ASHP AND ELECTRICITY COST

[Kesoolhe]

Evening Everyone,

 

We are concerned by the cost of our electricity bills, over £200-230 per month currently. Our house is approx 280m2, we have a Panasonic 12kw t-cap moon bloc ASHP, 400 l hot water cylinder with 100 l buffer vessel and UFH throughout. The build spec was extremely high with the timber frame u value at 1.1 and rational triple glazed Alu-clad windows with Ryterna RD80 doors. 

 

What should we be roughly expecting to pay.

 

Cheers

 

Keith

 

[SteamyTea]

Seems it is running at too high a temperature.  Has the outside unit frosted up at all?

 

This has been covered a few times on here, have a search about and see if you are experience thee same problems, usually the DHW temperature is too high and it is using the built in resistance heater.

Edited May 9, 2021 by SteamyTea

[TonyT]

How should we know?

 

we don’t know how long the heating is on for, don’t know the occupancy, unit cost, what the air test result result. Etc etc

[joe90]

Also depends where in the country you are, micro climate and all that. Yours is a little larger than mine, my U value is little worse, only have double glazing and my last monthly bill was £80. Check what temp your DHW is set to, makes a lot of difference (mine is set to 48’).

[ProDave]

Even me up in the Highlands in this cold "spring" where it snows, my monthly bill is substantially less that that.

 

I assume that is a type "U value 1.1" I would hope you mean 0,11?

[Kesoolhe]

Pro Dave, yes apologies the U Value of 0.11. 

The air test result was 6, I do have quite a few holes here and there that still need to be filled once the wall lights finally arrive, COVID delays allowing of course. 
 

Our standing charge is 20.64p and unit price is 15.51. 
 

We are a family of four, 2 adults and 2 children. 
 

We’ve just increased the DHW to 50 as it wasn’t hot enough to run a bath at 45 for the Mrs lol. 
 

Climate is good in Cambridgeshire, England. No harsh weather to report here Joe. 
 

 

[JamesP]

On 09/05/2021 at 20:20, Kesoolhe said:

Evening Everyone,

 

We are concerned by the cost of our electricity bills, over £200-230 per month currently. Our house is approx 280m2, we have a Panasonic 12kw t-cap moon bloc ASHP, 400 l hot water cylinder with 100 l buffer vessel and UFH throughout. The build spec was extremely high with the timber frame u value at 1.1 and rational triple glazed Alu-clad windows with Ryterna RD80 doors. 

 

What should we be roughly expecting to pay.

 

Cheers

 

Keith

 

Hi Keith

At first glance your costs seem about right. What EPC rating is your home?

An ASHP is possibly more expensive to run than an equivalent efficient gas boiler due to the unit cost being 3 to 4 times the cost of gas.

Is your home all electric? Can you separate out the ASHP units from the rest of the house and can you then break down DHW and heating. You might be running a fan heater in your garage....

I have been running a 8.5 Ecodan in a well insulated similar size home with MVHR and Solar PV accommodating 5 adults. This sunny April the PV generated more units than last July and August which all helps reduce the electricity consumption.

For the month of July 2020 the ASHP used 140 units for DHW, no heating required and in January 2021, 242 for DHW and 421 for heating.

Anyway it is all about reducing our consumption.

 

[Kesoolhe]

Thank you James.

I guess the next step is to invest in Solar PV for the long term.

 

We do have no doors on rooms too, due to supply delays. This I’m sure is having a huge detrimental effect to the efficiency of the system. Our garage although insulated and having a Hormann LPU 42 sectional door, still has a few cold spots that need addressing. I’m hoping this will help once I’ve dealt with these too.

[JamesP]

@Kesoolhe If you do fit PV, invest in a PV diverter if your cylinder has an immersion.

[Dave Jones]

On 09/05/2021 at 20:20, Kesoolhe said:

Evening Everyone,

 

We are concerned by the cost of our electricity bills, over £200-230 per month currently. Our house is approx 280m2, we have a Panasonic 12kw t-cap moon bloc ASHP, 400 l hot water cylinder with 100 l buffer vessel and UFH throughout. The build spec was extremely high with the timber frame u value at 1.1 and rational triple glazed Alu-clad windows with Ryterna RD80 doors. 

