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Converting cast iron radiators

We have a house with the old cast iron radiators. I love the radiant heat, but the radiators take up a lot of space. I am not interested in converting to forced air heat. However, I am also not crazy about the newer hydronic panels. I am guessing we can not afford to install the hydronic floors or ceiling (our house in 100 yrs old and had hardwood floors.) We are also wanting to install air condition. We were thinking so sort of high velocity or duct-less A/C system might be our best option. My biggest question is if it is possible to just replace the old radiators with either panel or baseboard heating, in the areas where we need the extra space, and not change the rest of the radiators. Is this possible or advisable?

Re: Converting cast iron radiators


Generally speaking, yes it is feasible to remove some of the rads & install some baseboard sections, however, I assume you're talking about radiators that a) don't have any leaks & have been used in the recent past for hot water heat, and NOT steam heat, and b) that the rads are in good shape, without any extensive rust or leaks.

In fact, it's advisable to keep as many of the rads as you can (providing, again they were previously used for hot water heat), and to place them strategically at various places around the rooms that are hard to heat in combination with either the standard box-fin aluminum baseboard fin elements that are bonded to the 3/4" copper tubing, or perhaps even some Baseray cast iron radiant baseboard sections; the box-fin aluminum fins are further sub-divided into standard heat output & high capacity output.

The reason given to keep the cast iron rads is that they provide a MUCH BETTER heat response, not only because they put out much more heat than baseboard elements, but also because they STAY HOT for a much longer period of time every time the t-stat calls for heat---this makes for a much more comfortable heated set of rooms throughout the house.

The minor disadvantage to older cast iron rads is that they are large & heavy, if they are old they may need a new paint job so they don't look out of place in your newly remodeled rooms---you will need an EXPERIENCED heating contractor who specializes in hydronic (hot water) heating upgrades, so that he/she will be able to arrange & mix & match the cast iron rads with the newer baseboard elements in the proper way for each of the rooms; the heating contractor has to be able to calculate how much heat output each cast iron rad will produce (as well as how much heat each room needs)---most of them are different sizes & each one of them produces different amounts of heat, calculated as BTUs/hour; the heating contractor must also do a HEAT LOSS CALCULATION to calculate how much heat the rooms, floors & entire house needs during the coldest periods of the year---be prepared to be able to tell the heating contractor if there is any insulation in all the exterior walls of the house & attic & if there are any drafty, old single pane windows they should be replaced with new vinyl double-pane windows---new insulation & double pane windows pay for themselves in a very short time in heat savings.

It is strongly recommended that you also talk to the heating contractor that will do the work about installing several ZONE VALVES with their own t-stat in the large living room & other needed parts of the house so that heat can be separately controlled in these areas; another alternative is to install thermostatic radiator valves (TRVs) on the rads or baseboard in main areas, such as the living room---check out the Caleffi site below for piping & rad components widely used in HW heating.

Your best bet at this point is to consult the Yellow Pages under "Heating Contractors" to find a contractor that specializes in hot water heating, look closely at the numerous display ads that are in this section of the Yellow Pages to see if it says that the particular heating contractor specializes in or does hot water heating---be sure to SPECIFICALLY ASK the contractor when you call them if they do hot water heating installations or rehabs (many of them don't).

For the air conditioning, I would recommend the mini-split ACs made by Hitachi, Sanyo, Mitsubishi, Friedrich, etc., or even a thru-the-wall high output AC if the house is not too big---thru the wall AC is much less costly than mini splits, but they produce much more air noise.


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