Heat pump advice

wittynamegoeshere

I'll just echo the comments from a few posts ago... we're currently considering a heat pump but only because mains gas is not available here.

If gas was available I wouldn't bother looking at a heat pump, just get gas and hopefully heat pumps will cost £1000s less next time around, once they're more normal.

The govt was talking about shoving hydrogen down the gas pipes. I don't know how practical this would be - probably not very, but it shows that this or other currently unheard of options may emerge in the future, perhaps heat pumps are just a step on the way to something else?  Perhaps we'll all have a nuclear generator in the cupboard under the stairs.

Gerry1

What does 'MIT ( monitoring service ) - £1610' mean? Is it a cost or a benefit?

Lewigreg081281

Gerry1 said:

What does 'MIT ( monitoring service ) - £1610' mean? Is it a cost or a benefit?

It’s a benefit basically Mitsubishi make that as a payment to us  

Swipe

I'd just get a hydrogen compatible boiler

Reed_Richards

Swipe said:

I'd just get a hydrogen compatible boiler

From https://link.springer.com/article/10.1007/s42154-020-00096-z

Importantly, the fuel source is hydrogen, which is an extremely light and flammable gas [2]. Hydrogen is the lightest of all the gases with a density of 1/14 of that of air. Under standard atmospheric pressure and 0 °C, the density of hydrogen is approximately 0.0899 g/L. It diffuses easily in air and has a high tendency to leak, which makes it difficult to be contained. Hydrogen has a wide flammability range from 4 to 75% and a very low ignition energy (approximately 10 times lower than that of classic hydrocarbons). In addition, the flame of hydrogen combustion in air is almost invisible and has a high temperature of more than 2000 °C.

You can purchase a boiler that can be easily converted to burn hydrogen but the challenges of getting hydrogen to your house are considerable.

[Deleted User]

Swipe said:

I'd just get a hydrogen compatible boiler

If it was that easy then the Government wouldn’t be pushing heat pumps. Even the current Energy Minister is a H2 sceptic. Producing H2 from electricity is a process with 60% efficiency and when used in a boiler there is a further efficiency loss. That said, by far the biggest challenge would be upgrading supply pipes. I suspect that H2 will have a role: most likely in small housing clusters around industrial sites or wind farms.

matelodave

Lewigreg081281 said:

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 

If you are using that amount of gas, or your house needs that amount of energy to keep it warm then a QrizB says theres no reason to assume that you'll need less energy to heat it - energy being kwh. TBH you'd be better off sorting out your insulation and draughproofing to see if you could make some improvements to your current energy consumption rather than hoping that a heatpump will be the magic bullet that saves you lots of money.

If you are having problems optimising the use of your gas boiler and it's controls then a heatpump can be even more problematic unless its properly set up and operated. They need a lot more understanding that a gas boiler and thermostat.

You do need to do some really careful sums to work out the costs - 1kw of useful heating energy from a heat pump with a COP of 3 (which is quite hard to acheive in the winter) will cost around twice the cost of 1kwh of gas and no doubt will remain so unless or until there a a great levelling of prices between gas and leccy. 

Even more difficult to justify is the difference in cost between a new boiler at say £3k to the cost of a heatpump installation at £16k (plus interest etc). If you RHI is dependent on a monitoring system then you may not acheive the calculated COP and therefore wont get the calculated RHI payments. 

If you are really determined to go down the heatpump rote then make sure you get at least three quotes from different companies, so you can compare them, not only pricewise but by system configuration, heat loss, RHI calcs etc performance and other parameters - they should all come out roughly the same for performance, heat loss and RHI even if the installation costs are significantly different. Do not just go with the one firm who's offerd a quote - research it throroughly and undestand what you are getting and how it works

shinytop

Lewigreg081281 said:

Gerry1 said:

What does 'MIT ( monitoring service ) - £1610' mean? Is it a cost or a benefit?

It’s a benefit basically Mitsubishi make that as a payment to us  

No they don't.  It's an extra RHI payment.  You get £805 up front and the rest over 7 years. It involves extra monitoring equipment that is quite expensive; I assume that's included in your quote. 

Others have covered most points but we have about 1/2 of your energy needs; our ASHP is also a Mitsubishi Ecodan but it's bigger at 14kW than your 11.2kW one. Be careful it's the right size. 

Be aware that maximum RHI is about £11500 (excluding the extra monitoring payment) and stays with your house if you move. 

I'd get more quotes if you want a heat pump.

Our ASHP is good but I'd have mains gas if I could. 

    

shinytop

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!.

Most of this is complete nonsense btw. 

danrv

shinytop said: 

Be aware that maximum RHI is about £11500 (excluding the extra monitoring payment) and stays with your house if you move. 

One reason I went with aircon. I probably won’t move but didn’t want to be committed.