Steam to hot water

doug_10

I got involved in a residential remodeling project that included coverting a portion of the home from steam heat to forced hot water and using only the steam boiler. The new heat includes three zones of baseboard radiation and one zone of radiant, all controlled with individual circulators. Total heat loss was calculated at 31,337 btuh. The steam heat sytem use to heat 18,000 btuh of this total, so 13,337 btuh is newly heated area. The original steam boiler is oversized and can handle the additional load fine. The remaining steam system has worked fine throughout this heating season.
I chose to connect the new hot water heat sytem to the steam boiler using an indirect fired water heater. I have done this type of installation before on a smaller scale by using a side arm type water heater off from a steam boiler with no problem.
I used a Super Stor 30 gallon indirect. This has essecially become my hot water boiler. The energy is created in the steam boiler. I piped from a point on the steam boiler just below the normal water line through the indirect and back to the bottom of the steam boiler. I originally circulated the steam boiler water through the indirect using a Taco 007 circulator. I have since replaced the 007 with a 0010. Pipe size is 1 inch. Please note that I also have a 60 gallon indirect connected in the same manner for domestic hot water and that is working fine. I increased the circulator from 007 to the 0010 because the three baseboard radiation zones do not heat well. The radiant zone with it's reduced water temperature heats fine. When all zones are calling the indirect is not able to maintain the 180 degrees that the baseboard zones were designed for. The temperature of the water leaving the indirect is only 150 degrees. I am now cosidering replacing the 30 gallon indirect with a 40 gallon commercial indirect. I will be increasing the square foot of heating surface from 15 to 40 inside the heater by doing this.
I would appreciate any comments and or ideas that may help me correct this poorly heating situation.

Ken_8

You don't happen to have a

tankless coil on that steam boiler do you?

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Roger Litman

Steam to hot water

With the use of three zones for heating and the possibility that your steam boiler is old, I would recommend that you consider changing the entire boiler from steam to hot water. That way you can usually get rid of piping in the basement that is in the way- get a system that does not have an added step in it that is less efficient and address any domestic water problem with max efficiency.I recommend that you use 300 Btu per foot for the baseboard radiation as this will allow you to get more even heat and run the boiler at a lower temperature, with much of the cost of the baseboard being labor, this is not signifacntly more expensive than using dummy and gives you a lot of flexibility

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doug_10

tank-less coil

No the tank-less coil had been removed. I welded a steel 1-1/4" coupling to the blank tank-less coil plate with a hole drilled through. This allowed me to connect 1-1/4" piping to the steam boiler just below the normal water level and pipe to the two heaters. (1 for domestic hot water and 1 for area heating)