Dave Osborne wrote:
Roger Mills wrote:

I would, however, query the comment which goes with C-Plan about being
completely obsolete and unsuitable for either new systems or
refurbishments. I agree about new systems, but there are still a lot
of gravity HW systems out there which would benefit from being
converted to C-Plan - which requires very little plumbing and delivers
considerable efficiency improvements relative to the status quo. The
only downside compared with a fully pumped system is that when just HW
is being heated, the boiler is on for longer than it otherwise would
be - albeit cycling on its stat rather than firing continuously.

Does anyone have any evidence that this does not meet Part-L, and
would thus presumably be illegal as an upgrade from a 'conventional'
gravity HW/pumped CH system?

I found a website which stated this:

"Recent changes to the Building Regulations have made semi-gravity
non-compliant, so fully pumped is the only layout currently suitable for
new installations. The Building Regulations now control boiler
replacements too, and effectively require conversion of semi-gravity
systems to fully-pumped whenever a boiler is replaced."

Clearly, the author of the above doesn't cite his sources and I have to
say I didn't check them either. If you think the above statement is
********, then please let me know.

The statement may be ok, but it still leaves scope to improve the
controls on an existing boiler when not replacing it (or the cylinder)

I'm still not sure about the way in which Y-Plan's mid-position valve
is depicted. As everyone knows, it has two microswitches and other
components in addition to the motor. I still tend to the view that we
should either show *all* internal connections (as for other types of
valve) or *none* (as per Honeywell's original Y-Plan diagram).

Ok, I thought about this. I am of the opinion that showing the full
internals of the mid-position valve would not be useful to the vast
majority of people and indeed, I couldn't draw it in the space available
at any reasonable scale. Also, I do not have such a valve to hand to
reverse-engineer the wiring details for. However, it is clear from

See my suggestion on the other response - there is a link to the
internal circus diagram as well.

Honeywell documentation previously cited that the white and grey wires
assert the valve and the orange wire is a switched output - which is
what I have indicated on the schematic. I am inclined to leave it as it
is and I don't see a downside in doing so - it is after all standard
practice over a wide range of electrical/electronic industries to show a
simplified form of internal operation of a device.

Yup, I think with a note that an "expansion" of the detail is available
elsewhere it would be ok.


--
Cheers,

John.

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