My boiler (Weil Mclain CGA Gold ~2003 install) failed the other day. After some help from a plumber and reading the manual, I replaced a few parts (more below) to get it running again. Now one zone is always hot, about 10 degrees hotter then set on the thermostat. There's no advice in the manaul for troubleshooting this type of issue (all the led's on the boiler are normal). The boiler shuts off periodically, only to start up a few minutes later. What are my next steps?
My initial guess is to checkout the thermostat. how do I do this? Do you remove it and cap the white (heat) line, keeping it from contacting the red?
What parts of the boiler do I need to look into and what order to track down the cause?
I have a (different) plumber coming tomorrow to check it out, but I'd like to try to solve it on my own if I can.
Tuesday night I woke up to no heat, and the boiler was off with the 'damper' led flashing. While trying to wake up/figure what was going on, the transformer that powers the two thermostates (for two zones) died in a puff of smoke.
Not really knowing what I was doing, I bought a new transformer and a new damper, installed them and the boiler still sat idle.
My plumber inspected the wiring with a multimeter and concluded the main board was dead. So I replaced that (he was busy at another site, and I was happy to save a few bucks doing it myself). After that, still no luck, so I decided to read the manual.
Following the troubleshooting flowchart, I found that the transformer driving the damper was dead, so I replaced that and everything started fine.
It was late the next day by then, so I called it a night. The following day I found my basement 10 degrees hotter then the thermostat was set.
I've tried cutting the power, letting the boiler start up again. Both thermostats "click" as they've always done when set the temperature from above to below the current temp, which I take to mean they are turning off the heat.
Any advice is much appreciated.