oil to air source heat pump

toadhall

Our oil boiler has just been condemned after 20 years good service. The parts are no longer available. OH is now looking at the option of an air source heat pump instead. Given the price of oil at the moment would anyone have any info on switching or any advice if you have one.
thanks

lohr500

We looked at doing the same last year. Had an old 36kW non condensing oil boiler that was over 30 years old. Like yourselves it was proving increasingly difficult to keep it running due to spare part availability.

We had a full survey done to look at switching to an ASHP. Because of the size and age of the property, it would have involved upgrading many of the radiator sizes and installing a 3 phase electricity supply to power twin ASHP units. Cost to convert was going to be £22k. At the time, we would have been eligible for the much higher value Govt grant that was then available. The calculations made by the specialist team estimated we could have got around £11 to £12k in grant payments if I recall correctly, paid in quarterly instalments over 7 years.

When I went through the numbers, from a cost saving point of view it just didn't make sense based on the relative cost of oil and electricity back then. I also had concerns over the grant structure as it involved paying upfront for the whole cost and then receiving the grant payback over seven years. With the added risk that if we decided to move house within the seven year window, the balance of the grant payments would have gone to the hew owners, not ourselves.

Looking back, and considering energy prices now, I am glad we didn't go ahead.

Our new oil boiler (Grant Vortex Blue 36kw External) has a claimed efficiency of 94.5% vs the old one which was 70%.
In reality I don't think the old one was that efficient.

Based on today's energy prices, with oil at £0.88 per litre and the EDF April capped electricity rate of £0.27 per kWh, I see the numbers looking like this :

1 litre of oil yields 10.35 kWh at 100% efficiency.
With a boiler efficiency of say 90% and oil at £0.88 per litre, this equates to £0.094 per kwh. 

The efficiency of ASHP centres around the COP figure which gives an indication of the efficiency gain. A COP figure of 3 would indicate that for every 1kwh of energy input, you get 3 kwh of heat out.

If you had an ASHP that could deliver a COP of 3 or more in the real world then the ASHP would deliver a lower heating cost per kwH than oil.

£0.094 for oil vs £0.27/3=£0.09 for the ASHP.

My understanding though is that the COP figure reduces with reduced external temperature. The very time when you probably want most heat in the house. So even the latest generation ASHP units with quoted COP figures of +/-4 probably won't be that efficient in winter.

Then factor in the likely movement in energy prices over the next two years. The predicted October cap is going to increase the cost of electricity significantly, with further rises predicted going forward. 

Who knows what will happen to heating oil prices, but my gut feel is that as kerosene is linked to the oil price and widely used in aviation as well as home heating, it won't increase at the same rate as electricity. Prices have softened over the past few months. 

But longer term I have no idea what the relative costs of electricity and heating oil will be.

All I do know is that if the cost per kwh of heating is broadly the same using today's electricity and oil prices, then I would stick with oil every day.

Our new Grant boiler came with a 10 year parts and labour guarantee, costs less than £100 for an annual service and is relatively simple compared to an ASHP. Total cost to replace our ancient oil boiler, including rerouting some pipework and changing the whole system to a valve controlled Y plan configuration was just over £5000. This also involved placing the new boiler externally, feeing up space in our kitchen.

From memory, the initial quote for a 17kwh ASHP system was £17k, but that was before the survey concluded we would need twin ASHP units and a 3 phase supply which bumped the cost to £22k.

In our case, if you took the lower cost estimate of £17k and knocked off the new £5k grant, it would cost £12k to switch to an ASHP today. Compare that to the £5k to replace the oil boiler.

With no apparent payback in energy savings at today's prices and the probability of the relative running cost of an ASHP increasing vs oil in the next few years, then I can't see the sense in moving away from oil.
Add to that the peace of mind of a 10 year Grant warranty with low annual maintenance costs and I would make the same decision to stick with oil every time.

Others will have different views, so don't base your decision solely on my input. But I hope it helps.     


 

dunstonh

Properties on oil tend to be older ones in rural area.  Often this raises the costs of installation of heat pumps. Not because of the pump itself but other work needed to make the heat pump effective.

Electrical system, insulation of walls and floors etc.  Windows and doors replaced, larger more efficient radiators, repairs and redecoration of things that cause visual damage.  Some of the things may not be necessary for your property but the more things that are required, the greater the cost will be.

And don't forget that heat pumps eat electricity.  Electricity is high and going to get higher.  So, if you are looking at this from a cost issue, the likely best option for the next 20-30 years is a modern oil boiler and change any older inefficient radiators to more efficient ones (decent modern radiators can be 50% more efficient than those from 2000).  We recently removed two old low-quality radiators in a room and replaced them with a single larger aluminium one with better heat output but less water needed to achieve it.  Heating less water to achieve similar output reduces your oil use.

QrizB

toadhall said:

Our oil boiler has just been condemned after 20 years good service. The parts are no longer available. OH is now looking at the option of an air source heat pump instead. Given the price of oil at the moment would anyone have any info on switching or any advice if you have one.

