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Posted by HeatPro on July 11, 2006 at 20:27:59:
In Reply to: Re: cast iron or finn type convectors posted by Janet on July 11, 2006 at 16:44:16:
Yes, the cycling rate would be affected by the time it takes to heat up the radiation and the heat storage of the radiation.
However, for hot-water heat, the same effect can be done with fin-tube radiation and another mass to store heat and give it off, such as a buffer tank of water.
As boilers have been used with fin-tube radiation or convectors for over 50 years without any problem about reliability due to more frequent cycling, it isn't a concern that you need attend. there are several ways to extend cycling. A gas boiler has no difficulty opening a gas valve several times a minute (the technique has been used.)
A more serious problem is if the boiler has too large an input for the radiation or many small zones where each zone thermostat demands heat, forcing it to short-cycle. As you are considering using a condensing boiler, it more likely has the controls in it to modulate the fire to alter the firing rate to match the conditions it is working in.
A more specific design with some planning can eliminate the need for cast-iron to achieve the same intent.