Posted by Harold Kestenholz - Hydronic Network on July 02, 2001 at 11:44:09:
In Reply to: Circulators or Zone Valves posted by mikey00 on June 27, 2001 at 13:24:30:
Main zone is 100 feet of cast iron baseboard. It is a mono-flow system (1 inch pipes loops around entire house with each section of baseboard tapping off of it).
*** This zone is good as is with a circulator.
Second zone is 24 feet of cast iron baseboard in basement (straight run).
*** This loop uses about 15,000 btuh due to the 24 feet of baseboard (about 1.5 gpm) it could be placed in parallel with the main loop using balancing valves or use a separate circulator (overkill.)
Third zone is for a blower for garage.
*** blowers are high-resistance small-tube devices that are best put on a separate circulator.
Fourth zone is for a proposed indirect water heater.
*** Indirect water heaters are usually high-resistance coils that are best served by a separate circulator, but occasionally the water is diverted from the main loop using a 3-way zone valve to give priority hot water.
Currently there are 3 circulators but they are old. First bid says you must use 4 circulators because it is a mono-flow system.
*** You do not HAVE TO use 4 circulators because it is a monoflow system, but it is not a bad idea for this work.
Second bid proposes zone valves and one circulator and says they are ok with mono-flow systems.
*** This bid may get you some problems due to undetermined resistance and flows for the whole system. If the contractor works out the resistances and flows of the loops before he starts, it can work fine. Zone valves are OK with monoflow systems.
Also says that there are no 1 inch zone valves but 3/4 inch should be fine on the line.
*** Taco and Braukman make 1-inch zone valves. 3/4-inch will work.
OPINION: I would go with a separate circulator for the monoflow circuit and perhaps the basement loop on a zone valve. Then use separate circulators for the garage blower and the hot water maker. The cost of the new circulators and relays is higher than one circulator and zone valves, but lower than repairing the old seals of the old circulators.
Who's right?
The customer.