Flow Concerns and Remote Thermostat Control

eheinkel

Hello everyone, first post here! Two part question, part 1. I am to the point in my closed-loop radiant heat design where I am researching on-demand water heaters. I installed a Takagi T-H3S for potable water years ago in my primary residence and have been extremely happy with it, so I will likely use Takagi again unless there is a good reason not to. The crux of my question/concern is, how do you keep the circulation pumps and the water heater itself from "fighting" over flow? When the whole system is up to temp, I don't foresee a problem. But, during startup when there may be a 70-80 degree delta initially, the water heater may only be able to heat at 3-4 gpm. Would the pumps be trying to push water through the heater faster than that, and how would they react to flow restriction from the water heater? Part 2. I would like to be able to monitor and control the thermostat remotely so as to "pre-heat" the structure prior to arrival etc. Does anyone have recommendations on a vendor/platform/technology to accomplish this? I am familiar with Nest thermostats, for example, on my gas furnace in my primary residence, not sure on compatibility with radiant heat controls. Thank You!

eheinkel

Here are some details on the design so far if anyone is interested or if it helps with my questions.

Jamie Hall

You will be much happier if you use a boiler made for heating -- which is a low head loss relatively high flow but low delta T design -- than a water heater like the Takagi -- which is a high head loss low flow high delta T design. Use the right tool for the job. Not, for example, that I can't pound in nails with my pipe wrench, but a hammer works better.