ok this one should take a few of you engineers back....?

Say hello to our friend the Feed Water Heater.

In a steam locomotive, water from the tender is used to keep the water level in the boiler constant. Both the engineer and firemen can control the insertion of water from the tender into the boiler. On locomotives with no feed water heater, the temperature of the water in the tender is the ambient temperature. The water in the boiler is at the boiling point. Adding relatively cold water to an operating boiler takes some of the energy out of the boiler. To improve the thermodynamic efficiency of the locomotive, it would be beneficial to preheat the water before it is fed into the boiler. The steam exhausted from the cylinders of a steam locomotive is still quite hot. Instead of releasing this steam to the atmosphere and wasting the heat energy contained within it, feed water heaters use this exhausted steam to preheat the water from the tender before it is fed into the boiler. The feed water heater usually replaced the injector on the fireman's side of the locomotive.

There are two basic types; closed system and open system. Each have their virtues and their drawbacks.

In an open feed water heater both the feed water and steam are allowed to mix. This required two pumps. One disadvantage of open feed water heaters was that the valve lubrication oil present in the exhausted steam was mixed with the feed water going into the boiler. A Worthington feed water heater is an example of an open feed water heater.

In a closed feed water heater the feed water is run through a small pipe which is contained in a chamber of steam. Condensed steam is collected and piped back into the tender. One disadvantage of closed feed water heaters was that the additional small copper piping was prone to leaks. The Elesco and Coffin feed water heaters are examples of this type. The company name "Elesco" was taken from "Locomotive Superheater Company". "LSCo" is pronounced "El" "Es" "Co" or "Elesco".

So, when under steam, the water in the tender is quite warm. In addition, after introduction of super heated steam engines, oil burners were equipped with fuel oil heaters as well, heated but steam passing through pipes in the fuel bunker. This too keeps the water in the tender nice and toasty, compared to the ambient temperature outside. It was not uncommon at all in that condensation usually formed on the outside of the tender water tank.

Most larger roundhouses had their own steam producing capability, so when the fire in the firebox was extinguished, the house steam kept everything operating and defrosted until it was time to pur a fire back in them for the next run.

Feedwater heaters on steam locomotives are easily identified by their location and shape. Elesco bundle type feedwater heaters were often contained within a cylinder mounted horizontally above the smokebox. Most all Texas Pacific had this type. They can also be partially inset within the top of a smokebox. Coffin feedwater heaters were designed to be contained within the top of a smokebox. However, when retrofitted, they were mounted in front of the smokebox. They are kind of ugly, to me. Worthington BL type feedwater heaters were often mounted on the side of a locomotive and may look like an air pump to the untrained eye. Worthington SA type feedwater heaters were inset into the top of the smokebox. By 1930 most steam locomotives were built with feedwater heaters and the Worthington SA type was the most popular.

And as Andy points out, the old puffer billy's were usually in a barn (engine house) when not working.

It is interesting to note that in Dunsmuir, California alone, no additive was needed in the water, it being that pure. The additive not only helped reduce the build-up of minerals boiled out of the water, but it kept the water from foaming up, which was more important, since excessive foaming will cause a boiler explosion.

Good question as always. Thanks for asking.

Edit: I forgot about the water towers.

Water is very hard to heat or cool. There was a huge volume of water in most water tanks and it never sat in the tank too long with lots of thirsty engines dropping in for a drink nearly constantly. So, it usually didn't have time to freeze. In areas where there was extreme low temperature, the water tanks were enclosed. Even with water towers not enclosed, the main water pipes were enclosed to prevent them from freezing, the lesser volume more prone to freezing.

That's why they kept engines in roundhouses.If they had to leave an engine outside not under steam they would have to drain it and blow the pipes out with compressed air.As for water tanks i have no idea.I think though they just drained some water out periodically.I have also seen pictures of heavily insulated tanks.It would take a long time for a water tank to freeze solid.I would have asked my dad as he was a steam engine guy back in the day but sadly i lost him a couple of months ago.

Calcium Chloride

we used to put braziers nearby,also near the water columns.