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ASHP AND ELECTRICITY COST


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7 minutes ago, PeterW said:

Or alternatively I can use a transmission network that currently exists to move electricity from existing generation plants that could be produced from any source, to power a heat pump that creates no emissions without having to change anything in the grid infrastructure. 

With a CoP of 3 or more.

 

So Hydrogen, created from RE, but burnt in a gas boiler will probably give you CoP of 0.3, maybe 0.4 if fed into a fuel cell.

RE generation may loose 8% on the way to the end user, and a battery may loose another 15%, so a CoP of 0.77, then the HP taking 50% of the energy but working at a CoP of 3 gives you 2.31.

Overall that will be a 1.54 multiplication factor.

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15 minutes ago, PeterW said:



 


We’ve done this before .. a heat pump will support as much hot water as you need. Sizing the system is the issue, it’s when installers don’t survey the property and assume the 180 litre hot water tank is “enough” for a 4 bed house. What isn’t understood is that the tank is acting as a buffer for usage in a gas fired house, and the boiler will be kicking in pretty quickly once 2 showers are running. If you don’t believe me, turn a standard boiler set up off (Usual 25kW boiler/210 litre tank) once the tank is at temperature and get 2 showers running. You’ll be out of hot water in about 8-9 minutes. The boiler kicks in and is essentially acting as a 25kW instant hot water heater into the tank. The downside with ASHP (unless you go very big) is they can’t provide the speed of recovery as it’s 25kW vs 12kW, so will need twice as long to recover. That is why you oversize the tank. 400 litre tank is £2-300 at most more than a 210 litre tank so in the scheme of things is negligible. 

 


 

 
 

 


 

 

sorry peter that'sts just not true. 

 

Turn  your hot tap full on and how many minutes until its running cold ? 20 ?  Now do that with 3 taps.

 

Combi/system boiler. zero problem, no need for expensive tanks all over the place etc

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3 minutes ago, SteamyTea said:

With a CoP of 3 or more.

 

So Hydrogen, created from RE, but burnt in a gas boiler will probably give you CoP of 0.3, maybe 0.4 if fed into a fuel cell.

RE generation may loose 8% on the way to the end user, and a battery may loose another 15%, so a CoP of 0.77, then the HP taking 50% of the energy but working at a CoP of 3 gives you 2.31.

Overall that will be a 1.54 multiplication factor.

 

 

You are not understanding why hydrogen will be replacing gas in the network. As more renewables come online the bigger  the problem of excess energy at times when its not needed. solar in the summer etc. My understanding this wasted excess will be turned over to hydrogen production, same at off peak times. So its essentially free. 

 

Similar will happen with electric cars, 70kw/h of energy sat on your drive will become part of the grid when demand is high power can be pulled from the cars to save non-green production, when supply outstrips demand back it goes.

 

Much greener all round. 

 

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4 minutes ago, Dave Jones said:

 

thats fine for expensive niche builds like the majority on here. For everything built prior to the millennium it would be hugely expensive to convert them to heat pumps let alone the massive heat pump cost on its own and it having to be replaced every 10 years or so again at massive cost.

 

They are not the answer and will be dropped as soon as hydrogen comes on line. It's a much better, cleaner and cheaper energy. 

You can easily look up how much energy a house uses, then calculate the size of heat pump needed.

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/946419/Sub_national_electricity_consumption_statistics_2005-2019.xlsx

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/946437/LSOA_domestic_gas_2010-19.xlsx

All the information is there if you care to look.

My house is 'Pre Millenium' and I use less than 2 MWh/year for heating.  Are you saying that it is impossible for a house like mine to be heated by an ASHP?

My last buy one house was a large, 3 story, end terrace Victorian place.  The gas boiler in there was 30 kWh.  You can buy a 30 kW ASHP.  Or buy 2 15 kW, which means you can use jut one for DHW heating (it could even be a 20 kW and a 10 kW).

 

You really need to keep up with the technology rather than have the 'a Morris Minor was a great car, if they made it today they would have a winner'.

 

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11 minutes ago, Dave Jones said:

My understanding this wasted excess will be turned over to hydrogen production

Or to turn on heat pumps, large industrial refrigeration, charge batteries, planned maintenance shutdown on other generation.

