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Dan in Medford
Converting cast iron radiators from steam to hot water or electric radiators?

Hi, I just bought an old house in Medford MA. The house was build in the late 20's and has a steam heating system with Sunrad radiators. While the system heats the house nicely, it can be loud when heating up. I dont want to wake the baby and I don't know the condition of the steam pipes and boiler.

Planning ahead, i am thinking of what to do when the system needs repair/replacement. I am considering a few options:

1) Continue to correct pipe pitches and add pipe insulation to reduce noise.
2) Convert to a hot water system - This would also prevent the baby from potentially burning herself on the hot steam radiators.
3) I hear there is a company in Canada, called ECORAD, that will refurbish old radiators, fill them with water and antifreeze and add electrical heating elements. This sounds interesting in that it would allow a separate thermostat for each room.

Notice that i each case, i am assuming that the old sunrads are still in good shape and wont leak.

Re: Converting cast iron radiators from steam to hot water or electric radiators?


This is always a hard one to call.

Complaints of loud banging noise from a steam system are usually caused by the cooled steam condensate returning back to hot water (normal) after the steam gives up its heat to the room & not flowing back to the boiler (not normal); the subsequent steam produced by the boiler slams into the water standing in the pipes & makes a loud bang---it can usually be fixed by making sure the steam valves on the rads and main vents are open & not clogged with crud; when the boiler comes on & produces steam, it quickly rushes thru the pipes/rads & pushes the existing air out thru the little vent at the end of the rad; when the heat of the steam hits the little vent at the end of the rad, there is a little bellows in there that closes to allow the steam to fill the rad & the rad to heat the room.

Sometimes the supply/return rad piping is pitched the wrong way, which also produces standing water condensate in the piping, instead of it flowing back to the boiler; a dirty system that hasn't been serviced recently can also produce these symptoms---why not call a local heating tech to see if the system needs routine service???

Sunrad are excellent cast iron rads that I think you should make every attempt to use in an updated hot water heating system, if possible; my preference has always been for HW heating systems, although there is still a small, but devoted number of adherents to radiator steam heat in the larger northeastern cities, especially NYC & Boston.

That said, it can cost lots of $$$ to maintain your present steam system, or even try to convert from steam to HW; rads designed for steam operate on approx 1 psi pressure & minor pinhole leaks in the rads don't matter too much; forced HW, on the other hand operates at from 20 psi to 30 psi, & thus can cause big problems with cast iron rads originally designed for steam.

Not only that, but converting to HW would entail buying a new HW boiler, updating the nearby boiler piping to supply/return manifolds & zone valves & probably draining the existing steam pipe distribution network & snaking 3/4" plastic pex piping thru the floor boards & walls, leaving the existing unused piping in place, & connecting up with (hopefully) the Sunrads, or copper fin baseboard, or Burnham Baseray cast iron baseboard (designed for HW); trying to use the existing large diameter distribution piping which was designed for steam would invite leaks & would quadruple the amount of water that would have to be used by the system making it inefficient & would burn a lot of fuel unnecessarily.

I feel an updated HW system would be a great advantage in a number of ways----you would burn much less fuel; the steam system noise & regular maintenance of blowing down the steam boiler, etc. would be gone, which is a big headache you'll get rid of; the new HW system would be ZONED with zone valves or thermostatic radiator valves, so that you could control the heat in ALL PARTS OF THE HOUSE (you would have T-stats in numerous sections of the house to easily control the heat in all parts of the house for better comfort), which affords a considerable increase in comfort & fuel savings; forced HW systems operate silently with little or no maintenance.

My recommendation would be that you DO NOT send out the rads for any service work (very expensive) & since you live in the Boston area, you have considerable access to heating service technicians who specialize in updating & converting steam heating systems to forced hot water---consult the Yellow Pages under HEATING CONTRACTORS & check the display ads in that section to make sure you call those techs who are EXPERIENCED IN HOT WATER/STEAM systems; you have the unique advantage of having a very wide selection or heating techs (forced HW/Steam is very popular in Boston) who will come over the house & give you a free estimate of what the job will cost---take your time & get at least 5 to 10 estimates on this job; the different techs will suggest several ways of doing this job, &, of course the cost estimates will vary considerably.

Make sure you get a WRITTEN CASH $$$ ESTIMATE (called a QUOTE) for how much the job will cost before the heating tech leaves the building.

By the time you've talked & consulted with 5 to 10 heating techs on this proposed project, you will have learned a lot more about what has to be done & how steam & forced HW heating systems work, & will be in a much better position to make an informed decision as to which way to go; after seeing a number of heating techs & listening to their renovation plan, you will find that eventually several of the proposals will "dovetail" into a certain direction that will probably be the best way to go.

Dan in Medford
Re: Converting cast iron radiators from steam to hot water or electric radiators?

Thanks for your very detailed response, great info. I also feel that i should mention that my wife went into labor while watching This Old House. :)

- Dan

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