Heat pump advice

Lewigreg081281

QrizB said:

Currently, mains gas is too cheap (or electricity too expensive) to make air-to-water heat pumps economically viable.

Imagine you need 12000kWk/yr of heat. Using gas at at 4p/kWh that's £480 (or £570 if you include the SC).

Heat pumps run on electricity and deliver a coefficient of performance (COP) of around 3; for every kWh of electricity you put in, you get three kWh of heat out. So that same 12000kWh of heat will need 4000kWh of electricity. At 20p/kWh that will cost you £800.

So let's look at your estimate. You're asked to pay £16000 up front (or take a loan to cover it) but will get back £200 a month, £2400 a year, for 7 years. That's £16800 *but* you're also spending £300 a year more on your energy, £2100 over 7 years. So over the period you're £1300 down. After 7 years the RHI payments stop and you're stuck buying electricity not gas.

This ignores interest payments (which will make the heat pump more expensive; their quote of £196/month for 10 years is a total of £23500).

If there are significant energy price changes (if gas gets more expensive, or if electricity becomes a lot cheaper) it could in future favour the heat pump. But you need heating now, not in 1/2/5 years time.

If you don't have mains gas but instead have oil/LPG/E7 the financial case for a heat pump is stronger. @Reed_Richards recently replaced his dead oil-fired boiler with a heat pump and reckons it's pretty close on cost.

Air-air heat pumps have a higher CoP, typically around 4, and can make sense but they aren't eligible for RHI payments (supposedly, because they can also serve as air conditioning in the summer and UK Gov't doesn't want to encourage that.) @danrv has just fitted one of these (see this thread) and we're all looking forward to seeing how he gets on during the winter.

Edit to add: most heat pump discussion takes place in the "other fuels" sub-forum, there are several substantial threads there.

Thanks. The figures were based in the below. Our tariff also ends at the end of October so it will increase. 

Our annual usage on gas Sep 20 to Sep 21 was 35965 so the £402.84 annual cost is way out from Zebra. Our boiler is probably around 10-15 year old and was in before we moved in so it won’t be great. 

I appreciate the help it just confuses me when it comes to energy. 

matelodave

I have a heat pump and have had it for eleven years. I'm very happy with it as it replaced storage heaters and the only other option was oil or lpg.

I reckon I get an average COP of around 2.5 which means that 1kwh of heat will cost me around 21.5/2.5 = 8.5p/kwh (now that Symbio have gone bust) . Even at 4p-5p/kwh gas would be still be a lot cheaper.

Take into account that a new boiler would cost around £3k compared with an out lay of around £16k (plus interest if you are borrowing the money) you'd need to get an awful lot of RHI to compensate. My installation (including underfloor hetaing cost me £14k and I my RHI payments totalled around £5k over 7 years.

TBH if mains gas became available, even at todays prices I'd probably pull it out and replace it with gas boiler and reduce my heating costs substantially. I

'd really only contemplate a heatpump if my options were oil, lpg or storage heaters

Lewigreg081281

This is what I was told today. 

 

Figures based on 7 yrs and current gas tariff ( will give you a higher saving on next tariff and further savings in April as the cap goes higher ) 

RHI - £11,200

MIT ( monitoring service ) - £1610

Energy saving- £3780

Full cost from design to installation incl p&L warranties and insurance - 

£16500 (And new radiators)

Oct Boiler Buy Back promo £660 cash back within 2 weeks of install 

Thanks 

This was the pump:

https://library.mitsubishielectric.co.uk/pdf/book/Ecodan_PUZ-WM112YAA_Monobloc_Air_Source_Heat_Pump_Product_Information_Sheet#page-1

what concerns me is I was told we get a higher RHI due to how inefficient our home is. Reading up on them you also need the home setting up often inc underfloor heating. Apparently our roof insulation isn’t great so again how great will the pump be. 

Thanks all

QrizB

Those numbers are very fishy. How can they claim a £3780 "energy saving" when you're swapping gas for electricity?

The Mitsubishi Ecodan range has a good reputation but there's definitely some creative accounting in there.

Lewigreg081281

QrizB said:

Those numbers are very fishy. How can they claim a £3780 "energy saving" when you're swapping gas for electricity?

The Mitsubishi Ecodan range has a good reputation but there's definitely some creative accounting in there.

QrizB said:

Those numbers are very fishy. How can they claim a £3780 "energy saving" when you're swapping gas for electricity?

The Mitsubishi Ecodan range has a good reputation but there's definitely some creative accounting in there.

They were basically saying our current gas cost would be halved based on our current tariff and annual usage. Olay the next appointment we’d get more accurate figures in writing. He estimated the saving to be even bigger. 

They even said if it isn’t and we’re not happy the £150 survey fee would be refunded. 

i was thinking the same as any saving we save in gas would mean an increase in electricity costs. Our current cost for this is:

Unit rate: 14.958 p/kWh

Standing charge: 21.000 p/day

 Suppose it’s also knowing the average cost to run it too. We also live right on the tops and the weather is unreal, windy and cold in winter and again reading up the seem to be less efficient in cold conditions 

chris1973

Stayed in a Airbnb during the beast from the east a few years ago, in a property heated by a ASHP. It was the coldest, most unpleasant experience of my life. Ok, it was a typical 1940's built property with just the usual double glazing , loft & cavity wall insulation etc, but so is mine and probably millions of other houses in the UK.

