On Sat, 22 Nov 2008 12:48:10 -0500, "RBM" wrote:


wrote in message
.. .
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


OK, sounds like typical Honeywell valve with two yellow wires and two red
wires. The red wires are the ones for the end switch. Typical zone valve
wiring is a birds nest mess, so be careful not to pull apart any splices
while you examine it. What you will find is that the red wires from all the
zone valves go together and are spliced to one pair of wires that go to a
relay box, probably on the face of the boiler, above the burner, and are
attached to the "T T " terminals in the upper left hand corner of the box.
Trace out the two red wires from the offending zone valve, and be sure they
are securely spliced to the others. Turn up the aquastat on the indirect,
it's zone valve should open, then the circulator should kick on. If the zone
valve opens, but the circulator doesn't kick on, strip back a little
insulation on that valves two red wires and touch the two wires together.
This is 24 volts , so no need to worry about getting fried. If, when you
touch the two reds together, the circulator comes on, you have a problem in
the valve, with it's end switch. The entire head of the valve is
replaceable, or you can possibly just get a new switch. Personally, I'd get
the entire head.



I checked the red wires and they were pretty secure with wirenuts.
I turned up the temperature on the front of the aquastat on the water
heater. The boiler kicked on and the zone valve opened for this zone.
Once the boiler turned off, I could hear water moving through the
circulator. The pipe below the zone valve was hot, above the zone
valve was also hot. A the water heater the pipe in from the boiler
was hot, but the pipe coming out of the water heater does not get hot.
None of the pipes on the return side get hot.

I also turned up the thermostat in one of the heat zones upstairs and
its zone valve opened too. So both its zone valve and the water
heater zone valve were now open. The circulator was still going and
within a minute or two, the pipes on the return side of the heat zone
was hot, but the return pipes for the water heater were still cool.

Do you think it could be air in the pipes inside the water heater? Or
is there someting else that could be wrong with the water heater or
another part of the system?

Thanks again for your advice.

Scott