Thermal Storage - Hot Water Storage Object

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Thank you for your quick reply! This is very helpful.

I do have a followup question. How can I set up the plant loop so that the boiler serves both the HW heater and the radiant floor, but serves the radiant floor first and then charges the HW heater when there is no demand for heat by the radiant floor? And then how do I get the HW heater to also serve the radiant floor?

You could set up a plant loop with a boiler (perhaps with small tank volume) in parallel with a HW tank on the supply side of the loop; define the desired temperatures for the HW tank, for the plant loop (with the loop setpoint manager), and for the the radiant floors separately. If this does not work satisfactorily, you could also use an additional tempering valve on the supply side of the plant loop.

I tried putting the HW tank in parallel with the boiler and that gave better results. I would like to try your suggestion with the tempering valve but I don't know how to use a tempering valve. I tried adding one to my plant loop but I got several severe errors (shown below). How would I add a tempering valve to my plant loop? -TemperingValve object needs to be on an ACTIVE branch -TemperingValve object setpoint node not valid. Check Setpoint manager for Plant Loop Temp Setpoint -TemperingValve object stream 2 source node not valid.

Thank you so much for your help, I'm very grateful!

regarding use of TemperingValve, I would need some more testing for myself. But it could help you to run some of the example idf files in the EP distribution. Or you could post another question on unmethours.