Thermo dynamics for hot water that runs off atmosphere

[Berneray]

I just don't get it.

Without going into technical details and empirical data ect ect....all these panels can do in a normal house is heat tap water to 55 degrees.

Now the EST in conjunction with DEFRA published a report entitled "Measurement of Domestic Hot Water Consumption in Dwellings". The samples 124 houses over a set period.

The report is incredibly detailed with loads of cool graphs and stuff and runs to 62 pages (email me if you'd like a copy)....but long story short they found the average spend per year on domestic tap was was at that time £105.

So say these panels save me £105 off my oil or gas...I still then have to pay for the electricity to run the compressor which appears to be about £8 a month....So the net saving cannot be more than £50 a year.

So why would I spend £5000 on something that is going to save me £50 a year.....

Or am I missing something...

 

[Berneray]

Anyone come across this new "MAGIC BOX"

The Magic Thermodynamic Box

Got it in an email earlier today....

 

[Earthstore]

I asked a question but as many others have been ignored.
So, the cost of heating my hot water per year is around £140 (it may be a little either way) So to install a system that costs £5000 + running costs does not make economical sense, even if it meant my hot water would be totally free, which of course these systems do have running costs, but let's just say it halved my hot water running cost, that would be 35 years to recoup my initial outlay, plus another 17 1/2 years before I am in profit so a total of 52 1/2 years...

Of course there may be the RHI, which IF it ever happens and IF this system is included in the scheme may help.
I am not disputing whether it works, I am sure it does to some degree but the sums just do not add up at all, or am I missing something here?

I must learn to type quicker, someone beat me to it, strange though the figures are similar....

 

[Berneray]

Completely agree with Earthstore........I just don't get it......

If you sat down with a customer and told him the system would take 35 years to recover its costs and and 17 to be in profit......how many do you think would go ahead.....

Can this product be sold ethically......I wonder

 

[jason121]

Anyone come across this new "MAGIC BOX"

The Magic Thermodynamic Box

Got it in an email earlier today....

I got it, ASHP giving COP 1/7 at 25 degrees and 1/3 at -15

 

[Earthstore]

Great news chaps, just realised if I buy one of these systems I could celebrate my 100th birthday with the fact that I had broken even. :cake:

 

[CES Heating]

Anything with "Magic" in the product title deserves a wide berth... Is it magical because they don't understand how it works?

 

[Gavin A]

I asked a question but as many others have been ignored.
So, the cost of heating my hot water per year is around £140 (it may be a little either way) So to install a system that costs £5000 + running costs does not make economical sense, even if it meant my hot water would be totally free, which of course these systems do have running costs, but let's just say it halved my hot water running cost, that would be 35 years to recoup my initial outlay, plus another 17 1/2 years before I am in profit so a total of 52 1/2 years...

Of course there may be the RHI, which IF it ever happens and IF this system is included in the scheme may help.
I am not disputing whether it works, I am sure it does to some degree but the sums just do not add up at all, or am I missing something here?

I must learn to type quicker, someone beat me to it, strange though the figures are similar....

the same applies to solar water heating systems though, and folk do still get them installed as well for a multitude of reasons.

I think the price point really should be about £3.5k for an installed water heating only system, which makes things a bit different, and I reckon the main market for this ought to be in new builds, or situations where they need a mains pressure tank anyway , which is circa £1k inc fitting, so the thermodynamic element is only £2.5k, and with oil / electric heating and no need to pipe the boiler / heat pump output to the

 

[Marvo]

I'm probably missing something obvious here but what is the advantage of using a solar panel instead of having a standard finned evaporator with a fan? When it all boils down to it all heat pumps are solar powered, with an old fashioned evaporator the sun heats the ground, the ground heats the air and the air evaporates the refrigerant giving it latent heat.

I have a refrigeration question as well, how does the solar panel heat pump prevent the superheat figures of the refrigeration system going off the chart on a hot day?

 

[Gavin A]

I'm probably missing something obvious here but what is the advantage of using a solar panel instead of having a standard finned evaporator with a fan? When it all boils down to it all heat pumps are solar powered, with an old fashioned evaporator the sun heats the ground, the ground heats the air and the air evaporates the refrigerant giving it latent heat.

it can draw heat both from the air and from solar radiation falling on the panel, an ASHP can only draw heat from the air, so in theory it should have a higher COP when it's sunny, and a similar COP when it's not.

no fan and less moving parts ought to also mean a longer life, and certainly less outdoor noise.

I'd expect they'd be a better option than ASHP in some situations and not in others, but they should be a valid option IMO.

I have a refrigeration question as well, how does the solar panel heat pump prevent the superheat figures of the refrigeration system going off the chart on a hot day?

there's no insulation on the panel, so it will presumably max at out around the 60-70 deg that PV panels max out at in the UK even when stagnating. I assume the refrigerant is ok to cope with this, but haven't looked that far into it / found those figures.

