Question on this schematic - why the zone valve?

[stee6043]

Can you guys tell me what the purpose of the zone valve is in this piping diagram? I assume it is only there to prevent flow through the heat zone when the boiler is running and heat is not needed in the zone, correct? If this is the case couldn't the same thing be accomplished with a flow check valve (for a lot less money)?

One other question: if the boiler is not running, storage is hot, and you have a call for heat from the heat zone what prevents flow through the boiler when the heat zone circ us running? If that were the shorter, less retrictive route would you not get most of your flow from the boiler (cold) and not storage? So do you need two zone valves/flow check valves?

Any comments would be most helpful...pumps and valves are the last thing on my list to purchase!!

 

[taxidermist]

I also have that drawing from Dave and it does not make sense to me. Call Dave he has explained what he was thinking when he drew a few of these for me. I am taking what I think will work best from all his drawings and doing my own plan.


As far as the boiler not running....I too am stuck on this one? I am going to have a supply line in the top of the tank and also a discharge to the pump then to DHW and forced air. I am wondering if the danfoss will cool and hold the return water at the boiler and then the return water to the tanks goes in the bottom of the tank.


Confused...
Rob

 

[stee6043]

I had the same thought on the Danfoss valve. The question is whether or not it will be able to prevent flow from the return line when it cools and closes. If it were that simple we wouldn't need flow checks or zone valves on systems with only storage and one heat zone...

 

[stee6043]

Anyone have any ideas??

 

[Nofossil]

I have a hard time reading the schematic. Is the green thing above the zone valve a circulator?

My suspicion is that the weighted check valves provide enough flow resistance so that flow will only go through the zone(s) (forced air furnace?) if the zone vales is open. When the zone valve closes, flow will have no choice but to go through storage.

If the green thing is a circulator, it would be needed in order to withdraw heat from storage. You're right that it would have some tendency to push water through the wood boiler, but if the boiler circ has a check valve that would help reduce that risk.

I think (only one cup of coffee here, so beware) that you could move the circ to just below the tee that goes to the wood boiler. In that case, storage charging flow would go backwards through that circ, but that's OK as long as it doesn't have an IFC.

 

[stee6043]

You're a good man, nofossil. Thanks. I think I may go the "better safe than sorry" route and use at least one zone valve in my system. Another $100 is nothing at this point. Sadly.....