Calorifier

[Guest]

But if you worry so much and treat your tank and drink the water, why would you get bacteria from the calorifier? It is a fact that most danger is with prolonged stored water between 20 and 50 degrees, you said yourself you don't know about this so what is your problem? Why will you get cross contamination? Why do you think an exploding tank is less of a risk? You are not very logical. What is this bacteria that grows rapidly with just a slight temperature increase?

I have lost the will to live.

[ChrisPy]

I think I've spotted the flaw in the argument......

 

Let's say, for the sake of argument, that the 8 litre EV contains 4 litres of water when the calorifier is cold and is pre-charged to 35psi. If it now absorbs 2 litres of water due to expansion, the pressure of the air in the EV, above the diaphragm, will rise (by Boyle's Law) to 70 psi. With that much I agree.

 

But so what...... Boyle's Law does not apply on the other side of the diaphragm as the calorifier contains a liquid not a gas. The pressure in the calorifier is not now 70psi as well. In fact, the pressure in the calorifier should stay the same, viz: the water pump's cut-out pressure (say 30psi) because any increased pressure due to expansion has been absorbed.

 

So the EV's diaphragm pressure must be ABOVE the water pump's (WP) cut-out pressure or otherwise the WP will fill the EV with water and no room will be left for expansion. But the EV pressure must also be BELOW the PRV pressure or else the expanding water will simply blow the PRV first. Hence with a typical PRV of around 42psi and a WP cut-out pressure of 30psi we set the EV to about 33-35psi.

 

Chris

1. please use absolute pressures

2. it doen't matter what fluid we are dealing with, the pressure in the EV is driven by the calorifier, there is no other source of pressure.

3. the calorifier pressure can be well above the pump cut-out pressure, even if there is no NRV. the pump provides minimal initial pressure. the warming water makes this rise.

4. the EV pressure can be set at anything you like. a low setting gives more available volume but the air-filled void will reduce more quickly at low pressures; a high setting gives more resistance to expansion but little volume. so it will always be a compromise. please see my (corrected) worked example.

 

................ back to skule

[Batavia]

I think I've spotted the flaw in the argument......

 

Let's say, for the sake of argument, that the 8 litre EV contains 4 litres of water when the calorifier is cold and is pre-charged to 35psi. If it now absorbs 2 litres of water due to expansion, the pressure of the air in the EV, above the diaphragm, will rise (by Boyle's Law) to 70 psi. With that much I agree.

 

But so what...... Boyle's Law does not apply on the other side of the diaphragm as the calorifier contains a liquid not a gas. The pressure in the calorifier is not now 70psi as well. In fact, the pressure in the calorifier should stay the same, viz: the water pump's cut-out pressure (say 30psi) because any increased pressure due to expansion has been absorbed.

 

So the EV's diaphragm pressure must be ABOVE the water pump's (WP) cut-out pressure or otherwise the WP will fill the EV with water and no room will be left for expansion. But the EV pressure must also be BELOW the PRV pressure or else the expanding water will simply blow the PRV first. Hence with a typical PRV of around 42psi and a WP cut-out pressure of 30psi we set the EV to about 33-35psi.

 

Chris

 

Apologies for the delay in replying, but there was a need to do some paying work!

 

As others have pointed out, your arguement still does not work.

 

In simplest terms, the pressure on each side of the diaphragm has to be the same - otherwise it will move in one direction or the other until the pressure is equalised. It does not matter which laws apply to the two fluids, as long as they are the appropriate ones.

 

Out of interest, do you have a stockcock which can isolate the calorifiern and a pressure gauge on the calorifier? If so, it would be interesting to do some tests to see what actually happens when the isolated system is heated up.

 

Also, are there any ASME VIII people (if we are going to look at this, at least get it done properly) out there who would like to work out the increased volume of the calorifier itslf as the pressure increases? I did some calcs, but the answer seemed to be too small (I'm not a vessel design person).

 

Chris G

[chris w]

Apologies for the delay in replying, but there was a need to do some paying work!

 

As others have pointed out, your arguement still does not work.

 

In simplest terms, the pressure on each side of the diaphragm has to be the same - otherwise it will move in one direction or the other until the pressure is equalised. It does not matter which laws apply to the two fluids, as long as they are the appropriate ones.

 

Out of interest, do you have a stockcock which can isolate the calorifiern and a pressure gauge on the calorifier? If so, it would be interesting to do some tests to see what actually happens when the isolated system is heated up.

