Does an ASHP stack up financially?

[SBMS]

Hi

A bit of context - currently about to start on a self new build - 280sqm 2.5 storey brick and block house. It’s green belt with no mains gas. North west of the UK.  
 

We are evaluating whether to go ASHP or sink an LPG tank. If we forget the install costs for ASHP which will be a fair bit higher than LPG, and the lack of ‘instant’ heat with ASHP, am I right in thinking it’s difficult to see how ASHP stacks up financially?

 

LPG prices currently hover around 35ppl to 40ppl. A litre of LPG contains roughly 7kWh of energy so equates to circa 5 - 6ppl. 
 

Assuming we averaged a COP of 3.5 on an ASHP, current electricity prices are circa 20p per kWh so energy cost for ASHP is roughly the same. But deviations in COP (especially as 3.5 would be unlikely for DHW) means it’s pretty close and LPG is likely to be more economical in the short to medium term - along with some functional advantages (instant heat, no large unit etc). 
 

My current thinking was to design the house for ASHP (oversize rads, UFH, unvented cylinder, mains electric circuit for future pump), put a 2k LPG boiler in, and only switch if LPG prices grew over electricity. 
 

I really want to go all in on this technology because burning hydrocarbons is ‘last century’ but I also want to be objective regarding the cost. 
 

Thanks in advance

Edited December 21, 2021 by SBMS

[Dave Jones]

you have no good options here. Obviously gas is the best and cheapest option but you cant get it so thats out.

 

You know the score with heat pumps by the sounds and they are a crap compromise but probably your best worst option. Add lots of solar as they are eye watering expensive to run when it gets cold and they stop working efficiently. Not to mention find somewhere to put a bunch of tanks so you don't run out of hot water, they cant heat and make hot water at the same time...

 

You will want underfloor heating everywhere to make use of the tepid water they create.

 

Cost wise, gas boiler 1k ashp 10k so no they will never pay themselves back.

 

Edited December 21, 2021 by Dave Jones

[dpmiller]

define "eye-watering" please

[ProDave]

I think most people discount an ASHP because of the high cost, and then compare the high cost of an ASHP with a £2K boiler.

 

I think most are looking at prices installed by an "ASHP specialist" at £10K or more.?  But before you dismiss that as too expensive look up the actual cost to buy an ASHP and pay a plumber and an electrician each a couple of days labour to install it.  You might find it is a lot cheaper.

 

Several of us on here have bought them cheap and DIY installed them.

 

Can't comment on likely running cost without knowing what you are building?  Something that just scrapes through building regs? or a passive house? or somethiing in between.  There is no doubt ASHP's work best with UFH throughout upstairs as well, and are better suited to low energy houses.

 

Don't forget the cylinder maintenance or standing order costs when working out the cost of LPG.

[ReedRichards]

28 minutes ago, Dave Jones said:

 

You will want underfloor heating everywhere to make use of the tepid water they create.

 

 

For best economy of operation you need the output water flow temperature to be as low ("tepid") as you can make it.  Typically that is lower for UFH than it is for radiators so if you mix the two you don't get any economic benefit from the UFH.  

[joe90]

Welcome @SBMS, unfortunately @Dave Jones must have had a bad experience with an ASHP as he is very negative about them, and don’t we know it? however there a quite a few here that have them and are very happy with them. Yes they are not like gas and produce hot water slowly but if designed correctly work very well. For example my house is well insulated but not quite passive levels and my 5KW ASHP keeps the house at 21’ with UFH downstairs only and a couple of electric towels rads upstairs. You will need a larger DHW tank and mine is full of 48’ water which is too hot to shower under and quite adequate fir all other uses. Mine can hardly be heard. Yes teamed up with PV would be a good as well. I bought my ASHP on EBAY cheap and installed it myself. Others will be along shortly with their experience.

[IanR]

49 minutes ago, SBMS said:

LPG prices currently hover around 35ppl to 40ppl. A litre of LPG contains roughly 7kWh of energy so equates to circa 5 - 6ppl. 

 

Can you still get LPG at that price? Local to me it looks around 67p a litre.

 

Day to day running costs for ASHP are lower than Oil and LPG typically, but not if you can currently buy LPG for under 40p per litre. If you can then LPG for you will be a similar cost (day-to-day) or slightly cheaper, at the moment.

 

The Government have stated they will move the Green Taxes from Electricity to Fossil Fuels. Currently there are 22% green taxes on Electricity, so this will move further in favour of Electricity, however they've only said it will be done this decade, so may be a gradual change.

 

Off-gas-grid, fossil fuel boilers are the low hanging fruit that will become the first victims of the move to Net Zero. iirc the plan is to ban their replacement from 2026.

 

Across the year a well spec'd ASHP costs the same to run as a gas boiler in respect to day-to-day running costs.

