Cheaper alternatives to E7 starage heaters?

Swipe

grizzly1911 wrote: »

Isn't this alchemy of sorts - 380% efficient;)

if you read up on how air conditioning works it won't sound so bizarre. What you get out depends on the outside ambient temperature but at this time of year at around 10C that figure is easily achievable with A rated units.

HappyMJ

grizzly1911 wrote: »

A little off thread fo rwhat the OP is after I think but I was always led to believe that there is no free lunch and if it seems to good to be true etc.

Isn't this alchemy of sorts - 380% efficient;)

They aren't heaters. They are heat pumps. They move heat from one location to another. Maybe not 380% but they are very efficient.

Richie-from-the-Boro

HappyMJ wrote: »

They aren't heaters. They are heat pumps. They move heat from one location to another. Maybe not 380% but they are very efficient.

My question last night [ unstated @ 380% ] was efficient when ? They are going to be used in this country in the 6 months Oct-Mar I accept the efficiency argument for this type of pump, but can't see the recycle air feature delivering anything like 200% in those cold months when the outside air is at zero degree or minus .. .. I have an open and inquiring mind on the subject and I'm ok with the argument that they are half those of gas or electric heating and less than 20% of a Calor / LPG heater suggested earlier, until I've done some research.

Richie-from-the-Boro

Someone correct me please ......


This [ originally posted by roger ] seems to be a KFR-33IW/X1c - Toshiba [Chigo] - unit. The internal unit is fitted to a wall in the room to be heated and cooled, the external unit is positioned outside the building, comes with all the bits, iuncluding 3.5m of Pipework and is listed on the eca.gov.uk website if you are a business rather than a home-owner. So it looks like a good bit of kit - any heat pump experts [ or novices ] out there want to prove me wrong and explain how """ "1 kW input you will get 3.8kW of heating """ on this ' temperate climate ' island I live on ?

HappyMJ

Richie-from-the-Boro wrote: »

Someone correct me please ......


This [ originally posted by roger ] seems to be a KFR-33IW/X1c - Toshiba [Chigo] - unit. The internal unit is fitted to a wall in the room to be heated and cooled, the external unit is positioned outside the building, comes with all the bits, iuncluding 3.5m of Pipework and is listed on the eca.gov.uk website if you are a business rather than a home-owner. So it looks like a good bit of kit - any heat pump experts [ or novices ] out there want to prove me wrong and explain how """ "1 kW input you will get 3.8kW of heating """ on this ' temperate climate ' island I live on ?

You are not wrong. It's only is 380% efficient of it's over zero degrees outside and in reality it's about 5 degrees. It won't be that efficient if it's Dec, Jan or Feb but they are more efficient than 100% but you will be paying standard rates on the leccy which then costs more than gas central heating but compared to LPG or oil it's usually cheaper. Then again it only heats one room and not the whole house.

Richie-from-the-Boro

Thanks for that HappyMJ

The UK average [ start Dec to end Mar ] over 30 years is under the 5 degrees point, so for three of the 5 cold months its inversion value would be worthwhile at 60p per day [ read it somewhere - I'll check ] leccy cost.

Swipe

They are fine down to around 0C (slightly higher in fog or sleet) which is when they start defrost cycling. It is these 5-10min periods of no heat that significantly affects the COP at colder temperatures.

jackshelac

Are you sure there charging you for e7 electric? BG have just increased their tariff from 4.54 to 5.96p 32% increase. Check your meter. If your being charged more than 7p per kwh they're overcharging you. I was overcharged by £400 last winter but eventually sorted it out. The meters are rigged so that the appliances stay on into peak rate so make sure you switch them off about 7am.

grahamc2003

Richie-from-the-Boro wrote: »

So it looks like a good bit of kit - any heat pump experts [ or novices ] out there want to prove me wrong and explain how """ "1 kW input you will get 3.8kW of heating """ on this ' temperate climate ' island I live on ?

It's misleading saying heat pumps can be 380% efficient. That's why they state that same figure as a cop - a coefficient of performance rather than an efficiency (sensibly defined, efficiencies are always 100% or less).

The cops are usually published for an ambient temp of 7C, and they don't take into account defrosting. The enregy used isn't used directly for heating at all - it's just used to drive a compressor to pressurise and liquify a fluid, and drive a couple of fans to blow air over a couple of heat exchangers (having said that, compressing a fluid does heat it up further). The hot fluid is then used to heat the room (by having room air blown over it), then it is vaporised, which cools it to a very low temp (-60C I recall someone saying) as well as losing latent heat, and then fed to the outside unit where ambient air is blown over it to warm it and absorb latent heat (of course even at -10, the working fluid will pick up quite a bit of heat), then the cycle continues. It just so happens that if it takes 1kw to drive the system, the rate of heat it can extract from the outside air is 2.5kw (at 7C, if the cop of 3.5 is correct - the other 1kw of heat comes from the compression).

So although inside the house, you are using 1kw of electricity and are producing 3.5kw of heating, the outside world has lost 2.5kw of heating. That situation equates to a cop of 3.5, not an efficiency of 350% (in engineering terms).

Also, with a self installed diy unit (i.e.without the system being purged by a high vacuum and carefully charged with pure refridgerant) I'd doubt the average diy installer would get the claimed cop (unlike professionally installed top of the range units, which probably would). Also, at higher ambients that 7C, the cop increases, and unfortunately, vv.

Richie-from-the-Boro

grahamc2003 wrote: »

It's misleading saying heat pumps can be 380% efficient. That's why they state that same figure as a cop - a coefficient of performance rather than an efficiency (sensibly defined, efficiencies are always 100% or less).

The cops are usually published for an ambient temp of 7C, and they don't take into account defrosting. The enregy used isn't used directly for heating at all - it's just used to drive a compressor to pressurise and liquify a fluid, and drive a couple of fans to blow air over a couple of heat exchangers (having said that, compressing a fluid does heat it up further). The hot fluid is then used to heat the room (by having room air blown over it), then it is vaporised, which cools it to a very low temp (-60C I recall someone saying) as well as losing latent heat, and then fed to the outside unit where ambient air is blown over it to warm it and absorb latent heat (of course even at -10, the working fluid will pick up quite a bit of heat), then the cycle continues. It just so happens that if it takes 1kw to drive the system, the rate of heat it can extract from the outside air is 2.5kw (at 7C, if the cop of 3.5 is correct - the other 1kw of heat comes from the compression).

So although inside the house, you are using 1kw of electricity and are producing 3.5kw of heating, the outside world has lost 2.5kw of heating. That situation equates to a cop of 3.5, not an efficiency of 350% (in engineering terms).

Also, with a self installed diy unit (i.e.without the system being purged by a high vacuum and carefully charged with pure refrigerant) I'd doubt the average diy installer would get the claimed cop (unlike professionally installed top of the range units, which probably would). Also, at higher ambient s that 7C, the cop increases, and unfortunately, vv.

Thanks Graham - I'll bump it for now [ so I can find it easier ] - :beer: