nexgen graphene heating panels

[Clive Osborne]

4 minutes ago, JSHarris said:

 

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.

No it's a room by room heat loss tool it just uses standard degree days etc to compare guides on running cost based on the results. 

[Jeremy Harris]

5 minutes ago, Clive Osborne said:

@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. 

 

The figures that @SteamyTea has given look spot on to me.  There are a lot of myths circulating about stuff like heat capacity in particular.

 

There are also lots of really poor heating installations around, that operate at well below their optimum efficiency.

[Clive Osborne]

Just now, JSHarris said:

 

The figures that @SteamyTea has given look spot on to me.  There are a lot of myths circulating about stuff like heat capacity in particular.

 

There are also lots of really poor heating installations around, that operate at well below their optimum efficiency.

That's very true I have seen some shocking ASHP installs where they have left the emmiters as per the gas boilers they replaced them with.They run at 45C and then wonder why people complain  . How do you calculate air changes in @SteamyTea last numbers. 

[Clive Osborne]

9 minutes ago, PeterW said:

 

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. 

That would explain it. Certainly in the case of combi boilers. 

[Jeremy Harris]

3 minutes ago, Clive Osborne said:

No it's a room by room heat loss tool it just uses standard degree days etc to compare guides on running cost based on the results. 

 

The challenge I found when trying to do a room by room analysis was determining the Δ_T, U value and relative ventilation heat loss between adjacent rooms. Just dealing with the outer thermal envelope, to determine the whole house heat loss, made life easier, and seemed to be more representative with regard to the way homes are often used and heated.  I could have used degree days, but opted to use the Met Office average climate data for our location instead.  As it happens that significantly over-estimates our true heat loss, as, being down at the bottom of a valley, with the house partially set back into a cutting in the hillside, so sheltered from the wind, means that we have a local microclimate that is around 1°C to 2°C warmer then the Met Office data.

[Jeremy Harris]

9 minutes ago, Clive Osborne said:

How do you calculate air changes in @SteamyTea last numbers. 

 

By extrapolation from the air permeability test data for any house built in the last few years (where this has been a requirement in Part L1a), or from the MVHR setting and efficiency if the house has MVHR.  For example our house has a low air permeability (the air test was 0.49 ACH @ 50 Pa) and I run the MVHR at 0.43 ACH, and the MVHR has an efficiency of about 85%.

[SteamyTea]

20 minutes ago, Clive Osborne said:

How do you calculate air changes in @SteamyTea last numbers. 

I could sit down and work out an estimate for the ACH based on HDDs, but it would only be a rough estimate.

Apart from a bit of extra insulation in my loft, changing the glazing from  3-8-3 to 3-16-3, making sure the old frames fitted correctly and a bit of extra draft-proofing around the back door, I have done nothing to the house.

When I first moved in, and having been used to an old Victorian house, but with a gas combi boiler, I was a bit fooling with energy.  My first years usage was almost 12 MWh, now it is about 3.8 to 4 MWh.

So about a third of the usage.  A large part of this was DHW, then I saw just how much I was being charged for water, so cut back drastically.

It is also a testament to just how good timber frame houses can be.  Mine is one of the first 6 of this design in Cornwall, then they build hundreds of them, if not thousands.  Apart from when I went away a couple of Autumns back for a month and did not leave any windows open, I have had no issues with condensation.

Condensation may be a concern if having a low air temperature inside the house and the ventilation is not idea.  No amount of FIR is going to solve that.  It would be an interesting area to study.

27 minutes ago, JSHarris said:

The challenge I found when trying to do a room by room analysis was determining the Δ_T, U value and relative ventilation heat loss between adjacent rooms

Something I had to do as a first year degree student.  Seem to remember the hard part was making the spreedsheet look pretty, rather than the actual calculations.

We were given the temperature and ACH to work from, which made life easy.  Was possibly that assignment that made me interested in thermodynamics more than any other, probably because it was a real world problem, unlike what I did for my 3^rd Year project, which was, in a way, similar, but a lot of equations and calculus to prove it.

