Unnecessary Zone Valves

c.t.kay

call heat-timer in nj. the telephone # 973 575 4004.ask for engineering/sales,they should be able to guide you in the correct direction with the equptment.

Michael Labriola

Role of zone valves when heat timer is used.

There is one steam boiler that services two 8-unit buildings. The two buildings are the same size. Each building has one zone valve. It's a one pipe system with steam traps at the end of each run that connect into a condensate tank. There is a pump that pumps the condensate back into the boiler when the boiler water is low.

In the past there has been one thermostat located in one unit in each building that would operate the zone valve for the entire building. When the zone valve opens up, the burner is started.

Having a single thermostat for each building has been problematic. If the person with the thermostat in their unit leaves a window open, the whole building is over-heated. We are about to switch to a steam timer device. This device will read the outdoor temperature and run the boiler for a fixed amount of time each hour based on the outdoor temperature. We don't plan to use any indoor temperature sensors. (This is NOT a Heat-Timer brand device, but it performs a similar function.)

Here is the question: Which would be a better choice:

(A) Wire up the new steam timer device to open and close both zone valves when there is a call for heat. Concern: when the zone valves close, the pressure in the pipes will immediately drop, even though the boiler is still generating steam for a brief time. From reading other posts, this doesn't sound like the best choice.

(B) Wire up the zone valves to always be open and have the timer device start the burner when there is a call for heat. Is it a bad thing to leave those valves open all the time? We also use the boiler for hot water, so the boiler may be running when there is no call for heat.

(C) Wire up a delay so that upon a call for heat, both zone valves open and the burner starts. When the call for heat stops, the burner stop immediately and the zone valves close after a delay (perhaps 2 to 3 minutes?). This sounds like the best choice to me. Does anyone see a problem with this?

Thanks for your help!