Dealing with frozen system...?

amuller

This is a 1920's column radiator system, originally gravity, of course. The present boiler is a ten-year-old Burnham atmospheric gas boiler with a stack damper above the draft hood.  I believe it is venting into an unlined chimney but haven't pulled the breeching to make sure.  Output is 75,000 btu/hr.  There is a bypass across the boiler.  No zoning.





The house has been through two Minnesota winters without heat.  It was apparently "winterized" in a clueless way or after freezing up.





The cast iron fittings on the two-inch basement mains are cracked in half.  Fairly careful visual inspection shows no obvious radiator cracks or water damage around them.  The one-inch and 3/4 inch fittings seem ok, even in the basement where the larger ones are split.  I haven't had a chance to pressure test anything and don't know whether the boiler block is bad.





The only way this scenario make sense to me is if the system was drained to below the first floor rads but the mains were left full.  In which case the boiler was probably not drained either?  What do others think?





Assuming the rads and boiler aren't bad, we'd like to revive the system.    Suggestions on how to approach this...?  I can repipe the basement lines in copper with no problem.  We'd probably like to incorporate thermostatic rad valves.  Should we think in terms of pri/sec pumping?





Thanks in advance

icesailor

Frozen System:

If the system had been converted to forced hot water, see if the flow check was opened. If you find it closed, and you didn't close it before the water was turned back on, you may be in luck.

If the flow check was closed, look to see if the cracked fittings in the cellar are only on the supply side and not the return. If you find that is the case, you may find that the radiators are OK. What happens is that if the person draining the house and heating system doesn't know about flow checks, or forgets to open it, water will be trapped in the supply side of the mains until the point of the return pitching back to the boiler. That point will be below the floor or will be the connection height above the floor at the lowest radiator where the water can drain through.

Want to know a disaster made? All those circulators with internal check valves. One stupid @#$^ing idea. They restrict the heck out of the flow, create massive cavitation. Plus, people (like me) who drain a lot of houses don't expect them in circulators and there is no way to tell they are there by looking at them. In other words, someone may not notice. If it weren't for anti-freeze, I personally may have been caught. Another unneccesary added expense for nothing.

amuller

Frozen system

Thanks, Icesailor.  I did a more detailed inspection and found some rads bad and some OK.  Smaller fittings--3/4 and 1" were mostly OK, larger CI fittings split.  More recent malleable fittings mostly OK.   No flow-check in the system. What a mess.....