We have a Columbia Emerald EM-125 oil boiler. 2 problems: water leaking from temperature control for hot water due to packing caused shortage in circ pump. Oil co. replaced circ pump with Taco brand (the green 008-F6 model). When temperature gauge under metal panel is increased to above 160 it makes a very loud mechanical humming/buzzing noise which persists intermittently before during and after the firing of the boiler. When turned down to 160 it ceases. Oil co. also replaced water packing but now we have little to no heat in our bathtub/ shower. The water in rest of house heats fine but we have tepid-to-cold showers with intermittent bursts of heat that are infrequent and short at best. Plumber visited and thought it may be our coils and we needed to replace our boil HOWEVER hot water was working fine prior to fixes provided by oil company. I'm lost, need help.
When the repairman was working on your boiler he may have dislodged some sediment inside the domestic water pipes that eventually went up to and lodged in the shower hot water faucet. This could cause a drastic reduction in the hot water flow to the shower.
Also, does the hot water work better when the room thermostat is calling for heat in which case the circulator is on and churning the water inside the boiler and about the hot water coil?
When cleaning anything including baby diapers, it is better to sweep off or scrape off as much solid and semisolid material as you can first. (1) Less cleaning fluid or detergent needs to be used, (2) Less of a mushy mess which in turn means that bleaches or disinfectants will be more effective.