@@YagiChanDan Thank you for answering me, my intention is to be able to reproduce this activity in a gas course that we are taking and I would like to be able to propose it to our teacher and I imagine that it would be useful to know the steps that he followed to carry out that test. Thanks for your time.
All boilers have to purge the combustion chamber before the ignition sequence as part of the safety checks. You get the same fan overrun for a few secends on shutdown. The "pre-purge" is partly to allow for small amounts of gas being passed by the gas valve which could lead to explosive levels of gas forming in the boiler. Try googling "LEL in natural gas".
I just had one installed and it's transformed the house to a comfortable warm dwelling with loads of jot water at high pressure after a vokera system boiler that was a poor install given tank pressure and volume. Viessmann vittodens 100w combi 35kw 2020, top piece of kit with 6:1 modulation. It is running very well controlled with Honeywell economy with HR92 smart wifi radiator valves. I have rooms adjusted in timing so the boiler modulated The boiler modulates down after 10 mins. Still too early to gauge fuel consumption but performance indicates it will be good.
@@daveramsay8598 Same here Dave my viessmann vitodens 100 26kw boiler is now into year seven and I’m over the moon with it mine modulates down within about five minutes but then it’s only a small house gas consumption has dropped around 30% compare to the old vaillant system , it’s very quiet very efficient ,simple to clean & service, It was a purchase I didn’t want to make! But to be honest looking back now it has been very economical and beneficial over the years I have had it. Well done viessmann
