Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 8 minutes ago, epsilonGreedy said: I think you have just claimed a microwave cooker offers no advantage over a conventional oven. If the objective of a house heating system is not to illustrate Newtonian conservation of energy or Victorian vintage laws of thermodynamics but is instead the objective is happy content humans then the company might be offering an "efficiency" gain. The notion of graphene coated walls glowing with IR rays bathing householders is interesting, though I suspect, as with any graphene based product, the promise will never be fulfilled. Not at all. I've already mentioned that I believe that the word efficiency may be being misused, but, unlike some other terms, efficiency doesn't have several different meanings. Most commonly the word has two common meanings: the good use of time and energy in a way that does not waste any: "What is so impressive about their society is the efficiency of the public services." energy efficiency: the difference between the amount of energy that is put into a machine in the form of fuel, effort, etc. and the amount that comes out of it in the form of movement Neither of these has any reference or connection to comfort, and if the Nexgen advertising material had referred to “around 55% more comfort than a Water based system”, rather than “around 55% less energy than a Water based system”, then I'd not have picked up on this point at all. Link to comment Share on other sites More sharing options...
SteamyTea Posted July 13, 2019 Share Posted July 13, 2019 (edited) 3 hours ago, Clive Osborne said: We know FIR is absorbed easily into the body by up to 30mm I am not sure that is strictly true. We have capillaries that carry blood to our skin surface, as well as sweat glands, to control kin temperature. Also, there are many organs that are that close to out skin surface (unless one is covered in blubber. Just been to Redruth and people look like seal pups there), so if FIR really can penetrate over an inch, then we would not be able to stand outside for very long. Also, the thermal conductivity of water, which is around 0.6W.m-1.K-1, or near enough the same as brick, plaster, soil, is not really relevant when it comes to efficiency. Thermal Inertia, which is what I think you are on about, is the product of specific heat capacity, density and conductivity, also plays no part in working out the efficiency in this scenario. If it was important, then efficiency ratio calculations would be quite complicated. Now who said about a microwave and a convection oven. There really is not much difference. It does depend on the shape of what is being cooked, but they both work by thermal conduction. Microwaves don't really cook 'from the inside'. They just jiggle water molecules effectively, starting off a convection process. Edited July 13, 2019 by SteamyTea Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 26 minutes ago, SteamyTea said: I am not sure that is strictly true. We have capillaries that carry blood to our skin surface, as well as sweat glands, to control kin temperature. Also, there are many organs that are that close to out skin surface (unless one is covered in blubber. Just been to Redruth and people look like seal pups there), so if FIR really can penetrate over an inch, then we would not be able to stand outside for very long. The upper and lower bound seems to be 1350nm and 650nm respectively, set by the start of strong absorption by blood and water. This article gives more detail: http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_035.pdf From that article it looks as if long wavelength IR barely penetrates through the skinss epidermis, so not very deep at all (µ rather than mm). Certainly doesn't look as if long wavelength IR penetrates the human body to anywhere near 30mm depth. What I suspect happens is that the surface of the skin warms from the radiated heat (skin isn't far off being a black body, with an emissivity of about 0.98), and this warmth is then conducted into the underlying tissue where it is felt. Link to comment Share on other sites More sharing options...
scottishjohn Posted July 13, 2019 Author Share Posted July 13, 2019 bottom line is nexgen needs to propose the ideal whole house heating system that would be more economical than passiv slab +ashp wet system etc specification from top to bottom so we can see how it might be used in a new build to best effect and then compare overall costs on initial build and running costs If they cannot do that then --they have not looked at it close enough to claim it can be a REAL whole house system and until they can show that then it will never become an alternative I can see it might have some retro fit applications to solve some problems ,but I need convincing that it is a REAL alternative to wet system . maybe solar PV + batteries have to be included in this system ? I want them to succeed Link to comment Share on other sites More sharing options...
SteamyTea Posted July 13, 2019 Share Posted July 13, 2019 1 minute ago, scottishjohn said: bottom line is nexgen needs to propose the ideal whole house heating system that would be more economical than passiv slab +ashp wet system Think it is more a case of comparing it to E7/E10 heating systems, which are very controllable now. Link to comment Share on other sites More sharing options...
