How to hookup a non pressure system to a pressure system

Tim Kreger

I need drawings and explainations on how to hook a non pressure outside furnace to an existing pressure oil furnace. I need the oil burner to be able to kick on for a backup system in case the outside unit goes out. Any diagrams would be helpful.

hr

Two things

on the mechanical side a heat exchanger will be needed. Contact a manufacture or rep for proper sizing. Just about all the boiler manufactures offer flat plat heat exchangers in their catalog.

Electrically, a setpoint control would call on the oil fired boiler when the temperature at the wood boiler fell to below a temperature you selected. What type of heat emitters do you have baseboard, radiant?

Piping wise, it would be best to have a knowledgable hydronics guy look at your current system and advise you. Hard to draw options without knowing what you have currently.

hot rod

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Dan Peel

Different options

Pressure is usable and even desirable in a system under many conditions - pressure is not absolutely necessary.
With reasonable design consideration you can twin the two heating sources - be aware that your will be subjecting the entire heat distribution system to significantly more O2 with the potential for increased corrosion.
As HR suggests you'll require an A stat to call the oil source only if heat is not available from the outdoor source. Get design assistance that adresses this specific setup.
Enjoy....Dan

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Steve Ebels

If the oil

Boiler has enough btu output to carry the load of keeping the outdoor unit heated you can just put an HX in the return line goin into the oil boiler. No further controls are really needed. If the wood dies down the oil burners aquastat we see the temp drop and kick it on. If the HX is sized right and the outdoor unit is carrying enough temp the oil burner will never "see" low enough temp to kick on it's burner except in periods of major load. I've done a lot of outdoor/indoor units that way and had no problems, The components just have to be sized right.

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