Heat Pump - KwZ usage through the roof

JEdelman

Hi,

We moved to a newbuild in March 2021 with gas and electric provided by heat pump. 

Each year, we are using around 17,000 kWh, according to British Gas, and spending more than £5,500 in the process. We are a family of two (and a dog) and it's an average-sized 4-bed house.

The heat pump installer insists that there is no problem with the heat pump and is claiming that volume of usage is normal, which I don't believe.

We also struggle to heat the house when the temperature drops below 5C. So much so that the radiators upstairs (it's underfloor heating downstairs) do not heat up and we struggle to get the house above 18C. The heat pump installer's advice was to fit bigger radiators - although I struggle to see this as a solution given the ones we currently have are cool to the touch when they should be blasting out heat.

My thought now is to find an independent energy assessor to carry out a report on what's going on but a number of Google searches don't throw up any obvious points of contact. 

I wondered if anyone had any advice?

Thanks for reading.

Netexporter

 although I struggle to see this as a solution given the ones we currently have are cool to the touch when they should be blasting out heat.

Heat pumps work most efficiently at lower flow temperatures but you need larger radiators to meet the heat loss from the room. Ideally you want a flow temperature close to 30 degrees, that will feel almost cold to the touch. However, try the flow at say 45 degrees, which may give you a reasonable balance between comfort and efficiency without other alterations.

It may be worth getting an assessment from a Heat Geeks registered installer. It is possible you could have a claim against the original installer if the design was inadequate for the situation.

Reed_Richards

JEdelman said:

Hi,

We moved to a newbuild in March 2021 with gas and electric provided by heat pump. 

Sorry, what?  Do you mean that the heat pump provides heating and hot water?

JEdelman said:

Each year, we are using around 17,000 kWh, according to British Gas, and spending more than £5,500 in the process. We are a family of two (and a dog) and it's an average-sized 4-bed house.

The heat pump installer insists that there is no problem with the heat pump and is claiming that volume of usage is normal, which I don't believe.

The installer is telling porkies or knows nothing at all about heat pumps.  Who would want to live in a normal sized house that cost so much to heat?  It's nowhere near normal.

JEdelman said:

The heat pump installer's advice was to fit bigger radiators - although I struggle to see this as a solution given the ones we currently have are cool to the touch when they should be blasting out heat.

Well that bit is correct in as far as it goes, but it was up to the installer to right-size the radiators and the area-density of your UFH pipes in the first place.  Heat pump radiators might get up to 50 C in the coldest weather but they will never blast out heat.  That's because some heat pumps are not capable of making the heating water that hot and if you had one that could do it it would be uneconomic to run - not that you don't have that already.

@Netexporter's suggestion for an assessor is as good as any.  Or if you know anyone who has had a heat pump installed that doesn't cost an arm and a leg to run then ask them who did their installation.   

tacpot12

The radiators shouldn't be blasting out heat. Heat pumps are only efficient if they are set to a low flow temperature and the low flow temperature means that you need more surface area to get heat into the property. Your underfloor heating has a very large surface area compared to the radiators, so downstairs might well feel more comfortable than upstairs as more heat is being emitted downstairs. This is usually a good arrangement because heat rises, so the bedrooms also get some heating from the underfloor heating on the ground floor. The radiators in a new build should have been sized correctly for the heatpump and the  level of insulation in the property. If they are not, you would seem to have some sort of claim against the installer. 

The heatpump should also have been sized for the level of insulation, but might have been oversized and is inefficient because of it. Again, if it is oversized and therefore inefficient you would seem to have some claim against the installer. 

You might be using the system incorrectly. Heatpumps need to be left switched on all the time, and the target temperature that your thermostat is set to needs to only vary between the high point (21C) and a low point of about 14C. So you would set the thermostat to your highpoint at times you expect to be home, and to 14C at times you are out. A set point of 18C is probably a good compromise overnight when people are in bed. If you have been using your heatpump as you would a gas boiler, you will incur a lot of extra cost for electricity. The only time you should set the thermostat to less than 14C is when you are away on holiday for a long time. It will take the heatpump a long time to rewarm a home that has been allowed to cool down to 10C or lower. 

Your problem might also be related to the amount of hot water you use and the size of your cylinder. If you have a small cylinder and expect to be heated to 60 or 70C you will incur a lot of extra cost. You need a large cylinder (300 litres is about the minimum for a family) and to only heat it to 45C. If they cylinder is too small, again you seem to have some sort of claim against the installer, but be aware that you probably don't have any sort of specification as to what the heating system should perform to, so it's a matter of opinion as to whether what you have is unacceptablely bad. 

The heat pump might also be set to run a Legionella disinfection cycle too frequently, although this is a rare misconfiguration. Heating to 60C for 30 minutes every two weeks is usually sufficient to manage the risk of Legionella. 

Your usage seems to be excessive. You should be spending less than half that amount on electricity. 
You should check your home insurance to see if you have legal expenses cover. If you do, you will have a legal helpline you can call for advice on how to hold the installer to account for the performance of the system.

You might need an expert report into the design and installation of the system, along with recommendations of the changes needed to make the system efficient. I'd recommend you contact a 'Heat Geek' to write such a report. Find a Heat Geek - HeatGeek

michaels

Do you have any metering that lets you know how much of your electricity use is the heat pump?

Does the heat pump provide hot water and how much hot water do you use?

Do you know if the UFH and rads are set up as separate zones?

matelodave

Youll get lots of random guesses about what might be wrong but lets find out what you've got, how its set up and how you are using it as all of these will affect the energy consumption.

