Old Coal Boiler

AMJ

I am buying a building with a coal boiler that has been converted to gas. It's very big and very old and it is covered in asbestos. It is on a Gravity Hot Water Pumped Heating system. I had a structural done and he said that the pressure guage is reading 30 lbs when it should be 15-20lbs. Also it was short cycling many times while were were down there and it was not a really cold day. The furnace does light up and just standing there we could feel the emnse heat coming from it while inthe basement. However, the tenant has to have the heat on 90 degrees just to get the house to 75-80 degrees. She has a 3 bedroom apartment with 6 good sized radiators , all of which are never hot just very warm.

I bled them all and I found only 3 of them spit out air, along with the black dirty water. I only bled them enough to empty about 1 gallon of water from each radiator. All the valves were open and the water temperature was warm and almost cool.

My Question is/are:
Do I need to bled the radiators more?
Does this mean the boiler pressure is too high and is preventing the hotwater from getting to the radiator?
Does this meand that the system is just not working and needs to be replaced?
Is there another test that I can do to see why the heated water is not making it up to the radiators?

Mike T., Swampeast MO

Sounds suspiciously like a circulator problem--either defective or wiring problems.

AMJ

Circulator??

I thought there was no circulator on a Gravity Hot water system. I thought in lieu of a circulator it relied on the hot water rising since it is lighter that cold water. Would there still be a circulator on this type of system?

Would you happen to have any images on these old boilers? I think the one in this builind is made in Holland. Do you know any brand names or boiler names that I could do search on the internet to find more information on what I am working with? And possibly find a company that can service this beast.

Dale

Heating Q and A

Take a look at the heating Q and A at the left. Some of the old systems discussed there didn't act too well when a pump was dropped in. Of course it could be the pump and that's what should be checked first. What is the boiler water temp and what is the stack temp, perhaps it's really dirty. How tall is the bld, up to 3 stories should be 12psi or so cold, 18 or so hot.

Mike T., Swampeast MO

You said "Gravity Hot Water Pumped System" so I guessed (incorrectly) that it had been converted to forced flow with a circulator. Do look for a circulator however. 30# sounds quite high for a gravity system unless it's REALLY tall or unless it's one of those strange systems that uses the air in the very top of radiators as its "expansion tank". Systems under gravity circulation usually have a tank in the attic with an overflow onto the roof.

If you find a circulator it will probably be configured to run whenever the thermostat calls for heat. The boiler will probably be configured to heat up to the aquastat setting at all times during the heating season.

If you find no circulator you might be able to get some additional flow by increasing the aquastat setting to 180° -190°. If already set at that level and you're certain that all valves are fully open, the pipes have likely scaled to the point that good gravity circulation is no longer possible.