radiant floor supplied from return line???

spacoli

Hi. I have a mod/con boiler circulating to existing cast iron rads and some standard baseboard heat. My supply temps average around 100- 130 down to around 25 degree outside temp. My return is usually around 7-10 degree lower. Still some tweaking to do yet with the delta. This is an on going project (house renovation)





I have two radiant floor loops that are not hooked into the system yet. Someone suggested coming off the existing return to supply the lower temp radiant floor. Nothing is zoned, so everything will be on at the same time. I will still have a mixing valve for the radiant that I plan to mix off the same return after the radiant return hit the main return.



It this possible? Will there be conflicts with two circulators? The radiant circulator  "boosting" the main existing circulator?



I don't know.....just asking?

Rich_49

How

is this system piped ? 

spacoli

Pictures

Not sure what info you want? Here is a picture of the near boiler piping.

knotgrumpy

I think

You are going to have to back up and get a few pictures that place your close-ups in context.

knotgrumpy

spacoli

More pictures

Sorry here are more

spacoli

Laying out piping on paper

After laying out the piping on paper, it seams to me if (in a standard installation) your pulling off the return from the mixing valve if needed to drop the supply temp. The mixing valve will be letting mostly it not all of cooler water in anyway. It shouldn't hurt to supply straight off the main return to the hot side of the mixing valve and then mix again with the radiant return to the cold side of the mixing valve. The only problem I would see is on mild days in spring and fall when the boiler is modulating temps really low. I think it would all work out in the end. I'm no pro, just a thought. Thoughts or opinions?