Solar heat to boiler conversion.

charles, sounds like you got the right idea. You can pipe the solar tank as you describe, cold water in, then hot water out to the cold water supply on the Amtrol, then hot water from the amtrol out to the house. Basically the solar is preheating the water coming into the amtrol keeping the thermostat satisfied and the boiler off. You can also add valves so you can use the solar tank only. Best to keep the solar tank separate from the boiler, otherwise the boiler may heat the water confusing the solar controller and keeping it off.

I would recomend that you pipe the system so that you can run either directly off the solar hot water tank or as a makeup to the Amtrol. I have the same setup and find that somewhere around this time of year in northern NH, that I no longer need the Amtrol as the water in the solar hot water tank is hot enough. Once you get to this point, the boiler will use natural gas to keep the Amtrol tank hot when it really isnt needed. If you turn off the zone to the Amtrol tank to save gas, you are essentially taking hot water from the solar and running it through a cold tank and it will take longer to get hot water to the tap. There is a way around this by installing a circulating pump to recirculate water from the solartank, through the Amtrol and back into the solar tank but thats getting complex even though it increases the amount of hot water storage.

A few precations are neccesary if you adopt this approach, The first one is that you need to have a tempering valve with a high limit between both of the tanks and the house. This keeps someone from getting scalded as the solar hot water can exceed 140F. There should be one off the Amtrol tank, but some plumbers skip it and trust the temp controller. The second precaution is to drain the Amtrol tank during the summer when you are running direct from the solar system. Its okay to leave the Amtrol on line for a few weeks with no flow, but having a stagnant tank full of luekwarm water for an entire summer has some potential for legionella and other bacteria especially if you are on well water and dont chlorinate.

I also have additional valves and piping so that I can isolate the solar tank, while keeping the hot water system on line, but thats getting into the overkill! (but it is handy when you are working the bugs out of the system).

     

Charles, just seeing how you made out. If your plan is to have the amtrol as a back up, you need to leave your boiler on, which is not what you want, I believe?. Hopefully you piped the system with the solar tank feeding the amtrol and installed a bypass to be able to operate the solar tank only. It is only then that you can turn off the power to the boiler and isolate the amtrol.
 There is one other way you can minimize using the boiler while still having it available for backup. Keeping the tanks in series, you add an aquastat control or high limit control to the pipe exiting the amtrol. Wire this control to the power of the boiler. Then when the temperature get below a certain set point, say 100 or so, it turns on the power to the boiler and it makes hot water as designed.
 So hopefully throughout most of the year, until you need heat, the solar tank will be hot enough to keep both tanks at a warm enough temperature and the boiler off.

Tom, I am still trying to figure out the best way to plumb/ integrate this system into my existing system.  Since, my Heliodyne system comes with two heat exchangers, my thought was to use the Sonnenkraft Solar Hot Water Module for my domestic hot water.  It has a single circulating pump incorporated into the module, which I assume is used for circulating water and not for circulating the glycol in the solar loop?  At any rate, my thought was to plumb the cold supply to this module and run the hot out from the  solar storage tank to the amtrol.  Next, for the radiant floor heat, my plan was to bypass the amtrol altogether.  My thought was since the H-pak has two circulating pumps (one for the solar loop and one for the radiant heat system??) that I would plumb the hot output from the H-Pak into the line from the boiler that supplies the floor zones.  I would then plumb the return from the floor zones into the cold input on the H-pak.  I would accomplish this using a couple of T connectors and install valves so that either the boiler or H-pak could be used to heat the floor space depending on my needs.  I am wondering however, if the circulating pump on the H-pak will be able to provide the function of circulating hot water to and from the radiant floor system?  I am also wondering if this is the best way to accomplish this, or if I would be better off just using the circulating pump on the H-pak to circulate hot water from the solar storage tank to the Amtrol and back?  The later seems like this would be duplicating the funtion of the Solar Hot Water Module mentioned earlier?  Also, I can't figure out how else to accomplish a DHW temp of 120 and a radiant floor temp. of greater than 120 while using the Amtrol for both?  Does any of this make sense?

charles, a little confusing. First, you say the heliodyne  has two heat exchangers. Are you talking about a tank that has two coils inside it? Or is there external piping with two pumps plumbed in acting as a heat exchanger? If it is external, then one loop/pump should be hooked up the panels and the other to draw domestic water from the solar tank.
 Also the "Module", are you talking about the hot water panel that goes outside in the sun? And it sounds like it has it's own integrated pump?
 Do you live in a zone with freezing temperatures? If so then there has to be some glycol in the system somewhere. Usually in the loop heading out the the panels. Then this loop should be connected to part of the heat exchanger.
 If you plan on using radiant heating, it is best to tie this into the same loop that goes out to the panels instead of trying to rob domestic hot water straight from the tank. Then you can isolate/control the radiant heat zone and the hot water zone using valves. Basically it comes down to take the heat you can get rather than trying to maintain a certain temperature limit.
 Doesn't make sense to circulate water between the tanks.