SteamyTea Posted July 13, 2019 Share Posted July 13, 2019 (edited) May be worth remembering what Richard Feynman has to say about this sort of thing: Edited July 13, 2019 by SteamyTea Link to comment Share on other sites More sharing options...
scottishjohn Posted July 13, 2019 Author Share Posted July 13, 2019 (edited) 3 minutes ago, SteamyTea said: Think it is more a case of comparing it to E7/E10 heating systems, which are very controllable now. could be ,but i,m thinking to 10 years from now when PV panels + battery storage could be very much cheaper and carbon base fuels are hit by taxation Edited July 13, 2019 by scottishjohn Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 1 minute ago, SteamyTea said: Think it is more a case of comparing it to E7/E10 heating systems, which are very controllable now. I agree, as the efficiency is likely to be much the same, but an E7/E10 system will have a significantly lower running cost, due to the use of cheap rate electricity. We run our UFH exclusively from E7, and this reduces the cost by over 30%, making it significantly cheaper than heating the house using gas. Link to comment Share on other sites More sharing options...
scottishjohn Posted July 13, 2019 Author Share Posted July 13, 2019 1 minute ago, JSHarris said: han heating the house using gas. you mean LPG --not mains Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 1 minute ago, scottishjohn said: you mean LPG --not mains No, mains gas. UFH running from an ASHP is already slightly cheaper than mains gas at normal electricity rates. At E7 cheap rate it's about 30% cheaper to run than a mains gas boiler. Link to comment Share on other sites More sharing options...
Nickfromwales Posted July 13, 2019 Share Posted July 13, 2019 2 hours ago, scottishjohn said: maybe solar PV + batteries have to be included in this system Be cheaper to just buy grid electric which has no maintenance, failure or replacement costs attached Link to comment Share on other sites More sharing options...
ProDave Posted July 13, 2019 Share Posted July 13, 2019 9 hours ago, Temp said: Its clear from this page... http://nexgenheating.com/cost-comparison/ That the claims are based on the argument that radiant heaters provide equivalent comfort levels at lower air temperatures. That can be true but in my experience radiant heat is more directional than you think. So you feel warmer on the side facing the heater. Fine if all your walls are covered in heaters. Sit at a table and your legs get cold. I'll wait until a housing association rips out gas central heating from their homes and replaces it with heating films and the tenants rave over the reduced bills and improved comfort. I will ask for the third time. Is the "efficiency" claim based on heating the house to a lower temperature because the radiated heat makes the occupants feel warm? Link to comment Share on other sites More sharing options...
Clive Osborne Posted July 13, 2019 Share Posted July 13, 2019 13 minutes ago, ProDave said: I will ask for the third time. Is the "efficiency" claim based on heating the house to a lower temperature because the radiated heat makes the occupants feel warm? Yes it's a huge part . Better on walls and ceilings with just a skim of plaster than under laminate. We do however no need any screed over the top. As I have said FIR benefits vary based on area and temperature . A larger area at lower temperature gives us better FIR Link to comment Share on other sites More sharing options...
Clive Osborne Posted July 13, 2019 Share Posted July 13, 2019 5 hours ago, JSHarris said: The upper and lower bound seems to be 1350nm and 650nm respectively, set by the start of strong absorption by blood and water. This article gives more detail: http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_035.pdf From that article it looks as if long wavelength IR barely penetrates through the skinss epidermis, so not very deep at all (µ rather than mm). Certainly doesn't look as if long wavelength IR penetrates the human body to anywhere near 30mm depth. What I suspect happens is that the surface of the skin warms from the radiated heat (skin isn't far off being a black body, with an emissivity of about 0.98), and this warmth is then conducted into the underlying tissue where it is felt. As I said before FIR varies greatly by temperature and what is directly in front of it. Link to comment Share on other sites More sharing options...
