Willis Heating System

[Harry Bloomfield]

So, thanks to you, I think I've now got my thinking straight about this, and do now understand 'how it works'.

Phew, got there atlas.

However, I'm still inclined to stick with what I most recently wrote - namely that I don't really see what advantage this external heater offers over having an immersion within the main tank at the same height (above base of cylinder) as the external one - do you?

OK... The difference/advantage is that, your usual immersion heater, to some extent, due to circulation, is trying to some degree, to heat all the water, above the bottom of the element. You get little choice on this, it's all, or none. Immersion elements have limited lengths, and only the water above the bottom of the element will be heated.

The Willis, can heat a very limited amount, with the hot water all concentrated just at the very top of the main cylinder. You have the choice of anywhere between a little, or a lot. The Willis is also able to heat all of the water in the main cylinder down to where the Willis cold connection joins the main cylinder at the bottom. That would add perhaps an extra third to my stored hot water capacity, over the existing amount...

At the moment I normally use my gas boiler, which heats much more water in the cylinder, and of course is cheaper to run, than does the immersion heater in the same cylinder, because the boilers coils, are located below the end of the immersion element.

 

[ebee]

I actually think I do understand, and I certainly have the ability to identify statements/assertions that I believe to be incorrect - but I just fear that I am perhaps 'missing something', since so many people (at least, in Ireland and NI) seem to have bought into the idea of the 'system' concerned.

However, the more that people fail to present me with an argument to the contrary which I can understand and accept, the closer I come to believing that I probably am 'correct' in my thinking and that a lot of these thoughts about the Willis system may be little more than 'myth', created by people who don't adequately understand the physics.

Despite that, I remain open-minded, so would welcome any credible explanations about 'what I am missing' (not just assertions of views that differ from mine!)

I agree - I would love someone would come up with an explanation as to why it actually works and I could have a blinding "Road to Damascus" experience and shout Eurika etc , after all just because I do not (yet) get it, does not mean that it does not exist. I do not see a way that it is remotely tangible! What am I missing?

 

[Harry Bloomfield]

I agree - I would love someone would come up with an explanation as to why it actually works and I could have a blinding "Road to Damascus" experience and shout Eurika etc , after all just because I do not (yet) get it, does not mean that it does not exist. I do not see a way that it is remotely tangible! What am I missing?

Obviously, I don't have such a system, and have never come across one in a domestic situation, though I have certainly seen similar in commercial/industrial locations. Work, it certainly does, as has we have tried hard to explain both the theory, and practical sides to John and anyone else watching the thread.

 

[ericmark]

What am I missing?

The old Willis website, it did have a detailed explanation of how it worked, but it seems to have vanished.

 

[ebee]

Actually, just to put the record straight.
I see two options - those in favour of the Willis wing the arguement by proving it.
Myself (and John) show it can not be proved.
I actually prefer that first option to come about if I have any choice about it.

I can envisage (slightly) one small difference with a Willis could be achieved by positional layout - the water leaving the Willis after heating could move at a higher velocity therefore perhaps "overshoot" a little before settling, I do envisage the overall difference being difficult to measure as a potential advantage though (alternatively, it could just be something else that I am wrong about).

Some years ago I met a problem I could not solve and it drove me half mad, but did eventually solve it by completely not thinking about it for a few days. One day, suddenly whilst looking in the mirror, shaving - I had that "Road to Damascus Event" , hey presto I got it (It was the "Monty Hall Conumdrum) simple once you got it and you kick yourself for not getting it earlier, you wonder how come you did not get it - will this one be another one of those???

 

[Harry Bloomfield]

hey presto I got it (It was the "Monty Hall Conumdrum) simple once you got it and you kick yourself for not getting it earlier, you wonder how come you did not get it - will this one be another one of those???

No, the Willis principle is simple, and fairly obvious how it works.

 

[SUNRAY]

Actually, just to put the record straight.
I see two options - those in favour of the Willis wing the arguement by proving it.
Myself (and John) show it can not be proved.
I actually prefer that first option to come about if I have any choice about it.

Are you asking 'us' to prove that hot water rises?

Are you asking 'us' to prove that central heating systems can work without a pump?

 

[EFLImpudence]

Some people do not seem to recognise the gravity of the situation.

 

[ebee]

Some people do not seem to recognise the gravity of the situation.

