Heat

Revo

Heat running with no stat?!?!?    I recently had a hydronic system that was heating the house with no call from either zone and no pumps running. The customer called me early in the day and said he sets the thermostats at 65 and the house is 77 degrees. So he put both thermostats in the "off" position. I arrived there the same day in the afternoon and observed both thermostats off, the zone controler idle, and neither pump running. Further observation I noticed both supply's and returns for each zone hot to the touch as if water was moving by itself!? Here are some of the system vitals: 3 section weil mcclain gold, oil fired, water supply off the top with checks on each zone, return water being pumped down to the base of the boiler, taco 2 zone controller with priority (which is off),, each zone has its own taco 007 pump, no checks in the return. Its a pretty basic system, but frustrating problem. The best I can come up with is that the water is moving by some kind of siphoning effect. Perhaps the checks are messed up, or checks need to be installed in the returns also.  Help!!!

SWEI

Checks on each zone

what kind of checks?  Can you post a picture of the zone pumps and associated piping?

STEVEusaPA

could be as simple as.........

A thermostat wire heating up and shorting out.  Or a problem with the aquastat.  Something is sending a signal (power) to tell the burner to fire.

When you got there and everything was hot, could've just finished a call for heat, or shut off on high limit, then satisfied the call for heat.  Or if like I said earlier, thermostat, low voltage wiring short, could've opened back and let the unit shut off.  I'd investigate those wires, and check them with a meter.  Disconnected on one end, and check continuity on the other.  If you see the numbers bouncing around or continuity, you have a short.

You didn't say if the boiler is used for DHW.  If it is, then I would initially follow SWEI's advice and look at the flow checks.