Unless you live in a massively insulated new build built to a plethora of Tree Hugging  EU approvals then don't bother, certainly they aren't suitable for older houses with average levels of insulation, or a stone cottage built in 1910!.

The radiators on the system I used are tiny, and barely get aired to the touch, and I don't think the system produced water temp above 47c degrees during my entire stay, in fact during the coldest night (-11c granted) the whole system shut down, flashing an 'E' number, and the owner told me it was probably too cold outside and the system had iced up!. Absolutely pointless if you can't even get aired radiators on the coldest nights of the Winter!.

I met the owner when I handed back the keys, and he admitted he had received a lot of complaints from guests about hot water not hot enough to wash dishes, and being cold during their stay because the radiators and UFH just wasn't up to the job. He even said he was no longer taking bookings during November - March because his Electricity bill was huge from having to run immersion heater back up to make the hot water hotter, and running Electric Heaters. 

Apparently the system (he had) also runs a immersion heater cycle to 65c every week burning off  even more expensive Electricity to complete a Legionella cycle. I suspect if the water this hot rocking system is producing won't even kill a bit of bacteria, its not going to be the most effective way to output heat into your home.

The Airbnb owner said that the system also has to be set to run 24/7 in order to build up and maintain any levels of background heat and heat the fabric of the building. Not sure what is 'Green' about running your heating 24/7. I run my GCH for around 6 or 7 hours a day in Winter, running 24/7 to warm the same building to the same level seems counter productive to me, if we are really saving the planet............course we are.

If you can't get a phone signal inside your new house, then you probably have internal insulation to the level where ASHP will be effective.......maybe. For people in older properties with only average levels of insulation, I seriously doubt that you will find it a direct like for like alternative for gas. But very good luck with that!.

QrizB

Lewigreg081281 said:

QrizB said:

Those numbers are very fishy. How can they claim a £3780 "energy saving" when you're swapping gas for electricity?

The Mitsubishi Ecodan range has a good reputation but there's definitely some creative accounting in there.

They were basically saying our current gas cost would be halved based on our current tariff and annual usage. Olay the next appointment we’d get more accurate figures in writing. He estimated the saving to be even bigger. 

They even said if it isn’t and we’re not happy the £150 survey fee would be refunded. 

i was thinking the same as any saving we save in gas would mean an increase in electricity costs.

So from what you wrote here your current gas use is 36000kWh/yr which is pretty high for a residential property. At 2.8p/kWh that's £1008/yr.

Let's assume (just for illustration purposes) that some of that is down to your boiler being dreadfully inefficient, around 67%, so your actual heat demand is 2/3rds of that - 24000kWh/yr. Let's also assme you get a COP of 3.

You will be buying an extra 8000kWh of electricity a year. At your current tariff of 15p/kWh that will cost you £1200/yr. You will be spending more on energy, not less.

Once your fix expires (next week!) you will most likely move to the Ofgem cap, around 4p/kWh for gas and 21p/kWh for electricity.. Those numbers become £1440 for gas or £1680 for the heat pump. You're still not making any saving.

Lewigreg081281

chris1973 said:

Stayed in a Airbnb during the beast from the east a few years ago, in a property heated by a ASHP. It was the coldest, most unpleasant experience of my life. Ok, it was a typical 1940's built property with just the usual double glazing , loft & cavity wall insulation etc, but so is mine and probably millions of other houses in the UK.

Unless you live in a massively insulated new build built to a plethora of Tree Hugging  EU approvals then don't bother, certainly they aren't suitable for older houses with average levels of insulation, or a stone cottage built in 1910!.

The radiators on the system I used are tiny, and barely get aired to the touch, and I don't think the system produced water temp above 47c degrees during my entire stay, in fact during the coldest night (-11c granted) the whole system shut down, flashing an 'E' number, and the owner told me it was probably too cold outside and the system had iced up!. Absolutely pointless if you can't even get aired radiators on the coldest nights of the Winter!.

I met the owner when I handed back the keys, and he admitted he had received a lot of complaints from guests about hot water not hot enough to wash dishes, and being cold during their stay because the radiators and UFH just wasn't up to the job. He even said he was no longer taking bookings during November - March because his Electricity bill was huge from having to run immersion heater back up to make the hot water hotter, and running Electric Heaters. 

Apparently the system (he had) also runs a immersion heater cycle to 65c every week burning off  even more expensive Electricity to complete a Legionella cycle. I suspect if the water this hot rocking system is producing won't even kill a bit of bacteria, its not going to be the most effective way to output heat into your home.

The Airbnb owner said that the system also has to be set to run 24/7 in order to build up and maintain any levels of background heat and heat the fabric of the building. Not sure what is 'Green' about running your heating 24/7. I run my GCH for around 6 or 7 hours a day in Winter, running 24/7 to warm the same building to the same level seems counter productive to me, if we are really saving the planet............course we are.

