The down side is two heat sources.
Closed hot water heating system.
Newer units have many zones with two water pipes linked to each zone.
A closed water heater system means that the hot water cannot expand beyond the valves and mix with the municipal water.
A quick visual inspection can tell us if there is obvious leakage corrosion or clogging of some automatic air separator devices and fdor some automatic air purge valves a simple step of opening a valve cap.
They can be used with radiators or radiant floor heating.
All water heaters waste heat energy even when the burner is off and the unit is sitting idle between heating cycles.
Closed loop water treatment.
One circulating heated water to the rooms and the other returning the much cooler water back to the boiler to get reheated.
Hot water systems are closed meaning that the water constantly circulates through the pipes and into the boiler.
If freeze protection is an issue than a closed system with anti freeze is a good idea.
The valves that are usually found in the closed systems are the check valve pressure reducing valve mixing valve backflow preventer and other.
Unlike conventional water heating systems closed hot water boilers should only be flushed when operation problems occur.
Water boiler a boiler is used to heat just the water as it boils the water and turns it to steam.
There is a third type called a combi water heater that can actually do both.
Closed loops that are not properly treated can cause significant corrosion damage.
Closed loops that are leaking can waste water and energy while causing corrosion.
These are for closed systems usually called hydronic systems and they are just for heating.
Hot water chilled water tempered water process water and glycol filled closed loops are often ignored when considering a water treatment program which can be a costly mistake.
In modern systems closed tanks are preferred.
Closed systems are often used in second homes or primary residences in areas prone to long power outages.
The expansion of water 4 7 from 0 o c to 100 o c can be collected in an open expansion tank above the rest of the system or inside a closed pressurized tank close to the boiler and safety valves.