There are several methods of heating domestic water and each method has it's advantages and disadvantages.  This article is designed to give you an insight into what may be the best method for you.


Indoor Boiler Indirect Hot Water Tank

For those of your who already have an indirect hot water tank (i.e. Boilermate) connected into your indoor boiler system as a zone all you have to do is supply the indoor boiler with heat from the outdoor boiler typically by a brazed plate heat exchanger and you have supplied both your heating system and your domestic water heating system. 

Indoor Boiler Internal Domestic Coil

In this application heating you domestic water is fairly simple.  If you are already using a brazed plate heat exchagner to connect your outdoor boiler to your indoor boiler system all you need is a separate small pump to circulate water through the boiler and back around through the heat exchanger, i.e. a "wrap around pump"

Outdoor Boiler Internal Domestic Coil

Although many manufacturers preach this as being the ultimate way of heating your domestic water I tend to disagree on every level except short run applications.  The problem is you need to have an extra set of 1/2" or 3/4" lines in the ground which gets very costly as your distance increases from the hot water tank to the outdoor boiler.  There are two ways this system is installed...

Sidearm Heat Exchanger

A cost effective hot water heating supplement.  Without a bronze or stainless recirculation pump a typical sidearm heat exchanger plumbed to the side of the tank between the boiler drain and pressure relief ports (used tees & copper x threaded adapters) is a supplemental way of heating domestic water.  It will keep your tank hot but the response time is not as fast as most desire.  A sidearm relys on a thermal syphon for the water to be heated and in general this is a slow process without a domestic side circulator pump.  For maximum efficieny, the outdoor boiler supply should go in the top 1" port of the sidearm and the return should come out of the bottom 1" port (i.e. opposing flows).  In any domestic water heating setup you should try to keep the boiler input water as hot as possible (generally 180 degrees F).

Brazed Plate Heat Exchanger (installed like a sidearm)

This method is installed similar to how a sidearm works and because of the greater internal surface area of a 10-20 plate brazed plate heat exchanger it works better than a sidearm.  Again, a pump can be added on the domestic side of the system to speed up response time. 

Brazed Plate Heat Exchanger (installed like an instant hot water heater)

This method is what I consider the best method in almost every application, there will still be certain applications where another method mentioned here may work better such as a retrofit application or special circumstances but typically this is what I would recommend to anyone as it is cost effective and has the most pros and the least cons

Write Review