Indirect heater question

newbie

The specs say my Weil-Mclain indirect heater looses "less than 1/2°F per hour." So why does my boiler cycle on and off every 15 minutes or so in the summer when no other zone is calling for heat? If my solution is to replace the OEM tank thermostat with one where the upper and lower temperature limits can be adjusted, does anyone know who sells one. Thanks.

newbie

Indirect water heater

The specs say my Weil-Mclain indirect heater looses "less than 1/2°F per hour." So why does my boiler cycle on and off every 15 minutes or so in the summer when no other zone is calling for heat? If my solution is to replace the OEM tank thermostat with one where the upper and lower temperature limits can be adjusted, does anyone know who sells one. Thanks.

hot_rod

I question the same

wonder where that number comes from? Seems all tank manufactures quote the exact number! Maybe they rate them in a 100 degree ambient room

You could have ghost flow or heat migrating into heating zones. Also piping loss around the boiler and tank. Does it have a DHW recirc system? If so, is it insulated and on a timer and or aquastat?

If the 1/2 degree figure were indeed accurate then 4 degrees in eight hours? That shouldn't even trip the aquastat for another boiler cycle.

Is you boiler set to maintain temperature, or only fire on DHW call in the summes?

hot rod

newbie

indirect water heater

There is no thermal syphon at work here. Pipes are insulated and automatic valve shuts off boiler supply water to heater when temperature is reached.

jim sokolovic

Indirect water heater tank insulation

Many brands of these have very good insulation, and the low temperature loss claims are true. Does your boiler have an aquastat that maintains a certain minimum water temperature within the boiler itself, which would turn on the burner even though no hot water is being used?

newbie

indirect water heater

But I hear you hotrod on that oft-quoted spec of 1/2 degree loss. I, too, see that everywhere.

newbie

Aquastat

There's a dial to set a high temperature limit on the boiler, which is currently set at 160 degrees. Is that the same thing?

Aidan (UK)

thermostat

The boiler is cycling on & off under the control of it's thermostat as it cools down. It's probably losing heat up the flue. Either the tank thermostat is defective or the boiler is being turned off by it's thermostat before the tank thermostat reaches it's setpoint. What temperature is the tank set at?

The tank (cylinder) thermostats are usually strap-on devices over here. My one reaches 60degC and the boiler shuts down for 10 hours or more, or until someone uses the hot water, assuming the kids haven't left the taps running. The tank thermostat is interlocked with the boiler, so the boiler doesn't fire unless there's a demand.

http://content.honeywell.com/uk/homes/Catalogue/Heating Controls/2.9 L641.pdf

kevin coppinger_4

the boiler is....

set up as a tankless...you could replace the honeywell 8124 w/ a 8148. that will set it as a cold start and only fire when there is a call for heat. The other option is to turn down the setting to say 140. kpc