Weil Mclean Bypass and Zone Valves

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Old 11-26-17, 09:14 AM
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Weil Mclean Bypass and Zone Valves

Long time lerker here needing a little bit of help. LONG POST

I have a Weil Mclean CGM 5 PI series 8 boiler I am replumbing to correct some issues. 4 Zone heating system. 1 Basement zone, 2 First Floor zones, 1 second floor zone.

Currently there are 4 circulators on the return side. On the supply side there is a seperate 3/4 port that is for the factory bleeder location. It is capped off. The supply piping is 1 1/4 immediately reduced to 3/4, flowing to T for the basement zone piping. It then flows to a bleeder, then a manifold leading to the other 3 zones. On the end of the manifold is a expansion tank.

The plan is the change the supply piping to 1 1/4, pipe to a Spirovent Jr. air eliminator. Attached to that will be the expansion tank and pressure reducing valve. I will then from the air eliminator to a curculator pump. then to a 1 1/4 mainfold with 3/4 outputs for each zone valve (Honeywell V8043E1012). I will have a 3/4 ball valve before and after each zone valve, and a 1 1/4 ball valve before the air eliminator. The old bleeder port that is capped off I would add a simple bleeder there to prevent trapped air.

This setup would allow me to pump away from the expansion tank.

Currently the burner is being powered by a Honeywell s8610u3009 ignition module with a high limit aquastat. The wiring is a mess, the burner only ignites when zone 1 calls for heat. the other thermostats are basically pump switches.

I have 2 modules that I will be adding, a TACO ZVC 406-4 to take care of the zone valve operation, curculator pump activation, and burner activation signal. The second is a Tekmar 260 to add outdoor reset capability. I have the Tekmar indoor sensor, outdoor sensor, and universal sensor.

The issue im running into is protection against thermal shock and condensation. Once the boiler heats up above 140, I do not want colder zones flowing in and below 140 F and causing condensation.

Secondly, This boiler does not have a LWCO, I was thinking of adding it to a T right at the supply side output above the boiler, possibly a Taco LTR0243T-1.

Third, Im assuming to prevent condensation and thermal shock I need a mixing valve. Because of multiple zones I believe I need to have an electric valve to keep temps above 140 F at all times. Im pretty sure the Tekmar 260 wont play nicely if it tries to reset below 140 F so I will keep the minimum reset temp above that.

Finally, There is not flame rollout or flue spill safety switches install.

The wiring flow chart is a little simple. Safety switches and LWCO will kill the power to the S8610U3009 module. Power would remain to the Tekmar 260 and Taco 406-4. I am adding a seperate 24 V transformer to supply R C to a Nest themostat I am installing. I do not want it to use the C from the Taco 406-4 becuase during the warmer months the cutoff switch is off and would power down all modules. The emergency swith on the boiler would cutoff all modules AND the 24V thermostat transformer. That one would remain on.

Im looking for recomendations on a automatic bypass valve and piping if needed. Safety switch locations, LWCO location, and overall advice is im going in the correct direction. I already have the Tekmar 260 and Taco 406-4, returning them would be a little bit of a hassle but I will if I have to. If my setup is all screwed up feel free to let me know, I have a little time. I still need to get 2 more zone valves, pressure reducing valve, and a handful of back flow valves for the supply and return zone piping.
 
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