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Taco 1 zone relay clicking crazy from indirect water heater

Hello. When you turn the thermostat up and call for heat, no problem. Relay clicks once and Burnham boiler turns on.
When someone is showering and boiler is NOT heating the house (thermostat down), the Taco relay will start to clicks wildly after they've been showering for several minutes and the relay clicks wildly for several minutes thereafter. Then, the boiler fires and it stops. Thoughts? Is it the indirect water heater thermostat on the front? Could it be the green Taco circulator causing the issue? I can't post a video of the clicking but I have some tight shots of the relay now. I'll get wider shotsof the system. 


  • Jamie Hall
    Jamie Hall Member Posts: 23,458
    edited April 2022
    There are a very few reasons why a relay would click -- and almost all of them boil down to either low voltage on the coil or the controlling device switching quickly. And low voltage is almost always either a bad controlling device or bad connections.

    So.. I'd be looking at the indirect water heater thermostat and the associated wiring.

    That is -- assuming that the water heater thermostat is controlling the relay. And I can't think of what else would be...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • MikeAmann
    MikeAmann Member Posts: 998
    I assume that the IWH thermostat is connected to T-T on the TACO.
    Try to catch it while it's doing the clicking, and short T-T at the TACO (only temporarily as a test).
    If the clicking stops and the relay stays latched, then you know that is the IWH thermostat or the wiring between.
  • HomerJSmith
    HomerJSmith Member Posts: 2,468
    Check the wiring connections from the tank aquastat to the Taco. That includes any wire nuts.
  • mrmegablocks
    mrmegablocks Member Posts: 2
    Following up on this topic a long while later:
    So the clicking on/off of the relay continue for a while after my initial posting. I tried some of the suggestions here, but ultimately it came down to the boiler not turning on at all one day. I found a great video on YouTube showing folks how to test a Power Head to see if it’s faulty. As it turns out, the Power Head clearly failed the test. I went to Home Depot, found the exact Taco Power Head, and installed it. The installation is super quick. Twist on and attach wires. The boiler fired up immediately after that AND the clicking problem went away completely. I think the Power Head was slowly failing since the clicking got worse over time. I heard that if it fails too frequently, there may be another issue, but this one was installed since 2015/2016, so I’m hoping it was an average failure.

    I still had an issue with the spill switch tripping. Not the fame rollout switch by the burner. That one is totally fine. There’s a spill switch near the flue that’a mounted on the open underside of the flew. This is outside the entire boiler outter blue shell of the Burnham, etc. Hope I’m making sense. It’s rated to trip at 200F and there’s absolutely no way it was getting up to that temp. Nothing I could observe blocking air flow. No smell or additional heat in the basement. The CO detector is brand new above the furnace and has never once gone off. This all led me to believe the spill switch was faulty. I bought a new one, waited for the old one to fail and then immediately installed the new one to begin my testing. It’s been a few weeks now and the new switch has not tripped. The old relay clicking issue I attribute to the Power Head is good.

    No major issues at the moment. The only issue I have at the moment is a minor one: My boiler does not heat my home anymore. We have an all electric Whole home heat pump now driving forced air. The boiler only is a heat source for the indirect hot water tank. I don’t like this arrangement anymore because of three reasons: 1) it seems inefficient, 2) gas usage still seems high despite gas only providing stove top (no oven), and hot water for two people. 3) despite having the aqua stat turned up a bit higher, and the water mixer at a fair temp,  there doesn’t seem to be enough hot water oftentimes. It’s ok but not great. The boiler kicks on during 1 shower, but it doesn’t really heat the water quick enough for a subsequent second shower right after to be hot-hot all the way through. And we’re not talking lengthy showers. Maybe 10mins each. Doesn’t seem right.
    long term id like to convert to either a direct gas water heater with the heat in the tank itself and remove the indirect setup. OR, a tankless water heater. I’m open to gas or electric for either solution idea but I’m leaning on gas because it has not gone up as much as electricity by the rate cost.

    anyway, some followup and some legend continued! I’m looking for advice and some quotes to compare who to go with and what to go with.