 

Also, are there any ASME VIII people (if we are going to look at this, at least get it done properly) out there who would like to work out the increased volume of the calorifier itslf as the pressure increases? I did some calcs, but the answer seemed to be too small (I'm not a vessel design person).

 

Chris G

This is an interesting problem and one which is not only interesting but counter-intuitive in parts.

 

I agree that the pressure either side of the diaphragm must be the same or else the diaphragm would move to take up the difference. Equally, if the calorifier pressure increases solely due to thermal expansion, as in this example, and we allow extra space (the EV) to accomodate that expansion, then the calorifier pressure can not increase.

 

Imagine we used the pump to pressurise the 60 litre cold calorifier to 30psi and, as above, we have an 8 litre EV pre-charged to 35psi. Assume an NRV on the cold inlet. Let's also imagine for the moment that we have a stopcock on the inlet to the EV which at the moment is open. The diaphragm will be fully expanded (ie: no water in it) since the EV pressure (35psi) is higher than the WP pressure (30psi).

 

Now let's close the stopcock on the EV and heat the calorifier water. The pressure inside the calorifier increases as the water expands. Let's say we have a super strong calorifier, with no PRV for the moment, and that it is strong enough to accomodate the 2 litre expansion without bursting, but there's high pressure nonetheless inside the calorifier.

 

Now let's slowly open our imaginary stopcock on the EV. (I say slowly so that any pressure change is isothermal and not adiabatic as would be the case in reality). As the EV fills with water (because the water pressure is now well above the 35psi of the EV diaphragm) so the pressure in the calorifier drops back to its original value (30 psi) because ALL the increased pressure due to the 2 litre expansion has now been accomodated in the EV.

 

In reality, if we don't have an EV, we know the increase in calorifier pressure is sufficient to blow a 3 bar PRV so the pressure is certainly above 42psi. If the EV, which previously had 8 litres of air @ 35psi, now accomodates 2 litres of water then its internal air pressure increases (by Boyle's Law) to (8 x 35 /6) = 47psi. This would still be more than sufficient to blow the PRV but that doesn't happen in reality if an EV is fitted, so the calorifier pressure must be less than 42psi despite the EV's internal air pressure being greater than 42psi.

 

Herein lies the conundrum.....

 

Chris

[RobinJ]

In simplest terms, the pressure on each side of the diaphragm has to be the same ..

This is where the problem with accumulators and expansions comes in, measuring the pressure when?

If the pump runs up to 25psi, a 5l accumulator set at 8psi when empty will fill up to just over 3l when pressurised to 25psi. If a 50l calorifier and expansion vessel are on the other side of a NRV, that too will start at 25psi, but as it heats up, will expand lets say by 4%, so its the volume that needs to be accomodated to prevent the PRV releasing, say around 2l. If the expasion vessel is set less than 25psi, it will already be partly full of water, setting it at 25psi will in theory mean it starts empty, but if the PRV is set at 40psi, that means that when the expansion vessel is half full, the pressure will be already up to 50psi! Its looking like you will need an expansion vessel that can accomodate 5l?

The higher the pressure on the feed side and the larger the calorifier, the bigger the expansion vessel needs to be - from this you can estimate it needs to be 10%-20% of the calorifier capacity!

If you can handle the volume, pressure will take care of itself.

[David Schweizer]

Good God, I really do wonder how some of us have managed to survive all these years with our simple installed sysytems, without knowing any of this scientific, technical stuff.

[Batavia]

Good God, I really do wonder how some of us have managed to survive all these years with our simple installed sysytems, without knowing any of this scientific, technical stuff.

 

It is quite possible to manage without the science (you just rely on experience or on someone else having done it for you), but if you are going to try and be scientific in public, then I feel that there is an obligation to get it right and not to mislead other people.

 

Chris G

 

This is an interesting problem and one which is not only interesting but counter-intuitive in parts.

 

I agree that the pressure either side of the diaphragm must be the same or else the diaphragm would move to take up the difference. Equally, if the calorifier pressure increases solely due to thermal expansion, as in this example, and we allow extra space (the EV) to accomodate that expansion, then the calorifier pressure can not increase.

 

Imagine we used the pump to pressurise the 60 litre cold calorifier to 30psi and, as above, we have an 8 litre EV pre-charged to 35psi. Assume an NRV on the cold inlet. Let's also imagine for the moment that we have a stopcock on the inlet to the EV which at the moment is open. The diaphragm will be fully expanded (ie: no water in it) since the EV pressure (35psi) is higher than the WP pressure (30psi).