Mavity will cause hotter liquids to rise and cooler liquids to lower , yes I will buy into that concept no problem there as far as I can see.
Therefore causing the water circuit to flow so a back boiler in an old fashioned coal fire or the immersion heater in the cylinder causes a flow so yes again, I can see that too and whether you had only one such driving force or one hundered of such then the result would be similar and would depend upon the total heat input and position of the heater(s) so I am ok with that. .
Most cylinders have one or two immersion heaters in them so they might be at different levels in the cylinder. and you might or might not have a back boiler in a fireplace too.

 

[SUNRAY]

Some people do not seem to recognise the gravity of the situation.

Just to confuse the situation further the heat source may be higher than the storage vessel.

I have expectation there would be reduced efficacy/efficiency.

I recall a friends non pumped heating installation in a very old house with a solid fuel boiler and a radiator one floor below it which was only ever 'warm to the touch' at best until he rerouted the heating return pipe from upper floors down via the lower floor to include the lowest radiator.

 

[JohnW2]

Phew, got there atlas.

Indeed - to a large extent, and thanks mainly to Sunray. Despite the fact that others have simply been telling me that their view was 'obvious' and effectively telling me that I was demonstrating some sort of idiocy or 'arrogance', from the very start I have been (I would say fairly 'humbly'!) repeatedly saying that I was sure that I was 'missing something fundamental' and asking for help - and Sunray is the only person who has really helped me to understand what it was that I had been missing!

... your usual immersion heater, to some extent, due to circulation, is trying to some degree, to heat all the water, above the bottom of the element. You get little choice on this, it's all, or none. Immersion elements have limited lengths, and only the water above the bottom of the element will be heated.

Agreed.

The Willis, can heat a very limited amount, with the hot water all concentrated just at the very top of the main cylinder. You have the choice of anywhere between a little, or a lot. The Willis is also able to heat all of the water in the main cylinder down to where the Willis cold connection joins the main cylinder at the bottom.

Something seems to have gone wrong with your typing - since the first and third of those sentences seem to be saying opposite things - the Willis system can either "heat a very limited amount, with the hot water all concentrated just at the very top of the main cylinder" OR "heat all of the water in the main cylinder down to where the Willis cold connection joins the main cylinder at the bottom" - but not both

I'm coming to think that how the Willis system works is probably crucially dependent upon its thermostatic control (where the sensor is and what temp it is set to. So long as it remains powered, it will heat water in the main cylinder until at least all the water above the level of the Will is have been heated - so seemingly exactly the same as with an immersion in the main cylinder at that height - I'm not yet sure about the parts of the cylinder below that.

 

[JohnW2]

I agree - I would love someone would come up with an explanation as to why it actually works and I could have a blinding "Road to Damascus" experience and shout Eurika etc , after all just because I do not (yet) get it, does not mean that it does not exist. I do not see a way that it is remotely tangible! What am I missing?

As you will have seen, I have at last come to understand to a fair extent - but I am still struggling to see how it really offers anything appreciably different (or 'better') than one can achieve with a 'high immersion (and thermostat) in the main cylinder.

Kind Regards, John

 

[JohnW2]

The old Willis website, it did have a detailed explanation of how it worked, but it seems to have vanished.

Yes, and as I said, there is remarkably little at all on-line about the Willis system - which might possibly be that not many people think that it hs got much to offer?

What 'explanations' one does find all seem to be majoring on the 'advantage' being that heats the water in the cylinder "from the top downwards" - but that, of course, is exactly what will happen with any means of heating the water in the cylinder, so it's hardly an 'advantage'

 

[JohnW2]

No, the Willis principle is simple, and fairly obvious how it works.

As I've implied, things are only 'obvious' to those to whom they are obvious - and the secret of being able to teach/help effectively is to be able to understand the problems of people to whom it is not obvious.

We had a prize example of this at school. We had an A-Level maths teacher who was a brilliant mathematician, with an Oxbridge PhD. However, things were so 'obvious' to him that he had virtually no ability to understand why they were not also 'obvious' to the students. For example, when asked how one step in a calculation followed for a previous one, he would answer with things like:
"because it does"
"because it's obvious"
... or, worst of all, ...
"because of the six intermediate steps between those two steps which are so obvious that they don't warrant mentioning or writing down"

 

[JohnW2]

Just to confuse the situation further the heat source may be higher than the storage vessel.

Perhaps - but that's where I have not yet fully got my head around some aspects, since it would seem to imply that an external heater (or high internal immersion) could potentially heat the entire contents of the cylinder, and I'm far from convinced that such is the case.

However, again, I think the thermostatic control of the Willis heater is probably crucial to what happens (or doesn't happen).