I have bought my Vaillant Thermocompact boiler around five years ago. It is working well expect that when the cylinder stat or room stat shuts off the gas, a demand light remains to spark & pump is running as well. I have replaced the main control board. Now what should I do?
Thanks a lot
The boiler’s central heating pump should run long especially when the gas shuts off due to the residual heat. Moreover, it is better to shut off the gas all of a sudden & try to run off the retained heat. I hope that this will solve your problem. In case the problem persists, do call a Vaillant boiler engineer for in-depth investigation.