Y plan - when should the pump run?

[dormermike]

Hi

Meant to ask this last year but didn't get round to it, and as the heating is on again i've started to notice again. Basically, the pump only seems to run when the boiler fires, as directed by the room stat (i'm not sure if the room stat starts the pump which then fires the boiler, or if the boiler turns the pump on..?).

My question is, is it right that the water should be circulating only when the boiler is generating heat? Wouldn't it be more efficient to have the pump circulating heat through the central heating pipes whenever the room stat is calling for heat, and the boiler then fire when the temperature of the central heating pipework gets below the value set by the boiler stat?

Its a Y plan with a honeywell wireless room stat, and boiler is a ideal mexico 2 (36kw). More of an operational question about y-plans in general i guess, though, as I couldn't get the answer by googling.

Thanks!
Mike

 

[Dan Robinson]

The pump is wired alongside the boiler's switched live so should run whenever the boiler is being called for.


Gravity hot water notwithstanding.

 

[dormermike]

The pump is wired alongside the boiler's switched live so should run whenever the boiler is being called for.


Gravity hot water notwithstanding.

Hi Dan - ok thanks, so if the pump is running when and only when the boiler is running, that is functioning properly as far as a Y plan goes, if I understand correctly?

Doesn't that leave a lot of heat inside the pipes inside or very near the boiler?
Thanks

EDIT; to confirm, it is a fully pumped system btw, open vented, with pump set to "2". I tried "3" but it didn't make much difference.

 

[Dan Robinson]

The boiler doesn't have to be firing.

But the valve's orange wire, boiler and pump should all be wired together.

 

[dormermike]

The boiler doesn't have to be firing.

But the valve's orange wire, boiler and pump should all be wired together.

Ah ok, which means the boiler may be being "called for" but not actually firing if the CH water temp is satisfied, in which case the pump may be running circulating the heat, but the boiler doesn't need to do anything.

Thanks - i'll check that out. I am not sure it is wired that way as the pump only ever seems to run when the boiler is actually firing.

Cheers
Mike