New Indirect heater Install Confusion

[Roger2561]

Hello, I'm in the process of installing a new 40 gallon indirect water heater to replace the "on-demand" one in the oil furnace. The following is my set up:

I have an outdoor wood fired boiler providing all the hot water to the 3 zone baseboard system in my house. Heated water from outdoor boiler enters house, goes through the oil furnace (in the event I lose the fire in the outdoor boiler the oil furnace takes over seamlessly), travels through an expansion tank and then to manifold where it breaks down into 3 zones (a 4th zone was installed but capped off, not being used), water returns through another manifold where it goes through a circulator pump and then out to the outdoor furnace to be reheated and waiting to be used when needed. Presently the oil furnace is providing me with all the potable hot water. Because I use the outdoor boiler as my primary source to heat the house, I want to take advantage of the "free" heat the wood boiler is providing me, tis the reason for the indirect water heater. First question; Can I simply tie into the 4th unused zone at the tailend of the manifold to get the hot water to heater? Second question; Can I connect the zone valve to the aquastat on the water heater to allow hotwater to flow through the heat exchanger to heat my potable hotwater? Third question; Will I need a circulator pump? Fourth question; If yes, where do I install in it? Thanks for taking the time to read post and for the any answers you can provide me. Roger

 

[johnjh2o]

Roger it can be done but it's a little more complicated then your making it sound. It has to be on it's own zone using another zone valve. That zone valve would be controlled by an aquastat on the indirect tank. It also has to be wired so the indirect tank is the priority zone. In other words the heating zones won't run until the indirect aquastat is satisfied.

John

 

[Roger2561]

Roger it can be done but it's a little more complicated then your making it sound. It has to be on it's own zone using another zone valve. That zone valve would be controlled by an aquastat on the indirect tank. It also has to be wired so the indirect tank is the priority zone. In other words the heating zones won't run until the indirect aquastat is satisfied.

John

John, Thanks for getting back to me. I appreciate it. The zone valve and aquastat I understand. I have them. The part where you said it needs to be the "priority zone" confuses me. How do I set it up for it to be my priority zone? Can I achieve that by having the aquastat temp on the indirect tank set lower than the water supplying the heat zones? I realize it may take a bit longer for the water in the tank to come up to the desired level but I live alone and I use only for taking showers or running the dishwasher which is once a week - the dishwasher once a week, not me taking showers once a week. Roger

 

[johnjh2o]

That depends on the make and type zone valves you have. It has more to do with electrical then plumbing. What your looking to do is if the indirect aquastat is calling to make hot water you don't want the heat to come on and lower the temperature in the boiler.

John

 

[Roger2561]

John, when the heating system was installed years ago, the HVAC guy left an extra zone valve behind in the event we suspected one went bad, he showed us how to change it as a quick and easy way of troubleshooting. It's a Taco 571-2 zone valve and was going to use that. Roger