@Reed_Richards did exactly what you're considering about 18 months ago. He has a thread here which you might find interesting. Towards the end of the thread he compares his costs on oil vs. the heat pump; he seems to be roughly breaking even, although it does depend on the relative costs of oil vs. electricity.

matelodave

It worth re-doing the sums based on the forecast cost of oil v the forecast cost of leccy to see how it will compare. This time last year I was on a very favourable electricity tariff and my total bill for the year was a gnats under £1000, at present the equivalent is around £2300 and come October I'm bracing myself for it to approach or even exceed £4000 and thats using the same amount of energy

You'll also need to factor in the upfront cost of converting/upgrading your heating system to suit a heatpump compared with just replacing the oil boiler. 

catclaires

Agree with a lot of the points being made above. We also looked into an ASHP just under a year ago to replace the elderly oil boiler in our new house and found the costs (almost £20K in total – we had three very similar quotes) prohibitive, not to mention the disruption, as we would have needed not only new radiators but new pipework to replace our current microbore. We had really liked the idea and had set money aside but just couldn't bring ourselves to commit to that cost. At the time, it was touch and go if we'd be able to get it done in time to get the old payback grant (which was estimated at around £7k for our house so not a million miles off the new £5k one anyway). The cost of electricity at the moment is definitely food for thought – much more than when we were looking.

If/when our boiler goes – we know it's at least 22 years old, so I do feel that it's on borrowed time! – I am pretty sure we'll be replacing it with a new condensing one. In the meantime, we are in the process of getting solar panels installed (the other big part of our original 'green' plans for the house) and also have a new log burner in the hope of using less oil this winter and also having some heat in the event of another Storm Arwen multi-day power cut!

orbit500

Think more like 2.3 SCOP and 55p electric: that’s 24p vs 9p and the hardware is 5 times the cost. Lunacy to even consider it.

Reed_Richards

orbit500 said:

Think more like 2.3 SCOP and 55p electric: that’s 24p vs 9p and the hardware is 5 times the cost. Lunacy to even consider it.

Seems to me like it's highly sane to evaluate the various options.  If heating oil is less than £1 per litre and your oil boiler is 90% efficient then you would be paying less than 11p per kWh.  I can just beat that now with my heat pump but probably not come October when electricity prices rise again, unless that has a knock-on effect on the price of heating oil.

gm0

>10-15 year capital investment.  Very uncertain future. 

In that period the UK needs to (will ?) invest heavily in significant additional electricity generation in part to enable gas and other fossil to ramp down. Which needs paying for.  As does the flow through - slower up, slower down - on the current cap extended financing.  So electricity returning to very cheap levels is unlikely.  But oil as domestic heating needs to go in the end to address carbon targets/warming goals. And that will inevitably happen via financial disincentives above and beyond market price for kero at some point.  There may be a fossil dip when wars come to an end or OPEC may smooth it out so high prices remain sticky.  Either way oil will be expensive too.  And government will nudge us in the end.  Here is the green energy grant albeit with all the strings. Oh and here is a new emissions aka oil levy to hurry you along.  Not yet but in the lifecycle of boilers going in now.  Quite possible.

Investments in lowering heat demand in your building are a no brainer

Of course heat pump technology is still evolving and new coolant and pressure options arriving from commercial settings first will make their way to domestic over a few years (to get to scale) and may improve achievable cop at higher temp for radiators in older and rural property with no practical way to retrofit a pad and low temperature UFH.  This moving target point argues for a delay in capital expenditure and adoption for people with that particular set of limitations (big building, rads, high peak demand). 

As I understand it the new ASHP nudge in the form of a grant doesn't let you do a hybrid solution where the oil boiler is kept alongside a smaller than peak sized ASHP for backup - a solution which from an operational and engineering point of view is what I prefer (for my particular building based on it's constraints) - at least based on current tech.  It is not acceptable for the new (expensive) solution to result in being cold.  So a single solution must be sized for peak (or thereabouts - light the fire, tactical use of oil filled radiators).

With oil still present the ASHP could be downsized.  This issue also relates to the deployment of car chargers and what in aggreagate will fit within a domestic single phase 100A supply.   Revisiting electricity supply in a rural setting can cost tens of thousands on its own.  DNO's love a new supply request as a way to pay to renew life expired but still energised infrastructure.   So it can be a hard project constraint in practice.

When it's damp and rather cold  by UK standards and the ASHP struggles to meet demand and gets into reversing and deicing i.e. COP plummets and electicity usage is up.  A kero solution can be cut in and the now moderately inefficient electricity solution off.    But this is a lot more capex and servicing to have it alongside.  The grant issue restricting this design as unsubsidised makes the situation less attractive again. 

toadhall

thanks for all the comments. We are having some surveys done, getting an up to date EPC and will go from there. Also now been told that the oil tank will need replacing too and since there are now new regulations I cannot just replace it to the same place
the costs are spiralling for both

dunstonh

toadhall said:

thanks for all the comments. We are having some surveys done, getting an up to date EPC and will go from there. Also now been told that the oil tank will need replacing too and since there are now new regulations I cannot just replace it to the same place
the costs are spiralling for both

My understanding is that the changed regulations for tanks only apply if you need to change the tank.   They do not apply if you are only changing the boiler.    The engineer will tell you that the tank doesn't comply with current regs, but you are not compelled to change the tank.   

Is your current tank damaged or at risk of failure?