So How Do You Maintain These Things?

This is the final chapter in the High Efficiency Condensing Boilers (HECB) journey. In this session we will talk about ancillary components, installation, and maintenance considerations common to standard boilers and specific to the HECB. The good news is there are not a lot of huge differences in maintaining a standard Efficiency Boiler (SEB) and an HECB. Let me hit the high points.

1) A Great Location - This punch list item is very similar. Just look at the IOM for the service clearance and install them in an appropriate location the insures there is adequate space to move and position the boiler. For interior and exterior installations housekeeping pads are a must. On exterior installations, be sure that external flue hoods, weather resistant coatings, and/or any NEMA enclosures have been considered on the boilers and associated pumps. A combination of Glycol,

heat tape, or insulation, or a pump freeze-stat could be your answer to freeze protection on system water pipes.

2) Where is the water? – HECB are designed to be run on a closed water system. There are guidelines on water hardness, Ph, Total Dissolved Solids, Iron, Copper, and Chloride levels upon start-up and for make-up water if that is needed. Air and dirt are never a good thing to have in your water systems, so an air and dirt separator is a piece of equipment to consider installing. They come as a standard inline, tangential, and coalescing types. You can add strainers, magnetic collection, blowdowns, removable tops, etc. to aid in collection and cleaning.

3) Fuel to Burn – The fuel piping and combustion air are vitally important.  The correctly sized piping, gas header, and PRV should be installed before connection to the boiler and tested for leaks.  Combustion air can be drawn from the surrounding spaces but can also be ducted with mechanical louvers to help with freeze protection.  Look to the manufacturers IOM for gas and combustion air pressure recommendations for proper operation. 

4) Vent that boiler – Condensing boiler venting can be made of CAT IV stainless steel or Polypropylene.  Some manufacturers claim that you can use PVC or CPVC, but it is of our opinion that this is not recommended, and, in most cases, the other options are cheaper and carry a lower on installation cost.  The key is to have the venting sloped toward the boiler so that it can be drained to the sanitary system (see IOM for slope).  After flue gases leave the boiler, a condensate neutralization kit should be installed in line to the drain.  All associated sanitary fixtures and piping that the condensate drains to should be made of non-corrosive materials.

5) System Temperature – One of the biggest problem points that we see in hot water systems is the misplacement of the system temperature sensor.  This detects the temperature of the supply water to the building system loop.  This needs to be located within 5’ – 7’ of the boiler piping connection point to the system loop. 

Sometimes this is installed too far out in the system, or sometimes not installed at all.  The boilers must have something communicating the system demands, or they short-cycle and fail to maintain proper set-point. In a Primary-secondary loop system, the decouple pipe needs to be the correct length.  It is recommended that this be no shorter than 12”, but can be up to 4 pipe diameters in length.  See diagram below.

6) What remains? - Maintenance, Maintenance, Maintenance.  If the boiler is getting water quality out of operating range, dirty air, improper combustion, or if it is short cycling due to improper temperature detection, then it will not run efficiently and will shorten the life of the boiler. Combustion should be evaluated and adjusted at least every 6-months, and water quality should be monitored weekly and adjusted as it migrates out of tolerances.   

Customers desire the energy savings that a HECB provides, so take these insights and considerations whether you are an engineer, contractor, or owner for the best installation and life of your next High Efficiency Condensing Boiler.