On Sat, 22 Nov 2008 07:43:12 -0500, "RBM" wrote:


wrote in message
.. .
Hello,

I have a Crown oil boiler and Crown megastor 40 gallon indirect water
heater. The system has 3 zone valves but a single circulator (water
heater is on zone 2).

Today we had only lukewarm water coming from the faucets. The zone
valve for this zone is open, the boiler is working and there is pipe
from the boiler to the water heater is hot. But the pipe coming from
the water heater returning to the boiler does not get hot.

The other two zones are getting heat so the circulator seems to be
working properly.

This problem has happened several times in the past few weeks and it
seems to start working again for a while.

Has anyone had this type of problem? I appreciate any advice that you
can offer to me.

Thank you in advance,

Scott

Most modern zone valves have a motor circuit, and an end switch. When
power is applied to the valve's motor, it cranks open and as it reaches
it's fully opened position, a cam closes the circuit on the end switch.
The end switch circuit typically turns on the circulator, and depending
upon the type of boiler controls, it may turn on the boiler as well. Most
zone valves have a lever to open them manually, however doing this doesn't
open the valve far enough to close the end switch. In some cases, a
damaged or worn zone valve will electrically open, but not close the end
switch and turn on the circulator. If you can identify the valve, I can
tell you how to prove the end switch circuit



The zone valves are Honeywell model YHV8043E1012. Thank you for your
reply and advice.

Scott