Octopus Price Increase

[Swwils]

the problem i see is that until gas increases to 1/3rd the price of leccy then HPs are going to be a hard sell. I do not understand why this is already not the case. Using gas to produce leccy somehow increases its cost to 4X . I really dont buy that but why i dont know.

Conversion losses, plant, repair & maintenance costs along with personnel plus make a return? I can see it. I don't like it but I can see it!

I can't convince myself on the HP's yet. In saying that, one day my gas boiler is going to fail and I'll be pushed to decide. Although in saying that it has been off almost the whole year so far

HP is more efficient than the gas itself, you literally get more energy than the gas itself contains if you use the gas to make electricity for HP to heat a home. Despite us being very good at burning gas in situ (96% efficiency isn't hard).

Maybe the gov should drop vat on electric used in heat pumps.

[openspaceman]

the problem i see is that until gas increases to 1/3rd the price of leccy then HPs are going to be a hard sell. I do not understand why this is already not the case. Using gas to produce leccy somehow increases its cost to 4X . I really dont buy that but why i dont know.

Has anyone a graph showing the COP of a heat pump as the outside temperature drops? I know it can be reach higher figures for a small drop between in and out but thought they struggled on a cold day.

As to the costs of generating and getting it into a house most of it is in the infrastructure rather than the fuel.

[Countrypaul]

the problem i see is that until gas increases to 1/3rd the price of leccy then HPs are going to be a hard sell. I do not understand why this is already not the case. Using gas to produce leccy somehow increases its cost to 4X . I really dont buy that but why i dont know.

Has anyone a graph showing the COP of a heat pump as the outside temperature drops? I know it can be reach higher figures for a small drop between in and out but thought they struggled on a cold day.

As to the costs of generating and getting it into a house most of it is in the infrastructure rather than the fuel.

Not quite a graph, but a table for various input/ouput tempeatures giving the COP for a Mitsubishi ASHP: https://library.mitsubishielectric.co.u ... AA#page-60

[openspaceman]

the problem i see is that until gas increases to 1/3rd the price of leccy then HPs are going to be a hard sell. I do not understand why this is already not the case. Using gas to produce leccy somehow increases its cost to 4X . I really dont buy that but why i dont know.

Has anyone a graph showing the COP of a heat pump as the outside temperature drops? I know it can be reach higher figures for a small drop between in and out but thought they struggled on a cold day.

As to the costs of generating and getting it into a house most of it is in the infrastructure rather than the fuel.

Not quite a graph, but a table for various input/ouput tempeatures giving the COP for a Mitsubishi ASHP: https://library.mitsubishielectric.co.u ... AA#page-60

Thanks

Well that is interesting if a little difficult to visualise. If we ignore the cooling bit, on the grounds that when you need the cooling the performance isn't as critical as PV will be supplying all the electricity, then even when the outside air is down to 2C the COP is above 3.75 when delivering hot water to an underfloor heating system at 35C and the other scenarios ( not that I understood them) looked better, a lot better if the outside air is 12C. So except in near freezing conditions ( a few days a year here in NW Surrey) it looks like if electricity is nearly 4 times the price of gas it pays.

It would have been a choice I would have made in a newer house with UFH while the £5k grant existed but now with the RHI gone and a dramatic increase in price of the installation I don't think so.

One of those air to air cheaper splits like Nowty fitted though...

[Moxi]

OSM,

I have often stalked these units in the past as a solution to my own DHW predicament, although for me space inside the cottage is difficult to find for such a large tank.

https://www.ariston.com/en-uk/products/ ... er-heater/

Moxi

[openspaceman]

OSM,

I have often stalked these units in the past as a solution to my own DHW predicament, although for me space inside the cottage is difficult to find for such a large tank.

https://www.ariston.com/en-uk/products/ ... er-heater/

Moxi

Is that the complete unit, i.e. it is only connected to electric and water? Any idea of the cost and diameter?

It looks good to me assuming it takes air from the room and dumps heat into the tank but where does the cold air go?

I somehow don't think I'd get my money back on that but if we had two teenage girls again it would be different.

[AE-NMidlands]

OSM,
I have often stalked these units in the past as a solution to my own DHW predicament, although for me space inside the cottage is difficult to find for such a large tank.
https://www.ariston.com/en-uk/products/ ... er-heater/
Moxi

Is that the complete unit, i.e. it is only connected to electric and water? Any idea of the cost and diameter?
It looks good to me assuming it takes air from the room and dumps heat into the tank but where does the cold air go?
I somehow don't think I'd get my money back on that but if we had two teenage girls again it would be different.

even if the cooled air is ducted and/or dumped straight outside you then have to heat incoming air to replace it... Unless you have a WBS which over-heats the building and use it to keep the air temp down!
A

[Moxi]

From past reading it is possible to duct incoming and outgoing air with valves so that you can bring in ambient outside air and exhaust cooled air outside when conditions dictate, then at other times they use ambient external air but vent the cool air to the house presumably in warmer days to keep the house cool. With two wall penetrations and two two way valves I suppose you can have any combination you like at the turn of the handles ?

It appealed to me (except where to put it) as it would allow me to use the WBS to boost the tank for DHW now and again in the colder months - but not got further than thinking about it and of course they ain't cheap (as in give it a go style budget) they start around 1800 quid 250 liter up to 3,500 quid for extras and such.

Daikin also do something along these lines now as well.

Moxi

[Oldgreybeard]

I looked at one of these years ago, a Chinese unit being re-badged and sold here by Ecocent ( https://www.earthsaveproducts.com/products/ecocent ). They had a valve system as an option to switch the intake from the air in the house to outside. TBH, the use of a bit of heated air from the house was not going to be an issue at all as most of it would have been waste warm air from the bathroom and kitchen. The unit would have really been recovering heat from activities where the waste heat was a nuisance, and in the case of drawing in waste humid air from the bathroom it would have been recycling heat anyway, so seemed to me to be a very sensible way of tackling the hot water problem.

The only thing that stopped me going ahead a few years ago was the experiences of one or two early adopters, who experienced corrosion issues in the stainless steel tanks. That, combined with a bit of research I did that showed that thousands of models like this are on sale on Alibaba, some identical at the time to the supposedly "British made" Ecocent, made me get cold feet and walk away. Having said that, I believe that all the issues over quality have now been sorted, so the chances are one of these would now be an OK purchase.

[openspaceman]

Yes after thinking on it for a while it struck me it may as well take in warmer air from the top of a room and vent the cold at floor level.

Still £1800 is more than what DHW will cost me for a long while, I still like it though.