 

[Jeremy Harris]

24 minutes ago, SteamyTea said:

Something I had to do as a first year degree student.  Seem to remember the hard part was making the spreedsheet look pretty, rather than the actual calculations.

We were given the temperature and ACH to work from, which made life easy.  Was possibly that assignment that made me interested in thermodynamics more than any other, probably because it was a real world problem, unlike what I did for my 3^rd Year project, which was, in a way, similar, but a lot of equations and calculus to prove it.

 

 

The bit I struggled with was making the model sufficiently dynamic that it would reasonably accurately deal with significant room-by-room variations in incidental heat gain.  At the time I was looking at including incidental heat gain in the model, and some aspects were reasonably easy (solar gain moving around the house through the day) but other aspects (variations in heat gain from cooking, or using the vacuum cleaner) were more difficult.

 

In the end I remembered that I'd set out to make a simple model, really for just comparing different construction materials, and opted to stick to the whole house, ignoring incidental gain altogether, on the basis that all that mattered really was getting a fairly accurate worst case heat loss. 

 

One interesting point is that the standing charge distorts the comparison of running cost by fuel type a fair bit.  I still think I need to try and work out a split for the electricity standing charge, as that charge would exist irrespective of the heating fuel chosen.

[SteamyTea]

2 minutes ago, JSHarris said:

I was looking at including incidental heat gain in the model

What Solver is for, or do it the easy way and just work out the hour by hour means, then add in the incidentals.  Then hit F9.

3 minutes ago, JSHarris said:

I still think I need to try and work out a split for the electricity standing charge, as that charge would exist irrespective of the heating fuel chosen.

I think because I don't draw anything from the grid 60% of the time, I should get a discount.

[Jeremy Harris]

2 minutes ago, SteamyTea said:

I think because I don't draw anything from the grid 60% of the time, I should get a discount.

 

Same here.  I'd guess that we're exporting to the grid for a fair bit of the time.  Right now my car is fully charged, the hot water system is fully charged, the washing is done and the house is sat exporting about 4.5 kW to the grid (for which we get paid a bit less than the peak rate import cost).

[SteamyTea]

4 minutes ago, JSHarris said:

for which we get paid a bit less than the peak rate import cost

Don't you get the deemed export and the actually generation payment, tax free?

[Jeremy Harris]

39 minutes ago, SteamyTea said:

Don't you get the deemed export and the actually generation payment, tax free?

 

We get FiT on the generation, plus 50% deemed export at 5.38p/kWh. 

[SteamyTea]

I forgot you are on E7 now.

I really must have a look at my electricity costs.  For me EDF were always been the cheapest (far end of the power cable), without exception, but they don't seem too competitive at the moment.

Trouble is, there is only £40-60/year difference on my usage.  I can easily save that by putting an inch less bath water in.

If I had a spare £10k, I would drill a borehole for my water and get a small HP to heat it up.  But as that is about 15 years worth of energy, hardly seems worthwhile.  It is like planting a tree, should have done it 15 years ago.

 

[Jeremy Harris]

6 minutes ago, SteamyTea said:

  It is like planting a tree, should have done it 15 years ago.

 

 

But then there's the old Greek proverb: "It is a wise man who plants a tree, knowing that he will never sit under its shade".

 

Not sure I'm wise, but I have planted 12 trees here now.

[SteamyTea]

13 minutes ago, JSHarris said:

Not sure I'm wise, but I have planted 12 trees here now.

I planted 2, one seems to have died.  I have been expecting rain, but looks like ti will start on the weekend, just as the school holidays start.

[SteamyTea]

3 hours ago, Clive Osborne said:

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

Get a copy of this book.

https://www.amazon.co.uk/Energy-Beginners-Guide-Guides/dp/1786071339

It is pretty good and I got it electronically from my local library.

Also there is the classic https://www.withouthotair.com/download.html free download

Then the OU books that the renewable courses use.

https://www.amazon.co.uk/Energy-Systems-Sustainability-Sustainable-Future/dp/0199593744

https://www.amazon.co.uk/RENEWABLE-ENERGY-SUSTAINABLE-GODFREY-PAPERBACK/dp/0199681279

I would say that the first two are compulsory reading and the second two are good for referencing.

