Protecting a hydronic system doesn’t start once the installation begins, it starts the second the deposit cheque is in the technician’s hand. While there are several more obvious tips and tricks to remember when protecting the hydronic system, there are some that aren’t as thought about as frequently that need to be highlighted. Those are the ones that could affect the way any contracting company conducts business.
There is a mistaken concept within the industry that it is acceptable to fill systems with tap water and expect everything to work flawlessly. The reality is that just because the water is safe to be consumed doesn’t mean it should be put into the boiler system. Potable water is for humans, not boilers.
Water quality is best handled by ensuring the water put in the system is up to par. When designing a hydronics system, it is good practice to use a digital feeder to fill the system and not an autofill. Make sure that the feeder is getting good quality water. Using products like demineralizers or TDS meters can ensure that the water isn’t too aggressive. In total, that would put the contractor at under $200 in tools.
Eliminating air from the system ensures good overall performance, but it also ensures that the system doesn’t fail. If the system has poor water quality and all air has been removed, the corrosion process is stalled.
That’s not to say that filling the system with tap water and using an air separator will be good enough for the system. It should still be filled with good water and with the use of proper air elimination to ensure that whatever is in the system will have minimal impact.
Air elimination is done using an air separator that utilizes a coalescing media to remove the microbubbles from the system. It is installed at the hottest point.
The reasoning behind this can be best explained by discussing boiled water. As the water heats up, more and more bubbles will form. That is the nearly five per cent air entrained in the cold tap water being squeezed out. Removing the air from where it originates just makes the most sense.
Now, this is a big one. I was recently at a small commercial project that had boilers installed without magnetic separation. This resulted in a serious problem. One heat exchanger had already failed and more would come.
When conducting retrofit installations, it is important to be vividly conscious of the existing components that are getting replaced. Namely, old piping in the building that is shedding its materials into the system over time, which was evident on this job site. And just because the boiler is scaled up doesn’t mean that it’ll fail.
You can put in a new condensing boiler and within a short amount of time, it will build up scale to the point where the heat transfer and performance have been negatively impacted, again. People grossly underestimate how bad water quality in boilers can impact the whole system. Fouling in Heat Exchangers by Hassan Al-Haj Ibrahim, Arab University for Science and Technology, is a good resource to learn more about the topic.
A study by Harwell Laboratories noted that 15 per cent of the costs of a process plant can be attributed to heat exchangers and boilers, and of this, half is caused by fouling. The more staggering statistic is that losses due to the fouling of heat exchangers in industrialized nations are about 0.25 per cent of their GDP.
Imagine buying a new car, filling it with the wrong fuel, and discovering the car’s mileage is permanently damaged without an engine change. That is what we are talking about with boilers and poor water quality. Scale reduces the boiler’s efficiency, and restricts water flow which increases pressure drops and lowers pumping capacity, resulting in comfort and performance issues.
Proper combustion setup is important, whether the system is natural gas or propane. The cleaner it burns, the better. Fuels like propane leave behind deposits when it is burned on the fireside of the tubes. The situation is amplified if the tank is not properly filled year-round.
In tests that have been conducted, it has been shown that 0.8 mm of scale reduces the heat transfer by 9.5 per cent. That is 0.03 inches! If there is 4.5 mm or 0.18 inches of scale, the boiler’s heat transfer has been reduced by 69 per cent.
There might be some people skeptical of the importance of system design and believe that a system design can be winged. The reality is that paying for a design will save money up-front and, more importantly, pay high dividends to make technicians profitable.
A design ensures that the pumps, pipes, and controls are sized correctly. This will help eliminate three or more unnecessary trips to the wholesaler to grab forgotten parts.
It’s a bit ironic when the contractor gets blamed when a piece of equipment fails prematurely. In a lot of cases, the failure is a result of a lack of maintenance; yet the reality is that contractors struggle immensely getting their customers to agree to maintenance. They see the cost of annual service as being prohibitive and not worth it.
Recently, I spoke with Derek Trudgen, HVAC supervisor at the Hayter Group, and asked him what his experience with maintenance on equipment is. He told me, “When we do our annual boiler maintenance, we typically charge $170. We clean the boiler and go through a detailed inspection list of 55 items and ensure the unit is meeting and exceeding factory specifications wherever possible.
“The homeowner doesn’t always see the value in our maintenance plans, but they all want to sign up after they have a problem. Most of our maintenance plans originate from us going out for a service call on a unit that has never been maintained. The homeowner, depending on how bad the system is, can face up to a $1,500 repair bill and are now on our annual maintenance program.”
People before profits
This is something that happens a lot and is something hard to solve. Very often, contractors will be asked to work on equipment that they are unfamiliar with. I recall my first experience seeing a geothermal heat pump. On that occasion, I packed up my tools and went back to the truck. Sometimes it’s good to understand when you might do more harm than good and walk away.
“The number one thing we much do to make sure we are the best is to partner with the best. We don’t want to sell ourselves short,” explains Brandon Farr, president of Farr Mechanical. “When you pick a good company to work with, you get really good technical support. There are also good companies that do shit work.”
Sometimes the simplest way to protect a hydronic heating system is to not do it at all. As a contractor, if you have never piped a boiler before, don’t do it without help. If you have never seen a hydronic heat pump, don’t pass go, do not collect $200. Get back in your truck and do the right thing.
Let somebody who is qualified do the work and put people before profits. The potential harm to the homeowner and your brand is not worth it.