Edited December 21, 2021 by IanR

[nod]

49 minutes ago, SBMS said:

Hi

A bit of context - currently about to start on a self new build - 280sqm 2.5 storey brick and block house. It’s green belt with no mains gas. North west of the UK.  
 

We are evaluating whether to go ASHP or sink an LPG tank. If we forget the install costs for ASHP which will be a fair bit higher than LPG, and the lack of ‘instant’ heat with ASHP, am I right in thinking it’s difficult to see how ASHP stacks up financially?

 

LPG prices currently hover around 35ppl to 40ppl. A litre of LPG contains roughly 7kWh of energy so equates to circa 5 - 6ppl. 
 

Assuming we averaged a COP of 3.5 on an ASHP, current electricity prices are circa 20p per kWh so energy cost for ASHP is roughly the same. But deviations in COP (especially as 3.5 would be unlikely for DHW) means it’s pretty close and LPG is likely to be more economical in the short to medium term - along with some functional advantages (instant heat, no large unit etc). 
 

My current thinking was to design the house for ASHP (oversize rads, UFH, unvented cylinder, mains electric circuit for future pump), put a 2k LPG boiler in, and only switch if LPG prices grew over electricity. 
 

I really want to go all in on this technology because burning hydrocarbons is ‘last century’ but I also want to be objective regarding the cost. 
 

Thanks in advance

We are building a similar size house over two floor No gas Oil no longer an option 

Tank gas or Heat pump 

We’ve decided on a heat pump 

 

On our previous build we had gas next to the plot and chose gas Much cheaper option and cheaper to run also 

[SBMS]

Thanks ProDave. I’m trying to compare them like for like and we are building well insulated. Like for like both energy sources are going to have to provide the same level of input energy so I’m just considering the functional and financial sides to the two technologies.  The LPG standing charges are fairly low - we’ve been paying £60 per annum for last 5 years with previous supplier. 

joe90 - if you were being completely objective, assuming that LPG were the same cost but  ASHP has higher install costs and I guess arguably were functionally more restrictive (even if that functionality is never used - because you’ve got a good setup), what would you say were the reasons for choosing ASHP in this scenario?

 

Ianr - yes my parents just signed a 2 year deal with extragas at 38ppl. I agree that there’s a political argument to go ASHP in the event green taxes increase on LPG.  In all likelihood I would suspect levies are focused on mains gas; LPG makes up such a tiny fraction of usage in the UK - and bearing in mind off grid properties are already limited in energy choice, I think it will be targeted last. But it’s certainly a point to consider and hence my covering by having a system that ASHP could be slotted into.  But for the next 5 years say, does ASHP make sense?
 

I guess what I am trying to cut through is the subjectivity around the topic (there’s a lot!) and for a well insulated, new build is there a compelling reason that I’ve missed to go with ASHP over LPG. 

[joe90]

14 minutes ago, SBMS said:

joe90 - if you were being completely objective, assuming that LPG were the same cost but  ASHP has higher install costs and I guess arguably were functionally more restrictive (even if that functionality is never used - because you’ve got a good setup), what would you say were the reasons for choosing ASHP in this scenario?

Even when I was planning this build a few years ago I wanted to get away from fossil fuels because of global warming . Perhaps I was lucky to find a (new) cheap ASHP on EBay . Then  I installed the ASHP myself and even designed the heating myself (with lots of help on this forum) didn’t fancy the large tank buried or not and standing charges (which a lot of people forget when comparing gas). I like the fact that an ASHP is basically fridge technology and that’s been around fir years with no major issues. Unlike me there are lots of clever bods here  that understand all the maths related to the subject, but mine works and I am very happy with it. The water is not tepid. Works fine even when the weather is cold and is not noisy.

Edited December 21, 2021 by joe90

[patp]

I think that ASHP's should always be paired with Solar (or wind/water). I cannot understand the Government pushing ASHP's without subsidising solar panels alongside them.

[joth]

32 minutes ago, SBMS said:

for a well insulated, new build is there a compelling reason that I’ve missed to go with ASHP over LPG

If your build is insulated and airtight enough, you might not need to do either. A lot of folks on here find direct electrical heating (Willis immersion heater with wet UFH, or plug in radiators) is sufficient.

 

280m2 is fair size - how many people will normal live there? If a large family, with all the bodies and cooking and XBoxen, not a lot of extra heat is required. If it's 2 people you'd need more.

 

Overall, the lower the annual heat demand, the less financial sense there is on investing in higher efficiency heat sources. 

