Tomato Energy

[johnb80]

Good question. I'm looking for someone with a heat pump to compare running costs with the Tepeo ZEB.

I have several heatpumps, 13 x air to air and 1 x air to water (14kW). How much power does a typical heat pump require is not a good question, too many variables - outside air temp, inside temp reqd, insulation etc etc. The way I approached it was to take a year of gas bills, with a guestimate of boiler efficiency (89%) for mine it was possible to work out the heat input requirements for my property and comfort levels etc. The performance of the heatpump (COP) is known and published. Armed with this data divide the heat input required by the COP divided by 100 this will give you the electrical input you need.

Example
Heat Input = 12,000 kWh
Boiler Efficiency = 90%
Heatpump COP = 420

From the gas bill heatinput shows 12000 kWh with an efficiency of 90% the gas purchased would be 12000 x 1.1 = 13333.33 kWh of gas 7.3p = £973.31

Heatpump
Heat input reqd 12000kWh with an efficiency between 250% & 530% :

COP 250% - 12000 kWh required = 12000 / (250 / 100) = 4800 kWh
Tariff average say 12p = 4800 x .12 = £576
COP 530% - 12000 kWh required = 12000 / (530 / 100) = 2264 kWh
Tariff average say 12p = 2264 x .12 = £271

Tepeo will be 100% efficient and can be run on off peak only.
Tomato off peak is 5p kWh, 12000kWh cost would be 120000 x 0.05= £600

As expected, the heatpump is cheaper even at the lower end of the performance specification. To get the best COP from a heatpump generally the flow temperatures' are tuned for best performance. The flow temperature is lower than that of a gas boiler. I did a trial with my system running the boiler at 35 degC flow temp and left it running24/7 for a week. The house was definitely more comfortable and it proved my house with it's radiator sizes and insulation would be fine. The Tepeo will run at normal boiler temperatures.

Im sure some 'experts' will argue my calculations above arent valid but I assure you in my case they worked really well and were just about on the button.

J

 

[Everest]

How much power does a typical heat pump require is not a good question

I am puzzled why that is not a good question

Armed with this data divide the heat input required by the COP divided by 100 this will give you the electrical input you need.

All good info, thanks but that's the energy required, not power. (i.e. kWh rather than kW).

edited to add: Where I asked:

Out of interest, how much power does a typical home heat pump require? And does it switch on and off frequently?

&

I'm more interested in power requirements than energy costs

... what I was meaning is how much instantaneous power does a heat pump draw - in terms of thinking of whether inverter / battery can provide that in addition to other household loads. And also, when not needing maximum power, whether it modulates with quick on of off switching (like an induction hob) or whether it linearly reduces power draw. Thanks.

 

[Gadget Geek]

I have several heatpumps, 13 x air to air and 1 x air to water (14kW). How much power does a typical heat pump require is not a good question, too many variables - outside air temp, inside temp reqd, insulation etc etc. The way I approached it was to take a year of gas bills, with a guestimate of boiler efficiency (89%) for mine it was possible to work out the heat input requirements for my property and comfort levels etc. The performance of the heatpump (COP) is known and published. Armed with this data divide the heat input required by the COP divided by 100 this will give you the electrical input you need.

Example
Heat Input = 12,000 kWh
Boiler Efficiency = 90%
Heatpump COP = 420

From the gas bill heatinput shows 12000 kWh with an efficiency of 90% the gas purchased would be 12000 x 1.1 = 13333.33 kWh of gas 7.3p = £973.31

Heatpump
Heat input reqd 12000kWh with an efficiency between 250% & 530% :

COP 250% - 12000 kWh required = 12000 / (250 / 100) = 4800 kWh
Tariff average say 12p = 4800 x .12 = £576
COP 530% - 12000 kWh required = 12000 / (530 / 100) = 2264 kWh
Tariff average say 12p = 2264 x .12 = £271

Tepeo will be 100% efficient and can be run on off peak only.
Tomato off peak is 5p kWh, 12000kWh cost would be 120000 x 0.05= £600

As expected, the heatpump is cheaper even at the lower end of the performance specification. To get the best COP from a heatpump generally the flow temperatures' are tuned for best performance. The flow temperature is lower than that of a gas boiler. I did a trial with my system running the boiler at 35 degC flow temp and left it running24/7 for a week. The house was definitely more comfortable and it proved my house with it's radiator sizes and insulation would be fine. The Tepeo will run at normal boiler temperatures.

