Timer replacement on a y plan system

[jaydebruyne]

So went to a job today, replaced an old Randall 130 mechanical timer with a Honeywell st9400c on a y-plan system.

Water channel fine. Heating channel was fine in that it sent a signal (if the room stat was calling) to the 3 port, but nothing on SL. Figured a faulty head. Replaced the head and same thing. So took off the head and manually moved the paddle and seems free as a bird.

I’ve said to the custard I need to drain down and replace the entire valve as I don’t think it’s pushing far enough to make the connection.

Thing is, when demand is on heating and the actuator kicks in, I can hear the micro switch click at the end (unless it’s the spring I can hear but I doubt it), but still nothing on SL.

Am I missing something obvious here? (Can you hear the 2nd guessing???)

 

[ShaunCorbs]

so you have 240 on heating calling and hot water (seperately) ?

 

[jaydebruyne]

so you have 240 on heating calling and hot water (seperately) ?

I have 240 coming from the thermostat to the white on the 3 port when heating is in demand, nothing on water if not in demand.

 

[ShaunCorbs]

I have 240 coming from the thermostat to the white on the 3 port when heating is in demand, nothing on water if not in demand.

Same with water and nothing on the heating ?

 

[jaydebruyne]

Same with water and nothing on the heating ?

Didn’t check that..

 

[jaydebruyne]

Same with water and nothing on the heating ?

But if I’m getting 240 on the white and the actuators moving over why wouldn’t that send 240 to SL (orange)? Unless the paddle isn’t moving over enough to make the connection..

 

[ShaunCorbs]

Correct doesn't need much for it to not contact

 

[jaydebruyne]

Correct doesn't need much for it to not contact

Looks like I’m draining down then Cheers Shaun

 

[ShaunCorbs]

Looks like I’m draining down then Cheers Shaun

S plan it

 

[jaydebruyne]

S plan it

Think they’re gonna convert to a Combi so no point.. but I’ll give them the option..

 

[doitmyself]

But if I’m getting 240 on the white and the actuators moving over why wouldn’t that send 240 to SL (orange)?

If you are talking about CH only, there needs to be 240V on the grey wire (from HW thermostat Sat/Programmer HW Off) as well as 240V on the white wire from room stat.

In mid-position (CH and HW) the boiler gets its SL directly from the HW thermostat, not via the orange wire.

 

[jaydebruyne]

If you are talking about CH only, there needs to be 240V on the grey wire (from HW thermostat Sat/Programmer HW Off) as well as 240V on the white wire from room stat.

In mid-position (CH and HW) the boiler gets its SL directly from the HW thermostat, not via the orange wire.

Stupid f***ing 3 ports 😀 I wondered if that was needed but thought if the actuator was in operation after getting 240 on the white it would make the connection..