 

What should we be roughly expecting to pay.

 

Cheers

 

Keith

 

 

for that m2 id say thats cheap. They are incredibly expensive to run compared to gas.

[NSS]

We have 165m2 with u-values of 0.14 (walls/roof), 3G windows (circa 0.7u), air test result of 1.6, 9kw Panasonic Aquarea T-Cap monobloc, 4k PV, power diverter, and our total import from the grid (no gas) is circa 5.2mW per annum (about £700). Your air test will certainly be hurting your consumption, as will having no PV, but even so £200+ per month seems high to me.

 

Oh, and we heat our DHW to 55C.

Edited May 15, 2021 by NSS

[IanR]

Is that price the average for the year, or for the last couple of months ie. March and April?

 

I also have a 12kw ASHP, which is a little oversized to the 8kw calculated, and I have 500l UVC + a 200l Buffer for the UFH. I'm around 450m^2 I think.

 

While I did put my heating back on for a couple of weeks in April, it's mostly been off since the start of March, so my current usage doesn't include heating and is around 1350 kWk for each of March and April. That's around £160 /mnth on my tariff.

 

I do have a couple of servers that run 24/7, that aren't the most efficient, so that pushes my usage up a bit.

 

I wonder if your Air tightness is effecting your energy losses, how much has your heating been on?

 

 

32 minutes ago, Dave Jones said:

 

for that m2 id say thats cheap. They are incredibly expensive to run compared to gas.

 

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

Edited May 15, 2021 by IanR

[SteamyTea]

25 minutes 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?

@Dave Jones has a hatred for heat pumps, but will never quantify his assertions.

[Dave Jones]

9 hours ago, SteamyTea said:

@Dave Jones has a hatred for heat pumps, but will never quantify his assertions.

 

their cost, drawbacks and negatives speak for themselves.

[Dave Jones]

10 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?

 

well the typical £10k heat pump installation would give you free gas for 15 years. A heat pump will be lucky to last half that time bore needing replacement.

 

Not to mention limited hot water, not working when very cold, huge electric cost etc etc

 

They will only over be a an expensive niche product for areas not on mains gas.

[IanR]

1 minute ago, Dave Jones said:

 

well the typical £10k heat pump installation would give you free gas for 15 years. A heat pump will be lucky to last half that time bore needing replacement.

 

Paid for by RHI, so not the case

 

2 minutes ago, Dave Jones said:

Not to mention limited hot water, not working when very cold, huge electric cost etc etc

 

Not a limitation I recognise - have you had an ASHP and experienced these issues?

 

3 minutes ago, Dave Jones said:

They will only over be a an expensive niche product for areas not on mains gas.

 

It's no "niche" now, and certainly won't be when Natural Gas is switched off.

[Dave Jones]

Just now, IanR said:

 

Paid for by RHI, so not the case

 

 

Not a limitation I recognise - have you had an ASHP and experienced these issues?

 

 

It's no "niche" now, and certainly won't be when Natural Gas is switched off.

 

 

No RHI when moving into a new build.

 

Yes have experience and never again, useless for a family. Workable for a pensioner maybe with limited demands.

 

Gas isn't going to be switched off, ever, its moving to hydrogen at some distant point. Worcester boilers are already hydrogen ready.

 

Heat pumps are bad for the environment, dead tech.

 

[IanR]

1 minute ago, Dave Jones said:

Yes have experience and never again, useless for a family. Workable for a pensioner maybe with limited demands.

 

I guess yours was a badly matched install then. Works fine for me with a family of 5 and 450m^2 house

 

3 minutes ago, Dave Jones said:

Gas isn't going to be switched off, ever, its moving to hydrogen at some distant point. Worcester boilers are already hydrogen ready.

