Keystoker Boiler; Upgrading with secondary blower
From NEPA Crossroads Knowledge Base
Upgrading Keystoker Boiler with secondary blower
Older Keystoker stoker units can be updated to perform as well as the current generation of stoker units being produced by Keystoker. A few years ago Keystoker made a change in their stoker. A small blower was added to continuously blow a small amount of air under the grate and through the fire in order to better keep the fire going between runnings of the stoker motor. For people who have an older Keystoker without this feature Keystoker has come up with an adapter that can be placed on the existing stoker body to attach this blower. Alternatively a do it yourselfer with a welder and metal fabrication skills can make their own adapter to attach this blower.
A hole must first be cut into the stoker body fan shrouding behind and below the stoker fan to permit the air from the secondary blower to flow under the grates. The sides of the stoker body are quite heavy at this point, about ¼” steel plate, but the metal between the two heavy plates where the hole must be cut is just a heavy gauge of sheet metal. Several methods can be used to cut this hole. With the stoker motor and fan removed it can be cut with a plasma cuter, a cutting wheel on a die grinder or drilling holes at the corners and using a reciprocating saw with a metal cutting blade. The adapter made by Keystoker fits over top of the stoker body and is secured by 4 self tapping metal screws. The gaps along the edge are sealed with furnace cement or high temperature silicone.
The blower is wired to run constantly. There is a shutter on the side of the blower to adjust the amount of air being blown through the fire. All situations are different but typically the shutter will be set around a third to half open. The air adjustment for the stoker fan generally does not need to be re adjusted.
After installing the secondary blower the timer can be adjusted for shorter run times. This should fix any problems you may have encountered with boiler overheating or fires going out, especially during times of the year when the boiler is just being used to supply domestic hot water.
Doing an Upgrade
Note: The following upgrade can be performed without the removal of the stoker from the boiler.
Here we have an older Keystoker stoker housing with motor and fan removed.
This is the small blower to be added and the adapter bracket as made by Keystoker.
The small blower will run continuously 24/7 and should be wired to a constant hot wire but one that is turned off with the furnace switch. There should be a fused shutoff mounted on or near the boiler that will turn off ALL motors, blowers, circulators or anything else connected to the boiler.