Multiple Secondary loops help.

pete0007

New here and new to this stuff, I read a bit and understand few things but there are lot of gaps….I have this setup right now as shown in the picture below besides what is in the green. In short, there is only one loop powered by built-in pump for the heat exchanger.

Stage1 : I'm trying to add the dark green loop section so as to heat part of the house with radiant underfloor heating. For the time being it is okay for water to air heat exchanger to run every time there is heat call on the manifolds.

Stage 2: Eventually I'd like to add the highlighted section so the heat exchanger can run independent of the radiant heat calls.

Given that, would that be correct way to connect, closely spaced T's and pumps to drive each of the manifolds and eventually the heat exchanger independently? Is there a better way to do this?

The plan is to eventually lower the SWT to 120 which is what I'm planning for the under floor heating.

Thank you for the guidance.

Big Ed_4

No , set it up three zones , Min 6" spaced tees , thinking 3/4" and 1" supplies. Tap the radiant in , with mixing valves down stream of the air handler . Set up the boiler for high temperature for the air handler . Let the boiler set the output …Attic , can't hurt to add the right glycol ….

hot_rod

there are a number of ways to pipe a primary secondary system. I like hydraulic separators for the multiple functions

Or closely spaced tees as shown. Use manifolds with mixing valves built in to simplify the radiant. Those tie into the header without the zone pumps shown

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Kaos

Important part there is reversing the flow as @hot_rod mentioned.

If that hydro coil pressure drop is not much, you can keep it on the primary loop. If you don't want it to deliver any heat, turn off the fan. The water can continue to flow through the coil, if the fan is off very little heat will be sent to the house. Saves a pump.

With modcons what matters for efficiency is return water temperature, supply temp is irrelevant. Your goal is to minizine RTW, so watch your flow rates. You want the most delta T you can get.

Also set up outdoor reset with an aggressive curve, easiest fuel savings.

pete0007

Thank you all for your inputs…I think I've taken all your ideas into account. I think it'd result in something like the picture below. This'd be the 3 zone setup. Does this look correct? Any blatant mistakes or suggestions for improvement?

Like @Kaos suggested, I could also save a pump and run the hydro coil in the primary itself. Also, I'm not trying to discount use of hydraulic separator, but given my space requirements and the existing caleffi air and dirt separator, closely spaced Tees seems more feasible.

hot_rod

Close, here is the "horseshoe primary loop. Add Webstone purge valves on every return, isolation valves on both sides of the circs.

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pete0007

Looks like this will fill both the needs, isolation and purge. Thanks again for all your guys help.

Kaos

How many of the bits are existing?

I would put the air coil on the primary side and a single mixing valve pump on the floor heat side. From there zone vales for each zone. Get a pump that can do either delta T or delta P control so it adjust flow based on what the zones are doing.

If your unit can be trigged to produce hotter water, you could have it kick into high temp mode whenever the hydro coil needs to run, the rest of the time it can run outdoor reset and only provide water hot enough for the floor heat loop. The idea is your mixing valves should only work when the hydro coil is running, the rest of the time the temperature is set by the boiler.

hot_rod

I don’t think the mix valve will work well if the boiler resets down to the low SWT you set the valve for. They want about a 20 degree hotter H side than the mixed outlet.

If the low temperature is a single zone, use a manual 3 way mixer. It’s temperature will float along with the ODR temperature.