 

You just don't understand the inefficiencies of hydrogen, it is like shutting down half your generation capacity.

When a wind or solar farm is designed, there are two numbers that are used.

Installed Capacity, MWp

Generation Capacity, MWh.

They are different, but both are known, it does not come as a surprise when night falls that PV stops generating, or that wind is variable.  Because these things are known, the actual estimates are very accurate.  You can, if you care to, look up the day ahead estimates and see how good they are.  But you won't.

Edited by SteamyTea
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5 minutes ago, SteamyTea said:

You can easily look up how much energy a house uses, then calculate the size of heat pump needed.

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/946419/Sub_national_electricity_consumption_statistics_2005-2019.xlsx

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/946437/LSOA_domestic_gas_2010-19.xlsx

All the information is there if you care to look.

My house is 'Pre Millenium' and I use less than 2 MWh/year for heating.  Are you saying that it is impossible for a house like mine to be heated by an ASHP?

My last buy one house was a large, 3 story, end terrace Victorian place.  The gas boiler in there was 30 kWh.  You can buy a 30 kW ASHP.  Or buy 2 15 kW, which means you can use jut one for DHW heating (it could even be a 20 kW and a 10 kW).

 

You really need to keep up with the technology rather than have the 'a Morris Minor was a great car, if they made it today they would have a winner'.

 

 

The problem is not just spending a fortune on a massive noisy pump to annoy the neighbours, its the massive rads needed or the cost of braking out the floors for ufh or simply insulating to modern standards. Who is going to pay for all this allice in wonderland nonsense ?

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I have a 1860 Victorian end terrace, nothing fancy about it.

 

just that I have year on year as general building improvements have taken place I have improved the thermal performance of the building, to lower running costs, for my old age when I will be living off my pension, and no doubt energy will be an expensive commodity.

 

Not sure why things need replaced every 10 years, my office has its air con still working after the install date 21 years ago.

well installed and maintained equipment will last.

 

 

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7 minutes ago, Dave Jones said:

 

The problem is not just spending a fortune on a massive noisy pump to annoy the neighbours, its the massive rads needed or the cost of braking out the floors for ufh or simply insulating to modern standards. Who is going to pay for all this allice in wonderland nonsense ?

You are deflecting from the argument, you are supporting Hydrogen, a typical troll tactic.

Are you going to claim that all pipework will need to be replaces next? ASHPs cannot be used in flats, that they kill kittens and give old ladies an attach of the vapours.

 

Keep on track, read the latest research and developments in operating modern heating systems, and the cost of equipment, it is hardly new technology, been around decades.

 

  

7 minutes ago, Dave Jones said:

Who is going to pay for all this allice in wonderland nonsense

The same people that pay for energy, us.

Where do you think money comes from?

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1 minute ago, Dave Jones said:

Not sure what about hydrogen is a troll.

I was commenting on your tactic in arguing a point.

You pop us as soon as people mention HPs, and tell them they are useless, then come along with a barmy solution to justify your stance.

That is known as trolling.

Now get a grip, read some stuff and learn.

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2 minutes ago, Dave Jones said:

The chap from Worcester Bosche explains it very cleary,


Ha, yes because he is selling boilers. No mention of the National pipe network needing massive updating and the cost of producing Hydrogen as mentioned in previous posts.

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1 minute ago, SteamyTea said:

You pop us as soon as people mention HPs, and tell them they are useless,


I believe you may have had a badly designed instal which makes you believe they all are. You cannot tell me mine is useless because it’s great, cheap to run and very efficient (and I designed and installed it ?). My build was not very expensive , insulation and attention to detail is cheap.

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8 minutes ago, Dave Jones said:

Combi/system boiler. zero problem, no need for expensive tanks all over the place etc


So I can run 3 bar at point of use and get hot water to 3 taps at 8 litres / minute from a heat pump based system. 
 

Find  me a gas combi boiler that can provide 3 bar pressure and 24 litres / minute...?
 