 

Now let's close the stopcock on the EV and heat the calorifier water. The pressure inside the calorifier increases as the water expands. Let's say we have a super strong calorifier, with no PRV for the moment, and that it is strong enough to accomodate the 2 litre expansion without bursting, but there's high pressure nonetheless inside the calorifier.

 

Now let's slowly open our imaginary stopcock on the EV. (I say slowly so that any pressure change is isothermal and not adiabatic as would be the case in reality). As the EV fills with water (because the water pressure is now well above the 35psi of the EV diaphragm) so the pressure in the calorifier drops back to its original value (30 psi) because ALL the increased pressure due to the 2 litre expansion has now been accomodated in the EV.

 

In reality, if we don't have an EV, we know the increase in calorifier pressure is sufficient to blow a 3 bar PRV so the pressure is certainly above 42psi. If the EV, which previously had 8 litres of air @ 35psi, now accomodates 2 litres of water then its internal air pressure increases (by Boyle's Law) to (8 x 35 /6) = 47psi. This would still be more than sufficient to blow the PRV but that doesn't happen in reality if an EV is fitted, so the calorifier pressure must be less than 42psi despite the EV's internal air pressure being greater than 42psi.

 

Herein lies the conundrum.....

 

Chris

 

I think that you could harness this argument somehow to make a perpetual motion machine....

[chris w]

Good God, I really do wonder how some of us have managed to survive all these years with our simple installed sysytems, without knowing any of this scientific, technical stuff.

...............and it's just plain interesting too. It's those that love the scientific approach, and are curious as to how things work, that have given the rest of mankind the tools, the toys and the benefits of that science.

 

YOU don't need to know how it works, but SOMEONE does!!

 

Chris

 

 

 

I think that you could harness this argument somehow to make a perpetual motion machine....

............funny you should mention that...........

Edited November 11, 2008 by chris w

[ChrisPy]

This is an interesting problem and one which is not only interesting but counter-intuitive in parts.

 

I agree that the pressure either side of the diaphragm must be the same or else the diaphragm would move to take up the difference. Equally, if the calorifier pressure increases solely due to thermal expansion, as in this example, and we allow extra space (the EV) to accomodate that expansion, then the calorifier pressure can not increase.

 

Imagine we used the pump to pressurise the 60 litre cold calorifier to 30psi and, as above, we have an 8 litre EV pre-charged to 35psi. Assume an NRV on the cold inlet. Let's also imagine for the moment that we have a stopcock on the inlet to the EV which at the moment is open. The diaphragm will be fully expanded (ie: no water in it) since the EV pressure (35psi) is higher than the WP pressure (30psi).

 

Now let's close the stopcock on the EV and heat the calorifier water. The pressure inside the calorifier increases as the water expands. Let's say we have a super strong calorifier, with no PRV for the moment, and that it is strong enough to accomodate the 2 litre expansion without bursting, but there's high pressure nonetheless inside the calorifier.

 

Now let's slowly open our imaginary stopcock on the EV. (I say slowly so that any pressure change is isothermal and not adiabatic as would be the case in reality). As the EV fills with water (because the water pressure is now well above the 35psi of the EV diaphragm) so the pressure in the calorifier drops back to its original value (30 psi) because ALL the increased pressure due to the 2 litre expansion has now been accomodated in the EV.

 

In reality, if we don't have an EV, we know the increase in calorifier pressure is sufficient to blow a 3 bar PRV so the pressure is certainly above 42psi. If the EV, which previously had 8 litres of air @ 35psi, now accomodates 2 litres of water then its internal air pressure increases (by Boyle's Law) to (8 x 35 /6) = 47psi. This would still be more than sufficient to blow the PRV but that doesn't happen in reality if an EV is fitted, so the calorifier pressure must be less than 42psi despite the EV's internal air pressure being greater than 42psi.

 

Herein lies the conundrum.....

 

Chris

Chris ......... the only conundrum is the one in your head.

 

I PM'ed you on this, but you haven't understood or apparently even tried to understand what I was getting at.

 

............... A word or two of advice - forget about 'isothermals and adiabatics'. And forget about fluid systems because you clearly don't have a clue.

How 'all the increased pressure can be accommodated in the EV' while the pressure in the calorifier drops back to its original pressure, I just don't know. It is only simple 'O' level physics to know that all pressures in a static fluid system are equal, except the head difference which we can ignore.

