Octopus Heat Pump

[Michael GilliganParticipant @michaelgilligan61133]

Some useful guidance here:

https://octopus.energy/heat-pump-help/hot-water/

🙁

We may struggle to accommodate all that in my little house

’though I do have an electric shower, so won’t need a big  tank

MichaelG.

[Dave WoottonParticipant @davewootton]

Michael

Our installer found us a tall thin hot water tank that fitted in quite a small footprint with the expansion vessels above it, another alternative is a horizontal tank that can go in the loft space, worth researching. We have only a small tank as there are usually only two of us and we have a shower room instead of a bath, and it has been perfectly adequate. It does look rather like something out of a 50’s sci-fi film in our airing cupboard!

 

[Michael GilliganParticipant @michaelgilligan61133]

[Michael GilliganParticipant @michaelgilligan61133]

Thanks for the info, Dave

When I chatted with Henry, he did mention a slim, but tall tank … which would better suit my available location.

MichaelG.

[MacolmParticipant @macolm]

Is storage at 50C adequate to prevent growth of legionella?

[Michael GilliganParticipant @michaelgilligan61133]

Good question … Various weaselly assertions are available, but it’s something that rather worries me.

MichaelG.

[Mark RandParticipant @markrand96270]

Theoretically, you need 60°C to kill legionella. I’ve run the tank at 50°C or less for 40 years and have no intention of changing. 😀

[John MCParticipant @johnmc39344]

Whats the incentive behind fitting a heat pump?   I fitted solar panels in pre SEG days so benefited from the FIT payments.   Back then “pay back” was all important, and over a reasonable time span, around 8 years for me, at least double that now, based on what I paid.

I’m watching HP developments closely with a view to, eventually, replacing my existing solid fuel setup.  As far as I can tell, “pay back” will never happen.   I’m gradually upgrading insulation, expensive but it does benefit any heating type.

Does anyone have some realistic running costs for a heat ump system.  I say realistic because with solat panels I’ve seen some unrealistic claims, virtually free electricity, pay back within 2 – 3 years and so on.   The same with heat pumps.  Speaking to a couple of users who can be relied on to be realistic, both say “about the same as before”, one had gas, the other soild fuel.

So, persuade me…

[Adrian R2Participant @adrianr2]

Heat Geek mini store is apparently designed to work where installation space is limited. It is backwards compared to a normal hot water cylinder in that the heat pump heats the tank and water to be used passes through. Not cheap standalone but might be cost and space effective as part of a complete install.

Heat Geek Mini Store

My son’s place has a heat pump. Can’t compare it to anything directly as it was installed as part of a full renovation by a previous owner but his electricity bills (no gas, no solar, no battery, no ToU tariff) have been less than quoted examples for dual fuel in an “average” small house. His service engineer said not to worry about legionella as the water you use comes treated from the mains and is only stored short term in a sealed dark tank.

[Dave WoottonParticipant @davewootton]

I think it’s once a week the heat pump is programmed to raise the hot water temp for a short while to kill off any bugs, happens in the night, might be twice a week.

[David JuppParticipant @davidjupp51506]

Re legionella, our heat pump system does a boost cycle for the HW cylinder once a week – heat pump on full, boosted by immersion heater to hit 60°C for an hour.

Re running costs – based on some rough assumptions about our old gas boiler (non-condensing, so not very efficient), estimated CoP for heat pump, and cost of gas vs electricity and looking at historic gas usage, I concluded that the combination of losses in old gas boiler, and CoP for heat pump would roughly match the multiplier for cost of electricity over gas (per kWh) – i.e. actual running cost likely to be similar.

The fact we had to upgrade loft insulation to qualify for the grant probably improved the numbers somewhat.  Capping off the gas and hence saving the standing charge also helped a bit.

If UK retail electricity costs ever reflect the generating mix, rather than wholesale gas price – the running costs might start to look better.

We had solar panels & battery storage fitted just before the heat pump, so our actual bills have dropped – but that required more capital up front.  We are quite lucky with the roof orientation, so the solar does make a big difference.

[Michael GilliganParticipant @michaelgilligan61133]

[Michael GilliganParticipant @michaelgilligan61133]

P.S.

That was the incentive … but the survey in October will inform the decision.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

[ Quiz Time ]

There are some very clever people on this forum, so I’m hoping that someone will be interested in this little puzzle:

Having lived in the bungalow for a full 4 years, I have used a total of  6600 litres of Heating Oil

The price has varied, but if normalised to my last purchase that would represent £9397.08

Treating the house as an ‘unknown constant’ in your analysis … What can we deduce about Life, the Universe, and Heat-Pumps ?

MichaelG.

[duncan webster 1Participant @duncanwebster1]

Veering off topic a little: we keep being warned of the electricity and cooling demand of data centres. These do not produce noise or other objectionable side effects, so build them in residential areas and use their rejected heat to heat the houses/flats. At the least it could be a cold source for a big centralised heat pump system, which would significantly improve the COP

[BazyleParticipant @bazyle]

Michael – your expenditure is over 2k per year and assuming you only need heating 150 days per year that is roughly £15 per day. At full rate electricity that is 100KWh per day. You could sit al day in front of a 1Kw electric fire for £8 though you would have steam coming out of your ears as the living room reached 100C with that much power input.
1KW into a heat pump all day would give you 3 times as much so 75KWh per day.

Putting this into BI (Bazyle’s Intelligence) instead of AI yields the advice that you need to stop heating the entire house and cut down to one or two rooms ie the workshop and the kitchen.

[mgnbukParticipant @mgnbuk]

Veering off topic a little: we keep being warned of the electricity and cooling demand of data centres. These do not produce noise or other objectionable side effects,

You might want to look further into that – seems those living next to them don’t agree ?

[Grindstone CowboyParticipant @grindstonecowboy]

(Roughly) on the data centre topic, I find that using my computer – and 3D printer – in the living room raises the temperature noticeably. Good in winter, not great in summer.

Rob

[Michael GilliganParticipant @michaelgilligan61133]

[Martin of WickParticipant @martinofwick]

If bazyls calculation is right (my electricity is near 30p a unit),  £15 a day fuel usage is out of order. As said, you would be better off just junking the lot right now and just use electricity (even before considering efficiency measures or even off peak tariffs and night storage).

ps. Have you checked your oil tank and supply lines for leaks?

[Michael GilliganParticipant @michaelgilligan61133]

[BazyleParticipant @bazyle]

Eeeeek Martin is right. My calculation somehow got a factor of two out in part of the estimate. So the £15 in electricity gives you 45KWh but the 1KW fire is still only £8 per day and is hopefully more than you need. It does depend on the house design. Often a bungalow has a living room across one end so 3 outside walls, and two bedrooms the other end each with 2 outside walls. In the middle are perhaps various other bits like kitchen and dining room. So if you can use the dining room as a winter living room you might have only one outside wall with much of the heat going to other rooms to keep them aired.

This is making me think of the possibility of a mini-split to heat/cool my dining room where I also have my computer, TV, and 3D printer.

[Peter Cook 6Participant @petercook6]

To what extent are you locking yourself into Octopus as an Energy supplier?

The website says “All three are designed with smart remote updates, diagnostics and work with our Cosy tariff.”

What happens if you want to switch energy suppliers?

 

[Michael GilliganParticipant @michaelgilligan61133]

[Adrian R2Participant @adrianr2]

If hypothetically you moved away from Octopus then you’d have to program the devices yourself to match the new supplier’s tariff, assuming that is also a time of use. Worth checking that they have that capability, and also that they do not rely on any tied internet services to continue basic operations. Using such services for monitoring and convenience is fine.

 

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