(BTW you won’t find a domestic boiler that can do this, the maximum flow from WB largest combi (8000 Life 50kW) is 20.3l/min at delta 35°C so around 43°C delivered to save you looking and the PRV reduces it to 2.1 bar max so you won’t get close. )
 

So if we are comparing apples and apples, your combi (which is around £4K installed now for the WB 50kW) has a lower overall pressure capability and lower flow rate to what I am describing so it’s not “zero problem” it’s “you can’t get close” 

 

18 minutes ago, Dave Jones said:

My understanding this wasted excess will be turned over to hydrogen production, same at off peak times. So its essentially free. 


No such thing as free electricity... and you can’t power a heat infrastructure with a variable power source.  The U.K. has the ability to store very little of its natural gas supply so is beholden to the European pipeline interconnectors for supply. Unless you convert the whole of the European network to hydrogen, you’re needing TWh of gas storage to provide supply sureity and at the time you don’t need gas ..!! To use the hydrogen created in the summer due to excess solar (your scenario) on a November evening you wound need several million cubic metres of storage as an inter seasonal store. 
 

Localised combustion of any fuel as a reliable and environmentally friendly heat source for domestic properties is a rapidly diminishing option, and you’re hanging on to this hydrogen powered combi argument based on outdated opinion and conjecture despite being presented with facts time and time again. 

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14 minutes ago, Dave Jones said:

The chap from Worcester Bosche explains it very cleary, then again he is probably a troll as well.


He’s hilarious ..!! He’s the one that starts talking about chipboard floors and glued down carpets from memory being a reason not to fit bigger radiators...

 

This is the WB Heat Pump page btw - they are spending millions investing in the technology. 
 

https://www.worcester-bosch.co.uk/products/heat-pumps

 

Just to save you looking, they quote the following :

 

207AEA7B-C670-43B0-885E-06366C7770D9.jpeg.00a9ea1fd87e84ff86c65aad9565767a.jpeg

 

I though you said they were expensive and would fall apart ..?? And are expensive to run...?? 

 

Seems WB disagree with you too - as to 99.9997% of the population ... 


 


 

 

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25 minutes ago, Dave Jones said:

 

The problem is not just spending a fortune on a massive noisy pump to annoy the neighbours, its the massive rads needed or the cost of braking out the floors for ufh or simply insulating to modern standards. Who is going to pay for all this allice in wonderland nonsense ?

 You seem to have a bee in your bonnet with heat pumps and as some have pointed out your experiences may cloud your judgement. When you read this thread there are far more positives than negatives especially from people who have built their own house to be highly insulated with a great air test result that suit the use of a heat pump. My electricity usage was about £120 for February and it is approx 330sqm house keeping the internal temp at 21. As people have said do your homework and put in a large cylinder and you will not have any problems so to speak. I had quotes for around £12,000 to fit my heat pump but bought a 9kw Pump myself and fitted it with my mate and loads of help from people on here for around £5500. No gas connection to pay for and with regards to it being noisy you cannot tell when it is running, in fact the noise from the mvhr vents is louder than the heat pump

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If we had installed an external heat pump it would have been a big expensive mistake, for us.

 

I just don't get why they are needed in a recent self build for space heating and if installed in a earlier built properties then they will struggle to fight against lack of insulation and airtightness issues.

 

For the installation costs I would rather invest in more insulation and airtightness.

 

For hot water a small heat pump makes sense.

 

There might be some times, say a cold morning in winter when a little instant heat is required but from reviewing the capital costs, installing a external heat pump seems to be an expensive way of providing this. Add servicing and potential for problems into the equation then it looks costly to me. Servicing and installation should be considered from the point of view of the majority of the UK population who have no knowledge in this area and perhaps don't want to.

 

For existing older builds I would keep using gas or oil. 

 

For self builds, insulate to a standard that you don't need space heating.

 

If anybody has some data I would be interested to know over the course of year, for a correctly sized heat pump for a new self build, how much of the capacity of a larger heat pump is actually being utilised for a space heating over the course of a year?

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13 minutes ago, Thedreamer said:

If we had installed an external heat pump it would have been a big expensive mistake, for us.

 

I just don't get why they are needed in a recent self build for space heating and if installed in a earlier built properties then they will struggle to fight against lack of insulation and airtightness issues.