 

You've not considered how much hydrogen may cost, should they ever work out how to produce it in the volume that would be required to heat homes.

 

The future will be better insulated and more airtight homes with a mix of hydrogen and heat pumps. Heat pump prices will come down, hydrogen will be more expensive than gas.

[Dave Jones]

1 minute ago, IanR said:

 

I guess yours was a badly matched install then. Works fine for me with a family of 5 and 450m^2 house

 

 

You've not considered how much hydrogen may cost, should they ever work out how to produce it in the volume that would be required to heat homes.

 

The future will be better insulated and more airtight homes with a mix of hydrogen and heat pumps. Heat pump prices will come down, hydrogen will be more expensive than gas.

 

Pretty much all the existing house stock isn't suitable for heat pumps knot to mention they are astronomically expensive which is why they need government subsidy for people to use them even in nich builds like yours.

[SteamyTea]

29 minutes ago, Dave Jones said:

Pretty much all the existing house stock isn't suitable for heat pumps knot to mention they are astronomically expensive which is why they need government subsidy for people to use them even in nich builds like yours.

You keep saying this.  But where is your evidence?

Put the wrong size system in any house and it will perform badly.

The main reason for government subsidies had little to do with the high cost of the equipment needed, if was more to boost the government at the time (Cameron's) green credentials.  It has probably increased the cost of installation, why many on here have just gone out and bought the kit and fitted it.

46 minutes ago, Dave Jones said:

its moving to hydrogen

Ah, the hydrogen economy, why would you do it.  As I have said before, it is like putting 10 gallons of gasoline in your car, then taking 4 out and pouring them down the nearest drain.

Hydrogen will be the niche product.

[TonyT]

Best insulate insulate insulate and get that air test from 6 to something of 1 or under.

 

then any heating source will cost a negligible amount to run 

[joe90]

48 minutes ago, Dave Jones said:

Pretty much all the existing house stock isn't suitable for heat pumps

You forget this is a self build forum where people build well insulated houses or recon their existing house to good levels.

48 minutes ago, Dave Jones said:

they are astronomically expensive

Not when you consider having mains gas installed into a new build plot (my heat pump was not very expensive)

48 minutes ago, Dave Jones said:

which is why they need government subsidy for people to use them

No, I had no gov subsidy.

 
P.S. mine runs very well, cheap to run and very happy with it ?

I believe they are not suited to all houses , those that are not insulated and very leaky. Also there are many installers that do not design the installation properly (several on here) which gives them a bad press.  RE hydrogen, the jury is still out on that one .

Edited May 16, 2021 by joe90

[SteamyTea]

4 minutes ago, joe90 said:

 RE hydrogen, the jury is still out on that one

Don't think it is, I posted up the government report on it.

 

Here is a bit from my favourite comic.

 

"One stumbling block any hydrogen energy revolution faces is storage and transport. Hydrogen molecules are so small they can leak out of containers, meaning pipe networks previously used for methane may have to be upgraded before they are fit for hydrogen."

 

And that is before the inefficiencies are taken into account.

It is much easier and cheaper to reinforce the local electricity grid than the gas grid.

 

I think people have a desire for hydrogen because it is similar to what we already have, but this is missing the point completely.

And if you combust hydrogen in air, you get oxide of nitrogen as well as water.  Nitric acid is not nice stuff.  Makes sulfuric and carbolic acid seem as mild as soap.

[PeterW]

1 hour ago, Dave Jones said:

well the typical £10k heat pump installation would give you free gas for 15 years.

So this isn’t like for like, you need to add the cost of a typical gas boiler, the installation of a gas supply and then the annualised servicing etc of both.  That gives you the Total Cost of Ownership. Comparing the two as you have doesn’t work unless you do this as you have compared Capex to Opex. 

 

1 hour ago, Dave Jones said:

A heat pump will be lucky to last half that time bore needing replacement.

Average life of a heat pump is far in excess of 10-12 years as there is very little to go wrong inside. As they don’t create anything corrosive or products of combustion they also don’t need anything like the servicing of a gas boiler. You can also do it yourself if necessary unlike gas. 
 

