Boiler problems - anti cycling mode?

ChrisH

Hi all,

Hope someone can help with this one.

In my flat, I have a Vaillant Turbomax boiler and have noticed that it repeatedly enters anti-cycling mode when firing.

In essence, when the boiler heats up to temperature, it will run for several minutes and then enter anti-cycling mode (I assume to avoid unnecessary wear). However, when it enters this mode the central heating pump also turns off, meaning that no water is piped to the radiators. After a delay of 5-10 minutes, the boiler and pump will then fire up again, all resuming normally until the anti-cycling mode kicks in again after 10-15 minutes or so.

Am I right in assuming that during the boiler's anti-cycling mode, the pump should continue passing the water through the system? At the moment, the radiators just start to cool down when the boiler cuts off - not particularly energy efficient!

We do not have a room thermostat, so there are no external controls manipulating the boiler.

Hope someone can help.

Many thanks :cool:

SShar

Hi Chris,

I think this is just how it operates

Pincher

Have a look at a feature called over-run. This keeps the pump running when the heat demand is off for a few minutes, presumably to cool down the heat exchanger, and use up the remaining heat. I think the issue is how to keep the zone valves open when the pump is running, because the boiler doesn't know it's safe to run the pump otherwise.

This brings up expansion and contraction stress, which probably is no good for the gaskets and possibly metal fatigue. My 30SX heats up gently, and doesn't go full power straight away, which I assume is to do with reducing expansion stress. It also goes low flame before the target temperature is reached, and takes its time getting there, so it doesn't have to cycle much. Ideally, if your house is losing 4kW, and the boiler is suppling 4kW on a simmer, there is no need to cycle at all.

gas4you

Is this a Turbomax Plus? If so the pump over run should be set to between 5-7 minutes.

Strangely I had to go to an Ecotec Plus doing the same this morning. In this case it was the diverter valve stuck in the HW position and therefore not letting the heated water circulate fully to the heating system when heat was demanded.