Cast Iron Solid fuel boilers

jakebastyr

Does anyone know of any antique cast iron solid fuel boilers still intact and available? Looking for a boiler to replicate a gravity system, so it would have to be pretty old to have large enough tappings.  I understand the challenges of dismantling and removing one, and the challenges of reassembling and stopping leaks. I'm located in NW Minnesota, but I may be willing to travel in order to obtain the right boiler.

leonz

Hello jakebastyr,

You do not need a 100 year old cast iron boiler with large tapping's to replicate a gravity hot water system in any case.

These boilers were originally hand fed coal boilers with shaker grates and many were converted to use natural gas or oil and most all of them are still in service.

I would advise you to purchase copies of CLASSIC HYDRONICS and HOW COME from the heating help bookstore as they are gold mines of information for a beginner and they really helped me.

AN overhead heating design will provide slow even heat for the entire home as the hot water is always rising and falling back to the basement and you will not require orifice discs to control the flow of water by using the correct piping connections to each radiator using unions, radiator valves and O.S. fittings.

A modern boiler with at least 2 top tapping's will suffice for this as you can pipe the hot water to more than one riser if needed by simply using Y's, elbows and unions of the same size reaching riser pipes of the same size and drop pipes of the same size.

Once you start making hot water it will rise to all the radiators and drop to the lower floor radiators using simple convection and expansion.

If you are doing new construction the simplest and least troublesome method of gravity hot water heating is the overhead piping method where there is a single main riser pipe to the attic or top floor and the open to air expansion tank and the riser pipe feeds hot water to the double elbow and then to the open to air expansion tank at the same time with a takeoff pipe coming from the riser pipe connected to the double elbow.

The hot water reaches the double elbow at the top of the riser and then travels to the open to air expansion tank while it moves to the properly sized take off pipes below it deliver the hot water to the radiators starting at the top floor and then the water in those radiators sinks to the lower floor radiators and then to the basement where the piping connects to the boiler sump header pipe.

You can use a new boiler to do the same SANE heating method with smaller piping as long as its piped correctly with a new boiler and you do not need a huge old boiler to do it.

If you are concerned about having enough water to keep the home warm you can purchase a large volume steel compression tank to act as a nurse tank for the system where the water returning to the boiler will always be large in volume and warmer as it enters the boiler sump. In installing the steel compression tank you would lay the steel compression tank on hard wood blocking connecting the drop pipe run to it and connect the piping to the boiler sump header.

You can have even more nurse tank water by adding a second tank to feed a second boiler sump header if you have overhead pipe runs going on both sides of the home.

You have to design the system correctly, and in so doing the hot water reaches the open to air expansion tank from the hot water riser and the upper most take off branches off the double elbow to the open to air expansion tank using the same size pipe and then dropping to the radiators to heat them.

The open to air expansion tank is fed with hot water by plumbing an upside down U at the base of the tank to allow the hot water to enter the open to air expansion tank to keep it from freezing and allow for expansion as you will be using 170-180 Fahrenheit Degree water temperature to create the convection need to cause the systems water to rise and work correctly.

The upside down U would be fed by a take off pipe coming from the hot water riser feeding one leg of the upside down U and the other leg would be piped to a tee with a reducer bushing to allow the hot water travel in the feed pipe back to the radiators and then back to the boiler sump.

If the attic if used for the open to air expansion tank is insulated all the better, if it is not insulated a hot water pipe coming off the central riser pipe should be plumbed to the side of the open to air expansion tank and the tank drain tapping connected to the piping to drain away into the radiators.
The tank and the exposed piping should also be insulated.

The expansion tank can be wrapped in fiberglass batts and then chicken wire can be used to hold the batts in place. Batt insulation can be used to insulate the overflow pipe by stapling it together too.

For simplicities sake filling and refilling the system with water can be done in the basement and the overflow from the open to air expansion tank can be piped to the basement using pex tubing or copper as it has no pressure to deal with. piping it to the basement lets you run the overflow to a floor drain near the boiler or the laundry sink where the overflow pipe can dump the excess water into the laundry sink and sanitary sewer.