First - more inf on your set up. Make and model of heatpump, what controls (thermostats, timers controllers etc) Rough sizes and type of radiators and u'f heating. 

As said above radiators for heatpump systems should be oversized and run at significantly lower temperatures than you may be used to with gas central heating. To go with that they should be run for a lot longer - using a heatpump system, especially with under floor heating like a gas boiler in short burst with the heat turned up is a recipe for disaster. So we need to know what your flow temperatures are and how long you are running it (info from the heatpump controller) what your room stats are set to and where are they situated. Do the rads have TRV's. Is weather compensation set

What is the temperature of your hot water and how often do you heat it (how much do you use). Do you know if you've got a backup heater or even an immersion heater - if you are trying to heat your water above around 50 dgrees then its likely that you also have an immersion heater flogging away as well.

You need to understand what you've got, how its configured and set up and you also need to learn how to use a heatpump as a heatpump and not as a substitute gas boiler.

MP1995

JEdelman said:

Hi,

We moved to a newbuild in March 2021 with gas and electric provided by heat pump. 

Each year, we are using around 17,000 kWh, according to British Gas, and spending more than £5,500 in the process. We are a family of two (and a dog) and it's an average-sized 4-bed house.

The heat pump installer insists that there is no problem with the heat pump and is claiming that volume of usage is normal, which I don't believe.

We also struggle to heat the house when the temperature drops below 5C. So much so that the radiators upstairs (it's underfloor heating downstairs) do not heat up and we struggle to get the house above 18C. The heat pump installer's advice was to fit bigger radiators - although I struggle to see this as a solution given the ones we currently have are cool to the touch when they should be blasting out heat.

My thought now is to find an independent energy assessor to carry out a report on what's going on but a number of Google searches don't throw up any obvious points of contact. 

I wondered if anyone had any advice?

Thanks for reading.

So you have put up with this for over 2 years?  As its a new build are other houses on the new build estate also having the same issues?

Reed_Richards

Do you get an EPC with a new build?  If you have one it should tell you how much energy you are calculated to use for your heating and hot water.  You can view it online.

My EPC says:

Heating this property
Estimated energy needed in this property is:

• 15,900 kWh per year for heating

• 2,987 kWh per year for hot water

This is for my 4-bedroom bungalow built in 1980.  So if I heated my property with electric panel heaters and my hot water with an immersion heater then I would expect my electricity bill for heating and hot water to be for about 18,900 kWh.  But I have a heat pump so last year my heat pump used a bit less than 5200 kWh to provide my heating and hot water.

Even if your heat pump was completely failing to pump heat and functioned purely as a direct electrical heater your electricity usage seems high.  

stripling

matelodave said:

Youll get lots of random guesses about what might be wrong but lets find out what you've got, how its set up and how you are using it as all of these will affect the energy consumption.

First - more inf on your set up. Make and model of heatpump, what controls (thermostats, timers controllers etc) Rough sizes and type of radiators and u'f heating. 

As said above radiators for heatpump systems should be oversized and run at significantly lower temperatures than you may be used to with gas central heating. To go with that they should be run for a lot longer - using a heatpump system, especially with under floor heating like a gas boiler in short burst with the heat turned up is a recipe for disaster. So we need to know what your flow temperatures are and how long you are running it (info from the heatpump controller) what your room stats are set to and where are they situated. Do the rads have TRV's. Is weather compensation set

What is the temperature of your hot water and how often do you heat it (how much do you use). Do you know if you've got a backup heater or even an immersion heater - if you are trying to heat your water above around 50 dgrees then its likely that you also have an immersion heater flogging away as well.

You need to understand what you've got, how its configured and set up and you also need to learn how to use a heatpump as a heatpump and not as a substitute gas boiler.

This is exactly the right response 👆🏻 If you can provide those answers there's some very knowledgable people here who can point you in the right direction.  Also, if it is heat pump AND gas what powers what?  What is the gas doing? That's an odd combination. 

TheElectricCow

JEdelman said:

Each year, we are using around 17,000 kWh, according to British Gas, and spending more than £5,500 in the process. 

Some very good advice and pointers from the other users above, but this part in particular caught my eye - when you say “according to British Gas”, is this 17,000 kWh just a figure they’ve given you, or have you made sure this yearly estimate is accurate based on your own readings?

Have you been able to determine roughly how much of that usage is attributable to the heat pump (I believe some models will record information on energy consumption, as can independent energy monitoring devices), or could there be any other high usage appliances in the household significantly contributing to this? It would seem very odd for such a large amount of consumption to be going towards producing heat for a house that isn’t able to reach your desired temperature on cold days.

matelodave

Reed_Richards said:

Do you get an EPC with a new build?  If you have one it should tell you how much energy you are calculated to use for your heating and hot water.  You can view it online.

My EPC says:

Heating this property
Estimated energy needed in this property is:

• 15,900 kWh per year for heating

• 2,987 kWh per year for hot water

This is for my 4-bedroom bungalow built in 1980.  So if I heated my property with electric panel heaters and my hot water with an immersion heater then I would expect my electricity bill for heating and hot water to be for about 18,900 kWh.  But I have a heat pump so last year my heat pump used a bit less than 5200 kWh to provide my heating and hot water.

Even if your heat pump was completely failing to pump heat and functioned purely as a direct electrical heater your electricity usage seems high.  

mine is similar, 12,565 kwh for heating and 2,759kwh for hot water = 15,324 but my heatpump only uses around 4500kwh from our total annual electricity consumption of around 7200kwh so the OP's 17,000 looks like a very dodgy estimate rather than based on actual meter readings