Mod-Con with Cast Iron Radiators

Jolly Bodger

I recently installed a Lochinvar Knight on an old converted gravity hot water system. I sized the boiler to the available radiating (cast iron collum radiators) and factored in the heat loss on the piping. While I have no complaints form the home owners, but I noticed how long it takes to get the system up to operating temp. The Knight is 1/2 the size of the cast iron boiler that was in there. The question is, should a boiler in these situations be oversized to speed up the start up time? I am running the outdoor rest and I know you want a slow heating cycle especialy with these large radiators. Maybe there is a better way to run this system. Maybe it's running perfectly and I'm too just used to copper fin tube.

Chas_2

not baseboard

i think your used to baseboard ,i am running baseboard and i have 1 cast doing a spare room .i wish the home had all cast lower water temp and more even heat .as things are i'm running my baseboard at 140 on design day and my home is much more comfortable then the high temp were made to believe are necessary don't worry if you mod con is set up right with outddor reset and the rght curve it should putt along and meet your indoor settings without short cycling and with out over shooting your temp if the HO ain't complaining again don't woory peace and good luck clammy

Mark Eatherton

Slow is good...

it avoids overshooting and subsequent shut down on high limit. My system NEVER shuts off, and my gas bills are the lowest they've ever been.

One interesting feature of the Knight is the Boost Feature. You can program it to override the ODR schedule during a sustained call for heat. You tell it how often you want to boost the temperature, and how many degrees you want to boost it until it hits the programmed limit. As soon as the call for heat is dropped, it resets itself to zero. But if the occupants are happy, I wouldn't touch it.

There is also a feature for ramping capabilites. The typical American CFT boiler runs full out until hit hits the operating limit. With the Knight, you can program it to act like an American, or like a European (slow ramp UP and slow ramp DOWN), which avoids unnecessary overshoot of bouncing off of the operating limit. This change requires a lap top computer if memory serves me correctly. But it IS worth the price of admission.

This ain't your grandpas boiler any more...

ME