How does hydronic heating deserve its own section on a blog titled “Hot Water Thanks to the Sun?” Hydronic systems are designed to heat hot water, as well as radiant heat and other types of residential heating systems. They may or may not include solar.
These systems can include domestic hot water, commonly using an indirect tank.
You may notice that some of the following drawings mention a specific brand. All hydronic equipment, however, is largely adaptable to other manufacturers.
GLOSSARY
Here are some terms you may encounter. It is absolutely not complete. Hope it’s helpful.
- Combi: A boiler that creates home heating and has a separate internal heat exchanger to produce domestic hot water, without an external tank. DHW production follows the same principles as a tankless water heater.
- DHW: Domestic hot water
- EMC: (Electronically Commutated Motor) pump for variable speed pumping, some boilers manufacturers include the pump internally, or as an accessory.
- Indirect tank: A tank sized for the home’s hot water needs, that is usually heated by a boiler sending heat to the tank’s internal heat exchanger.

ELU right tank 1′ header, zone valves
85,000-150,000 BTU boiler and tank for radiant floor and DHW. Boiler has tank on left, with 1″ header and zone valves. Boiler has internal primary pump.

ELU left tank 1in header ZV
85,000-150,000 BTU boiler and tank for radiant floor and DHW. Boiler has tank on left, with 1″ header and zone valves. Boiler has internal primary pump.

EFTU tank 1.25, 150-199 boiler
150,000-199,000 BTU boiler and tank for radiant floor and DHW. Tank on right, with 1¼” header and zone valves. Boiler has internal primary pump.

Large snow melt
Large snow melt system with multiple manifold distribution. One zone, but lots of manifolds. Use for driveway and sidewalks. This design was for driveway and sidewalks for a small medical office. 150,000-199,000 BTU boiler.

Snowmelt for large residence
Home radiant heating system with snowmelt. The patio uses snowmelt, along with bridge walkway and garage. 85,000-150,000 BTU boiler

EFTU-150WBN boiler w/ 1.25in headerss
150,000-199,000 BTU boiler and indirect tank with 1¼” header, ECM pump and zone valves going to the manifolds.

Combi boiler/water heater small system
Combi boiler/water heater (tank is not required) for a small radiant heating system within the size capabilities of the internal boiler pump. 1″ headers. 85,000-150,000 BTU boiler. Cabin or small home

Combi boiler/water heater for cabin
Combi boiler/water heater (tank not required) for a small radiant heating system within the size capabilities of the internal boiler pump. 1″ headers. 85,000-150,000 BTU boiler. small home

Boiler without internal pump
Primary-secondary plumbing with indirect tank, controlled by the boiler.

Boiler with indirect tank, DHW
Primary-secondary plumbing with indirect tank, controlled by the boiler. Tank can go on right or left.
200 or larger

Cabin radiant heat with solar DHW
Small home cabin system with indirect tank for radiant floor. Solar DHW with backup. 85,000-150,000 BTU boiler.

Small snowmelt system, possible water heating
Small snowmelt system with indirect tank, with alternate possibility for water heating. Sized for 85,000-150,000 BTU boiler. can be adapted for other boilers.

Boiler with indirect DHW
Boiler with indirect tank, ECM pump feeding five zone valves. 85,000-150,000 BTU boiler.

Boiler with indirect tank, 4 zones
Boiler with indirect tank for DHW, 1″ headers, EMC delta-P pump, servicing four zones. 85,000-150,000 BTU boiler.

Solar hot water heating/DHW system
Solar hot water heating system. Phoenix modulating water heater with matching tank; solar drainback system and eight panels.
We’ve added a glossary that is absolutely not complete, but may provide a few answers as you begin.