Wednesday, March 13, 2013

Why is the Pump Mounted on the Rear of the Outdoor Wood Furnace

It doesn’t come up often but we’re sure many people would like to know.  Why is the pump mounted on the rear of the outdoor furnace? 

The simple answer is that this is an easy place that every installation can utilize. 

There is a little more to it.  The circulator pumps used by Hawken Energy (and probably all circulator pumps used in the industry) can not PULL water to feed themselves.  Water must be supplied by gravity to lubricate and feed to the pump impellers which PUSH water through the loops. 

The circulator pumps sold by Hawken Energy use the water provided as the lubricant around the internal rotor.  This wet rotor design spins an impeller that pushes the water through the system. 

By installing the pump on the back of the outdoor furnace, on the lower fitting to be exact, we insure that water will always be gravity fed to the pump.  Installation on the upper lines from a Hawken unit may allow air to feed into the pump causing problems with the circulation.

It’s commonly asked if the pump can be installed inside of the home or building.  The answer is: As long as gravity will feed water to the pump without airlock. 

If the building is higher than the pump location on the outdoor furnace or if the lines dip and rise considerably then gravity might not push the water all the way to the pump because of air lock.  If the lines feed downhill to a basement or lower location then placing the pump inside the building is acceptable.  The pumps are quiet when operating normally. This option appeals to some for maintenance or access reasons. 

It is also important to note that the pumps should be installed so that the shaft of the motor is level to the ground, with the faceplate plumb (see fig 1).  The volute, the end of the pump that receives and feeds water, may be mounted in any orientation as long as the shaft is level.  Improper mounting may reduce the life of the pump.   

Fig. 1

Posted by Don Squire - Hawken Energy Outdoor Wood Furnaces
Bookmark and Share

No comments:

Post a Comment