Buderus S120 not activating boiler

squidler4

When I turn on the hot water in my house the boiler does not fire up to heat up the hot water in my indirect water storage heater. If I turn on my baseboard heating this will activate the boiler which in turn heats up the water in the DWH. What is the most likely cause of the problem a faulty Honeywell Aquastat Controller on the Buderus tank or is there another issue going on?

Thanks

kcopp

Looking at that zone valve I wonder if that is toast.....

spoon22

Look at the zone valve there is an end switch that makes contact to turn on Burner . The valve may be open ,but the end switch probably isn't making replace the valve and problem should be solved.

squidler4

Thanks for the quick responses. I am not at the house right now but will follow-up on your suggetsions when I get there.

Zman

spoon22 said:

Look at the zone valve there is an end switch that makes contact to turn on Burner . The valve may be open ,but the end switch probably isn't making replace the valve and problem should be solved.

I agree!
Welcome to the wall spoon 22

squidler4

Just an update: this is a vacation house that I just opened up after winterizing it last November. The problem seems to have worked itself out without my help but I had a cold water line break under the house so tomorrow looks like. Plumbing day for me. Thanks for everyone's help.

rick in Alaska

Definitely replace that zone valve. Like spoon said, most likely the end switch is sticky. The zone valve has also been , or still is, leaking. Looks like possibly antifreeze in the lines? Have your heating guy replace it when he gets there and that should stop your water heating problems.
Rick

squidler4

Another update: Probelm wasn't fixed because I lost hot water again so I took the wires off the thermostat and put them together but nothing happened other than a small spark. I moved the switch from auto to manual on the valve but nothing. The switch moved without resistance unlike the other two controllers. I started to take the cover off and the boiler kicked in so this must have jarred something loose in the controller. The leaking controller is not the one the DWH is wired to. There IS antifreeze in the lines, I never knew I just assumed it was water. Thanks Rick in Alaska.

So it looks like I need 2 new controllers and then to learn about dealing with antifreeze in my system. Thanks again for everyones help.

kcopp

The zone valve head can be replaced w/o getting into the system. The glycol had prob gone acidic. It needs to be flushed out, the system cleaned w/ a good cleaner such as Fernox F5. Then flushed out again and either replaced and
/or a good inhibitor added.

billtwocase

ditto on the welcome spoon22

billtwocase

also, I would replace the base/ball and head. Antifreeze leaks and Honeywell zone valves are not a good combination, and most likely the shaft is binding due to the stem leak