Im sure some 'experts' will argue my calculations above arent valid but I assure you in my case they worked really well and were just about on the button.

J

Cost over what time period?

 

[Gomev]

I love that intelligent use of control systems. Out of interest, how much power does a typical home heat pump require? And does it switch on and off frequently?

Have at look at EVMs first annual breakdown using the whiteboard of truth.

 

[DBedford]

9 year payback.... for heat pump solar and batteries , and pointless with a heat pump only

If only I was 40.

Why don't we look for payback on a laptop? because they not attached to a monthly usage cost, pointless comparison.

 

[Everest]

Have at look at EVMs first annual breakdown using the whiteboard of truth.

Thanks - all interesting, but what I was asking is how much instantaneous power does a heat pump draw - in terms of thinking of whether inverter / battery can provide that in addition to other household loads? And also, when not needing maximum power, whether it modulates with quick on of off switching (like an induction hob) or whether it linearly reduces power draw. Thanks.

 

[Gadget Geek]

9 year payback.... for heat pump solar and batteries , and pointless with a heat pump only

If only I was 40.

Why don't we look for payback on a laptop? because they not attached to a monthly usage cost, pointless comparison.

All electrical items in your house have a usage cost, particularly white goods, by the fact that they are plugged in and using electricity you pay for. I try to go for the most energy efficient items, but I never consider the payback period on a new washing machine, fridge/freezer, induction cooker etc.

 

[Everest]

I try to go for the most energy efficient items, but I never consider the payback period on a new washing machine, fridge/freezer, induction cooker etc.

True - but would you not consider the payback period of the differential cost of buying something more efficient? Say, for example, you could but a fridge/freezer for £400, but for £500 you could buy one that is more efficient, but otherwise identical. Wouldn't you consider how much more efficient and decide (for example) that if the £500 one only saves you £5 a year, you'll give it a miss, but if it saves you £75 a year compared to cheaper one, then it would be worth the extra?

 

[Gadget Geek]

True - but would you not consider the payback period of the differential cost of buying something more efficient? Say, for example, you could but a fridge/freezer for £400, but for £500 you could buy one that is more efficient, but otherwise identical. Wouldn't you consider how much more efficient and decide (for example) that if the £500 one only saves you £5 a year, you'll give it a miss, but if it saves you £75 a year compared to cheaper one, then it would be worth the extra?

No.

 

[johnb80]

Thanks - all interesting, but what I was asking is how much instantaneous power does a heat pump draw - in terms of thinking of whether inverter / battery can provide that in addition to other household loads? And also, when not needing maximum power, whether it modulates with quick on of off switching (like an induction hob) or whether it linearly reduces power draw. Thanks.

I run a 14kW Mistubishi Heatpump along with several Mitsubishi Aircon units. The nice thing with the Mitsubishi units is that theyre not on or off they adjust the speed of the compressors and fans to match the load. Theres no massive switch surge to upset your inverters. I have just watched my heatpump start from zero to the highest demand, the power ramped up over 45 seconds for zero to 5kW. In normal operation i.e. maintaining a steady temperature a constant 0.7 to 1.5 kW is the norm for me dependent on outside air temperature.
Inverter heatpumps are way more desirable than the cheaper on/off ones.

 

[johnb80]

No.

Really?

