Getting close to a combined UFH and rads installation fed from a condensing
I want to wire for UFH priority as that will have a greater operating window
due to the setback temperature.
Initial thoughts had been: use a second digistat to fire the boiler for the
single UFH zone, pop a zone valve on the rads flow wired to the house
digistat in order to fire boiler and open the rads when required.
Q1. Would it be better to use a mid-pos valve to achieve:
Output to UFH / Output to rads /
Output to UFH & rads -- it gives me a rads
Assuming standard Honeywell colour scheme, looks like I will be leaving the
grey 'hold in last position' live when no heat is required and I'm concerned
that the orange output is listed as ~100v. Their guide does not recommend
leaving the valve permanently energised, is it likely to be 'held' in the at
rest or mid position anyway, I see the normal S-plan wiring will do much the
Q2. Is this good practice or am I reading too much into this?
Q3. Providing the boiler switched live with 240/100v rather than 240/0v
surely that can't be a good thing?
THis is the wiring logic:
At rest > valve to port B (UFH)
White live > valve to port A&B (UFH & rads)
White & grey live > valve to port A (rads), 240v on orange
Grey live > hold valve in last position, ~100v on orange
| On .__________________________
|_______./ ........... |White
| Off ._ :Boiler : .........
| :Switched : :Mid pos: Port A >Rads
| UFH :..L......: :Valve : Port B >UFH
| On .____________|___________:.......:
| Off .__________________________|