nexgen graphene heating panels

[PeterW]

1 minute ago, Clive Osborne said:

To me that's 281 watts per square meter on heat loss calcs.

 

Can you show how you get to that figure ..???

[SteamyTea]

281 Wh.m^-2.day^-1

 

kWh = Energy

kW = Power

[Clive Osborne]

Normally using u values and full heat loss calculations.  I am working in comparison to how we calculate. Covering 100% of the floor or heating 116 watts per square meter. The storage heaters may be oversized. 

[SteamyTea]

3 minutes ago, Clive Osborne said:

Normally using u values and full heat loss calculations.

If you already know the power, or energy, needed, there is no reason to do full calculations.

But when I did, I got a similar result.

Having done full MCS/RHI calculations via software and manually, I find that they generally match existing usage.

To give you an example, I was chatting to a fellow that had UFH and an ASHP fitted.  He was saying that the running costs were not much less than his old oil system to radiators.

With a bit of questioning, I found out the house was a lot warm, around 6°C and he used to heat DHW with an electric immersion heater.

 

[Clive Osborne]

12 minutes ago, PeterW said:

 

Can you show how you get to that figure ..???

Simply 13500 / 48. We work in sq meters with standard room heights . Then I compared covering 100% of the area with Nexgen. I am only doing it as a comparison.  If people want something on a wall heating air rather than 100% of the floor or ceiling radiating out at 28C that's upto them. How many hours it would be on etc is another issue. I would need to know U Values etc. We can only compare to heating the whole area. I have to date never done over 80% coverage of a floor or ceiling. Also the whole area is heated not wires or strips with silver paste

[Clive Osborne]

1 minute ago, SteamyTea said:

If you already know the power, or energy, needed, there is no reason to do full calculations.

But when I did, I got a similar result.

Having done full MCS/RHI calculations via software and manually, I find that they generally match existing usage.

To give you an example, I was chatting to a fellow that had UFH and an ASHP fitted.  He was saying that the running costs were not much less than his old oil system to radiators.

With a bit of questioning, I found out the house was a lot warm, around 6°C and he used to heat DHW with an electric immersion heater.

 

Yes been doing Heat Loss calcs for heat pumps for many years . Bit we dont calculate in cubic meters and our air change calc is different.  Hence I can only compare covering 100% of the floor or ceiling without full data. I have never done a calculation when a ASHP was the same price as storage heater. I also would use a cylinder with a heat pump built in rather than heat with just an immersion. Bloody hell he must have been freezing in winter 6C is a huge difference. 

[SteamyTea]

3 minutes ago, Clive Osborne said:

Bloody hell he must have been freezing in winter 6C is a huge difference. 

Yes, and his installer of the UFH only added 25mm of insualtion.

13 minutes ago, Clive Osborne said:

Simply 13500 / 48

That is the energy per floor area calculation, not the power calculation.

[Clive Osborne]

6 hours ago, SteamyTea said:

Yes, and his installer of the UFH only added 25mm of insualtion.

That is the energy per floor area calculation, not the power calculation.

Regardless I got it wrong anyway ! I was thrown by the 13,500 figure. Apologies.  So if you have 1.2KW of heating I make that 25 watts psm going into the house. I would have to so a full heat loss calc for what is going out. I would never go that low on a 1980s build unless it's been seriously updated. Regardless of the form of heating even an ASHP but that's just my opinion. At 12 watt psm I would say that's passive standard.

[Jeremy Harris]

Years ago I wrote this heat loss model:  Heat loss calculator - Master.xls which has been shown to work fairly well.  Quite a few here have used it over the years and found that it gives a reasonably accurate estimate of heat loss.  The two main flaws in it are that it takes no account of thermal bridging losses (unless these are included in the overall fabric U value figures, which would be normal design stage practice) and it also takes no account of incidental thermal gain (gain from occupants, appliances, solar gain etc).  For sizing a heating system it seems fine though, as it gives a worst case heating requirement.

 

FWIW, our heating system normally works at around 5W/m² on average.  In extremely cold weather (-10°C OAT), with no occupants in the house and no incidental thermal gain the heating could get as high as about 22 W/m², but we've never seen it get that high. 

 

At 22 W/m² the floor surface temperature would be about 296.45 K, so the peak radiated wavelength from it would be roughly 9.78µ. 

