Honeywell Smartfit queries

["Paul Gordon" <paul@xxxxxxxxxxxxxxxxxxxxx>]

Hi All,



I'm trying to get to the bottom of if and how I can use Honeywell
Smartfit with a mains pressure combi system....



The two flavours (S-plan & Y-plan) differ only in respect of the valve
configuration needed to control both central heating, AND hot water
supply by switching between rads & hot water cylinder...



Clearly, having a combi system, I don't have a hot water tank, so I
don't see that I have any need for any pipework / valves / plumbing at
all?



The Honeywell Smartfit guides only show installation diagrams for a
traditional cylinder system, so not a huge amount of help...



My thinking is that the combi takes care of this internally, - it
automatically switches to DHW when it is called for, and at all other
times provides CH... - Smartfit has no need to modify this at all, - all
I need it to do is to provide an electrical interface to the CH control
circuit to simulate the demand for heating.. - which is provided as
standard anyway by the boiler junction box connections to the base unit
isn't it?



I'm beginning to think that this S-plan & Y-plan stuff that has had me
vexed for ages is actually totally irrelevant?... - Could I not just
hook up the electrical parts of Smartfit, (i.e. the boiler junction box,
the base unit, and room unit), - and just not fit the redundant parts..
- i.e. leave the cylinder sensor and valve in the box... - would
Smartfit work without these components installed? - would it throw a
hissy fit?



Anyone think I'm wrong?



Paul G.





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