Tekmar 256 and L8124

lotsofH2O

I am working to install a Tekmar 256 to a Honeywell L8124C aquastat for an oil fired boiler. The boiler has 3 heating zones and a DHW zone. I am using ZR and the common (terminal 2) on the aquastat to drive a relay connected to terminals 7 & 9 on the Tekmar. This is working correctly to indicate when there is a boiler demand.



I would appreciate some help identifying where on the aquastat to connect the Tekmar boiler relay terminals 5 & 6.



Attached are the L8124C schematic and picture for reference.



Thanks

Steamhead

The simplest way

is to run a 24-volt cable from the TT terminals on the oil burner primary (which would be jumpered in your application- remove the jumper before connecting the cable) to terminals 5 and 6 on the 256. That way the 256 will control only the burner, while the circ will run anytime there is a call for heat.



If the oil primary has no TT terminals (for example a Honeywell R4184) replace it with a newer one which does. The new one should have a 15-second trial for ignition.

lotsofH2O

Tekmar 256 connections for 5,6 terminals

Ah, so that' the key. The oil primary does not have the T-T connections. That's an easy fix. Thanks for the help.

Steamhead

Glad to help

check out the latest Beckett GeneSys and Honeywell controls. Nice stuff!