Weil-McLain

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Old 11-04-20, 05:14 AM
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Weil-McLain

Good day.Purchased a multi unit building that has Weil-McLain boiler Gold CGI-6-PIN series 2 with White-Rodgers 1311-102 zone valves and thermostats. It also has a TEKMAR 256 hooked up.
Reading the Weil-McLain boiler manual, from what i understand, the return water is not to go under 130F
Should i set the TEKMAR so that the minimum water temp is 130F ?
Now when the outside temperature goes above freezing and based on the Tekmar setup, i might need only 110F water temperature to maintain room temperature.
What is the correct setup.

 
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Old 11-04-20, 10:04 AM
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Natural gas will condense around 130F, hence Weil Mclain's warning. The condensate will collect in your boiler and harden into a cement like material that will eventually block heat exchange and destroy the boiler. If water temperature coming into the boiler is sustained below 130F, condensation can occur on the heat exchange and wreak havoc.

Where is your probe for the Tekmar ODR attached? If its on the return side (ie water coming into the boiler after the convectors), then setting the minimum to 130F is fine(maybe a little higher to play it safe). If its on the supply side, then you will have to determine what the minimum supply temperature is that you can give that results in return temperatures of >130F. I do this by turning on all of my zones of heat. This puts the biggest load on the boiler and will cause the greatest temperature drop across supply and return water. I find what the lowest supply temperature is that will give me a return temperature of at least 130F (probably do 140F to play it safe). That is what I would then put into my tekmar as the minimum. Most systems are designed to give a 20F drop from supply to return but its always good to check that.

I would also make sure that your boiler controller or zoning panel also have a circulator hold off in place. This is a setting that will stop the circulators from running until the boiler hits a certain temperature (usually 130F). This helps prevent the circs from running before the boiler is warm enough, wich results in too cool of water returning to the boiler and possibly causing condensation.
 
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Old 11-04-20, 02:18 PM
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Thanks for the input. The Tekmar probe is set on the return line after it leaves all the zone valves . The zone valves were installed on the return line.
 
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Old 11-09-20, 11:21 AM
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Weil-Mclain

I would like to update the current thermostat with a Honeywell Focus PRO 5000 but nut sure where the wires go on the new thermostat
Right now they are BLACK=4 RED=Y,6 WHITE=5



 
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