splitting a zone to add indirect heater

Joe Plumb

I have a client who recently added a huge tub and multi -outlet shower.

Here is the situation. The home is on slab with the boiler approximately eighty feet away from the bathroom. The boiler piping for this area of the home is underground. Just outside the bathroom, in a small area beneath the floor, is the air handler for the master bedroom/ bath. My question is, would it be possible to split that zone to add an additional indirect heater dedicated to the master bath? I was thinking of adding zone valves to separate the two units and possibly, if necessary, increase the size of the pump at the boiler. If that were at all possible, I would than have the challenge of controlling the two units and prioritizing the hot water demand.

Currently in the space below the floor we have ample piping to connect to the existing  1  1/4" boiler supply and return to the new indirect heater. My concern is the size of the piping and the wiring and placement of zone valves and control.

This is one of two ways I can think of to increase the hot water supply. The other is to change out the current 40 gallon Amtrol unit and replace with a bigger Weil McLain Smart indirect.

Finally I would like to add the boiler is roughly 75% glycol due to the underground piping. Any feedback would be helpful.