ceiiinosssttuu
New Member
I have a wood boiler with (2) 300 gallon hot water storage tanks. I use the hot water in the tanks to heat my radiant floor when the boiler is not firing. The boiler system has a loading unit (pump that circulates water from the boiler into the tanks and controls the return water temperature into the boiler), and a circulator (supply) pump to supply the hydronic manifold, which has a mixing valve to control the temperature of the water going into the floor.
Here is the problem: (see photo below)
When the supply pump is off but the boiler is firing and the loading unit is circulating hot water to the tanks, I notice hot water "backing up" into the return line of my manifold, through the mixing valve. Foolishly, I did not put a check valve in here when I built this system. My question is: where should I put check valves, what kind, and how many, to prevent hot water from backing up into the manifold instead of all going into the tanks? Ideally, I would put some kind of spring check in the supply line just upstream of the mixing valve, but would this stop the hot water that the loading unit is circulating, since it is going in the same direction? What about a gravity check - I didn't think this would be an option because it would be upside-down in this case. Is there a mixing valve the opens when it is "pulled" instead of "pushed"? Do I need to re-plumb my mixing valve altogether some other way?
Here is the problem: (see photo below)
When the supply pump is off but the boiler is firing and the loading unit is circulating hot water to the tanks, I notice hot water "backing up" into the return line of my manifold, through the mixing valve. Foolishly, I did not put a check valve in here when I built this system. My question is: where should I put check valves, what kind, and how many, to prevent hot water from backing up into the manifold instead of all going into the tanks? Ideally, I would put some kind of spring check in the supply line just upstream of the mixing valve, but would this stop the hot water that the loading unit is circulating, since it is going in the same direction? What about a gravity check - I didn't think this would be an option because it would be upside-down in this case. Is there a mixing valve the opens when it is "pulled" instead of "pushed"? Do I need to re-plumb my mixing valve altogether some other way?