Why are new boilers/pumps constantly on?

FuzzyFrog

I got a new pump/boiler recently. It's a gravity fed regular boiler feeding a 4 bed house.

In the old boiler set up, both the pump and the boiler only ran when the boiler was on. In the new setup the pump (energy efficient I'm told) is constantly on and the boiler itself is also always on (ie it is wired with a permanent live, I don't mean it's always running)

I was told that the boiler needs this permanent live as it goes through some kind of shut down process and it needs to be on to shut down effectively. I was never given a reason for the pump being constantly on just that the cost is extremely low.

1) Why is the pump now always on?
2) What harm would there be in waiting say 20 minutes after the boiler has been turned off (so it can shutdown effectively) and then turning both the boiler and pump off? (I have a switch that can override the permanent live).

I've attached an image of the pump.


Thanks

DGOBS

It shouldn't be always running (just over running when your system is shutting down) may not be wired correctly

What boiler?
External pump?
Hows it wired and what time controls?

FuzzyFrog

What boiler?
Ideal Logic H18

External pump?
As in external to the boiler, if so yes.

How's it wired
I'm not sure I could answer that accurately. All I know is the boiler has a permanent live and the pump would always be humming away irrespective of the boiler running or not. The setting I have the pump at in the pic attached in the original post corresponds to the following "Proportional Differential Pressure. Setting suitable for heating and cooling systems with high pressure drop (radiators with thermostatic valves)"

and what time controls?
I have a thermostat on the wall, one of the analogue time clock ones.

John.G

This is the second case I have seen on here re one of these smart pumps being wired permanently on because perhaps someone thought that they are smarter than they really are.
The boiler needs both a switched live and a permanent live, the switched live enables the boiler to run for its enabled time via timer/thermostat and zone valve(s) if installed, the boiler should then supply this switched supply to the pump, this means that once the boiler is enabled then the burner will stop/start controlled by the boiler thermostat but the pump will run continuously (but only during this enabled time), the boiler permanent live is required as the boiler control will use it to keep the circ pump running (pump over run) for a few minutes to cool down the boiler heat exchanger after which the pump stops until the whole sequence is initiated by the switched live again.
The permanent live is also sometimes used in conjunction with a frost stat to fire the boiler and run the circ pump at very low ambient temperatures (~ 5C) but are rarely fitted to gas boilers as these are generally indoors.

Does you system have zone (motorised) valves fitted?.

FuzzyFrog

Thanks for the explanation.

Does you system have zone (motorised) valves fitted?.
I don't have zone valves fitted.

So if I understand you correctly the switched live of the boiler, when it is active for a period of time initiated by the thermostat, not only enables the boiler stop/start but will stop/start the pump also when the time period is over. By stop I mean no electricity is running through the pump.

John.G

Yes, to be clear, the circ pump will stay running for the whole of the switched time period, and yes, I mean that then there will be no electrical supply whatsoever to it, but the boiler (burner) will cut in/out depending on the boiler water thermostat set point temperature setting, when the time period has elapsed then there is no switched supply to the boiler also. Each time the elapsed time is over then the pump will (or should) be kept running for a few more minutes and then switch off.

FuzzyFrog

Thank you for the clarity.