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©FBI 2003
Greetings to the readers of GEM from sunny England. Yes, as I write, it's August
and we've had several days of hot sunny weather, which means that the media is full of hysteria about "record
temperatures", "global warming" and "drought". Actually, in the UK, it only takes 3 consecutive
days of any particular kind of weather to bring the nation almost to a grinding halt. How the rest of the world
manages to cope with their various extreme conditions doesn't seem to register! In the world of engine restorations,
the answer is to ask the advice of friends on the Stationary Engine Mailing List, who may have encountered similar
problems. In this case, the query was from someone in the Australian state of Victoria (in the bottom right hand
corner of the country, I know - I looked it up!), which is in its seventh year of drought. stationary-engine@atis.net
* Currently in and around Melbourne we have water restrictions - largely
voluntary. Filling engine cooling tanks, while not banned, is a bit of a waste. My Southern Cross P has a 110 liter
tank on it. The water in the top is usually hot enough to steam, but the water in the bottom never gets hot.
I'm considering putting a much smaller 40 liter tank on it. The engine uses an endothermic cooling system - ie.
not pumped - the water siphons when it gets hot enough.
I know that the top pipe will have to be level with or slightly above the head inlet pipe so that water will always
cover the combustion space. Usually I have the lower pipe lower than the engine outlet - this is the bit that I'm
not sure matters. To use the smaller tank I have to build up its height so its top pipe matches the engine top
pipe. This means that the water from the bottom outlet will have to flow horizontally rather than downwards - will
this matter? I think probably not as the system depends on heat not gravity but I do not want to find out the hard
way.
Anyone got any thoughts on this?
* Sure! 110 liters is an awful lot. You could go to quarts instead of liters, because they're considerably smaller.
If you only have metric water available, you could put a secondary tank inside the original. The original would
only be to maintain the original look. The secondary will be nearly same height, but smaller cross section. A large
pipe might work well for the secondary.
* I've seen a picture of a similar setup, in which a smaller tank is inside the main tank and is used for situations
where the engine won't heat up properly. It cannot be seen from the side so all the public see is a standard tank.
It's not a good thing to have an engine running too cold either.
* How about applying the "brick in the toilet tank" principle?
Put some bulky vertical object in the large tank to fill much of its space without changing the level of the water.
The question of pipe angles was a surprising subject for conflicting opinions.
* As long as the water in the tank is at a higher level than the head,
the pipe to it can be horizontal. As for the bottom pipe, horizontal will work, too. The main thing is to not let
any part of the water jacket run dry.
* Horizontal will work, even uphill as you will have pressure from the head of water above the outlet of the tank.
* In my opinion, the top pipe should slope up at least slightly. Doesn't matter much for the bottom pipe. If the
top pipe slopes down at any point or has a high point in it, air or steam could collect and stop thermo-siphoning
completely. I also think it's poor design in a thermosiphon system to use a thermostat or valve in the top pipe,
for the same reason. If the valve's not opened, or the thermostat sticks, steam will push the water out of the
head through the bottom pipe. The empty head will heat up and possibly crack. With the flow restriction in the
bottom pipe, and an open upsloping top pipe, it's no problem if you forget to open the valve restricting coolant
flow.
As long as there's water in the tank above the opening of the top pipe, steam bubbles will escape up the pipe to
the tank, the jacket will stay full of water, and you're effectively running with hopper cooling.
* It wont thermo- or endo-siphon unless that tank is full and the top of the water in the tank is above the highest
part of the cylinder. The bottom pipe is easy. The top pipe should run up at a slight angle (preferably but not
imperative). The hot water wants to be on top and only needs a little help to float up through this system.
How about 4 cinder blocks or a 12v bilge pump? I can cook the heck out of them in my Reid tank in the blistering
sun, and they keep ticking. With a bilge you don't have to fill it up all the way.
This response was from another Australian, hence the references to unfamiliar engine marques!
*Although on an entirely different bent, my McDonald C type is hopper
cooled as is my
Roseberry 3C. I had the tank made for the Roseberry as per the factory instructions, which in retrospect were for
the engine running under load.
As I was trying to curb costs I reasoned that the one tank would also be more than sufficient for the McDonald
and therefore I could share it between them. The tank maker thought I was wrong and as it turned out, he was right
and I have since had new tanks made for each engine.
The problem was that the engines ran way too cold which was a disaster for the McDonald being a diesel as they
usually only ran at just above an idle. Even when on display running a grinder there was never a long enough running
time or load to get the engines warm enough with the huge tank.
I see many Roseberrys running a 20 liter drum with a great head of steam at rallies. Good for boiling lunch and
letting the onlookers think they are 'steam' engines but way too close to being too hot for my liking! I have also
seen a couple of false tanks (one inside the other) and these work well while maintaining to right look.
The original question in this discussion had been asked as someone was preparing to take his engines to a show,
and some of the responses came in a little late for that show, but not too late for lessons to be learned!
* You turned out to be exactly right about having a slight upward slope
to the pipe. I had it horizontal - fortunately I use clear pipe and can always see if the water is moving. About
an hour in, the pipe emptied of water and filled with steam & air. From then on, about every 15 minutes or
so I had to loosen the hose clamp at the engine end and let the steam and air escape to be replaced by water. Wish
I had read your advice before
the show!
I think I'll go make the tank an inch higher and run the engine for a bit and see how much difference it makes.
* l bet even a very slight upslope in the top pipe will help a lot.
Expecting air or steam to move "up" with a horizontal pipe is about like expecting water to drain off
of a flat roof. That usually doesn't work too well, either.
Great idea using a clear pipe to test it out in practice!
That's all for now. I'm off to water the garden before a hosepipe ban is announced. Not to mention that's a chore
which usually guarantees rain within 24 hours!
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©FBI 2003