Weil Mclain GV-3 locking out on low temp

burto

hi guys, have a GV-3 Series 4 Gold gas boiler feeding two hydro-air units. Unit is intermittently shutting down on low return temp. If temp drops below 140 degrees the bypass circ tries to mix some supply to raise temp. Would like to loose this feature any thoughts

icesailor

That feature is there for a reason. Disable it and destroy the boiler with cold water returning. The condensation destroys the cast iron HX.

burto

yeah your right. I ordered a new return water sensor, maybe that will help. last week it was below zero so that didn't help.

burto

installed a new return water sensor. installed a low limit on supply and set to 150*. Being a cold start boiler , this should help ,when both of those hydro units kick on they suck the heat right out of boiler.

icesailor

burto said:

installed a new return water sensor. installed a low limit on supply and set to 150*. Being a cold start boiler , this should help ,when both of those hydro units kick on they suck the heat right out of boiler.

You need to read the I/O manual for the correct settings. When properly set, you will not "suck all the heat right out of the boiler". The system pump is supposed to stop. The boiler pump is supposed to keep running.

If it is doing what you describe, you have turned it into a "cold Start Boiler" and you will be defeating the purpose of the boiler design.

Is it piped as the I/O manual describes?

Here's the I/O manual for a GV Series 3 boiler.

The control strategy is supposed to limit water going back into the boiler to 130 degrees. If it is getting lower, it will kill the boiler.

http://www.weil-mclain.com/en/multimedia-library/pdf/weil-mclain-pdf/products/discontinued/discontinued-boilers/gv-boiler/gv3manual.pdf

burto

thanks for more of your input and the manuals. I will re-think the whole thing and ask if the call came back in. Ill take some pics if I go back. I could see the amps on the motors changing(modulating) between supply and bypass but there so quite.