Do's and Don'ts

Below are descriptions of jobs that ModCon Service and Support, Inc. has been to over the years. Shown below are several incorrect installations of modulating condensing boilers. It is extremely important to make sure that you are hiring the most qualified technicians to work on your boilers.

Whether you have a boiler from HTP, Triangle Tube, Lochinvar, Peerless, Burnham, Weil McLain, Bosch or Buderus, ModCon Service and Support, Inc., is the most qualified company to service and/or install your boiler. Please email us with any questions or for further details regarding these Do's and Don'ts of modulating condensing boiler installations.

The exhaust is lower than the make-up. Both of these are too close to the A/C compressors.

The best way to vent on a horizontal, is to bring the exhaust higher than the make-up.

Another concentric horizontally installed in front of a shrub. This is not a preferred installation. To correct this, put an elbow on the end of the concentric, a two-foot piece of pipe vertically and a 45 to divert the exhaust away from the building.

This application shows a concentric in a corner. Even with the extension added to the concentric we still have re-circ issues. The way to resolve this is to put an elbow on the exhaust vertically for two feet, then put a 45 pushing the exhaust away from the building.

This application shows a concentric on the horizontal, in a corner. When I opened up this boiler, it was packed with snow. Never install exhaust and make-up near a corner and A/C compressors.

This application shows concentrics on the horizontal with both the exhaust and the make-up are on the same level. In this situation, the exhaust will come back into the make-up. Observe the spotlight above the concentrics. When I opened up the cabinet there were a lot of moths and bugs inside the cabinet.

There is nothing about this installation that is correct.

This concentric was installed on the horizontal without an elbow. The A/C installers installed the compressor after the boiler was installed. Please observe the damage to the compressor. Always make sure that your exhaust is going to be unobstructed, even after you leave. I personally do not recommend installing a concentric on a horizontal.

When I first got to this job, there was no elbow diverting the exhaust away from the A/C compressor. Even with the elbow, it’s not a good application.

The exhaust and make-up are at the same level which causes huge re-circ issues. This does not even take into consideration that there are cars directly beside it in the driveway.


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71 Westech Drive
Tyngsboro, MA  01879


Rich Swatton
Master Plumber MA

Service Technicians

Bret Chisholm
Master Plumber MA

Luke Tsouvalas
Journeyman Plumber MA