1 hour ago, Dave Jones said:

Not to mention limited hot water, not working when very cold

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. 

 

1 hour ago, Dave Jones said:

No RHI when moving into a new build.

Back to Capex - you’ve paid for it as part of the build so what’s the issue ..?  If they U.K. standard for new housing was the same as Southern Ireland and the zero carbon targets then we wouldn’t have this issue moving forward. 
 

1 hour ago, Dave Jones said:

Yes have experience and never again, useless for a family.

I guess this was a retrofit under one of the “schemes”..?? A lot of these were done by people who used to fit solar panels, cavity wall insulation before that .... and they are neither heating engineers or specialists. I’d hazard a guess it was poor design that was the issue here not the heat pump. Bit like complaining your Ford Focus can’t beat a Ferrari off the lights ...

 

1 hour ago, Dave Jones said:

Worcester boilers are already hydrogen ready.

In the lab yes, on test rigs yes, they have less than 3 years real world data of actual usage and the biggest change is changing the jet on the boiler. Been doing this for 40 years with LPG so it’s a no brainer but .... it’s not as clean as you think it is...!! Burning anything in pure oxygen is fine, it’s 2H + O = H2O plus some nice heat. Then add all the other stuff in air, the nitrogen compounds are still there, just ask TfL about this with their hydrogen buses. 
 

Your other issue is the problem of transportation and detection. You add mercaptan to natural gas to make it smell, and the reason is so you can find leaks. Our natural gas network is leaky ... but the volatility of natural gas (the nice methane mix) is much lower than hydrogen. So we will need to work out how to stop that lovely hydrogen leaking out as it’s a tiny molecule not the massive long chain hydrocarbon - welcome to the situation where you “could” use hydrogen in a standard boiler with a new jet and a pressure change, but 80% of the infrastructure to get it there would need updating. 
 

1 hour ago, Dave Jones said:

Pretty much all the existing house stock isn't suitable for heat pumps

Assertion.. Assumption..? Or a blind guess ..?? If you size the heat pump and the radiators to the heat load and heat loss of the building, then any building can be heated with a heat pump. If you don’t believe me then you may want to check what an aircon unit is and how they heat places such as exhibition centres with them and not gas boilers (hint, they are heat pumps)

 

1 hour ago, Dave Jones said:

Not to mention they are astronomically expensive

Are they ..? 9kW heat pump with all the bits is change of £4k, cheaper if you buy non-inverter. The £10k you’re usually quoting .? That’s the “MCS Premium” for installation to get RHI and it’s not rocket science to install a heat pump. As a balance, I’ve seen quotes of £3,500 to install a gas boiler into an attic plus £1500 for a new hot water tank so they are comparable in price when you consider any plumber can fit a heat pump, to work on gas you are required to be GSR. 
 

1 hour ago, Dave Jones said:

Heat pumps are bad for the environment, dead tech.

On what basis are they “bad for the environment”..?? Burning of fossil fuels is bad for the environment, and you’ve completely missed the “how to create hydrogen” issue as you need energy to split the water in the first place to fuel your hydrogen generation. So you are going to take clean energy I take it (ie no fossil fuel based generation) and then use it to inefficiently split water (which you will have to purify first, possibly even use reverse osmosis) then inefficiently compress the hydrogen (using energy generated from..??) then add the smells etc, and finally transport through an upgraded network to a property where you will inefficiently burn it to produce heat and create combustion products ..? That is environmental impact of a massive scale in terms of creation, storage and transmission of a volatile gas that still hasn’t got a fully proven long term benefit. Just so you can use that lovely box on the wall you have always been told is the only way to heat water...??
 

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. 
 

And you call my heat pump bad for the environment ..??
 

 
 

 

 

[Dave Jones]

59 minutes ago, TonyT said:

Best insulate insulate insulate and get that air test from 6 to something of 1 or under.

 

then any heating source will cost a negligible amount to run 

 

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.