting to see if anyone said it before I made the comment, I haven't really heard anyone else say this.
Heat pumps dont do that ramp up to heat like traditional heating does.
Been a while since I looked into Heat pumps , and I did not do so in enough detail for my liking, but they need to be designed or set up to meet a certain demand and then operated at that continuously.
The whole idea of turning them on/off to meet a demand is what I would have thought, counterproductive, inefficient. I am astonished this hasn't come up from the supplier/installer.

KCross

Latro wrote: »

3kWh of night usage would not be anywhere close to justify switching. 3kWh x 0.13 x 30days would cost only about 12 euro per month on Energia discounted rate.

What does that calculation prove/disprove?

You need to look at the whole house, not just the heat pump. There is background load plus the heat pump plus hot water. You can then optionally add in appliances (dishwasher etc) if you wish.

The 3kWh I mention is a guideline not a set figure and is a breakeven point only.


During the cold spells the heat pump will be working hard during the 9hrs of night rate. It would use multiples of 3 units. During the summer it will just be heating hot water but you still have the background load and average it out for the year.

You dont need alot of night usage to justify going on night rate.

Latro

KCross wrote: »

Did you not read the 2nd paragraph?

The heat pump will be heating his domestic hot water everyday so that should be timed for night rate. There is the background load of the house which will also be there. Uness he has an odd usage profile and uses huge amounts by day that he cant shift to night it will pay to have night rate.... and, as I said, check his usage by taking some readings and he wont be long finding out.

I read and edited my post to reflect that.
As mentioned before 3kWh would not be the breaking point. Not even close.

It would have to be a lot more. I'd say at least 12kWh to break it even. I didn't calculate exactly. It is from top of my head.
They are very unlikely to use that much between 11pm and 8am.

They could try hard to shift their usage but would it be worth it to rearrange your live for a doubtful few euro gain?

Because of the defrost cycle A2W needs substantially more energy when ambient temperature approaches about +2 degrees and this is very typical night in Irish climate.
On the other hand it is very rare during the day. Savings would be minimal if any at all.

Latro

KCross wrote: »

During the summer it will just be heating hot water but you still have the background load and average it out for the year.

You dont need alot of night usage to justify going on night rate.

Heat pump usage during the summer on the night rate is insignificant and not worth considering as savings would be in cents per day here. On top of that also it would be offset a little by lower ambient temperature. I have one and I tried it all. It is not worth it.

There are 6 people in the house. No matter how hard you discipline them, they will use most of the energy during the day. Background load in the night is very small.

Also as I mentioned before, who wants to live around electricity usage regime for a doubtful few euro per month gain.

KCross

Latro wrote: »

It would have to be a lot more. I'd say at least 12kWh to break it even. I didn't calculate exactly. It is from top of my head.

Indicative figures...

Lets say someone currently uses 9000kWh for the year with 20% of it at night.
Lets say they pay 13c/kWh on a 24hr basis.
Lets say they now switch to night rate of 14c/7c for day/night and an additonal €45 on standing charges.

Current cost - €1170
Day/Night - €1008+€126+€45(standing charge)=€1179

So, they are at break even at 20%.
20% night usage is low. Its relatively easy to get to 50%+ on night without changing your lifestyle.

Each to their own here. You're not convinced, thats fine. I'd say let each person take meter readings of their own and figure it out for their house as we all have different usage profiles.

Latro

1874 wrote: »

What this guy says,
Was reading through the thread, waiting to see if anyone said it before I made the comment, I haven't really heard anyone else say this.
Heat pumps dont do that ramp up to heat like traditional heating does.
Been a while since I looked into Heat pumps , and I did not do so in enough detail for my liking, but they need to be designed or set up to meet a certain demand and then operated at that continuously.
The whole idea of turning them on/off to meet a demand is what I would have thought, counterproductive, inefficient. I am astonished this hasn't come up from the supplier/installer.

This is spot on.
When running a heat pump most savings are not in reducing operating time but in lowering flow temperature. It will switch off itself when it meets certain criteria.
Ideally the heat pump should provide "live" the same heat energy as it is current loss. You should not charge your house in advance or play a catch up.
This is not good for your comfort, wallet and the device lifespan.

Experiment with lowering flow temperature, find the best settings, switch it on and forget. If you have weather compensation option, use it, it's the best way to run it.
No installer will do it for you. They can provide some baseline but will not set it optimally. Every house and its occupants' habits are different.

hero25

Thanks for the advice from various parties. TBH, no point in trying to change lifestyle habits with 4x teenagers, so that's not a runner.
As an example..... during lockdown in April 2020, the hot water usage jumped by 65% compared to April 2019.
Also, I find after 4+ years that the less you interfere with the heatpump settings the better. It's set at its current setting for about 3 years now & we're happy with those and the comfort it gives.
I will take the meter readings at night and in the morning over a period to see what kind of night usage we have.
As I said previously, we've an annual Electricity bill of ~ 2300euro, I cant see it dropping drastically.

graememk

hero25 wrote: »

Thanks for the advice from various parties. TBH, no point in trying to change lifestyle habits with 4x teenagers, so that's not a runner.
As an example..... during lockdown in April 2020, the hot water usage jumped by 65% compared to April 2019.
Also, I find after 4+ years that the less you interfere with the heatpump settings the better. It's set at its current setting for about 3 years now & we're happy with those and the comfort it gives.
I will take the meter readings at night and in the morning over a period to see what kind of night usage we have.
As I said previously, we've an annual Electricity bill of ~ 2300euro, I cant see it dropping drastically.

If you have a digital meter, it's most likely already already recording your day night ratio

If you press the button on the meter it will cycle through all the different menus.

0 is 24hr and then 1 and 2 is day or night, I can't remember what way round it is.

sarah88

Hi,

We have a Daikin heat pump in a new build. I'm looking to tweak the settings to maximise efficiency with our electricity night rate. Looking at the hot water tank schedule, they have set it to kick in at 7am-9am and 5pm-7pm. It works great and we are never without hot water but is mostly using the day units. Can anyone advise on their own set up while being able to heat the tank overnight?

Many Thanks,

Sarah

keno-daytrader

https://www.boards.ie/discussion/comment/118542852#Comment_118542852

What is the target temp of the hot water set to?

How many people in the house?

KCross

And to add to the previous posters questions, how many litres of water does your tank hold?

Ultimately though it will be down to how much water you use. If you have a few people who like long showers or baths you may run out of water if it’s all heated at night with no day top up.

Best thing to do is probably set it to heat the water at 6-8am only and then see what happens. If someone complains of having a cold shower you’ll need to reassess! :)

FYI. I’ve a 300l tank with a young family of 5 and we rarely run out of water. All heated between 6-8am.