 

Oh, again I implore you to use absolute pressures when making such calculations. Even a 15year-old doing physics knows that.

 

PS. I hope your advice on electrics (that I don't pretend to understand other than following the codes and standards) is not equally flawed.

 

Please leave it or we are in danger of Catweasel jumping off the top of the Anderton lift in utter despair.

[Guest TerryL]

name='chris w' date='Nov 11 2008, 09:38 AM' post='296104']

...............and it's just plain interesting too. It's those that love the scientific approach, and are curious as to how things work, that have given the rest of mankind the tools, the toys and the benefits of that science.

 

YOU don't need to know how it works, but SOMEONE does!!

 

Chris

I wish you did, you should have paid attention in physics instead of pulling your plonker at the back of the class!

 

I've heard of your German blonde but she must be grey by now as in the '70's she used to do business in her VW camper van on the Celle road. For a box of compo rations she would put a show on for the lads, did you find my mates glasses?

 

Must go, got to fit a 150 litre cylinder supplied with an 8 litre expansion vessel, work that out.

 

BTW the program posted earlier is flawed, it can't cope with lower pre-charge pressures.

 

P.S. I can confirm your electrics are just as flawed! Where's Gobbo's email?

[Denis R]

I've heard of your German blonde but she must be grey by now as in the '70's she used to do business in her VW camper van on the Celle road. For a box of compo rations she would put a show on for the lads, did you find my mates glasses?

Terry, that really wasn't necessary. Is there no way we can keep contributions invective free?

[smileypete]

Now let's slowly open our imaginary stopcock on the EV. (I say slowly so that any pressure change is isothermal and not adiabatic as would be the case in reality). As the EV fills with water (because the water pressure is now well above the 35psi of the EV diaphragm) so the pressure in the calorifier drops back to its original value (30 psi) because ALL the increased pressure due to the 2 litre expansion has now been accomodated in the EV.

 

Right...

 

If the pressure on the air side of the EV has been raised due to reducing it's volume, the pressure on the water side of the EV MUST be the same, and therefore the pressure in the calorifier MUST be the same too!

 

You cannot reduce the pressure in the calorifer without reducing the pressure in the EV.

 

And to reduce the pressure in the EV to it's original value, the air side MUST be allowed to expand to its original volume, which it CANNOT as long as the water in the calorifier remains expanded due to being heated.

 

Ho hum....

 

cheers,

Pete.

Edited November 11, 2008 by smileypete

[chris w]

Chris ......... the only conundrum is the one in your head.

 

I PM'ed you on this, but you haven't understood or apparently even tried to understand what I was getting at.

 

............... A word or two of advice - forget about 'isothermals and adiabatics'. And forget about fluid systems because you clearly don't have a clue.

How 'all the increased pressure can be accommodated in the EV' while the pressure in the calorifier drops back to its original pressure, I just don't know. It is only simple 'O' level physics to know that all pressures in a static fluid system are equal, except the head difference which we can ignore.

 

Oh, again I implore you to use absolute pressures when making such calculations. Even a 15year-old doing physics knows that.

 

PS. I hope your advice on electrics (that I don't pretend to understand other than following the codes and standards) is not equally flawed.

 

Please leave it or we are in danger of Catweasel jumping off the top of the Anderton lift in utter despair.

 

Hey buddy...... no need to be a total prat - you made your point. I am no expert in fluid mechanics and don't pretend to be. You've been reading too many of TerryLicense(sic)'s posts. I am very capable of understanding, it may be that your PM wasn't clear - or has that not occurred to you or that I didn't agree with you.

[chris w]

P.S. I can confirm your electrics are just as flawed! Where's Gobbo's email?

I was holding back on Gibbo's email until you made your next idiotic statement so that I could catch you on the maggot........

 

OK you asked for it................. (and with Gibbo's permission)

 

First of all a compliment from Gibbo to you, viz: "He seems better than us two at rubbing people up the wrong way!"

 

 

1. With reference to battery sensing vs machine sensing. You stated that machine sensing is better. However, Gibbo says.............

 

"Well that's an odd viewpoint. "Battery sensing is usually better in a typical narrowboat (because cable sizes are usually too small) as it compensates for the losses in the cabling. However an oft overlooked problem is that very few chargers/alternator controllers have a separate negative sense lead (some of Sterlings' do) and therefore only losses in the positive cables will be dealt with. Losses in the negative cables won't be affected, they will still exist. That itself isn't a good enough reason to install battery sensing as it's easier to simply put the cabling right! But if a controller is going in anyway then to not use battery sensing would be plain stupid. I'd still rather remove the losses than try to compensate for them.