 

[johnb80]

9 year payback.... for heat pump solar and batteries , and pointless with a heat pump only

Not really pointless, youre doing your bit for saving the planet

If only I was 40.

That makes no difference, even if you were 40 you be dead within a short space time by many different unfortunate happenings. (I'm glad youre not BTW, I wouldnt have many people to cross swords with on a regular basis

Why don't we look for payback on a laptop? because they not attached to a monthly usage cost, pointless comparison.

Damn it, I've got to agree with you on this one.

 

[Everest]

The nice thing with the Mitsubishi units is that theyre not on or off they adjust the speed of the compressors and fans to match the load.

That's really good to know, thanks.

 

[Gadget Geek]

Really?

Yep. I look at the alphabetical rating sticker and the price and pick the most efficient one within my budget.

 

[JonnyG]

Anyone near Derby?

Check out the shop

https://www.tomato.energy/stores/derby-store

 

[Grandadgeorgec]

My switch to Tomato Lifestyle from Octopus Go did not go ahead on the 20th as planned. I emailed them and received the following reply. Facebook is indicating lots of prospective users similarly affected.

"Good Morning,
Thank you for reaching out to us and we truly do apologise for the inconvenience and delay in getting back to you.
We regret to inform you that we have been unable to complete your transfer at this time. This is due to ongoing issues with our switching servers and MPAS system.
Due to this, we have been unable to register this.
Once the switching servers are running, we will attempt to switch this supply over to us. We are currently in the process of getting this issue fixed, this has been logged and once this has been resolved we will then register this site accordingly. Our teams are actively working on combatting this.
We sincerely apologise for any inconvenience this has caused and greatly appreciate your patience and cooperation."

 

[JonnyG]

Yes there are a lot of similar Trustpilot reviews which is probably one reason they only have 4.1 stars rating on there. Fortunately my switch occured on time but I had to ring them up to confirm it had switched as I didn’t get any confirmation from them.

It will be worth persevering with them IMHO, especially if your tariff is agreed, as energy prices seem to be only going up for the next 6-9 months.

If you call them try around 4pm and opt for the "new user" option. I got straight through in 20 seconds and was quite suprised as that seems to be another complaint (the delay in answering)!!

Today's news:-

Energy price cap: Bills to rise by more than expected in April

Regulator Ofgem says a household using a typical amount of energy will see its annual bill rise by £111.

www.bbc.co.uk

 

[Grandadgeorgec]

Yes there are a lot of similar Trustpilot reviews which is probably one reason they only have 4.1 stars rating on there. Fortunately my switch occured on time but I had to ring them up to confirm it had switched as I didn’t get any confirmation from them.

It will be worth persevering with them IMHO, especially if your tariff is agreed, as energy prices seem to be only going up for the next 6-9 months.

If you call them try around 4pm and opt for the "new user" option. I got straight through in 20 seconds and was quite suprised as that seems to be another complaint (the delay in answering)!!

Today's news:-

Energy price cap: Bills to rise by more than expected in April

Regulator Ofgem says a household using a typical amount of energy will see its annual bill rise by £111.

www.bbc.co.uk

This could get expensive for Tomato. I do hope this doesn't contribute to them going under.

The OFGEM website states:

Delays switching supplier​

Suppliers must switch your electricity or gas supply from your old supplier to your new supplier within 5 working days. If they do not, your new supplier must pay you £40. The £40 will be paid automatically into either your energy account or bank account.

Extra compensation if there are delays switching or fixing mistakes​

Suppliers have to pay you compensation you are entitled to within 10 working days. If they do not, they have to pay you an extra £40. This is part of our ‘Supplier Guaranteed Standard of Performance’. These standards make sure that suppliers put things right and that you are paid for a problem that was their fault.

 

[DBedford]

Not really pointless, youre doing your bit for saving the planet

Really?

 

[johnb80]

Really?

Yes of course, not burning stuff helps dramatically with pollution.