 

At 5 W/m² the floor surface temperature would be about 294.75 K, so the peak radiated wavelength from it would be roughly 9.83µ

 

Overall efficiency for this maximum heating condition (excluding the COP of the heat pump, and only considering thermal efficiency) would be 92.3%. 

 

Electrical power efficiency for this maximum heating condition, (electrical power input versus useful heat output to the rooms in the house), would be 249.2%

 

I look forward to seeing your data in due course, @Clive Osborne, as it would be interesting to model your heating system performance alongside the above wet underfloor heating system and compare the relative efficiency between the two different heating methods, and compare the peak wavelength radiated from each, perhaps.

 

 

[Clive Osborne]

1 hour ago, JSHarris said:

Years ago I wrote this heat loss model:  Heat loss calculator - Master.xls which has been shown to work fairly well.  Quite a few here have used it over the years and found that it gives a reasonably accurate estimate of heat loss.  The two main flaws in it are that it takes no account of thermal bridging losses (unless these are included in the overall fabric U value figures, which would be normal design stage practice) and it also takes no account of incidental thermal gain (gain from occupants, appliances, solar gain etc).  For sizing a heating system it seems fine though, as it gives a worst case heating requirement.

 

FWIW, our heating system normally works at around 5W/m² on average.  In extremely cold weather (-10°C OAT), with no occupants in the house and no incidental thermal gain the heating could get as high as about 22 W/m², but we've never seen it get that high. 

 

At 22 W/m² the floor surface temperature would be about 296.45 K, so the peak radiated wavelength from it would be roughly 9.78µ. 

 

At 5 W/m² the floor surface temperature would be about 294.75 K, so the peak radiated wavelength from it would be roughly 9.83µ

 

Overall efficiency for this maximum heating condition (excluding the COP of the heat pump, and only considering thermal efficiency) would be 92.3%. 

 

Electrical power efficiency for this maximum heating condition, (electrical power input versus useful heat output to the rooms in the house), would be 249.2%

 

I look forward to seeing your data in due course, @Clive Osborne, as it would be interesting to model your heating system performance alongside the above wet underfloor heating system and compare the relative efficiency between the two different heating methods, and compare the peak wavelength radiated from each, perhaps.

 

 

Of couse it will be interesting although it's the air heating market and off gas grid we concentrate on until they release the next version of SAP . We obviously go above the heat loss level but I still cant see a 1987 house with storage heaters heating air at 12 watts per sq meter heat loss even in Devon. Its certainly ended up an interesting post after a rocky start ! If you are ever near Andover it would be good to meet. Every day is a school day ! 

[Clive Osborne]

1 minute ago, Clive Osborne said:

Of couse it will be interesting although it's the air heating market and off gas grid we concentrate on until they release the next version of SAP . We obviously go above the heat loss level but I still cant see a 1987 house with storage heaters heating air at 12 watts per sq meter heat loss even in Devon. Its certainly ended up an interesting post after a rocky start ! If you are ever near Andover it would be good to meet. Every day is a school day ! 

I will look at the spreadsheet and send over my last heat pump version 

[SteamyTea]

I suspected that you were getting muddled between installed capacity, energy and power a while back

On 13/07/2019 at 23:13, SteamyTea said:

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.

 

It is an easy mistake to make, most of us do it.

3 hours ago, Clive Osborne said:

Regardless I got it wrong anyway ! I was thrown by the 13,500 figure. Apologies.  So if you have 1.2KW of heating I make that 25 watts psm going into the house. I would have to so a full heat loss calc for what is going out. I would never go that low on a 1980s build unless it's been seriously updated. Regardless of the form of heating even an ASHP but that's just my opinion. At 12 watt psm I would say that's passive standard.

It is important to make this distinction otherwise the calculations for efficiency just become nonsense numbers.

 

A watt [W] is a joule per second, both Watt and Joule were people, it is why, under the SI system the abbreviation is upper case i.e. W, J, but written in full starting with a lover case. a kelvin, which is named after Lord Kelvin, is the same. You don't have °K, that is saved for the celsius scale, which used to be known as the centigrade scale. Celsius was a person, so C when shortened, celsius when in full, unless talking about the man.

 

A Wh is the energy delivered, stored or available and can be in many forms, but basically come down to kinetic [moving] or potential [stored].  This is a small unit, so is usually prefixed with a k, M or G for kilo [1000], mega [million], giga [billion].

