I’ve posted on my Viessmann boiler before and here is my latest posting. These boilers are very common in Europe. They have a computer controlled injection fan. Then, the gas, being propane or natural gas is ignited in a drum shaped combustion chamber / heat exchanger. There is a black seal at the top of the drum. You can see it if you remove the front cover of the white cabinet.
That seal seals between the exhaust piping and the combustion chamber. If it starts to leak you will see drips of acidic water come down from the seal area and there will be a slight gassy smell, especially when the boiler stops running.
You remove the plastic top at the top of the boiler. Pull the plastic top off and the you can see the rubber seal against the stainless steel drum. Pull out the old seal. Clean the metal lip. Insert the new seal and make sure the metal of the boiler slips into the slot of the seal. Replace the white piece and insert the four screws to hold it down. As usual I am assuming you are a licensed boiler tech or gas fitter. Hope this helps someone. Here are some pics.
That seal seals between the exhaust piping and the combustion chamber. If it starts to leak you will see drips of acidic water come down from the seal area and there will be a slight gassy smell, especially when the boiler stops running.
You remove the plastic top at the top of the boiler. Pull the plastic top off and the you can see the rubber seal against the stainless steel drum. Pull out the old seal. Clean the metal lip. Insert the new seal and make sure the metal of the boiler slips into the slot of the seal. Replace the white piece and insert the four screws to hold it down. As usual I am assuming you are a licensed boiler tech or gas fitter. Hope this helps someone. Here are some pics.