Help with Aquastat L8148E

ruinexplroer

I've been struggling with my system on and off for a few years. I've had a couple professionals in to look at it, but typically they won't touch my system saying it's too old and only offer to replace it at a hefty fee. The only exception seems to have caused more harm than good.

I saw your discussion at http://forum.heatinghelp.com/discussion/139899/issues-with-replacement-of-honeywell-l8148e-aquastat and realized you folks are far more skilled than the people I can hire. Perhaps you can help me get the heat back on.

My Boiler is a 1999
HB Smith G100-W-5

Aquastat L8148E
GVD-6 (damper)

3 zones using
Automag AA3/4-14
Automag 3-wire thermostats (RS 260 I think)

The aquastat and damper are only 3 years old and when the system will fire, it works fantastic. The last professional to work on it put in a new aquastat and damper, but clipped all the molex connectors using cap nuts in their place.

In any case, my system won't fire as of late. The thermostats will call, the switch makes a satisfying click and the circulator does it's thing. The pilot is lit, but burner simply doesn't light up.

I have some skill with a multimeter and am more mechanically inclined than most, but have no formal training in this area. I think the problem is either the aquastat (no voltage difference over the burner posts) or the damper (no voltage across any of the 4 wires).

Reading the issues some have had with the solder job on the aquastat, I'm thinking it may need to be replaced again, but I'd like your opinion and can I replace it with a L8148J and ditch the damper? I've had so many problems with the damper it's in the manual open position all the time anyway.

My gratitude to those willing to share their expertise.

kcopp

Check for a proper ground. Look for a corroded screw or loose connection. If its a simple gas pilot there is not a whole lot to wrong.

delta T

When you hear your satisfying 'click' and the pump starts working, check for voltage at the gas valve. There should ~24 v across the two wires connecting the valve. If you have power there, but the burner does not light, then it is most likely your gas valve that is bad. When the aquastat relay closes it should energize both the pump and the gas valve (assuming the boiler temperature is below the setpoint of the aquastat)

As kcopp said, check all your wiring connections to make sure they are sound, pay careful attention to spade terminals and screw terminals and make sure they are free of corrosion or anything else that could cause a faulty connection.

Where are you located? we may be able to recommend someone near you.