 

For the installation costs I would rather invest in more insulation and airtightness.

 

For hot water a small heat pump makes sense.

 

There might be some times, say a cold morning in winter when a little instant heat is required but from reviewing the capital costs, installing a external heat pump seems to be an expensive way of providing this. Add servicing and potential for problems into the equation then it looks costly to me. Servicing and installation should be considered from the point of view of the majority of the UK population who have no knowledge in this area and perhaps don't want to.

 

For existing older builds I would keep using gas or oil. 

 

For self builds, insulate to a standard that you don't need space heating.

 

If anybody has some data I would be interested to know over the course of year, for a correctly sized heat pump for a new self build, how much of the capacity of a larger heat pump is actually being utilised for a space heating over the course of a year?

I understand what you are saying but sometimes you do not want to just have a box purely filled with insulation. We embraced Passive but without sacrificing the looks of the house and the way we want to live. So for us a heat pump was necessary to be able to have a really warm house which needs heating from November to March (I think as we only moved in December) but yet still have very large windows and live as exactly as we would like to without the house dictating how we live.  

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17 minutes ago, Thedreamer said:

just don't get why they are needed in a recent self build for space heating and if installed in a earlier built properties then they will struggle to fight against lack of insulation and airtightness issues.

That is true for any heating system though. This is such a misunderstood point that it has become binary. 

 

19 minutes ago, Thedreamer said:

anybody has some data I would be interested to know over the course of year, for a correctly sized heat pump for a new self build, how much of the capacity of a larger heat pump is actually being utilised for a space heating over the course of a year

You need to define the question better.

If two matching capacity systems were fitted to two identical properties that where in the same climate regime, with the only difference being the fuel source, you may well get different operating hours, but that tells you nothing.

Take E7.  By its very nature it only operated up to 7 hours in any 24.

Compare that to a gas system that may run for 18 hours, or 1. You have learnt nothing about efficiency, running costs or comfort levels.

May as well ask how often a front door can be opened when buying one.

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45 minutes ago, PeterW said:

No such thing as free electricity... and you can’t power a heat infrastructure with a variable power source.  The U.K. has the ability to store very little of its natural gas supply so is beholden to the European pipeline interconnectors for supply. Unless you convert the whole of the European network to hydrogen, you’re needing TWh of gas storage to provide supply sureity and at the time you don’t need gas ..!! To use the hydrogen created in the summer due to excess solar (your scenario) on a November evening you wound need several million cubic metres of storage as an inter seasonal store. 

Important thing to note here: when you make hydrogen by electrolysis only about a third of the cost comes from the electricity, there are some pretty big costs associated with the plant, storage, distribution, etc. Even if the electricity was free, you're looking at 10p/kWh for green hydrogen once the infrastructure is fully developed. In reality it'll be more expensive, since the plant costs are so high that you won't only run them when there is surplus electricity on the grid.

 

10 minutes ago, Thedreamer said:

If anybody has some data I would be interested to know over the course of year, for a correctly sized heat pump for a new self build, how much of the capacity of a larger heat pump is actually being utilised for a space heating over the course of a year?

Fag packet maths, based on the Passivhaus standard because it's easier:

  • 15 kWh/m2/year for heating, or 10W/m2 peak load - in reality the two are usually pretty close so let's assume that the notional "well insulated" new house hits both standards.
  • Make it a fairly large house - 200m2 to make the maths easier - and assume that hot water use is also 15 kWh/m2/year which seems to be a reasonable assumption for a reasonably efficient system.
  • 3000 kWh/year for hot water, 3000 kWh/year for heating.
  • 8.2 kWh/day for hot water, plus **peak** heating load of 2kW → 56.2 kWh/day, requiring a 2.3 kW heat pump to satisfy it. Round up to 3kW.
  • COP assumed to be 3, so compared to resistive heat only the saving is ~4000 kWh/year. At 20p/kWh, that's £800/year saving from using a heat pump.
  • Even if you oversize to a 5kW heat pump, you're looking at paying £3k for a monobloc unit → 4 year payback time.
  • Assuming you did go for a 5kW unit, it would be running at full power for 600 hours/year to provide sufficient heating - just under 7% of the time - and the same amount again to provide hot water.

