Newby Geothermal Radiant Installation

bradtinkers

Hi all, I've lurked around for a while and now could use a second set of eyes. I will do my best to explain my project and will update with any missing information. I'm brand new to this so take it easy on me.

I'm currently assembling my system and I'm stuck currently over thinking everything which has paralyzed my progress. So I'm looking for opinions to see if I'm ok with what I have or should change/add things.

So here is a sketch of the setup, I am running a climatemaster tcw060 for radiant heating and cooling with air handlers. The system has 4 zones. Zones 1 and 2 have radiant floors and an air handler each, Zones 3 and 4 are radiant ceilings. I'm using Tekmar 557 and 553 thermostats coupled with a Tekmar 406 house controller.

So here is where it currently sits because I keep second guessing everything. Nothing is soldered yet.

So my questions are on the layout. Are things placed where they should be i.e. the air and dirt separator, expansion tank and the fill/purge valves? (which are hidden behind the box there)

Should I add anything? Like gauges, test ports, relief valve, isolation valves, balancing valves?

Should I do a 2 or 3 pipe buffer tank setup and should I have unions and ball valves on each line to the it?

Also how should I size the back up electric boiler? The full 60,000 btu's or half?

If you read this far, thank you. I could really use the help/reassurance.

Hot_water_fan

That’s a whole lot of circulators. Can you do it with 2?

What handles DHW?

hot_rod

a two temperature system? Can the shop be a zone without adding another pump?

The 3 pipe is the way I would pipe that tank

bradtinkers

I don't see how I could do it with 2. I could merge the two air handlers to 1 pump, but that's the only elimination that I see possible. The radiant loop needs to be able to regulate it's water temp during cooling to keep from causing condensation.

Yes the shop could be a zone without another pump but with 3 garage doors, and being in Wisconsin, I figured constant circulation would be my best bet against freeze protection.

DHW is handled by the desuperheater to a non powered water heater run in series with an electric water heater.

hot_rod

This might simplify it? Just connect the electric boiler to the buffer, no need for the close tees. If you want it to carry the load if the HP fails, you need to size it as such?

A mixing valve, sized properly for the radiant. A motorized valve if you want to run chilled water?

To constant circ the garage use a 3 way zone valve. Zone valve power off it just recirculates the loops. When a heat call comes in, it opens the other port and pulls from the buffer, hot or chilled.

Screenshot 2024-11-20 at 12.06.57 PM.png

bradtinkers

Ok, that makes sense. Thank you Hot_Rod!

Kaos

Heat pumps are not boilers, you should not be mixing down the temperature for floor heat, mixing down temp reduces COP. You want to set the temp for your heat pump to be what your radiant needs and no more. If you need those FCU for heat, I would try to configure the hydraulic circuit so the floor heat is downstream of the FCUs so it uses the FCU return water.

Most people underestimate how much sensible cooling is needed. In most cases, once you are done with the latent cooling with your fan coils there is pretty much no sensible cooling left.

None the less, if you do want to do cooing with your radiant panels, add a low temp fixed mixing valve to it (set at some temperature near your summer time indoor dewpoint). Since the mix valve will only work to limit the minimum temperature, it won't do anything during the heating season which is what you want.

Does your buffer tank take a heating coil? Simpler than an external boiler.

The minimum size heating coil would be to keep your place from freezing. This is usually about 60% of your 99% design heat load in colder climates, the size of the GSHP is irrelevant for sizing backup heat.

When cooling with hydronics, everything cold will sweat. This includes simple things like pumps, shutoff valves or drains. Make sure you a have solid plan on how to insulate all those bits including the lines going to the FCUs. Any gaps on insulation like when going through framing will sweat, so insulation needs to be continuous.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1821346#Comment_1821346

There may be a time when the FCUs are not running, so it is not a reliable way to temper the radiant. Size those coils for the lowest SWT. nIt that is within 10° of the radiant design, one temperature may work.

I don't believe that Lochinvar buffer has an element port? it would be handy however.

DCContrarian

"Most people underestimate how much sensible cooling is needed. In most cases, once you are done with the latent cooling with your fan coils there is pretty much no sensible cooling left."

Yep. And as far as I know there is no methodology for calculating just the latent load the way that Manual J calculates your entire cooling load.

Air handlers are kind of miraculous in that the more humid it is, the more humidity they remove. They do that automatically. So people designing traditional HVAC systems haven't had to worry about latent heat removal, they just size for total load and the air handler takes care of it.

That said, in large swaths of the eastern US conventional air conditioning just barely keeps up with humidity in the summer. If you live in a place where the big box stores have shelves full of dehumidifiers in June, radiant cooling just isn't going to work for you.

Kaos

https://forum.heatinghelp.com/discussion/comment/1821349#Comment_1821349

I have something similar with my air to water setup. The higher temp rads are first and the floor heat is fed by the return water from them. When the rads are running, the supply water is just about right for the floor heat, when the rads are off, the water is hotter but not enough to change things much. The floor heat zone will be satisfied more quickly is about the only thing I notice. This is running on outdoor reset so runtimes are pretty long so there is decent overlap most of the time.

With something like FCUs and radiant cooling, I can see this working quiet well as the FCU RWT temp should be above dewpoint but still cold which is what you want for your radiant panels. You would still need the low temp mixing valve just in case when the FCUs are off.

bradtinkers

I realized I failed to mention I also have a whole house dehumidifier to help remove humidity and bring in fresh air.

DCContrarian

https://forum.heatinghelp.com/discussion/comment/1821374#Comment_1821374

There's no way of guaranteeing that will be enough dehumidifying.