During our first fire in the fireplace boiler the hot water was not getting out of the stove. I took some thermal photos to try to capture where the heat was going. The photo appears to show that the hot water was in the primary loop but it never got hot enough to open the zone valve to allow the heated water to move to the storage tank. Even when I opened it manually, the warmer water did not flow through the pipes to the storage system. UPDATE: I later realized the return loop was “blocked” by the mixing valve allowing only some return water back to the stove.
The internal temperature of the water in the stove was very hot, almost 200 degrees, and the pump was working hard and getting hot itself.
The system was not working according to plan, so it was back to the drawing board to change the plumbing layout of the stove. I first thought that the connections should be closer to the primary secondary type of system–maybe I should have planned it this way to begin with! In the original plan, I was following diagrams that came with the stove, so it appears I had a bit of misdirection to overcome. The original plumbing diagram had the takeoff for the storage loop at the top of the stove and that is how I plumbed it.
The plumbing looked a bit crooked in this layout where a ball valve allowed shut off of water through the primary loop. I had tried closing this during the burn hoping to force water into the pipe that goes to the storage tank but it was not flowing through the stove properly.
The new layout has the “tee” lower on the primary loop. The connection to storage was moved from the top of the boiler to within a few inches of the supply return in a secondary arrangement. I added another Taco 006 pump in place of the zone valve to pump water into the secondary loop and that is now controlled by the Honeywell 6006 aquastat which is set to turn the pump on at 120 degrees and off 30 degrees lower.
The existing plumbing was disconnected with the orange release clips for Sharkbite fittings. Imagine if I had to disconnect soldered pipes to correct the system! Thank goodness for Sharkbite!
I am a frequent customer of Supply House but also check on ebay and Amazon to be sure I am getting the best price for the items I order. This new Taco 006 was $129 from ebay. The box is from my Sharkbite fitting order.
The secondary loop “tee” is at a 90 degree angle, with the return coming from below. I tried to make this tee as small as possible while still having room to disconnect the pipes if necessary. It is definitely less than the maximum twelve inches for the separation of the primary and secondary loops but it is not in the “closely spaced tee” arrangement.
I also removed the check valve at the stove high point because the tapping led me to believe that the hot water was having trouble getting out of the stove into the pipes against the resistance of the check valve. It does not seem in retrospect that a check valve was even required at this point.
The new plumbing was completed and I opened the supply valve to refill the tank, the stove, and the piping. After I stopped hearing an active trickling sound, I turned on the pump to see if there were leaks. I could not believe that I took the whole thing apart and put it back together and did not have one leak. Must have been my day.
The plumbing actually looks neater with the changes, which must mean it is closer to correct! I can’t wait to try a fire and see if the new system works as designed and the second pump gets warm water to the storage tank in the utility room.