Clive Osborne Posted July 13, 2019 Share Posted July 13, 2019 20 minutes ago, ProDave said: I will ask for the third time. Is the "efficiency" claim based on heating the house to a lower temperature because the radiated heat makes the occupants feel warm? This is true of FIR panels. It is why we work on lower temps and greater coverage . People claim a 1.2KW heater on one wall will heat a 20 sq meter . We have found this not to be the case. Very little FIR into the room just radiant heat. 23 minutes ago, ProDave said: I will ask for the third time. Is the "efficiency" claim based on heating the house to a lower temperature because the radiated heat makes the occupants feel warm? 5 hours ago, JSHarris said: No, mains gas. UFH running from an ASHP is already slightly cheaper than mains gas at normal electricity rates. At E7 cheap rate it's about 30% cheaper to run than a mains gas boiler. Not from my experience I would never pull out a mains gas boiler over a ASHP or Nexgen . It's amazing when people compare existing running cost of a gas boiler to a ASHP . How about you turn the gas boiler down to the same flow water temp and increase emitter size as they do with a ASHP and then compare. They would not compete. I would never recommend to replace mains gas with Nexgen or ASHPs unless it's the customers desire for whatever reason. In the case of mains gas Solar PV an example. As for mains LPG, Standard electric or oil I would recommend Nexgen. Link to comment Share on other sites More sharing options...
Clive Osborne Posted July 13, 2019 Share Posted July 13, 2019 5 hours ago, scottishjohn said: bottom line is nexgen needs to propose the ideal whole house heating system that would be more economical than passiv slab +ashp wet system etc specification from top to bottom so we can see how it might be used in a new build to best effect and then compare overall costs on initial build and running costs If they cannot do that then --they have not looked at it close enough to claim it can be a REAL whole house system and until they can show that then it will never become an alternative I can see it might have some retro fit applications to solve some problems ,but I need convincing that it is a REAL alternative to wet system . maybe solar PV + batteries have to be included in this system ? I want them to succeed I have never said it's better than mains gas. I have never sold a ASHP to anyone on mains gas or Nexgen on the basis of saving money. But the future is electric and we can have a 1.2 sq meter using the full benefits of FIR no screed and around 100 watts a sq meter. More efficient than heating air Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 7 minutes ago, Clive Osborne said: Not from my experience I would never pull out a mains gas boiler over a ASHP or Nexgen . It's amazing when people compare existing running cost of a gas boiler to a ASHP . How about you turn the gas boiler down to the same flow water temp and increase emitter size as they do with a ASHP and then compare. They would not compete. I would never recommend to replace mains gas with Nexgen or ASHPs unless it's the customers desire for whatever reason. In the case of mains gas Solar PV an example. As for mains LPG, Standard electric or oil I would recommend Nexgen. The hard evidence suggests otherwise, especially for an ASHP that heats up a high heat capacity slab, via UFH, using E7. I'm 20 miles or so from you, and you're more than welcome to visit, look at our systems, and then say that an ASHP costs more, or uses more primary energy, than a gas boiler (we have had both, a condensing Vaillant combi, and now a 8 kW ASHP that only ever runs on E7 when heating the house. One key aspect is that UFH only needs a low flow temperature (never more than about 28 deg C), so is very well matched to the most efficient operating conditions for an ASHP, and less well suited to the typical operating conditions for a gas boiler. Link to comment Share on other sites More sharing options...
Temp Posted July 13, 2019 Share Posted July 13, 2019 Its still quite hard to find energy cost comparison data but this site has been running for awhile and claims to take into account the efficiency of the system. For example they told me their figures for ASHP assume its connected to UFH. Perhaps Nextgen should submit their data and try and get a place in the table. https://nottenergy.com/resources/energy-cost-comparison/ Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 29 minutes ago, Clive Osborne said: As I said before FIR varies greatly by temperature and what is directly in front of it. TBH, and without in any way which to be rude, I'm not at all sure you have really looked at the evidence. FIR and IR-C are pretty much the same thing. In general, long wavelength infra red is defined as being a wavelength of around 3µ to 50µ at the shortest wavelength to 1000µ at the longest wavelength. This paper that I linked to earlier in this thread: http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_035.pdf seems to show that IR-C/FIR only penetrates the skin to a depth of a few µ, so doesn't get anywhere near the 30mm penetration claimed earlier. If you have peer reviewed evidence that shows that IR-C/FIR does penetrate deeper than the epidermis, then it would be interesting to see it. Link to comment Share on other sites More sharing options...
ProDave Posted July 13, 2019 Share Posted July 13, 2019 5 minutes ago, Temp said: Its still quite hard to find energy cost comparison data but this site has been running for awhile and claims to take into account the efficiency of the system. For example they told me their figures for ASHP assume its connected to UFH. Perhaps Nextgen should submit their data and try and get a place in the table. https://nottenergy.com/resources/energy-cost-comparison/ If they priced electricity at something more like a decent retail rate of less than 15p per KWh the table would be a fairer comparison. (Why are they quoting 20.99p per KWh?) That would give 5.55p per KWh for an ASHP which is comperable to mains gas. 1 Link to comment Share on other sites More sharing options...