 

 

[MikeSharp01]

2 hours ago, SteamyTea said:

I can easily save that by putting an inch less bath water in.

Even more if you have a shower one supposes.

[SteamyTea]

3 minutes ago, MikeSharp01 said:

Even more if you have a shower one supposes

Yes, but a bath is my luxury, and it gets my body moving properly.

[Clive Osborne]

5 hours ago, JSHarris said:

 

The challenge I found when trying to do a room by room analysis was determining the Δ_T, U value and relative ventilation heat loss between adjacent rooms. Just dealing with the outer thermal envelope, to determine the whole house heat loss, made life easier, and seemed to be more representative with regard to the way homes are often used and heated.  I could have used degree days, but opted to use the Met Office average climate data for our location instead.  As it happens that significantly over-estimates our true heat loss, as, being down at the bottom of a valley, with the house partially set back into a cutting in the hillside, so sheltered from the wind, means that we have a local microclimate that is around 1°C to 2°C warmer then the Met Office data.

I will find the blank spreadsheet and post it on here. It had parts about being open to the elements. 

[Clive Osborne]

5 hours ago, JSHarris said:

 

By extrapolation from the air permeability test data for any house built in the last few years (where this has been a requirement in Part L1a), or from the MVHR setting and efficiency if the house has MVHR.  For example our house has a low air permeability (the air test was 0.49 ACH @ 50 Pa) and I run the MVHR at 0.43 ACH, and the MVHR has an efficiency of about 85%.

Do you use the heat extracted ? 

[Jeremy Harris]

1 minute ago, Clive Osborne said:

Do you use the heat extracted ? 

 

Yes, that's what an MVHR unit does (Mechanical Ventilation with Heat Recovery).  Ours is pretty typical, and recovers around 85% of the heat that would other wise be wasted from ventilation.  Bonuses are that the consistent ventilation rate ensure nice fresh air in the house all the time, and there's a pollen filter on the intake, so the house stays pollen free.

[Clive Osborne]

Just now, JSHarris said:

 

Yes, that's what an MVHR unit does (Mechanical Ventilation with Heat Recovery).  Ours is pretty typical, and recovers around 85% of the heat that would other wise be wasted from ventilation.  Bonuses are that the consistent ventilation rate ensure nice fresh air in the house all the time, and there's a pollen filter on the intake, so the house stays pollen free.

Yes I understand that's pretty typical but some use it directly in a all in one heat pump cylinder 

[Clive Osborne]

2 hours ago, SteamyTea said:

Get a copy of this book.

https://www.amazon.co.uk/Energy-Beginners-Guide-Guides/dp/1786071339

It is pretty good and I got it electronically from my local library.

Also there is the classic https://www.withouthotair.com/download.html free download

Then the OU books that the renewable courses use.

https://www.amazon.co.uk/Energy-Systems-Sustainability-Sustainable-Future/dp/0199593744

https://www.amazon.co.uk/RENEWABLE-ENERGY-SUSTAINABLE-GODFREY-PAPERBACK/dp/0199681279

I would say that the first two are compulsory reading and the second two are good for referencing.

 

 

Thank you. Some bed time reading 

[Jeremy Harris]

2 minutes ago, Clive Osborne said:

Yes I understand that's pretty typical but some use it directly in a all in one heat pump cylinder 

 

Doesn't work well without some careful management of air flow rates.  There are some exhaust air heat pumps that are smart enough to ensure that the house isn't over-ventilated when heating the cylinder, like the Genvex units, then there are some fixed speed Chinese made units that will massively over-ventilate the house in order to pump enough heat into the tank. 

[SteamyTea]

49 minutes ago, Clive Osborne said:

Some bed time reading

I have just read C P Snow's Science and Government lecture.

Still valid even though it is almost 60 years since he delivered it.

Last week was Club of Rome's Limits to Growth. Not valid and basic premise was wrong, and still is wrong.

Now back to Rachel Carson's Silent Spring. If you want to learn a lesson about bad science and selective evidence, this is the book to read.