gas. valve. when. the. fumes. are. continual-
ly. forced. back. into. the. environment,. in. a.
quantity.that.can.be.dangerous..If.the.boiler.
repeatedly. stops,. it. will. be. necessary. to.
carefully. check. the. chimney,. and. to. carry.
out.all.modifications.and.take.all.measures.
necessary. to. restore. it. to. an. efficient. wor-
king.state..
After. every. intervention. carried. outon. the.
600
500
400
300
200
100
0
82
device,. check. correct. functioning.. In. the.
case.of.replacement,.use.only.original.spare.
parts.
3.10
HEAD AVAILABLE TO SYSTEM
(fig. 17)
Residual. head. for. the. heating. system. is.
30 OF ErP
200
400
shown. as. a. function. of. rate. of. flow. in. the.
graph.in.fig..17..
25 OF ErP
600
800
1000
PORTATA.(l/h)
FLOW.RATE.(l/h)
1200
Fig..17