Thanks for pointing me to Gary's flow diagram.
I already have the hydronic radiant heating system in place with a circulating pump and valves controlling flow to different (6) zones in the house. Thus I thought that for space heating I would just need to put a heat exchanger coil in series with existing pump.
If I understand you well, for water heating I could simply do as if the water heating loop would be an additional zone in the house thermostatted with a different set point. That seems interesting: saving on additional pump and having just one heat exchanger coil. The problems I see are the following:
What do you think?
Martin Eau, soleil , le ventEau, soleil, le vent[ Parent ]
I don't quite understand. Do you mean I could have heating zones running at a lower pressure than water heating loop without mixing the two? Do you mean by putting a heat exchanger coil in the domestic hot water tank? This what I would have liked to avoid and that your tanks I thought could allow to avoid.
Thanks or your help.
MartinEau, soleil, le vent[ Parent ]
Doesn't have to be a coil: Vertical pipe-in-pipe works. You can build that with copper pipe, Ts, and reducers - then wrap it with insulation. Hook one section to the tank at top and at/near the bottom (i.e. T off the sediment drain tap for the bottom if your tank doesn't have a tap low on the side). Pump the hydronic water in the top and out the bottom of the other part of the exchanger, to create an efficient counter-current setup. (Convection will drive the tank water in the bottom and out the top.) The tank circuit will be a convection loop rather than pumped, so use the part of the exchanger with the least resistance to water flow. (You'll probably want to make that the inside pipe so you don't lose part of the heat you've transferred into the tank part of the circuit by conduction to the air from the outside of the outer pipe. Make it big to minimize friction.)
Alternatively you could pull the insulation off your water tank temporarily and solder a coil of copper tubing to and around it before restoring the insulation. Again pump the hydronic water in the top and out the bottom to create an efficient counter-current heat exchanger (since the hot water will rise to the top of the tank).[ Parent ]
Meanwhile any flaws in the fittings will cause a leak of the outer circuit water to the surrounding area, rather than between the two circuits.[ Parent ]
OK. Then solder a coil of copper tubing to a hunk of copper pipe, wrap it in insulation, and you're all set. Hydronic water through the coil top-down, convection loop between bottom and top of water heater through the inner (fat) straight pipe.[ Parent ]
