Re: Using Comfort to control heating system

[Nigel Orr <Nigel.Orr@xxxxxxx>]

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At 10:28 04/09/00 +0000, you wrote:
>house get.  2) During spring and autumn we need to reset the timer to
>heat for a shorter time because even if the valves have switched off
>the house still gradually heats up

Probably best to do that anyway, just knock 30 mins off the 'on' time when
the weather gets warmer.  Even heat from the boiler itself will heat the
rest of the house a bit, as well as from pipes, hot water tank etc.

It could of course be more sophisticated than that, looking at external
temperature trends etc to decide when to turn the heating on.

> Should I fit conventional thermostats / T-valve for zones or should I
>get Comfort to monitor temp and control the controller?

I've currently got Comfort controlling heating, with direct control of the
gas valve (hot water) and control of the pump via a room thermostat
(heating).  Whatever 'smartness' I add, I'll definitely keep the mechanical
room 'stat', just as a cutout in case some more sophisticated control gets
confused and tries to superheat the house... if it's set a few degrees
above the maximum temperature that will be required, it won't affect normal
operation.

My system is currently gravity hot water, so it's quite simple and
reliable, but not as efficient as a fully pumped system, or a zoned system
as you are proposing.

>if Comfort is the way to go - has anyone done it and if so how?

Not with multiple zones, but the wiring isn't much more complex.  I've got
2 DIN rail mounted relays (similar to the ones on the comfort website), and
set up responses so the pump relay will not turn on without the boiler one
(the pump response is something like 74,11,0,0,0,0 so it automatically goes
on to the next line which is 'switch boiler on for 90 minutes, then switch
pump and boiler off'.  If I need hot water only, I just go to the latter
line.

You would need an additional 2 relays (actually, probably just one, can't
work it out in my head!) for 'heating demand upstairs' and 'heating demand
downstairs' to switch the appropriate valves- there is usually an output
from the valves which enables the pump once the valve is open.

If you're doing it yourself, do get a book about plumbing or central
heating (Readers Digest and Collins both do DIY manuals with plumbing info-
have a browse in the bookshop!), as there are conventions for wiring to
stop you accidentally closing all the valves with the boiler and/or pump
running!  It's better to do that as a mechanical failsafe rather than with
cunning programming of responses...

Hope that helps get you started!

Nigel