So a kWh, not Kwh, or KWH, or killa wot our, is made up of smaller units, joules and seconds.  A second, is not named after a person, so is lower case when abbreviated.

So there are 3.6 million joules in a kWh, 1000 joules per second, times 3600 seconds in an hour.

Just to put that into perspective, a joule is the force needed to move 1 kg 1 metre.  Force is mass times acceleration.

 

 

 

 

[SteamyTea]

18 minutes ago, Clive Osborne said:

Devon

I am in Cornwall, we do things right here, not like that lot in Devon, ask @joe90about planning in Devon.

Devon is just a place one has to travel tough to get to civilisation.

 

[joe90]

1 minute ago, SteamyTea said:

I am in Cornwall, we do things right here, not like that lot in Devon, ask @joe90about planning in Devon.

Devon is just a place one has to travel tough to get to civilisation.

 

 

Thanks mate????? (but your right about planners, I have heard more stories since my fiasco regarding planners down here).

[Clive Osborne]

4 minutes ago, joe90 said:

 

Thanks mate????? (but your right about planners, I have heard more stories since my fiasco regarding planners down here).

I was born on Somerset I am not in a position to say anything 

[SteamyTea]

39 minutes ago, Clive Osborne said:

but I still cant see a 1987 house with storage heaters heating air at 12 watts per sq meter

Why not.

It only takes 1 joule to raise 1 g of air by 1°C

I have 1.2 tonnes of air in my house and 48600000 j a day to use.

So if there were no losses at all, then I could raise that 1.2 tonnes of air by 40.5°C.

Heating air is easy, though it does take more energy to heat than granite [SHC of air is 1 J.g^-1.K^-1, granite is 0.8 j.g^-1.K^-1]

 

Edited July 15, 2019 by SteamyTea

[Jeremy Harris]

53 minutes ago, Clive Osborne said:

I will look at the spreadsheet and send over my last heat pump version 

 

Out of interest, why would a heat loss spreadsheet care about the heat source? 

 

I can see that the heating source would be of use in a running cost comparison, as costs vary a great deal, per kWh of heat delivered, between different fuel types, but can't see how the heat source can have any bearing on heat loss/heating requirement (as heat loss = heating requirement for any given set of conditions).

 

I recently did a running cost comparison, for a typical year for our underfloor heating with different fuels and came up with these figures, which may be of interest (costs include standing charge/LPG tank rental, etc) :

 

LPG fired boiler running UFH = £336.49

 

Peak rate electric boiler running UFH = £329.05

 

Oil fired boiler running UFH = £218.91

 

Off peak (E7) electric boiler running UFH = £206.43

 

Mains gas boiler running UFH = £143.76

 

ASHP at peak peak rate running UFH = £102.87

 

ASHP at off-peak (E7) rate running UFH = £89.25

 

Arguably the standing charge for all the electric heating options should be reduced in proportion to the ratio between heating electricity use and non-heating electricity use, as that standing charge will apply irrespective of the heating system used.  I didn't bother to make that adjustment, but it would tend to reduce the cost of the electric heating options by around £40 p.a. or so if I was to do this.

 

[SteamyTea]

7 minutes ago, JSHarris said:

Out of interest, why would a heat loss spreadsheet care about the heat source

I often think it is because we use the word heat to mean temperature.

Must be time for our favourite song.

 

Edited July 15, 2019 by SteamyTea

[scottishjohn]

2 minutes ago, JSHarris said:

LPG fired boiler running UFH = £336.49

 

 

ASHP at peak peak rate running UFH = £102.87

 

 

I would agree with this whole heartedly as that is exactly what i found when changing heat source ONLY from LPG to ASHP

 not be any calculation but simply by comparing before and after energy bills

 

[Clive Osborne]

4 hours ago, JSHarris said:

 

Out of interest, why would a heat loss spreadsheet care about the heat source? 

 

I can see that the heating source would be of use in a running cost comparison, as costs vary a great deal, per kWh of heat delivered, between different fuel types, but can't see how the heat source can have any bearing on heat loss/heating requirement (as heat loss = heating requirement for any given set of conditions).

