I am having a problem with my furnace it is a forced hot water system
using old cast iron radiators. The burner will turn on when the
thermostats call for it but the circulators will not turn on. If I tap
on the aquastat relay (Honeywell L8148A0) a few times they will start
for awhile usually until the burner lights again then the circulators
will shut down again. Is there anything I can do short of calling a
burner tech. It the relay repairable? What will it cost to have
installed?

Thanks
Scott