GV100 Problem

Lar

I've got a nat gas HB Smith GV-100, forced hot water, hot surface ignition boiler.

I have an intermitant ignition failure problem. The ignition box is a white rogers with the dummy lights (codes) which show ignition lockout.

When I found the boiler in a failed state, the draft inducer fan was running. I traced the circuit (through the vac swtich,etc)which had 24 volts on both sides. I also had 120v to the ignitor, but no glow. I changed the hot surface ignitor.

The boiler worked fine for a week and then failed to light again. This has happened twice in the middle of the night. If you shut the power off and then on, the boiler fires up fine. I'm at a loss to know what to change next.

The 24 volts to the gas valve is fed from the WR ignition box. That 24v circuit is completed though the draft inducer relay. That relay is fed from the transformer. You can see a diagram of the circuit here: http://www.geocities.com/nemilair/hbsmith_gv100_schematic.jpg

I'm thinking I'll try changing the WR ignition box next. It's either that and/or the draft inducer relay (although the draft inducer itself works every time).

Any thoughts? Any experience with these boilers?

Thanks, Larry

Mark Eatherton

If I'm not mistaken...

The flame sensor for that boiler sits between two burners. If you have low gas pressure, or excess air being drawn through the combustion chamber, the WR ignition module can't "see" the flame and will lock out.

Try checking the gas pressure at the manifold. If its OK, then check the flame sensing rod. If you can turn it to the side (CAREFULLY, it is extremely brittle) then your problem should go away. Otherwise, check to make sure there is a good ground between the burner assembly and the frame ground for the WR ignition module.

ME