 

I recently did a running cost comparison, for a typical year for our underfloor heating with different fuels and came up with these figures, which may be of interest (costs include standing charge/LPG tank rental, etc) :

 

LPG fired boiler running UFH = £336.49

 

Peak rate electric boiler running UFH = £329.05

 

Oil fired boiler running UFH = £218.91

 

Off peak (E7) electric boiler running UFH = £206.43

 

Mains gas boiler running UFH = £143.76

 

ASHP at peak peak rate running UFH = £102.87

 

ASHP at off-peak (E7) rate running UFH = £89.25

 

Arguably the standing charge for all the electric heating options should be reduced in proportion to the ratio between heating electricity use and non-heating electricity use, as that standing charge will apply irrespective of the heating system used.  I didn't bother to make that adjustment, but it would tend to reduce the cost of the electric heating options by around £40 p.a. or so if I was to do this.

 

Exactly that reason comparison to ASHP Biomass FIR GSHP running costs.  Just a guide for people no other reason. Been a while since I have done one to be honest.  

[Clive Osborne]

5 hours ago, SteamyTea said:

Why not.

It only takes 1 joule to raise 1 g of air by 1°C

I have 1.2 tonnes of air in my house and 48600000 j a day to use.

So if there were no losses at all, then I could raise that 1.2 tonnes of air by 40.5°C.

Heating air is easy, though it does take more energy to heat than granite [SHC of air is 1 J.g^-1.K^-1, granite is 0.8 j.g^-1.K^-1]

 

@JSHarris what are your thoughts on this ? Its electric storage heat at 12 watts per sq meter for a 1987 build. It goes against what I have been taught. But as I said before every day is a school day ! Its interesting for sure. Is it really that simple ( not the working out part I appreciate that's beyond most people ) but the principal? Do we go overboard on sizing ? I have seen some huge KW oil boilers in relatively small places. 

[Clive Osborne]

4 hours ago, SteamyTea said:

I often think it is because we use the word heat to mean temperature.

Must be time for our favourite song.

 

Purely guide on running cost 

[PeterW]

2 minutes ago, Clive Osborne said:

Do we go overboard on sizing ? I have seen some huge KW oil boilers in relatively small places. 

 

Usually to provide DHW demand. A number of heating boilers can modulate down to 5-7Kw, but when in DHW mode (especially combi’s) can be putting 32Kw into the incoming mains water to get a reasonable temperature and flow. 

[Jeremy Harris]

15 minutes ago, Clive Osborne said:

Exactly that reason comparison to ASHP Biomass FIR GSHP running costs.  Just a guide for people no other reason. Been a while since I have done one to be honest.  

 

So it's a cost comparison tool, not a heat loss calculation tool, is that right?

 

I can see the benefit of that, as long as the same heating requirement is used for all fuel types.

 

I just had a look at the running cost of a high efficiency biomass system to add to the above.  Using the current price of wood pellets here, and a typical efficiency figure for a state of the art pellet burning boiler, then the annual running cost using the same heating requirement case as before, would be £131.46, so mid-way between the running cost for an ASHP at peak rate and mains gas.

[Clive Osborne]

5 hours ago, SteamyTea said:

I suspected that you were getting muddled between installed capacity, energy and power a while back

It is an easy mistake to make, most of us do it.

It is important to make this distinction otherwise the calculations for efficiency just become nonsense numbers.

 

A watt [W] is a joule per second, both Watt and Joule were people, it is why, under the SI system the abbreviation is upper case i.e. W, J, but written in full starting with a lover case. a kelvin, which is named after Lord Kelvin, is the same. You don't have °K, that is saved for the celsius scale, which used to be known as the centigrade scale. Celsius was a person, so C when shortened, celsius when in full, unless talking about the man.

 

A Wh is the energy delivered, stored or available and can be in many forms, but basically come down to kinetic [moving] or potential [stored].  This is a small unit, so is usually prefixed with a k, M or G for kilo [1000], mega [million], giga [billion].

So a kWh, not Kwh, or KWH, or killa wot our, is made up of smaller units, joules and seconds.  A second, is not named after a person, so is lower case when abbreviated.

So there are 3.6 million joules in a kWh, 1000 joules per second, times 3600 seconds in an hour.

Just to put that into perspective, a joule is the force needed to move 1 kg 1 metre.  Force is mass times acceleration.

 

 

 

 

You probably heard a wooshing sound as a lot of that went over my head. But I will go through it all again