Hello, I'm new to the forum! Please see next post:-)

Hello, I'm new to the forum! I came across this site while researching options for my Radiant Floor Heat system, since the manifold or actuator sprung a slow leak forcing me to do some homework on replacing these 2 items.
First, let me tell you about my system. I bought it as a DIY kit in 1999 and it's been running and working great since 2000. It's, brace yourself, an OPEN SYSTEM . I know, I know... from what I've read over the last few weeks (here and elsewhere) is that most pros highly look down on this type of system. So be it, I didn't know then, it has actually worked well for us, none of us has contracted legionnaires disease, it was what I could afford, and I'm still alive today as I write this. Regardless, it's what I have and winter will be here before I know it.

The system consists of:
>94,000 btu Polaris Combo heater
>6 zone Rehau manifold with Rehau 24V 3W actuators (p/n 260166) >Rehau Raupex ½" PEXa tubing (***I've only had (4) 500' runs in use since installation - a 2 story addition, each ~550sf with one 500' length each between the floor joists, and an existing 600sf circa 1950 house that I ran 2 lengths of 500' between the joists (combined for 1 zone))
>White-Rodgers thermostats for each zone
>Nix Technologies Inc. Zone Master 2000 Millennium edition controller
>Laing Model SM-1212-ST-26 Circulating Pump (1/15 HP, 3400RPM, 140W, 1.2A, 8.5uF. 230°F max temp, 150 psi(10 bar) mas pressure)

The system as it is set up seems pretty simple: the Polaris heats the water (I have it set at 140°), an outlet at the top of the tank goes to a mixing valve which also has the cold water supply connected (tee'd off from the line that supplies the bottom of the unit) to mix the house hot water. On the side of the Polaris unit, there is an "Out to heating system" pipe that the Laing pump is attached to, which feeds the supply side of the Rehau 6 zone manifold(via ¾" PEX). Each zone has an actuator that will open the valve when the thermostat tells it to (and I believe will also turn the pump on). The water loops through the 500' of tube and goes back into the Return side of the manifold. The Return side of the manifold is attached (via ¾" PEX) to the Polaris tanks "Heating System Return".

And that's that. Sooooo, I ordered a new Rehau Pro-Balance 6 zone manifold & some actuators to replace my old ones to get this thing up & running for the winter. BUT, I still am worried (even though I've ran fine for 12 years) about the possibility of getting my family sick. Seeing that I have tubing run, and a heat source, and a manifold, how complicated will it be to convert what I have to an indirect system? What's the best heat exchanger? How many degress less will that heat my radiant water for the heat? Do people build custom kits for this type of thing?

Thanks for reading my book. Thoughts are appreciated!
Thanks,
Greg

why are you replacing the manifold?

cutting in a heat exchanger, pump, and controller isn't the biggest deal in the world. the heat exchanger should be sized for your heat load. we would usually add a variable speed injection controller to the new pump to add "reset" to the radiant water temp and improve comfort.

It had a leak, i think coming from the pin that the actuator moves. Since the manifold is vertical, it dripped down onto the other 3 actuators and now they are pretty much corroded onto the manifold. Anyways, the new manifold arrived and I need to change it out. I thought of trying to keep as much of the water in the PEX as I could, but it's looking like I'll need to drain them to change this thing out.

To answer one of your questions about temp differences, I have about a 20 degree difference in water temp from the water entering the heat exchanger on the water tank side, to the temp of the water entering the radiant side. My tank (a Vertex 100 in my case) is set at 125 degrees F, but does not reheat the water until the water temp drops to 105. The water temp coming from the heat exchanger to the radiant side, is usually 100 degrees depending where in the water heating cycle the Vertex is.

-Rosalinda

I looked at a picture of a Polaris on Amazon, and am not exactly sure how many hot water out and returns it has. If it has 4, as appears in the pic I looked at (2 out 2 returns), you would use 2 of them and have, hot water out to the pump (brass) to the heat exchanger, from the heat exchanger, to the tank return. Put shut offs either side of the pump, so you can isolate it from the rest of the system for servicing, so you do not have to drain the heat exchanger or water tank to remove the pump. On the radiant side you have, hot water out from the heat exchanger, a fill fitting to top up the system and do the initial fill and purge, a pressure relief valve, an air eliminator and pressure tank, the pump (can be cast iron since this side will be closed) with shuts offs either side of the pump, and then the manifold. I don't know what all your present manifold has, but you want a drain at the lowest point of the manifold, temp gauges and a pressure gauge. The control turns on both pumps when heat is called for.

I don't know if it would help, but if you email me I can send you a picture of my system.

-Rosalinda

Thank You Rosalinda, 20° is pretty significant! I just finished installing my new Rehau Pro-Balance manifold this weekend and the temp coming from the side of the tank (there is 1 output for radiant heat system on the Polaris) and into my manifold is 138° - 140° entering the manifold, and by the time it loops back to the Return side of the manifold it is then 120°. So it appears I'd already be starting off at a disadvantage because I pretty much need the water to be at 140° to make this system work. I dont' think I want to run at 160 and max this thing out day in and day out. Hmmm, the things to ponder.
Thanks,
Greg

The easiest way to solve this would be to add a hot water heater for domestic hot water, and just use the Polaris for the heating system.

-Rosalinda