Replacing a fuse on an Vaillant Ecotec gasburner

Last night a big thunderstorm hit my home.

Ligtning hitting Sealand Denmark

During the storm a lightning actually hit the house/so close to the house that it went into the electrical system. Luckily the legislation about electricity in danish households requires that electricians installs HPFI and thermo fuses, so after the a white spark out of a wall plug, the HPFI and thermo fuses kicked in and took down the whole system.

…. or so I thought. The lightning had actually been fast enough to hit the control unit of my Gas Boiler – It would not turn on this morning to heat water for the day.

This post will show how to open a vaillant ecotec gasboiler and exchange the fuse(s).


Turn off your boiler before doing anything. Disconnect it from the wall plug. Use original fuses. If in doubt – STOP! Do not tamper with the Gas part of the heater! If the fuse blows again, do NOT substitute with something that can not blow! Do call an qualified repair man if that happens!

And finally: if you blow up yourself and/or your house/friends/families/dogs/whatever I can not be held responsible! Do not trust a stranger on the internet just because you are trying to save a few bucks!

Safety before anything else!


With the disclaimer out of the way, lets get going. First locate the front of your boiler. It will look like this.


The front of the boiler is held in place by one screw on the bottom:


Remove the screw with a screwdriver


Remove the front by pulling outwards after you have ‘unclipped’ it (there are two clips to secure it besides the screw)


You should now be able to look inside the boiler. If you are unsecure, stop. Remember the disclaimer!


Grab the to white, apply pressure and pull down the control unit like this:


Now we are going to open up the control unit.


Locate the fuses:


Exchange the fuses. On the vaillant you have two spare fuses on the inside of the control unit:

Assemble the whole lot back and turn on the boiler again. Hopefully it will come back to life. If it doesn’t something is seriously wrong – call an vaillant approved repair man.

And …. do not forget to order a new fuse right away!

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