 

There is a new £5k grant on ASHP coming in in April, but seems unlikely it will apply to new builds. But at least you get the VAT saving 

 

[nod]

I recently visited the build show at Harrogate The HP suppliers seemed to think the grant for new properties would be reduced to £1500-2000 Which is a shame 

Accompanying us was friends who have recently completed there third self build 

They are on tanked gas and bitterly regret it  They think that running costs will be at least a third more than piped gas 

[joe90]

2 minutes ago, nod said:

They think that running costs will be at least a third more than piped gas 

But bottled gas has always been more expensive than mains gas!

[nod]

1 minute ago, joe90 said:

But bottled gas has always been more expensive than mains gas!

Yep

We couldn’t understand there decision 

The hearing -Electrical contractor convinced them that the PV would pick up the slack 

It hasn’t 

[Marvin]

1 hour ago, SBMS said:

 is there a compelling reason that I’ve missed to go with ASHP over LPG. 

Hi SBMS

 

Having renovated our bungalow 4 years ago and installing an LPG boiler at the time, and then converting to an ASHP this year, I would say that if you are going to "leave the door open" for a future ASHP you'd better do a dummy run of the requirements before hand and prepare, because retro fitting one through your new building could be a right pain in the backside. 

 

@joth is of course completely right.  Your only fighting to keep the heat in. If the building is resistant enough you can get away with very little heat. The additional cost of insulation and airtightness versus the cost of installing and running heating means that as my brother says either way you pay. But the difference is if you stay to reap the rewards. The ASHP, MVHR, PV and EV combo suits us.

 

[SBMS]

29 minutes ago, nod said:

I recently visited the build show at Harrogate The HP suppliers seemed to think the grant for new properties would be reduced to £1500-2000 Which is a shame 

Accompanying us was friends who have recently completed there third self build 

They are on tanked gas and bitterly regret it  They think that running costs will be at least a third more than piped gas 

The current draft regulations seems to specifically include self build properties, see regulation 7 in the DES’ draft legislation for the boiler upgrade scheme:

 

Requirements for new-build properties
7. A property meets the requirements in this regulation where—
(a) any building that forms part of that property was built principally with the use of the labour or resources of the first owner (including where the resource was a loan which the first owner was liable to repay), and
(b) the property has not, while the building was built or at any subsequent time been owned wholly or partly by a person who is not an individual.

 

from:

 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1040470/Draft_Boiler_Upgrade_Scheme__England_and_Wales__Regulations_2022.pdf

 

so it does look like 5k grants are available for self builders, just not property developers. Would welcome anybody else’s interpretation of the regulations!

[SteamyTea]

50 minutes ago, patp said:

I think that ASHP's should always be paired with Solar (or wind/water). I cannot understand the Government pushing ASHP's without subsidising solar panels alongside them.

Subsidies, grants, incentives etc are there to help the transition from fossil fuels. They are really designed to help the manufacturers and installers, not the end user.

It is, and not in hindsight, a shame the the original FiTs was so generous to the end user. This has had a negative affect in future purchases of not only PV, but also micro thermal generation.

So linking grants (or whatever) for HPs only if another renewable technology is installed will kill the market dead.

The biggest problem is that the general public still think that solar and wind farms cost several times more than the equivalent gas generation. This was true 15 years ago, but they are now the cheapest options (UK windpower would be even cheaper if we installed on land, but our new agricultural policy has stopped that, as did the previous policy with the moratorium on land based windpower).

 

What will change people's minds is legislation. When you only have the choice of electrical, the choice is resistance or heat pumps.

[SBMS]

30 minutes ago, joe90 said:

But bottled gas has always been more expensive than mains gas!

Ironically at the moment LPG is sitting around 5.5ppl and mains gas Is around 4ppl - on govt price cap so a third more sounds right. Come April, will the price cap shift mains gas nearer to LPG levels? Average standard mains gas charges are 20-25p per day equates to £70-90 per annum, same as standing charges for LPG tank. 

[ReedRichards]

Apart from the standing charge for the LPG tank, will you have to pay to get it removed when you eventually have to?  Would you get a low temperature LPG boiler?  Will you provision for an "airing cupboard" in case you need a hot water cylinder at some time in the future?  

[Andehh]

2 hours ago, Dave Jones said:

 

 

You know the score with heat pumps by the sounds and they are a crap compromise but probably your best worst option. Add lots of solar as they are eye watering expensive to run when it gets cold and they stop working efficiently. Not to mention find somewhere to put a bunch of tanks so you don't run out of hot water, they cant heat and make hot water at the same time...

 

You will want underfloor heating everywhere to make use of the tepid water they create.

 

Cost wise, gas boiler 1k ashp 10k so no they will never pay themselves back.

 

 

I'm not sure I agree with any of that!

 

For our new build, £14k for a full plumbing + ASHP installation vs £11k for Gas boiler from our builder. Have mains gas as an option but both builder & architect strongly encouraging ASHP,  hoping with the £5k grant to smooth the transition. My research suggests they are entirely appropriate for certain properties, entirely inappropriate for others - our new build being an ideal case for ASHP.