If you have a more efficient or smaller house - and particularly if you can use less hot water - then the payback time will get longer. I'm really struggling to see a heat pump not making sense though.

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14 hours ago, IanR said:

Why is it more expensive than Gas? I pay 12p kWh with a COP of around 4, so that's costing 3p/unit?

 

The Energy Cost Comparison below (which i think is run by Nottingham  University?) is the only one I've found that tries to compare running costs of different fuels and systems. Last time I looked they were saying raw electricity per kWh was typically 3-4 times mains gas. Combine that with the lower figure they use for the COP (2.7) and ASHP becomes much more expensive.

 

Scroll down to the table

https://nottenergy.com/resources/energy-cost-comparison/

 

Obviously it is possible to do better but it does seem to need a near perfect install.

 

 

 

 

Edited by Temp
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40 minutes ago, Thedreamer said:

I just don't get why they are needed in a recent self build for space heating

 

My house was PHPP calculated to be at the 15 kWh/m2/year energy loss threshold. In reality it's slightly better than that due to making the most of solar gain.

 

But I still need a 6.5kW heat source at times to maintain 21 degrees. ie. when it's been overcast for several days and the average temperature hasn't got above 0 degrees.

I didn't at the design phase, nor do I now feel that the peak heating demand could realistically be provided by an electric heat exchanger in the MVHR and some electric radiators.

 

54 minutes ago, Thedreamer said:

For hot water a small heat pump makes sense.

 

And combine that with the need for Hot Water, an ASHP absolutely makes sense.

 

16 minutes ago, Temp said:

 

The Energy Cost Comparison below (which i think is run by Nottingham  University?) is the only one I've found that tries to compare running costs of different fuels and systems. Last time I looked they were saying raw electricity per kWh was typically 3-4 times mains gas. Combine that with the lower figure they use for the COP (2.7) and ASHP becomes much more expensive.

 


That is based on a Big 6 Standard rate for electricity of 19.43p a unit and a 2011 "best" COP 2.7, and the result is 2.7 times more than gas.

 

At an actual 11.725p per unit of electricity and an average COP of 4, the ASHP cost comes down to 2.93p per unit - slightly cheaper than gas. 

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23 minutes ago, Temp said:

Energy Cost Comparison below

From the same website.

 

"Average prices shown are based on the supply of fuel volumes suitable for a medium-sized domestic property (around 16.5MWh of annual heat demand), quotes taken from suppliers within the East Midlands region"

 

So very limited in scope.

 

You really have to establish your own energy usage and prices.

Luckily though, a kWh is a derived unit of energy, so no need to convert that bit.

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2 minutes ago, IanR said:

didn't at the design phase, nor do I now feel that the peak heating demand could realistically be provided by an electric heat exchanger in the MVHR and some electric radiators

Don't quite understand what you mean there.

Are you saying putting a 6.5 kW heater in your MVHR outlets would not hear your house.

Or swapping your existing thermal emitter (no idea what it is) to strategically placed electric radiators would not heat the place.

 

Two points.

MVHR has, generally, too low a mass flow rate. 

The key in my previous response was 'strategically placed'. You could get very different results with only one 6.5 kW heater in a small upstairs bedroom, compared to 26, 250W, heaters evenly spaced around the house.

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2 minutes ago, SteamyTea said:

Don't quite understand what you mean there.

Are you saying putting a 6.5 kW heater in your MVHR outlets would not hear your house.

Or swapping your existing thermal emitter (no idea what it is) to strategically placed electric radiators would not heat the place.

 

Two points.

MVHR has, generally, too low a mass flow rate. 

The key in my previous response was 'strategically placed'. You could get very different results with only one 6.5 kW heater in a small upstairs bedroom, compared to 26, 250W, heaters evenly spaced around the house.

 

The MVHR has too low a flow rate to transmit 6.5kW to the house, and to provide the required heating via electric radiators would need them to be placed in more or less every room so the capital cost is not insignificant - probably similar to the cost of the UFH system (not the ASHP). 

 

In reality, I didn't consider electric radiators, or in fact radiators of any description, because I didn't want them on my walls. 

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