Weil-McLain GV90+ manual Common problems and solutions, Symptom Common Causes Possible Corrections

GV90+ gas-fired water boiler — User’s Information Manual

Common problems and solutions

Symptom	Common Causes	Possible Corrections
Rapid cycling — boiler	Thermostat installed where drafts	Locate thermostat on inner wall away from
turns on and off frequently	or heat affect reading	heat sources or cool drafts.
	Heat anticipator in thermostat	Adjust thermostat per manufacturer’s
	adjusted incorrectly	instructions.
	Incorrect limit setting	Set limit according to system needs.
		Maximum setting is 200°F. Increase limit
		setting to decrease cycling.
	Insufficient water flow through	Check all valves to and from boiler. Return
	boiler	to proper setting.
		Confirm circulator size.
Frequent release of water	Expansion tank sized too small	Call qualified service technician to check
through relief valve		expansion tank operation and size.
	Flooded expansion tank	Call qualified service technician to check
		expansion tank operation.
	Inoperative limit control	Call qualified service technician to replace
		limit control.
Need to frequently add	Leaks in boiler or piping	Have qualified service technician repair
makeup water		leaks at once to avoid constant use of
		makeup water. Makeup water can cause
		mineral deposits which, in turn, can cause
		boiler section failure. Do not use petroleum-
		base stop-leak compounds.
Black water condition	Oxygen corrosion due to leaks in	Have qualified service technician repair at
	boiler and piping	once. Keep pH of water between 7.0 to 8.5.

Part number 550-142-055/0411 13