In a parallel add on boiler installation it is recommended that the return to the wood boiler be plumbed in between the circulator pump and oil boiler return. The problem I see with this is the possibility of pushing water to the wood boiler when the oil boiler is working and the wood one is not in use. So you stop it with a valve right. Well what if you are not home to shut the valve when the wood boiler goes out? Can you tap into the return line on the oil boiler prior to the pump? This would prevent feeding the wood boiler when it is not in use and hopefully the wood boiler will be pulling the water back it needs when it's working. Lets say that I leave the t-stats and zone valves on the oil boiler and turn down the aquastat on it and just run the wood one at a higher level to keep the oil one satisfied. So if the wood boiler is moving water and no zone is calling for heat the water will feed backwards through the oil boiler possibly turning the oil boiler circulator pump backwards. If this is happening and a zone calls for heat and opens, when the oil boiler circulator starts will it be able to overcome that possible backwards rotation that is occurring?
This would be the easiest way for me to tie these boilers together with my current plumbing. Easier is better and with a swing checks on the supply and return the oil boiler couldn't push to the wood one but the wood one could push to the oil. I just don't want to have to throw a valve every time the fire goes out.
This would be the easiest way for me to tie these boilers together with my current plumbing. Easier is better and with a swing checks on the supply and return the oil boiler couldn't push to the wood one but the wood one could push to the oil. I just don't want to have to throw a valve every time the fire goes out.