 

[Vegelen]

it can draw heat both from the air and from solar radiation falling on the panel, an ASHP can only draw heat from the air, so in theory it should have a higher COP when it's sunny, and a similar COP when it's not.

no fan and less moving parts ought to also mean a longer life, and certainly less outdoor noise.

Gavin, Are you going to replace your current water heating system with Thermodynamic solar?

 

[Gavin A]

Gavin, Are you going to replace your current water heating system with Thermodynamic solar?

no.

I installed a solar water heating system 4 years ago which should be good for 30 years or so, I'd be pretty silly to replace it now.

If I were off the gas grid though, particularly if I was using electric for water heating, and didn't have a solar water heating system already, I'd probably install one of these panels plus solar PV. That's the sort if situation I see these possibly working in if the price was right, though I'd expect it'd need RHI payments to make it really financially viable.

- - - Updated - - -

that and new build eco homes off the gas grid.

 

[Gavin A]

btw, when I say this is likely to be better than an ASHP, I should probably point out that I don't advocate using ASHP's to replace condensing gas boilers either, as an ASHP is currently higher carbon than a condensing gas boiler for water heating.

 

[Marvo]

there's no insulation on the panel, so it will presumably max at out around the 60-70 deg that PV panels max out at in the UK even when stagnating. I assume the refrigerant is ok to cope with this, but haven't looked that far into it / found those figures.

60-70 deg on the evaporator is very very high compared to standard refrigeration systems. The negative effect this will have is on the compressor, not the refrigerant itself. I would have grave concerns about the the long term reliability of this system.

 

[The Solar King]

Its is good to see some more technical discussion of this technology, even without firm performance data. At the other end of the scale, how is this equipment going to avoid icing and what defrost cycle is available?

The running costs element is critical to its viability. Normal Solar Thermal has zero costs for energy production and pretty low running costs - a fluid change every five years and a pump if you are unlucky during it's lifetime. Properly designed and installed it will provide 50-55% of an annual hot water requirement. In some parts of the UK, this figure can be higher. This is the cost comparator. The cost of the fuel for auxiliary water heating enters the equation. As alluded to in this thread true running costs for thermo dynamics in UK conditions is currently unavailable.

There is a lot of hard work going on with DECC to make normal ST viable under the proposals for the RHI. If this is successful and IF the questions raised about thermo dynamic equipment can be answered by the manufacturers, then at some stage it may be included. However, the complexities currently involved in the RHI consultation over issues such as bi-valency, and issues surrounding what this technology is finally defined as may still exclude it.

I think the one thing the opinions expressed in this thread shows is the true market for appropriate use of this equipment IF it's performance can be validated is very very small. Use in conjunction with other technologies means it would need to to be compatible with a multi-coil thermal store or hot water storage vessel, not just a dedicated tank. If it is not compatible, you are possibly in to a two tank design, with all the space implications that entails.

 

[steve k]

I have a refrigeration question as well, how does the solar panel heat pump prevent the superheat figures of the refrigeration system going off the chart on a hot day?

The gas isn't in the evaporator long enough for it to be affected by the outside temperature.
When I commissioned the system I first posted about the systems had a saturated suction temperature of -12 deg C and a pipe temp at compressor inlet of 4 deg C, giving a compressor superheat of 16k. I didn't measure the evaporater superheat as the pipe run was so short.
I would not expect this to change whatever the weather / ambient conditions.

**Edit**

Colder outside temps could cause more problems for the refrigeration system than the hot. This is due the possibility of un-evaporated liquid refrigerant finding it's way back to the compressor.
To get around this possible problem, the systems I have installed have the suction line coiled around the compressor to boil off any remaining liquid refrigerant.

Steve

Steve

 

[steve k]

a pic to illustrate

Steve

 

[steve k]

how is this equipment going to avoid icing and what defrost cycle is available?

It can't....if you were to incorporate a hot gas defrost system into this, as in a commercial freezer, the refrigerant would shoot through the evaporator at about 70 deg C, the same as the hot surface temperature discussed in another post at a pressure of appx 300psi.

I have pressure tested the evaporators at 250psi with no ill effects.

Steve

 

[The Solar King]

So running at sub zero ambient temperatures, the panel will ice up?

 

[steve k]

60-70 deg on the evaporator is very very high compared to standard refrigeration systems. The negative effect this will have is on the compressor, not the refrigerant itself. I would have grave concerns about the the long term reliability of this system.

The compressor regularly deals with temperatures like these, it's what they do. Compress low (temp)pressure gas into high (temp)pressure gas.
It is this hot gas that heats up the water.

Steve