Injection Mixing for In-Floor with Baseboards

altaflyer

I'm replacing a 30year old boiler with a LAARS FTF. The system utilizes baseboard and in-floor concrete radiant. The copper riser from the horizonal supply and companion G-1558 are designed to inject return water Lleft riser) with hot boiler output (Right). My question-

"Without a check valve on the L-Riser, won't the main supply receive cool return all the time and dilute the boiler output to the main supply?

Jamie Hall

Nice press connection work. Pity that it makes absolutely no sense at all. And a check valve isn't going to help.

The principle is sound — and used all the time for radiant floors or the like taking their hot water supply from a primacy manifold. But. To make it work, there is a line from the return from the floor (there is also a line connecting to the primary manifold) to the cold inlet of a thermostatic mixing valve (it's nice if that can be controlled by an outdoor reset). There is a line from the primary manifold (the boiler circulation loop) to the hot inlet of the mixing valve. The output from the mixing valve goes through a pump and on to the radiant floor.

The baseboards are their own secondary circuit, with either zone pumps or zone valves and a single pump, coming off the primary loop manifold and the returns going back to the manifold in the usual primary/secondary way.

hot_rod

I can't see enough of the boiler piping to see what you have.

Here is a common way to do a simple primary secondary, a mixing valve is a better way to blend down temperature. What you have would need a couple valve, one in the cross over, one on the supply. Then you adjust to get a desired temperature.

Know as a dumb mixing concept because it has no way of knowing or adjusting output temperature. A thermostatic mix valve would, however.

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