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What unit to use with panel rads and sidearm
I am trying to setup a cheap backup for my wood boiler. The plan is to use panel radiators and a sidearm heat exchanger on a electric water heater. So can I use a condensing tankless water heater to save money or should I go straight to a condensing boiler? Remember this is a backup and I want to keep it cheap, but it needs to be able to heat the home for inspection and be able to kick on if the fire goes out in the wood boiler. It also must be wall hung and small to fit in the pantry with the washer/dryer n water heater. I was looking at the navien condensing water heaters cause PVC is a cheap vent?