If it's a fairly modern boiler, with a domestic coil, it will probably have
a triple aquastat relay mounted right on the front of the unit. It'll
probably say Honeywell on it. If you have one like this, it will have two
adjustable dials inside, One for high temperature cut out, and one for low
temperature cut in. This type of boiler is designed to maintain a tank of
hot water for both domestic and heat. If the low temp cut in is set to low,
it won't fire up unless the heat thermostat is raised. Check to see that the
high temp cut out is set for 180 and the low temp cut in is set for 150




"andy everett" wrote in message
news:xXnWh.104$Zm.10@trndny03...
My brother-inlaw has problems with his hot water supply. The furnace heats
the house OK but the hot water, supplied by the furnace, seems to work
best only when the furnace is also heating the house. It seems like the
furnace has the wrong control, one for a furnace that only supplies home
heat. Assuming that the furnace has the proper control does it seem that
the control has failed in some way such that the furnace will cool all the
way down when there is no demand for home heat and thereby allowing the
heat exchanger coils to no longer heat the domestic hot water?

Thank you for any ideas,
andy