Hydronic Heating Pitfalls

We recently did a boiler replacement and in-floor heating job that underscored just how much damage some installers can do when operating with only a cursory knowledge of hydronic heating. A quick-and-dirty install by an inexperienced operator can lead to painfully expensive repairs later on.

 

The Problems

We were called to investigate leaks in the under-floor heating system of a 5000 square foot home. This heating system was between ten and fifteen years old, was already operating on its second boiler, and was exhibiting major continuous leakage and poor operation.

We performed water tests, checked pH levels, pressure testing, etc. and determined that the boiler was basically shot and had to be replaced, along with the metal fittings in the system. Condensation had caused gradual corrosion inside the boiler’s cast-iron heat exchanger. This corrosion deposited in the lines in the form of magnetite– a magnetic oxide of iron, particles of which floated through the system and ultimately aggregated into deposits restricting the fluid flow, thereby causing the boiler to work even harder.

In addition, the garage was sinking due to too much heat being delivered to the underfloor; the water temperature was much too high, causing a cycle of expansion and contraction that actually moved the floor around to a point where it caused the heating pad to split and burst.

 

The Causes

This all was the result of insufficient controls and running the incorrect boiler type. True, that boiler could easily generate enough heat for the entire house, but having the entire system on one zone controlled by a single thermostat meant the boiler chronically ran too long and at too high a temperature. Under these circumstances, attaining a normal room temperature at the thermostat’s location meant sweltering temperatures elsewhere in the house– the areas in closer line proximity to the boiler. Meanwhile, other areas of the house would be too cold. The gradual accumulation of magnetite deposits in the lines only made this situation worse.

 

The Solution

In the course of the job we installed a high-efficiency IBC condensing boiler along with an additional eight thermostats, engineering zoned temperature control for comfort throughout the home. This constituted a complete redesign of the system so they now have controllable heat in the right places, and the new IBC boiler can run at an appropriate lower temperature. With proper maintenance, this boiler should give a lifetime of service.

We also sealed the leaks and power flushed the system using chemical cleaner and a large flushing machine. Once the system was completely flushed, we found a shocking amount of magnetite deposits had come out of it, enough to fill a large pail. This was all a byproduct of corrosion from the old fittings and the boiler interior.

 

Hotter Is Not Better

In-floor heating systems are meant to be run at a temperature no higher than 29°C. Having a high floor temperature might rapidly warm up a room, but it also can create an unnatural feeling where your feet feel warmer than your head; in time this can lead to a “hot head syndrome” where you start to feel nauseated and dizzy.

 

Conclusion

To recap: running the wrong boiler for the application, with the wrong controls and the wrong setup, eventually led to catastrophic failure where there was no heat in the house, the system was leaking, and the garage floor distortion split all the underground parts to the point where they can no longer be used.

There are a lot of plumbers out there with a basic knowledge of hydronic heating, but without a thorough understanding, it’s too easy to make catastrophic mistakes that can cost a LOT of money years down the road.

We’re happy and proud to say this client was very pleased with the results.

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