Temp Posted July 13, 2019 Share Posted July 13, 2019 They say where they get that figure in the notes at the bottom... "Electricity:Based on an average of the 6 major electricity suppliers’ online prepayment, credit and direct debit tariffs, including standing charges and VAT, but not Economy 7. Data used are the Tariff Comparison Rates (TCR) provided on the 6 major energy suppliers’ website." Link to comment Share on other sites More sharing options...
Jeremy Harris Posted July 13, 2019 Share Posted July 13, 2019 4 minutes ago, Temp said: Its still quite hard to find energy cost comparison data but this site has been running for awhile and claims to take into account the efficiency of the system. For example they told me their figures for ASHP assume its connected to UFH. Perhaps Nextgen should submit their data and try and get a place in the table. https://nottenergy.com/resources/energy-cost-comparison/ Interesting site. Not sure about the prices they are using though. We pay 15.729p/kWh peak rate, that site quotes 20.99p/kWh peak rate. We run our ASHP for heating exclusively on the E7 rate, which is 8.148p/kWh. Using their ASHP COP, then at peak rate the cost would be 5.8p/kWh and at the E7 rate we use the cost is really 3.01p/kWh, much cheaper than mains gas. In reality, our ASHP always runs with a COP of well over 3, usually around 3.5, so the true running cost is closer to 2,5p/kWh, much less than half the cost of a boiler running on mains gas. 1 Link to comment Share on other sites More sharing options...
Clive Osborne Posted July 13, 2019 Share Posted July 13, 2019 48 minutes ago, JSHarris said: The hard evidence suggests otherwise, especially for an ASHP that heats up a high heat capacity slab, via UFH, using E7. I'm 20 miles or so from you, and you're more than welcome to visit, look at our systems, and then say that an ASHP costs more, or uses more primary energy, than a gas boiler (we have had both, a condensing Vaillant combi, and now a 8 kW ASHP that only ever runs on E7 when heating the house. One key aspect is that UFH only needs a low flow temperature (never more than about 28 deg C), so is very well matched to the most efficient operating conditions for an ASHP, and less well suited to the typical operating conditions for a gas boiler. To compare properly you would have to have the flow temp of the gas boiler at 28C I assume ? Link to comment Share on other sites More sharing options...
Clive Osborne Posted July 13, 2019 Share Posted July 13, 2019 29 minutes ago, JSHarris said: TBH, and without in any way which to be rude, I'm not at all sure you have really looked at the evidence. FIR and IR-C are pretty much the same thing. In general, long wavelength infra red is defined as being a wavelength of around 3µ to 50µ at the shortest wavelength to 1000µ at the longest wavelength. This paper that I linked to earlier in this thread: http://ec.europa.eu/health/scientific_committees/emerging/docs/scenihr_o_035.pdf seems to show that IR-C/FIR only penetrates the skin to a depth of a few µ, so doesn't get anywhere near the 30mm penetration claimed earlier. If you have peer reviewed evidence that shows that IR-C/FIR does penetrate deeper than the epidermis, then it would be interesting to see it. I have and will post in when i am in the office.Remeber i have said wavelength changes with temperature. Also not being rude I have said that many times its FIR and Temperature needs to be right. We have some very expensive test equipment to hire and an expert to use it coming soon. The purpose of this is to measure exactly the difference. We use FLIR cameras all the time but at our price level tolerances are as not great as it could be . Let me post independent test results as promised. Then we can comeback to this. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted July 13, 2019 Share Posted July 13, 2019 2 hours ago, Clive Osborne said: People claim a 1.2KW heater on one wall will heat a 20 sq meter Scratching my head a bit here. That works out at 60W/m-2 I heat my house with 12W.m-2 I think you may be getting installed capacity and mean power delivery a bit muddled. This also seems a bit odd and adds to my suspicions. 2 hours ago, Clive Osborne said: But the future is electric and we can have a 1.2 sq meter using the full benefits of FIR no screed and around 100 watts a sq meter. More efficient than heating air Link to comment Share on other sites More sharing options...
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