Laars HH 250 boiler replacement problems

mars_6

Hey guys I have a Laars HH250 nat gas boiler that I have installed in place of a 1959 Crane CI boiler. The old piping was circa 1959 simple one supply and 3 zones return. we went to fire this system up now piped primary secondary and have run into some some control issues I could use some help with. This system has a vent damper and on fire up with the boiler control set to Auto it would not send 24V to the ignition control. I suspected a possible faulty vent damper and told my tec to bypass this with the bypass plug that comes with the unit. During his installation he lost the vent damper jumper. I have tried to jump the vent damper safety with the damper open but have had no susces in getting this unit to fire other than in the constant circ mode when the boiler fires constantly. and is supposed to shut down on high limit. but the boiler is not responding to the high limit and will act as a run away boiler. The electrical schematics are fairly simple but the controls are acting as if the system is by passing the aqua-stat? I have tried to wire the Honeywell S8600 aqua-stat through the auto reset aqua-stat bypassing the whole safety chain but there is no effect. the Honeywell control continues to fire. I have many of these systems out there and have never run into a situation that makes as little sense as this. anyone have any thoughts? I appreciat any input any could give to this situation as we have bad weather for the next few days and they have a very challenged child living in the house. Thanks guys Matt Rossi. Four Seasons Heating.   

mars_6

another system I saw

Another thing I observed was that the boiler would not go into high fire, this is a 2 stage boiler. The Honeywell control was flashing a fault code while firing that the control was not reading the correct micro amps through the flame sensor? I am getting 26 volts to the control for what that's worth. Thanks Matt 

Zman

MV

Matt,

If you have a call for heat, you should have voltage to the 24v on the honeywell.

If all they safeties have been satisfied, you should have voltage to the MV on the honeywell.The safety switches are in series, so you should be able to follow them with your meter. The jumper on the damper switch goes across the 2 middle ones (2 &5)

I am not sure how you pump controller or lack of high limit is playing into this. Is something miswired? Be careful you are not jumpered from the control side to the safety side at the vent damper.

Carl