If you can't get a phone signal inside your new house, then you probably have internal insulation to the level where ASHP will be effective.......maybe. For people in older properties with only average levels of insulation, I seriously doubt that you will find it a direct like for like alternative for gas. But very good luck with that!.

chris1973 said:

Stayed in a Airbnb during the beast from the east a few years ago, in a property heated by a ASHP. It was the coldest, most unpleasant experience of my life. Ok, it was a typical 1940's built property with just the usual double glazing , loft & cavity wall insulation etc, but so is mine and probably millions of other houses in the UK.

Unless you live in a massively insulated new build built to a plethora of Tree Hugging  EU approvals then don't bother, certainly they aren't suitable for older houses with average levels of insulation, or a stone cottage built in 1910!.

The radiators on the system I used are tiny, and barely get aired to the touch, and I don't think the system produced water temp above 47c degrees during my entire stay, in fact during the coldest night (-11c granted) the whole system shut down, flashing an 'E' number, and the owner told me it was probably too cold outside and the system had iced up!. Absolutely pointless if you can't even get aired radiators on the coldest nights of the Winter!.

I met the owner when I handed back the keys, and he admitted he had received a lot of complaints from guests about hot water not hot enough to wash dishes, and being cold during their stay because the radiators and UFH just wasn't up to the job. He even said he was no longer taking bookings during November - March because his Electricity bill was huge from having to run immersion heater back up to make the hot water hotter, and running Electric Heaters. 

Apparently the system (he had) also runs a immersion heater cycle to 65c every week burning off  even more expensive Electricity to complete a Legionella cycle. I suspect if the water this hot rocking system is producing won't even kill a bit of bacteria, its not going to be the most effective way to output heat into your home.

The Airbnb owner said that the system also has to be set to run 24/7 in order to build up and maintain any levels of background heat and heat the fabric of the building. Not sure what is 'Green' about running your heating 24/7. I run my GCH for around 6 or 7 hours a day in Winter, running 24/7 to warm the same building to the same level seems counter productive to me, if we are really saving the planet............course we are.

If you can't get a phone signal inside your new house, then you probably have internal insulation to the level where ASHP will be effective.......maybe. For people in older properties with only average levels of insulation, I seriously doubt that you will find it a direct like for like alternative for gas. But very good luck with that!.

This is my concern with where we live as it is crazy in winter and is know for how windy and cold it gets. 

Our house is a 1970s at guess and the guy was commenting on how bad it was energy wise, so I was thinking once purchased they’d blame that and we’d then spend a fortune on new insulation, windows, underfloor heating etc. 

Lewigreg081281

QrizB said:

Lewigreg081281 said:

QrizB said:

Those numbers are very fishy. How can they claim a £3780 "energy saving" when you're swapping gas for electricity?

The Mitsubishi Ecodan range has a good reputation but there's definitely some creative accounting in there.

They were basically saying our current gas cost would be halved based on our current tariff and annual usage. Olay the next appointment we’d get more accurate figures in writing. He estimated the saving to be even bigger. 

They even said if it isn’t and we’re not happy the £150 survey fee would be refunded. 

i was thinking the same as any saving we save in gas would mean an increase in electricity costs.

So from what you wrote here your current gas use is 36000kWh/yr which is pretty high for a residential property. At 2.8p/kWh that's £1008/yr.

Let's assume (just for illustration purposes) that some of that is down to your boiler being dreadfully inefficient, around 67%, so your actual heat demand is 2/3rds of that - 24000kWh/yr. Let's also assme you get a COP of 3.

You will be buying an extra 8000kWh of electricity a year. At your current tariff of 15p/kWh that will cost you £1200/yr. You will be spending more on energy, not less.

Once your fix expires (next week!) you will most likely move to the Ofgem cap, around 4p/kWh for gas and 21p/kWh for electricity.. Those numbers become £1440 for gas or £1680 for the heat pump. You're still not making any saving.

Thanks. The gas usage is a concern as we only have the heating on a couple of hours in the morning and the same in the evening (when it’s cold). It’s not been on for months. We also have a gas hob too. Other than that I can’t see why it’s so high. A lot of friends are paying £90-110 and ours was at £170. 

Looks like a new boiler might be the best option 

Reed_Richards

There is nothing magical about a heat pump that means that it won't work with a poorly insulated house.  It's like any other sort of boiler, you just need a bigger output for a house that loses heat faster.  But unlike other boilers the efficiency is very sensitive to the water temperature you use in your central heating so you would almost certainly have to replace your radiators with ones with a larger surface area so you can use a lower water temperature.

We have just seen that when gas prices go up then electricity prices go up in tandem.  So although a modern ASHP might achieve an average 300% efficiency (giving you 3 kWh of heat for every 1 kWh of electricity) a gas boiler would still be cheaper to run.  However I think an ASHP may compete reasonably well with heating oil on running costs.

I have had an ASHP for 10 months and it has kept the house perfectly warm and seems to be on target to use about a third of the energy that my old oil boiler did.  It was expensive to install but the RHI payments will offset a lot of that eventually.