The open to air expansion tank should have a water level gauge tube mounted in the side of the tank
which will make monitoring the water level in the system much easier and you will be able to fill it as needed if it is a vertical tank. A saddle tank can be hung in the roof joists if the attic is well insulated too. If I remember correctly the overflow drain piping is on top of the saddle tank in that mounting method.

The saddle tank we had hung in the ceiling as an open to air expansion tank did not require an overflow pipe as we use baseboard heating on a ground floor with a circulator.

(In England they use livestock water tanks to feed the hot water to the radiators rather than an open to air expansion tank and cover the tank with marine plywood)

AS the gravity hot water system from the home water supply it is a closed system and you can protect it better using non-toxic boiler antifreeze with no worries as you can use a garden hose to fill it at the nearest water tap that has a back flow preventer which could be the cold side of the laundry sink.

OH, do you know what the best part or an overhead gravity hot water heating system is?????????????????

THE BEST PART IS YOU NEVER EVER HAVE TO BLEED AIR FROM THE RADIATORS of an overhead system as it rises to the open to air expansion tank and dissolves and exits through the overflow pipe on the side of the tank to the basement laundry sink or floor drain.

By piping the overflow to the basement you eliminate the need to pipe an overflow pipe up through the roof to let it drain into a rain gutter.


I hope I did not forget anything.

jakebastyr

Thank you for all your input leonz.  I am planning on designing an overhead system very similar to what you have described.  The problem I am finding is that I can't find a suitable boiler in for burning wood in the US that has large enough tappings, or even tappings at the top.  I am fairly confident in my calculations so far in the early stages of design that I am going to need some fairly large piping for my risers and returns.  So I figured one of the old boilers would be the easiest candidate.  If I could buy a suitable new boiler I would.  I do plan on burning wood, also the main purpose of a gravity system to avoid using electricity.  I am designing the structure and the heating system together as I feel that is the best way to have a system that provides comfort and works well.  If you have any recommendations for new boilers I would greatly appreciate your input.  

retiredguy

Instead of a gravity hot water heating system, you could install a steam system instead. They are as dependable as hot water, easier to install, much less expensive, can be zoned, are quiet and are less subjected to freezing of the heating medium since the piping and radiators do not contain a lot of water. The Guys on this site would be a lot of help to you for the installation. Think of the way your ancestors heated their homes.

hot_rod

Probably find a steel boiler for burning wood. The Euro imports all have 2” all they way down to the 30-40 Kw size , Much easier to clean also, which can be a weekly task if you burn green or high moisture wood. The Euro boilers will all be gasification also, efficiencies into the 80% range.
Keep an eye on Marketplace, Craigslist, et.
Tarm, EKO, Atmos, Froeling, BioMass are some of the brands.
Www.new horizon store.com is an importer I purchased from, woodboiler.com. Is another.
They may know where used ones are available.

Emisivity

Hi Jakebastyr,

I have two Cast Iron Boilers you are welcome to take a look at. One is currently disconnected and designed for an old Eureka fitting system. The other is retrofit for gas and is part of a two pipe hot water system. They were originally coal burning. The one still in use still relies on it's attic expansion tank. Both date from 1909-1912. If you are interested I am happy to provide pictures.

psb75

I have a Buderus three-pass sectional cast iron wood/coal boiler. It works great with a 1000 gal. non-pressurized storage tank. It has two inch tappings but I'm piped with 1 1/4". I have it working with a return circulator pulling from a Termovar condensate protection valve. But I also have a dump-zone (for grid down situation) wherein a powered-closed, zone valve opens and the loop thermo-convects to cast-iron rads on the upper floors.
This is an earlier generation of Euro, solid fuel boilers than the powered, down-draft gassifiers. Biasi made them too. There is also a French version. They are sectional. More sections for more BTU output.
They work great if you use fully seasoned wood and burn them hot and use thermal storage. Older, up-draft Tarm boilers also work well in this set up. They are plate steel, not cast iron, high volume boilers. I'm thinking these up-draft boilers were made from the latter 70's into the late 90's. Then gassifying came into vogue. These sectional boilers (Buderus, Biasi, etc.) have a "wet grate" meaning the water jacket completely surrounds the fire. Not with the Tarm though. Alas, the Danish co. Tarm, no longer exists.