In an earlier contribution to this discussion,
Rob Horton wrote:

As you can guess from the title, I have a Y-Plan central heating
system. The 3 way valve controller has a lever on it and there
appears to be two positions for it to be in. Left, marked as Auto and
right, marked as Manual. For some reason (probably by mistake by the
previous owners) the lever has always been at a position midway between
Auto and Manual.

Dumb question I know, but what is the difference between Auto &
Manual? When I experimentally move the lever to Manual it feels like
there is some internal gearing that is being moved as there is slight
resistance to motion.

The only instructions that I can find on the web are how to install
Y-Plan systems. What I want to know is how to operate the system and
why I should want Manual instead of Auto and vice-versa.

Incidentally, I have noticed that when the hot water comes on but not
the central heating, some of the radiators that are close to the hot
water tank and the central heating control gear, heat up. Could this
be a symptom of the (presumed) incorrect setting?

Thanks.

The valve has 3 positions:
* HW only (the rest position, when unpowered)
* HW + CH (the mid position)
* CH only

Depending on the heating demands generated by the control system
(programmer, room and cylinder thermostats, etc.) a low-geared motor in the
actuator moves the valve to either the mid or CH-only position. A spring
returns the valve to the HW-only position when power is removed from the
motor.

In normal operation, the lever must be in the Auto position. The manual
position forces the valve into the mid-position and is useful when filling
the system - or as a short-term fix if the motor fails, since it then allows
you to get some water to your radiators, which wouldn't otherwise be
possible.

If the valve is in the HW-only position, and you move the lever to Manual,
you will feel some resistance since the gearing has to spin the motor at
high speed. When the valve has moved to the mid or CH-only position by the
motor, the lever doesn't do anything - and moves quite freely.

If in the summer, when you only want hot water, the valve is manually moved
away from the HW-only position, the radiators will indeed get hot while the
HW is being heated.

HTH.
--
Cheers,
Roger
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