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adding forced hot water to steam system

We're adding a room to our home and we are considering options for heating it. We've eliminated tacking on to the existing one pipe steam system, because this room would be at the "end of the line" and we've found that the steam takes longer to reach the extremities of the rooms. Are forced hot water baseboards a viable option? Can this be easily tied into the steam system? We're also considering electric baseboard.

Re: adding forced hot water to steam system

How big is the home and the new room...

Re: adding forced hot water to steam system


Rachel asks a good question---you would have to determine if the present steam boiler has sufficient extra heating capacity to heat another room.

To calculate this, you can see if there is a "btu/hour" rating stamped on the boiler (should say something like "input 100,000 btu/hour" or "output 80,000 btu/hr")---if the output is in EDR, one of the sites shows how to calculate btu/hr from EDR.

You can then compute the amount of heat loss the house experiences on a cold day---a very rough approximation is obtained by multiplying the total square footage times a heat factor between 30 btu/hr and 60 btu/hr---the free heat loss calculations below are more accurate.

Thus if the house is 2000 sq.ft. X 40 btu/hr heat loss = 80,000 btu/hr to heat the house.

If the boiler's output is 100,000 btu/hr and the addition is 15 X 10 = 150 sq.ft. X 40 = 6000 btu/hr to heat the addition, the boiler would in this case be big enough.

If the boiler is in good shape & has small access ports for the new piping, yes, it can be used to install a hot water baseboard zone.

Your first step should be to consult your present boiler service tech---if you feel they are experienced & competent to do the job---if not, you can contact the heating supply dealers in your area to get a reference of techs experienced in steam heating.

Consult the Yellow Pages under "Heating Equipment-Supplies, Parts"---ask to talk to the parts counterman for a referral.

Below are several articles on this procedure.

A Taco 007 bronze pump can be substituted for the B&G Series 100 bronze pump, as it is 1/2 the price & just as good.

Also Google "Hot water zone on steam boiler" (without the quotation marks) for more sites.

Electric baseboard is also an option, although usually an expensive one---after you do a heat loss calc on the room addition, determine from the local electric baseboard supplier what the monthly cost would be to heat with electric before you make a commitment.


Re: adding forced hot water to steam system

Yes, that was me....boy how the memory goes. I do appreciate all of the suggestions and links. I didn't do the heat loss calculation, but our plumber looked at the furnace and feels it's more than adequate to add on to. I guess my general question is, cost-wise, since this is a new room (12x12) and will be properly insulated, would electric baseboard be all that expensive to use here? It's just one room, not the whole house. I realize that connecticut has some of the higher electric costs in the country.

Re: adding forced hot water to steam system

It's a one pipe system. And pardon the vernacular, it's indeed a boiler. I did not post the rating of the boiler (don't have it in front of me), but am confident that the plumber was speaking the truth when he told me there was plenty of capacity for an additional room. Also, since my original post, we've solved a fair amount of our slow steam problem simply by replacing the thermostat. But since we won't be doing anything further to "tune up" the steam system at this point, and cost is a consideration, we'll likely go with an alternate method of heating the new room. Hence the question about electric baseboard.

Re: adding forced hot water to steam system


The closest estimate I can come up with for an electric baseboard installation would be based on the 12' X 12' room @ 144 sq.ft. @ 40 btu/sq.ft. = 5760 btu/hr to heat the room in your area.

This would equate to 7' or 8' of elec. baseboard @ 1750 watts for ~$100 for the unit, plus perhaps $300 installation, wiring, parts.

Estimated operational costs would be (assuming .14/kwh for elec. costs & 12 hrs/day usage)= 1750 watts X 12 = 21000/1000=21kwh/day X 30 days (monthly) = 630 kwh/mo. x .14/kwh = $88-$100/monthly elec. operating costs.

If your elec. cost is slightly lower & you ran the baseboard only 8 hrs/day during heating season, it may cost ~$42/mo during heating season.

If the room has 2 exterior walls and lots of windows/limited insulation, the elec. cost would be higher.

You would have to compare these numbers with whatever the plumber quotes as the proposed installation cost of the hot water zone from the steam boiler.

You'll probably be paying $500-$600/year for elec. heat (plus installation)---this adds up quickly---it makes the hot water zone seem more attractive---you should be able to pay off the cost of the HW installation ($1500?) in 2-3 years (by avoiding the elec. bills)---and you won't have that elec. bill hanging over your head every month.

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