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Setting up Cooling Tanks

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Traffic has been relatively light on the internet Stationary Engine mailing list this month, largely due to the big event in our annual calendar, the Tri-State Gas Engine Show at Portland, Ind. As one wit put it, within minutes of arriving at the showground, there was a group of friends from five countries the USA, Australia, England, Holland, and Pittsburgh! The range of engines and availability of parts at this show is unsurpassed, and even this year's rain failed to dampen the enthusiasm for a week of intense, engine related indulgence and socialising.

The Antique Tractor Internet Servicegroup (ATIS) was setup not far from the OFES (Oil Field Engine Society), and there was much visiting between the two, particularly as we had our first oilfield engine there, with one week to learn from experts how to start and run it before she is shipped to England. So this month's article is in recognition of the close friendships between ATIS and the OFES, being an answer to a question one list member posed concerning his Reid, although the information will equally apply to any tank-cooled engine.

As ever, the following comments reflect a variety of opinions that surfaced during this discussion.

I need some direction in setting up a cooling tank for a 15 HP Reid. The tank I plan to use is 5-foot tall, about 2-feet in diameter. What height in relation to the cylinder does the bottom of the tank need to be placed? Is there a certain length that the pipes exiting the cylinder need to be before they turn towards the tank? Do the pipes need to be horizontal, or level with the cylinder? At what level, or position, do the pipes need to enter the tank? Any help will be appreciated.

My opinion is that the pipe coming from the top of the cylinder to the tank should enter the tank below the water level in the tank, the pipe from the bottom of the tank to the engine should be near the bottom of the tank, and probably a drain valve at the bottom of the tank would be a good idea.

By keeping all pipes below the water level the water will thermosiphon, with hot water entering the tank at the top and cool water returning to the engine from the bottom of the tank.

The Lister cooling tanks (for working engines) all show the base of the tank a few inches below the bottom connection to the engine, to allow rust and sludge to drop out, and the top connection a fair bit down from the top to allow for hot water to evaporate without uncovering the top connection to the engine.

Make sure that the top pipe angles upwards towards the tank. If it is level, it may get an air lock and the thermosiphon may stop working.

I have not long finished the plumbing on my Blackstone - I set it up to work on thermosiphon. The three main concerns for me were:

First: top pipe to enter tank under the water level the tank would be filled to so thermosiphon would work properly.

Second: that the bottom pipe (coming from underneath the tank) had a drain tap fitted to it to allow the emptying after a run.

Third: an in-line tap (gate valve) which allows me to restrict the flow of water running through the engine to allow it to run pretty warm. My engine is an oil engine and it works much better if it is running pretty warm.

For interests sake, I had my top pipe curved and running up on a slight angle more for cosmetic reasons than anything else. I wanted it to look good. I also have a dummy tank inside the tank which only holds about one-third the amount of water you would imagine from the outside tank.

I know nothing about Reid engines, but a tank 5-foot by 2-foot would hold a s*%T load of water!! Do you really need that much? If you rally it, you want to make sure you can drag it out of the bog that is caused by all that water once you pack up. Could be a good project to make a dummy insert, as well.

If you're not actually going to be working your engine you have great latitude here. I noticed that oilfield engines in the 15 HP range at Portland tended to have cooling tanks of around 30 gallons, but my tank that size is a bit small for my hard-working 6 HP Listeroid Diesel. Lister originally recommended 50 Imperial gallons for temperate climates, 70 for tropical, for the 5 HP 5/1 diesel.

Your ideal arrangement for a thermosiphon setup would be to have the line from the tank to the engine inlet (bottom line) near horizontal, with the tank bottom nearly even with the bottom of the engine's cooling jacket, and the outlet line from the engine to the tank sloping all the way up from the jacket outlet to the tank inlet at a substantially higher level, but with enough space over it that the outlet will always be covered with water when the engine is running.

If you let the water fall below this level, you now have a hopper-cooled engine, which will not circulate and cools by boiling. If the top pipe doesn't slope continuously upward, it can lock with air or steam bubbles. I use a manually controlled gate valve in the bottom line to restrict coolant flow for warmup. If I forget and leave it closed, the coolant will boil and keep the engine from overheating. Steam can escape up the top line to the tank and the jacket will stay full of water. If the top line were obstructed, steam would push water out of the head and out through the bottom line, then the dry head would overheat and warp or crack. An automatic thermostat really isn't necessary with such slow temperature changes as these engines encounter. If you want to use a centrifugal pump to circulate water (not necessary), you have a lot of latitude in tank and pipe placement. You just have to make sure the jacket can't siphon dry when it's shut off.

I notice from the thread that important steps as I understand them have been covered, especially to make sure there is a slight rise in the pipe from the cylinder to the tank for the thermosiphon effect. The hot water wants to rise. It also may serve you well to have a flex coupling on one end for expansion and vibration dampening.

I may have missed a post, but in some, not all, kerosene burning installations the tank is plumbed so as to furnish water and not circulate water. This regulates the temp at 212F, which is a good operating temp for kerosene engines. In those, a line is sometimes plumbed above the water level and provides some condensation to return to the top of the tank above the water level. I have a 10 HP FM Z on a wood splitter plumbed in this manner. The engine stays full, operates as hopper cooled.

There has recently been a thread discussing the setup of a thermosiphon cooling system for larger engines. I'd like to offer an effective alternative that Craig Prucha developed. When we setup a half-breed recently, we briefly considered a thermosiphon cooling system and rejected it because of the hassle of an elevated cooling tank.

Craig's highly effective approach simply uses a 55-gallon drum sitting on the ground or trailer near the engine. The cooling water inlet to the engine is -inch heater hose. At the tank end of the hose is a Rule Model 24 submersible bilge pump. It's 12-volt, draws about 2 amps, and pumps 360-gallon-per-hour. The discharge from the engine is also -inch heater hose dumping back into the open-top drum.

Craig had done a lot of 'product testing' before finding a pump that ran reliably in hot water. Tillie's cooling tank was nicely steaming whenever she was running. We ran her from Monday through Saturday at Portland without recharging the battery. My friendly local supplier sells these pumps for $16.95. It's a good idea to pack a spare pump so you can swap it out if it dies at the show.

Good advice from people who have tried and tested these methods of tank-cooling their engines!

Portland was also a time of transition, as we met up with both Judy Whiteside, former advertising manger of Gas Engine Magazine, and Richard Backus, the new editor. The changes in the magazine were a topic of much discussion on the showgrounds, and as a group, we wish the best to the outgoing team who have taken such good care of our interests over the years, and every success to the new staff.

Engine enthusiast Helen French lives in Leicester, England. Contact her via email at: Join the ATIS mailing list at: