W-plan pump run on

[Basher]

not sure why they have labelled it as normally closed.....it is closed whilst calling for heat, exactly as shown

That is standard nomenclature. The contacts "normally closed" are connected when the thermostat is not doing anything, i.e. not hot.
When heat is applied, i.e. the system is activated to produce heat until the set point is reached, then the contacts will eventually open and the heating stops.
If you called them 'normally open', and you connected those contacts to the heating, nothing would happen!

Same with a relay. "Normally closed" means the unactivated state.
I was just brought up with this convention in electronics, and don't understand the issue!

 

[davidwf]

surely "normally" equates to satisfied - i.e. the water HAS heated up and no further action is needed....so in its' normal state it is satisfied .....the connections and make / break indications are correct, just the nomenclature is confusing
in a roomstat the contacts are normally (i.e. satisfied) open, closing when heat is required
we could probably argue and counter argue this until the cows come home.....😁

 

[davidwf]

the only other thing I can think of - but dont understand why - is that the 15mm bypass gate valve around the pump was open about 2 turns
As the system has no TRV's I have fully closed this now.....could it have possibly affected anything ?
I understand WHY it is provided on a system with TRV's but not in this installation........this is a W-plan system remember so surely as the diverter will be either HW or CH (or, if it ever gets stuck, somewhere in between as was the original issue) and with no TRV's fitted to any rads there is no need for a bypass valve / loop as the water will always have somewhere to circulate

 

[John.g]

This is similar to your one, I think the description might be less confusing if it just left out the "Normally" and describe it like on the EPH pipe/cylinder stat.

 

[John.g]

the only other thing I can think of - but dont understand why - is that the 15mm bypass gate valve around the pump was open about 2 turns
As the system has no TRV's I have fully closed this now.....could it have possibly affected anything ?
I understand WHY it is provided on a system with TRV's but not in this installation........this is a W-plan system remember so surely as the diverter will be either HW or CH (or, if it ever gets stuck, somewhere in between as was the original issue) and with no TRV's fitted to any rads there is no need for a bypass valve / loop as the water will always have somewhere to circulate

One could understand if the bypass was between the boiler flow and return because (on a Y plan anyway) a separate 2 port Motorized valve is supposed to be installed additionally on the cylinder coil because it fails shut whereas a MPV or Diverter valve will fail open to the cylinder.

 

[davidwf]

This is similar to your one, I think the description might be less confusing if it just left out the "Normally" and describe it like on the EPH pipe/cylinder stat.






View attachment 95025

thanks....
yes, so my diagram and wording is correct....c +1 calling, c+2 satisfied..... maybe just that wording would be simpler