46
Trouble-shooting:
Poor Water Flow
or little or
No Heat
1. Check to make sure that the furnace is full of water. Simply open the valve on the
front until water flows out of the overflow tube. DO NOT block off the overflow
tube!
2. Make sure you have a good fire!
3. A. Check to be sure the pump is running when the thermostat is raised.
B. Your inside furnace fan should come on at the same time.
C. See if air is blowing out of the vents.
4. Make sure that the water is hot. You can check this at the drain on the stove, or
at the pump by removing the Pex Pipe and turning on the pump.
An infrared thermometer is VERY useful for trouble-shooting and they are very
inexpensive now – as little as $10 from Harbor Freight!
5. Watch the fan to see if it comes on when the water temperature drops in the
furnace. You can test the fan by connecting the two wires at the thermostat
together
AFTER TURNING OFF THE POWER!
If the fan comes on when you connect the two wires, but it won’t come on by
itself when the water temperature drops, you need to replace the thermostat.
These are standard hot water heater thermostats available for about $5-8 at any
good hardware store.
In most cases the flap on the side of the fan should only be open ¼ to 1/3.
6. Turn off both valves so that water won’t drain out. Separate the two valves
(shown on previous page) at the Pex Pipe between them.
7. First open the right shutoff valve with the large handle. If water flows out freely,
then you know that there isn’t a blockage there. Close the valve.
8. Insert the left plastic valve and pipe in a 5-gallon bucket. Open the valve. Turn on
the pump by turning on the furnace (raising the thermostat if necessary).
9. Record the amount of time it takes to fill the 5-gallon bucket. Turn off the plastic
valve. Compare that figure to the one you wrote down on the inside of the
furnace, near the valve, when it was installed. If the figures are the same or very
close to it, you can assume that the pump is working properly and that there
aren’t any blockages. However, you may have a heat exchanger with a coating of
minerals on it such as lime. This will need to be cleaned as it will inhibit heat
transfer. (See heat exchanger cleaning procedure at end of this section)
10. If the figures are lower than original, proceed to step 11 to find out why the
flow is so low.