 

Whilst no expert in heating systems, I am a Mechanical Engineer with a career in Energy Sustainability - long term Electricity is the answer -vs- Fossil fuels, from a political point of view (Russia & OPEC) from a sustainability point of view (cheap Renewables & self generation). Throw in storage & Nuclear and 'green government taxing fossil fuel' vote winning its a no brainer over the next several years. Hydrogen is a laughably hopeless cause for anything other then large industrial equipment.

[SBMS]

14 minutes ago, ReedRichards said:

Apart from the standing charge for the LPG tank, will you have to pay to get it removed when you eventually have to?  Would you get a low temperature LPG boiler?  Will you provision for an "airing cupboard" in case you need a hot water cylinder at some time in the future?  

Good point regarding the tank removal charge - especially if we are sinking it. Would likely have to buy it off the provider. I would provision for a system LPG boiler with an unvented cylinder so that at a later date only the heat source (boiler) were switched out. Would a cylinder for a gas boiler be compatible with an ASHP or would that need replacing too?

[SBMS]

1 minute ago, Andehh said:

 

I'm not sure I agree with any of that!

 

For our new build, £14k for a full plumbing + ASHP installation vs £11k for Gas boiler from our builder. Have mains gas as an option but both builder & architect strongly encouraging ASHP,  hoping with the £5k grant to smooth the transition. My research suggests they are entirely appropriate for certain properties, entirely inappropriate for others - our new build being an ideal case for ASHP.

 

Whilst no expert in heating systems, I am a Mechanical Engineer with a career in Energy Sustainability - long term Electricity is the answer -vs- Fossil fuels, from a political point of view (Russia & OPEC) from a sustainability point of view (cheap Renewables & self generation). Throw in storage & Nuclear and 'green government taxing fossil fuel' vote winning its a no brainer over the next several years. Hydrogen is a laughably hopeless cause for anything other then large industrial equipment.

This is really interesting - is this a recent quote? A 3k price differential in capital outlay is certainly compelling. We are not at the quoting stage yet so perhaps my assumption that ASHP install costs would be 5-10k higher than gas are simply wrong. Are you currently building?

[Temp]

2 hours ago, SBMS said:

LPG prices currently hover around 35ppl to 40ppl

 

Are you sure..

https://www.globalpetrolprices.com/United-Kingdom/lpg_prices/

69.3p/L

 

As for running cost comparison.. the only Web site I know that does a half decent job is here...

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

Scroll down to the table and see "Pence per kWh (after boiler efficiency)"

 

 

 

[Iceverge]

Pondering heating systems can be like pondering how to climb Everest from base camp for self builders. Its impossible to know the exact best route without first knowing the best route. 

 

I gave nights upon nights considering this. I came to the conclusion that there is no two houses alike and even if there were, no two sets of occupants would behave the same. Calculations and modelling only go so far.

 

Objective data is impossible to find, every consumer with a novel system thinks their own goose a swan. Every installer is prejudiced by familiarity and margin on installation. Every salesman only wants to pander their wears. I got so fed up with all this going around in circles I decided not to install any heating at all. Bold, rash, stupid, maybe, but if we were going to part with heaps of our cash I wanted to be sure. 

 

We built to passive house standards, a little beyond in theory. Put a direct UVC for DHW on night rate electricity. I borrowed a 2kW electric heater, plugged it in in the hall, and got to work regularly recording the electricity meter and feeding the results into a spreadsheet. Over a few months it was possible to isolate the DHW usage and now I'm working on the space heating. By March I'll have a full year of data of exactly our usage, to the kWh. No guesswork, no modelling estimates, just two numbers. DHW and space heating.

 

So far DHW 10kWh/day for 2 adults and 2 small children. Space heating is broadly in line with PHPP, maybe slightly more. I must get a thermal imaging camera to check for any weak thermal spots. Also it's been very dull. I'll know more soon.  I have aims for an A2A heat pump and solar PV. When I have my exact usage I'll be able to estimate if they're worth it. 

 

In hindsight I think we should have installed UFH pipes and run them from a Willis heater. While my current radiator was free, anything that I'd actually like to look at in the house permanently certainly isn't.  Also , half our heating is on expensive day rate electricity. With UFH and a willis heater we could shift it all to cheap night rate with the slab as a storage heater, like @TerryE

 

It wouldn't have been much hardship to get an UVC with a heat pump coil to futureproof also.   

 

 

TLDR:

1. Pathologically minimise your heating demand in design and construction stage.  

2. Install UFH + willis heater  and a heat pump compatible UVC. 

3. Run your house for a year on E7. 

4. Use the data to make the best decision. 

 

 

 

 

 

 

 

 

 

Edited December 21, 2021 by Iceverge
Punctuation