Gas, Hot Water Boiler did not start at all

Yesterday late afternoon/evening I inspected a house with gas, hot water boiler heating system of a modern design with electronic ignition (mfr date 1992), which did not start at all, though the unit appeared to have gas and electricity, and all the wiring from the thermostat (which was a simple, round thermostat with no switches, just a mercury bulb) to the boiler appeared fine.

The gas knob was on, the valve in the gas line was open, but nothing at all happened when I turned the thermostat up. No “bump” when the mercury hit the contacts, and no spark to the igniter. It was as if the power was off to the unit, but there appeared to be power to its circuit, and there was no switch on the unit or in the line, only a switched outlet on the junction box from which the power to the unit was run, which was on, and into which the cord for the automatic water level filling system was plugged. I turned the system off, and followed the lighting instructions, turning everything back on again, but again, nothing.

I told the client there appeared to be a problem with the electronic ignition system, but I’ll check it out, and if there’s something I missed, go back today to run the unit.

The property’s not far from where I live, and I’ve no inspections today, just the report from yesterday’s job to work on, so going back would be easy.

I could not find any sort of “reset” button or any such other feature along those lines. I know there was gas to the house, as the gas water heater was working, and the only gas valves I saw to the boiler were open. Can there be something I’m missing?

I had that a couple of times. The circuit board had to be replaced on both of them.
Refer to a HVAC contrator and let them deal with it.

Thanks, Jerry. That’s what I will put in my report as the most likely cause.

How much does that usually run? About in the $200-250 range?

No need to guess at the repair cost Frank.

You may open yourself up for problems.

What if it comes in a $500?

I just want to know myself, and perhaps give my Client a general “ballpark figure” idea, off the record, if possible. In my report I’ll suggest having a licensed HVAC professional check it out, of course. He’s got a decision to make, as there are many minor defects in the property. He’s a referral client, from his brother, who was also very pleased with the very thorough job I did.

Hello Frank,
Why would you do that? That is well outside the scope of a home inspection. It is just a guess. If you are wrong, and you have at minimum a 50/50 chance of being wrong, it does not help your credibility with the buyer or the Realtor (if one is involved). It always best to stick to facts and leave all troubleshooting to the expert in the field. Unless you know the cause, don’t speculate as to the reason. The unit does not respond when normal operating controls are used…end of story. No exercising of valves, or re-lighting pilot lights. All of these practices open you up for liabilities that are unnecessary. If the house burns down that night after you “fiddled” with it, you were the last one to touch it.