 

Obviously, if split charge diodes are used then battery sensing is an absolute must."[/i]

 

2. With regard to undoing the battery while the alternator's running, which you state will have no adverse effect whatsoever. However Gibbo's viewpoint is.......

 

 

"In a narrowboat, whilst the alternator is working relatively hard (ie bulk or the beginning of acceptance), if the battery is disconnected it is almost a certainty that the alternator will be damaged, and probably a lot of other equipment on board as a result of the voltage spike. If the alternator is disconnected it is almost certain that it will be damaged.

 

In a vehicle it isn't quite so straight forward. Most modern vehicle alternators have a minimal amount of protection built into them against this type of damage. It won't work when the alternator is working hard but it might do when in the later stages of acceptance.

 

Note that this only applies to relatively modern vehicles. Older vehicles will simply wreck the alternator the minute anything is disconnected because all this protection didn't exist. Which is the case in boats. There is no protection anywhere. Disconnect the battery............ bang goes the alternator and lots of other stuff."

 

 

If there were a poll asking whose advice people would take on electrics, either yours or Gibbo's, the one vote for you, would be you. So do you still disagree with Gibbo or will you have a sudden and remarkable epiphany?

 

At least some people occasionally appreciate what Gibbo and I have to say on electrics. I haven't noticed anything but derision, disagreement and scorn for your contributions. Further, with your reference to the Celle Road..... I knew that's the only way you could get laid - you're clearly "buy" sexual 6515930

 

Have you tried reading this click here

[ChrisPy]

Hey buddy...... no need to be a total prat - you made your point. I am no expert in fluid mechanics and don't pretend to be. You've been reading too many of TerryLicense(sic)'s posts. I am very capable of understanding, it may be that your PM wasn't clear - or has that not occurred to you or that I didn't agree with you.

 

 

 

......... nuff said

 

Edited November 11, 2008 by ChrisPy

[smileypete]

C'mon Chris, read post #212 and tell us which part of it doesn't make sense to you.

 

cheers,

Pete.

Edited November 11, 2008 by smileypete

[chris w]

C'mon Chris, read post #212 and tell us which part of it doesn't make sense to you.

 

cheers,

Pete.

I'm not saying it doesn't make sense nor am I saying it is incorrect. What I am saying is that someone earlier showed that the EV will be at 70psi due to Boyle's Law. If you are saying the calorifier water is also at this pressure, then how come it doesn't p*ss out of the PRV at a rate of knots. Fitting the EV kills PRV overflow immediately.

 

Further, if the water expands and hence its pressure increases yet we then provide room for that expansion, why would its pressure remain high? I'm just looking for straightforward fluid mechanics answers to these questions.

 

Chris

[ChrisPy]

I'm not saying it doesn't make sense nor am I saying it is incorrect. What I am saying is that someone earlier showed that the EV will be at 70psi due to Boyle's Law. If you are saying the calorifier water is also at this pressure, then how come it doesn't p*ss out of the PRV at a rate of knots. Fitting the EV kills PRV overflow immediately.

 

Further, if the water expands and hence its pressure increases yet we then provide room for that expansion, why would its pressure remain high? I'm just looking for straightforward fluid mechanics answers to these questions.

 

Chris

because most of the time we are dealing with real world situations where:

- the system is not always initiated at the pump cut-out pressure,

- there is a significant length of piping conected to the calorifier outlet,

- the temperature differences between cold inlet and the calorifier are not usually at the maximum possible values,

- there is air trapped elsewhere in the system,

- the copper calorifier will expand slightly,

- and other conditions that others will come up with, no doubt.

 

if you did a test in laboratory conditions with minimal legths of piping and controlled maximum inlet pressure and differential temperature you would find that the conclusions of others are valid.

 

it is however quite reasonable to make a judgement that the worst case conditions will rarely be met, and not to install a vessel of the theoretically required size. But when the worst case conditions do occur, the PRV will blow off.

[chris w]

because most of the time we are dealing with real world situations where:

- the system is not always initiated at the pump cut-out pressure,

- there is a significant length of piping conected to the calorifier outlet,

- the temperature differences between cold inlet and the calorifier are not usually at the maximum possible values,

- there is air trapped elsewhere in the system,

- the copper calorifier will expand slightly,

- and other conditions that others will come up with, no doubt.

