How to Recover Water from Boiler Flue Gas

What You'll Need
Condensing Heat Exchanger

When running a boiler some of the heat produced by the system is lost when gases escape into the flue. The heat and water carried by those gases are not only a significant loss to the inside of the house, but also contribute to heating the outside atmosphere, and is considered one of the factors in global warming. The basic principle would be to contain those gases inside the flue, although the levels of carbon monoxide and other toxic gases would cause concern. Recent advancements, however, have provided another alternative, and with a few simple steps, you can fit a device which will help you to recover heat and water from boiler flue gases.

Step 1: Altering the Boiler

Fitting a condensing heat exchanger will help you to catch water escaping through the flue. Firstly, turn off all your electrical sources at the mains, and any gas or other fittings. Then remove the flue from the top of your boiler. You should see two pipes fitted to the edge of the boiler. These supply gases to the flue. Remove the lower portion of the flue, keeping the top intact.

Step 2: Installing the Heat Exchanger

Position the heat exchanger on the wall, near to the top of the boiler. Screw tightly on to the wall, making sure that it fits securely. Take your pieces of pipe, and use these to connect the boiler to the holes in the heat exchanger. The pump in the exchanger will now push the gases around, and then draw off hot water, passing it back into the boiler. Caulk around the edges of the heat exchanger, the pipes and the top of the boiler.

Step 3: Connecting the Flue

Now bring the pieces of flue you removed from the boiler, and place them inside the flue. There will be a connection point on the top of the heat exchanger. Place the flue edges onto this, and then caulk around the outside. Caulk again to connect the inner and outer chambers of the flue, and check for leaks before you continue.

Step 4: Wiring up the Heat Exchanger

You will need to connect your new device to the electricity supply. Take the wires from the back of the heat exchanger and connect them to the power supply in front of the transformer. Keep the connections tight, and then operate the system for a few minutes in order to ensure that it is all working correctly.

Step 5: Operating the New System

Once you have installed your heat exchanger, the water should be transferred back to the boiler automatically. You may notice a lowering of your heating bills as one indication that the system works. You should also check the water levels in the boiler using the sight glass, taking care that you are not loosing too much through the operation of the new system. Clean your heat exchanger regularly to keep it working efficiently, and change the filters in the condenser regularly to prevent the growth of disease.