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Adding on to a steam radiator system

We've got a 2-pipe steam radiator system in our 1920's home. It's worked ok for the current size of our home, but we're planning an addition and we're not sure that adding on the system would be wise. Currently, the rooms at the far end of the ststem take longer to heat and that's been a bit of a problem. We don't want to tax the system any further, asking it to heat additional rooms. Should we add a second heat system for the new rooms, and if so what kind? Or would this be a good time to upgrade the whole house to something more modern and reliable?

Re: Adding on to a steam radiator system


Could you provide more info as to your general location, how much gas or oil you burn each heating season, the sq.footage of the house, was the boiler originally installed when the house was built, is the heating output (btu/hr) listed on the boiler,do you have insulation in all the exterior walls and the attic, do you have a service person now that is knowledgeable on steam systems, have you consulted with contractors on how much a changeover (say, to hot water heat) would cost?????

I know, a lot of questions; but it's extremely hard to accurately answer your post without more info on these issues.

The basic idea of trying to determine if the boiler has the capacity to heat 2 additional rooms is to find out how many btu's/hour the boiler is putting out on a cold day, and determining how many btu's/hour are oozing out of the house on a cold day.

As D.W., suggested, heat loss calculations are used to make this determination.

Thus, if you calculate that the house has 100,000 btu/hr oozing out of it on a cold day, and the boiler puts out 70,000 btu/hr, then the boiler is too small to meet the heat demands of the house.

Or, using the HLC's you may find that the boiler can put out 70,000 btu/hr, and that the house heat loss is also about 70,000 btu/hr; this would mean that you would not have adequate capacity for the additional 2 rooms.

Free heat loss calculation sites are below; the bgm and propane sites are rudimentary; the Slant/Fin site is comprehensive, but takes an hour to load on most systems.

A very rudimentary HLC is done (assuming 8' ceilings) by taking the square footage of the entire house (including the boiler room & other heated rooms) and multiplying by 40 (or 50 if the house is less insulated, or the windows are loose).

Thus a 1400 sq.ft. house X 40 = 56,000 btu/hr to heat the house; 1400 sq.ft. X 50 = 70,000 btu/hr to heat the house.

Each room can be done separately:
a room 20' X 20' = 400 sq.ft. X 40 = 16,000 btu/hr to heat this room; or 400 sq.ft. X 50 = 20,000 btu/hr to heat this room.

The heat output of each radiator can be calculated by going to the radiator sites below and doing the calculation.

If you total up the heat output of ALL the rads in the house, this is another way of determining the btu/hr output of the heating system.

You can calculate the heat output of each radiator(s) in each room to calculate the btu/hr for each room in the house.

The problem you're having with 2 balky rads is probably due to a clogged or defective steam trap inside the rad.

You will have to locate an experienced steam heat contractor in your area who can easily fix this problem.

As to the MAIN question of whether the steam system should be upgraded, or a new hot water system installed, that can't be answered over the internet.

You will have to have several contractors come in to give you a dollar quote for what it will take to get you an economical, well-working heating system, and possibly think of combining AC in the same system while you're at it, if you don't have AC now.

To find experienced steam/hot water contractors contact the local heating supply houses (Yellow Pages) and ask the counter man to recommend several.

I suspect you're wasting a tremendous amount of fuel each winter if the boiler is over 20 year old.

Modern hot water heating boilers are no bigger than a large suitcase, and yet have engineering innovations that reduce fuel consumption by 30% to 50%.

In these days of crazy fuel costs, it may well be that you will LOSE a lot of heating money if you do nothing to upgrade to a more efficient system.

Thus you should also calculate the fuel savings realized by installing a new system.

Old steam systems typically operate at only 50% efficiency (the other half of the fuel goes up the chimney as wasted money), have to heat up ~50 gallons to run the system, and are of outdated design.

Newer hot water systems operate at 85% to 95% efficiency, have a much better combustion chamber design, and use much less water in the system (15 gallons).

The first step is to make sure you have R19 insulation in all exterior walls and R40 in the attic; this can be blown in from the outside in one day's time.

Hot water systems are inherently much more flexible and easy to work with, can be easily zoned off and require less attention than a steam system.

The referral by D.W. to Heating Help.com is a good one; there are many fine articles on steam and hot water systems at that site.

Also Google "Converting from steam to hot water",""Two-pipe steam system how it works","What is a two pipe steam system?", "Steam to heat house can provide comfort","Replacing 1920's two-pipe steam, original boiler".

Please post back.


Re: Adding on to a steam radiator system

Thanks Jack, or is it Mr. Shack? Anyway, I've got some homework to do! Thanks for the great information, I learned a lot, just from your post. I will post back. The furnace is a Dunkirk, btw and is probably around 10 years old, so not too old. The house is just over 1,000 SF, but likely has some heat loss as it's roughly 80 years old.

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