Gravity Fed Boiler System

Looking at getting a coal boiler for the house to use on existing oil boiler system. I found a boiler that I really like uses no electricity gravity fed system. At one point the house had a really old coal boiler on the system from the 50s. How do I know if my system will work with a gravity fed system. My oil boiler does have a circulation pump on it I wouldn't mind setting the system up on the coal side to use the pump if I need to. Any way I can easily tell if I can use a gravity fed system on my existing baseboard heating plumbing. 2 story house plus basement. There are no heaters in the basement.

Welcome to the forum,

To figure out if your system is gravity flow, one of the first things to look for are very large supply and return pipes, 2" or bigger. Gravity flow will only work well with large diameter pipes. If your system has pipes less than 2" and it has a pump, it's not likely a gravity flow system.

Also, I don't think you can do a "add on coal boiler" with a gravity flow system.

-Don

Gravity flow will not work well with only baseboard heaters. I had baseboard heaters in the living room and dining room with a stand up cast iron radiator in the bathroom and the kitchen. The bathroom would gravity flow just fine when I manually opened the zone valves. The kitchen not as well but it is still warm. The boiler is in the basement with the kitchen on the first floor and bathroom on the second floor. That rad on the second floor gravity flows like crazy.

I pulled out 10 feet of baseboard in the living room and replaced it with a cast iron stand up radiator in series with two existing baseboards in the dining room. Guess what? I never had ANY gravity flow until I put that cast iron radiator in and manually open the zone valve. For gravity flow to work you need elevation not only with the piping but in the radiator as well. Hot rises, cold falls. That action in a radiator is what gets the gravity flow going as well as elevation with the piping.

My supply and return pipes are all 3/4 inch copper. I was in one house that had 1/2 inch pex with stand up cast iron rads and the gravity flow system worked when you manually opened the zone valves.

You have a pump and controls, use them and save yourself an awful lot of grief. Attempting this will be an exercise in futility.

Yeah I think I decided just to goal with a coal stove and use the boiler system as a backup.

Bungiex88 wrote:Yeah I think I decided just to goal with a coal stove and use the boiler system as a backup.

What you install depends if you want to heat the entire house evenly or not. The boiler can also produce domestic hot water.