the heat exchanger into the hole for a test fit. Ideally the
tubes (D and E) should stick out of the plenum [see diagram on
previous page]. The header and tubes (F) can stick out of the
plenum as well, if necessary.
long as the whole coil surface (B) is in the plenum, you should
be good even if a little more of the header (F and even G)
test fitting it, try to determine how much tape is needed around
it. A different amount (thickness) may be needed on different
sides. You can purchase different thicknesses of tape so that it
will fit and seal properly.
foam tape around the outside of the heat exchanger to seal it
off so that it fits tight and air canít blow by it.
heat exchanger needs to be installed so it wonít move around.
The easiest way is to fabricate some pieces of metal into an
ĎLí shape, approx. the length of the heat exchanger like
the heat exchanger carefully into the plenum to check the fit
again. If all looks good, you can seal off the ends of the heat
exchanger and the hole you made in the plenum with foil tape
made for ductwork. Input lines should be at the bottom, unless
Installing a Heat Exchanger that is Longer than the Plenum
You can install a heat exchanger in a plenum that is smaller than the length of the heat exchanger. This is a good ideal because you will get the whole core inside the ductwork. Only the frame will stick out 1" (on each side). Proceed as follows.
the lines at the top and bottom of the plenum, usually 4 inches
long (the width of the heat exchanger).
another line vertically, between the other two cuts, right in
the middle as shown.
the heat exchanger through the front hole to the back hole. So
that it protrudes front and
the core of the heat exchanger will be entirely within
the plenum. (Item B)
If you want a heat exchanger for a plenum that is 18" x 18", then that is the size of heat exchanger to buy and the outside dimensions will be 18" x 20".
the sheet metal to the edge of the heat exchanger. This is item
G in the diagram above (Page 23). Using channel-lock pliers to
crimp it, it makes a very nice professional looking
installation. Input lines should be at the bottom inlet unless
not only forms a virtually airtight seal, but it also supports
the heat exchanger as well.
transition was built here so that a larger heat exchanger for
the outdoor wood burning furnace, could be used with smaller ductwork.
customerís photo of his heat exchanger installation for his outdoor wood burning furnace..
Bleeding a Heat Exchanger
You need to have two cut-off valves in the return line - one with a drain. With the pump running (turn the thermostat up to 90 F so that the pump comes on), simply close the brass valve on the return line quickly, holding it for 3-4 seconds. Then open the valve. Repeat the procedure at least 4 times.
If youíre unsure if all the air is getting out, you can separate the 2 valves at the Pex Pipe between them, after turning off both valves so that water wonít drain out.Insert a clear pipe in a 5-gallon bucket fro the drain valve. Close the other valve in the return line. Open the drain valve. Then simply close the valve on the return line quickly, holding it for 3-4 seconds. Then open the same valve again. Repeat the procedure 4-6 times. That way you can see if bubbles are coming out of the line.
BTU Load Calculator | Hydronic Wood Furnace | Wood Heating Costs-vs-Gas & Electricity
Installing a Heat Exchanger
Serving VA, GA, TN, NC, and SC
© Copyright 1995-2014
* Some building codes may allow a
homeowner to be their own contractor and do much of the work themselves.
In other locales a licensed electrician and plumber may be required to do
the actual hookup.