"Roger Mills" wrote in message
...
In an earlier contribution to this discussion,
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, as it stands, may well be correct - but it doesn't cover
the situation where a zone valve is inserted into an existing gravity
system to convert it to a C-Plan *without* changing the boiler. I have
occasionally - via this NG - suggested that people should consider this
option when they complain either that the HW gets *too* hot or that they
have to turn the boiler stat down to prevent this - with the result that
the rads are not hot enough. A C-Plan system solves this problem by
providing independent control of HW and CH *and* provides a boiler
interlock - ensuring that the boiler switches off when both demands are
satisfied.

Am I suggesting that they do something which is *illegal*?

I think you've done a great job with the diagrams!
--
Cheers,
Roger


I would suggest that installing a new boiler and keeping a C plan in place
or installing a new boiler and installing a C Plan would not meet part L.

Installing a C plan in an existing gravity HW system would be good practice
according to the regs. Best practice of course being the fully pumped set
up.

Adam