- This topic has 5 replies, 4 voices, and was last updated 23 years, 4 months ago by
Harold Kestenholz.
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Anonymous
House is two story with daylight basement. Also have indirect hot water heater. Zoned now for two-heat, one hot water. I want to add third heat zone in basement. Will require going up to ceiling and back down to radiators. Should I add another circulator? Any other suggestions helpful?
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There is rarely a problem with a pump being able to serve a zone when the other zone valves are closed. The problem appears when all the zones are open at once. The pump has to be able to pump all the water needed to provide heat in all the loops when they are all open. This is determined by knowing the amount of heat required by each zone then adding them up. The total heat required in btuh, divided by 10,000 is the required gpm the pump must deliver at the highest resistance the pump must encounter. This gpm capability is found in the pumping charts published by pump manufacturers.
There are helpful design computer programs online to give you the maximum gpm flow of pumps through 3/4 and 1/2-inch tubing. There are also helpful design procedures that lead you through the steps to properly design multi-zone systems using zone valves and circulators at: http://www.hydronic.net
Sorry there is no simple answer to the question, the answer depends upon the heat requirements of each zone and the pumps you have available or plan to use. This is the work that an experienced heating plumber learns to estimate and install hot water heat properly.
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As an aside, many folks like quick-and-dirty answers. The domestic hot water loop is better served by an individual circulator. The other zone could then be transferred to the zone valve that served the water heater.
Another quick fix is to just serve the new loop by a new circulator. Both of these suggestions would probably settle the matter without a brain drain learning the technical information.
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This is determined by knowing the amount of heat required by each zone then adding them up. The total heat required in btuh, divided by 10,000 is the required gpm the pump must deliver at the highest resistance the pump must encounter. This gpm capability is found in the pumping charts published by pump manufacturers.
There are helpful design computer programs online to give you the maximum gpm flow of pumps through 3/4 and 1/2-inch tubing.Harold Sizing this system ONLY by the BTU requirements and NOT taking into consideration
1- Temperature of the water
2- Velocity (FPS @ 220)
Too much of either will cause all kinds of great stuff like fast erosion and noise and guaranteed system failure.
Being more conservative I like to under size the actual demand in GPM so if an apprentice or stumble bum ditch digger or Home center escapee should decide to raise the water temperature with an indoor out door set up the higher temperature wont have adverse effects on the piping
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quote:
Originally posted by Harold Kestenholz:
As an aside, many folks like quick-and-dirty answers. The domestic hot water loop is better served by an individual circulator. The other zone could then be transferred to the zone valve that served the water heater.Harold,
Thanks for the quick and dirty solution. Do you see any problems adding a circulator in front of the primary circulator for all the zones? Otherwise have a major rework to do.Another quick fix is to just serve the new loop by a new circulator. Both of these suggestions would probably settle the matter without a brain drain learning the technical information.
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If ‘in front of the main circulator’ means to take a tee off the same manifold pipe between the boiler and the existing pump, then you will be OK. Running the new pump as a separate loop from the boiler supply to the boiler return is the usual way to make a separate zone.
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