Contending with Cooling
Greetings from sunny England to the readers of GEM. As I write it's August, and as we've had several days of hot sunny weather the media is full of hysteria about 'record temperatures,' 'global warming' and 'drought.' Actually, in the UK it only takes three 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, a query came 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.
And so on to the discussion that attracted my attention this month on the Stationary Engine Mailing List. As ever, the following comments reflect a variety of opinions that surfaced during this discussion.
Currently, we have largely voluntary water restrictions in and around Melbourne. As such, 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 -i.e., it's not pumped - the water siphons when it gets hot enough. I know 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 have 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 the 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 sees 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 subject of surprisingly 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. It can even angle 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 think it's poor design in a thermo-siphon system to use a thermostat or valve in the top pipe, and 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 top pipe sloping upward, 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 won't thermo-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 (preferable, 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 four cinder blocks or a 12-volt 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 Rose berry 3C. I had the tank made for the Rose berry 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 1 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 it usually runs at just above an idle, and even running a grinder there was never a long enough running time or big enough 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 the right look.
The original question in this discussion was 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 and air, and from then on I had to loosen the hose clamp at the engine end every 15 minutes or so and let the steam and air escape. 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.
I bet even a very slight up-slope in the top pipe will help a lot. Expecting air or steam to move 'up' with a horizontal pipe is like expecting water to drain off of a flat roof. Great idea using a clear pipe to test it.
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 that usually guarantees rain within 24 hours!
'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.'
'I bet even a very slight up-slope in the top pipe will help a lot. Expecting air or steam to move 'up' with a horizontal pipe is like expecting water to drain off of a flat roof. Great idea using a clear pipe to test it.'
Engine enthusiast Helen French lives in Leicester, England. Contact her via e-mail at: Helen@insulate.co.uk You can join the Stationary Engine List on the Internet at: www.atis.net