I have a Teledyne Laars Max D100 Boiler w/ indirect hot water. It is a cold start boller. It has separate Hi Lo limit controls. Hi limit set at 200F, Lo limit set at 180F. Problem: When thermostat calls or heat, boiler heats up to about 165F & burner cuts out. As water circulates boiler temp starts to drop. When boiler temp drops to about 155F, burner kicks back in & heats up to about 165F again & continues back & forth until thermostat is statisfied. Why isn't boiler operating between the Hi Lo control settings?