RE: Boiler control update and query

["Kevin Hawkins" <lists@xxxxxxx>]

Dave,

Do you have any internal thermostats that are on any zoned areas or
radiators that have a time clock on them ? I have some Digistats where I
can
set 3 differerent temps for 3 time periods in one day. This effectively
changes the dynamics of my whole system. I have some rooms that aren't
heated in the morning for example. The clue has to be in something that is
timed I feel or something that is 'open' or 'closed' but only in the
evenings.

I wonder if this is something that happens once your thermostat has
actually become satisfied. Have you anyway of noting if this happens in the
morning ? Maybe the oscillation of the temp in the morning and lunchtime is
just the boiler actually kicking ON and OFF based on the water temp inside
itself, whereas in the evening the room thermostat is actually turning the
boiler ON and OFF. I am guessing it is not a modulating boiler from the
graph.

Lastly maybe you have thermostatic radiator valves - and as some of
these kick in and close down radiators then they will cut off large volumes
of water or reintroduce large volumes of colder water back to the flow.
This
could cause sudden dips in the temperature as they open and a reduction in
circulating water volume as they shut off,  this could create higher
peaks...


The graph is very interesting and I shall have to have a go myself.
Where have you tapped the water temp on the boiler.

Kevin


> -----Original Message-----
> From: Dave McLaughlin [mailto:dave@xxxxxxx]
> Sent: 16 December 2003 23:37
> To: Ukha
> Subject: [ukha_d] Boiler control update and query
>
> Hi All,
>
> My new AVR Microcontroller based boiler control is now
> operational and has been for about 3 weeks now. It works a
> treat and is high tech enough for me as a gadget freak!!! :o)
>
> One thing puzzles me though and that is the temperature
> cycling of the boiler. This link will take you to the
> website with a page showing the boiler chart.
>
> http://www.embeddedcomputer.co.uk/Projects/Controller/Boile
> rCharts/boilercha
> rts.html
>
> http://tinyurl.com/zjzo
>
> At the bottom I give a description of the heating cycle
> and I am puzzled to the larger temperature cycling in the
> latter part of the evening. This is the same each day. The
> chart only shows the last 24 hours of each day on a rolling cycle.
>
> The temperature of the boiler is shown as the green trace.
> Has anyone any idea why I am seeing a much larger cycle at
> night. It always starts off the same as the morning and
> midday cycles, but gradually increases. The strange part
> is that it goes much lower too.
>
> I thought it was something to do with the outside temp as
> the boiler is located in the garage, but tonight (the
> chart on the website was uploaded
> tonight) has been a few degrees warmer than the last few
> nights which where down to and below zero.
>
> Any ideas?
>
> Regards
> Dave...


UKHA 2004: 15th and 16th May 2004

http://www.automatedhome.co.uk
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