 

if you did a test in laboratory conditions with minimal legths of piping and controlled maximum inlet pressure and differential temperature you would find that the conclusions of others are valid.

 

it is however quite reasonable to make a judgement that the worst case conditions will rarely be met, and not to install a vessel of the theoretically required size. But when the worst case conditions do occur, the PRV will blow off.

I don't buy this - that it's all down to a far-from-ideal system.

 

I will try to find some pressure gauges and fit them to the hot water output pipe and the EV. At least that should tell me what is actually happening. I'll also fit a valve on the EV inlet so that I can isolate the EV for experimental purposes.

[David Schweizer]

It is quite possible to manage without the science (you just rely on experience or on someone else having done it for you), but if you are going to try and be scientific in public, then I feel that there is an obligation to get it right and not to mislead other people.

 

Chris G

I agree, which is why I am keeping quiet on the suject, but what worries me ist that there seem to be several people clainming to be experts who do not agree with each other.

 

 

...............and it's just plain interesting too. It's those that love the scientific approach, and are curious as to how things work, that have given the rest of mankind the tools, the toys and the benefits of that science.

 

YOU don't need to know how it works, but SOMEONE does!!

 

Chris

 

But I already know how it works, and could probably build a working calorifier for myself. It is really a very simple piece of equipment. I just find the debate on the very fine scientific detail a bit OTT for this type of Forum.

 

By the way Chris, I collect, use, and restore old tools, so I do share your interest in their history and development. I have also contributed the results of some of my research to written works, and am preparing more for publication now.

 

God I am sounding like one of you now!!

Edited November 11, 2008 by David Schweizer

[smileypete]

I'm not saying it doesn't make sense nor am I saying it is incorrect. What I am saying is that someone earlier showed that the EV will be at 70psi due to Boyle's Law. If you are saying the calorifier water is also at this pressure, then how come it doesn't p*ss out of the PRV at a rate of knots. Fitting the EV kills PRV overflow immediately.

That was an example, not a real world measurement.

 

The calculator at the link I gave will give the EV size that's guaranteed to work.

 

However in practice, an undersized EV may work for a number of reasons, including the ones ChrisPy gave.

 

 

Further, if the water expands and hence its pressure increases yet we then provide room for that expansion, why would its pressure remain high? I'm just looking for straightforward fluid mechanics answers to these questions.

It's a bit like blowing up a balloon with one deep breath. Once the balloon is blown up, the pressure inside it increases and CANNOT return to it's original value UNLESS that extra lungful of air inside the balloon goes back into your lungs.

 

It's just the same with an EV, once the water in the calorifier is heated and expands, the pressure inside the EV increases, and the extra pressure CANNOT subside UNLESS the heated water cools down and shrinks to it's original volume.

 

cheers,

Pete.

[RLWP]

It's just the same with an EV, once the water in the calorifier is heated and expands, the pressure inside the EV increases, and the extra pressure CANNOT subside UNLESS the heated water cools down and shrinks to it's original volume.

 

cheers,

Pete.

 

Or you use the hot tap.

 

Richard

[chris w]

It's just the same with an EV, once the water in the calorifier is heated and expands, the pressure inside the EV increases, and the extra pressure CANNOT subside UNLESS the heated water cools down and shrinks to it's original volume.

 

cheers,

Pete.

So are you saying that the pressure in the calorifier is greater (!!), if we heat it up so it expands by a couple of litres, and we accomodate that expansion in an EV?

 

Chris

[Guest]

Chris ......... the only conundrum is the one in your head.

 

I PM'ed you on this, but you haven't understood or apparently even tried to understand what I was getting at.

 

............... A word or two of advice - forget about 'isothermals and adiabatics'. And forget about fluid systems because you clearly don't have a clue.

How 'all the increased pressure can be accommodated in the EV' while the pressure in the calorifier drops back to its original pressure, I just don't know. It is only simple 'O' level physics to know that all pressures in a static fluid system are equal, except the head difference which we can ignore.

 

Oh, again I implore you to use absolute pressures when making such calculations. Even a 15year-old doing physics knows that.

 

PS. I hope your advice on electrics (that I don't pretend to understand other than following the codes and standards) is not equally flawed.

 

Please leave it or we are in danger of Catweasel jumping off the top of the Anderton lift in utter despair.

You may be too late I'm afraid:

 

[Batavia]

I am no expert in fluid mechanics and don't pretend to be.

 

But you could become one - personal tutorials are avaiable locally, in exchange for beer.

 

Chris G