Also ich habe einen Biomeiler mit 8 IBCs (4 fuurs BioGas und 4 zur Aufnahme des Wassers) gebaut und der normnale zweiflammige...
A heat exchanger is recommended to keep the two systems - central heating and biomeiler - separate.
The heat exchanger should correspond to the heat output your require. Over-sizing the heat exchanger is not a problem, under-sizing would be. An over-sized heat exchanger will give you some comfort to increase your biomeiler later. An under-sized heat exchanger will transfer enough heat into your central heating system. Larger, over-sized heat exchanger will reduce pressure loss for the pump.
The heat exchanger will be connected to the flow and the return of your central heating; best straight into the feeds from an existing boiler. Please add a flow restricting valve if the boiler is still in use to prevent boiler heat to enter the heat exchanger in order not to waste energy. You could use a motorised valve.
The heat exchanger should be located inside the house and should be well insulated.
If you use an indirect hot water storage (buffer) tank you may not need a heat exchanger as the buffer tank may have a heat exchanger build in.
You now need to connect your biomeiler to your heat exchanger. On short distances you may use standard central heating piping and isolate it well.
For longer runs we recommend the use of standardised "district / area heating" pipes. They come ready made with two pipes side-by-side, well insulated and protected to be buried in the ground or run over ground.
You might have alternative solutions in mind and we would be happy to discuss them - just add them to our forum or send us an email.