Central Heating question

[Bugsy]

Can anyone advise as to whether it is correct/advisable to have the pump running full-time?

Our boiler system, like many, I suppose, is controlled by a timer in the boiler room. When we bought the house the pump was wired to be on permanently. I changed this and put both the pump and boiler on separate timers but the heating engineer who has just serviced our boiler says that the pump is better left on 24/7.

Seems a waste of electric to me.

.

[Gluestick]

The pump only needs to be on when the boiler is enabled Bugs: what on earth would be the point of running the pump if the boiler stat has turned off after the room stat/s and the TRVs have closed down?

 

[Quillan]

First my disclaimer.: I have only ever installed and worked on UK systems (in my own house) and French ones may be different.

The pump is normally controlled by the boiler by either a 'pump overrun thermostat' in the boiler or the difference between the inlet and outlet temperature of the boiler in conjunction with a room and/or hot water tank stat which tells the boiler to turn on or off.

The reason the pump will overrun is to ensure the water does not continue to heat once the flame has gone out. This is because the boiler 'jacket' retains latent heat and will continue to heat the water after the flame has been turned off.

How the pump if controlled is really down to individual makes of boiler.

Whichever way the pump should be connected to the boiler and not operated separately. It seems to me that probably something went wrong so the pump was wired directly to the boiler timer so at least if the boiler is supposed to be on the pump will run. You should not control the pump with a different timer or switch as it could cause problems with the boiler and in the absolute worse case cause the jacket to crack or even explode. But of course even after the boiler has been switched off by the timer the pump should still run on until the boiler has cooled down. Likewise it should not be left on all the time because it will take the water longer to heat from a 'standing start'. I guess you have to trust your professional boiler engineer but leaving it on 24/7 does not sound right to me. Perhaps you can ask around and try a different engineer and explain the problem to him. Try contacting the company that made the boiler and ask them for an approved engineer in your area might be the best idea.

You can read more about (UK) boilers here Pump Overruns 

 

[Sunday Driver]

"the heating engineer who has just serviced our boiler says that the pump is better left on 24/7."

I read this to mean that the pump should be wired so it's available 24/7 for on-demand use by the boiler rather on a separate timed feed.  Not necessary running continuously.....