I am planning to retrofit a modified indoor wood burning hot air furnace (now located outside in a shed)with a coil to heat water that will store in tanks under 0 pressure (they will be vented). This water will be circulated through a water-to-air heat exchanger in the outflow plenum of my existing hot air furnace, which is located indoors. Circulation will be continuous, and the hot air furnace blower will turn on and off via its own indoor thermostat. My question is: what GPH flow do I want to create in this loop that comes from the coil in the woodburning furnace and on through the heat exchanger? I am trying to optimize the flow, so that I do not create water that is either too hot or too cool.

Can anyone help me with this?

Thank you.

-- Hal Houghton (houghton@empireone.net), May 18, 2001

Answers

can you get it to pump with a zero pressure??? Why not hook up a hot water tank to it to keep some pressure? AS to the GPH,,, your going to have to do trial and error,, without all the spcifics to the amout and temp of the water,, it will do impossiple ti figure out the GPH you want for a specific temp

-- stan (sopal@net-port.com), May 18, 2001.

You could fit your storage tank with an Aquastat that would control the water temp for you. Not sure if your storage tank is built around the firebox. Our commercially built outdoor furnace has a water tank surrounding the firebox, and the aquastat controls the combustion fan and intake damper. If your tank is seperate from the firebox, the aquastat could turn a circulation pump on or off as needed. Our house thermostat turns on a fan that extracts heat from an "A" coil in an old gas furnace. At the same time, it also turns on a 1/7 HP pump that circulates heated water from the boiler through the "A" coil. The water lines between the "A" coil and the boiler are insulated and do not cool much between cycles.

-- Paul (hoyt@egyptian.net), May 21, 2001.