There is an artistry when it comes to hydronics. Every component of the system is placed together, creating a masterpiece. That isn’t to say that there aren’t any miscalculations or misapplications. In the previous issue, we highlighted some of the most common “party fouls” that I have seen over the years. We are going to cover a few more in this issue.
Not using balancing manifolds
I am still seeing applications where copper stock manifolds are used for hydronic heating systems. When I was still doing installations, I used them because I frankly didn’t know better.
Let’s assume we have a bungalow with four rooms — two rooms need 10,000 btu/h and two of them need 30,000 btu/h. How are you going to make sure the flows are right with a copper stock manifold? You can’t.
CSA B214 14.3.4 clearly states that when we do these installations, we need to ensure proper design flow rates are achieved. That is a tough task with every room needing a different flow rate and no manifold balancing valves. Just about every manufacturer makes balancing manifolds, so there are lots to choose from.
Piping boilers like it’s still 1984
One of my original mentors used to always tell me, “This is how we have always done it; nobody has ever complained.” The reality is repeatedly doing it wrong doesn’t make it right. Just because they never called me back to fix it doesn’t mean it worked. My competitor very likely went in and fixed it, which is why I never heard about our system’s problems. Don’t let this be you.
Take advantage of technology, like PP-RCT piping that is taking Canada by storm and has been used extensively across North America. Typically, you weld PPR pipe using socket fusion or butt fusion but now, with the advent of electrofusion, you can fuse pipe up to 12-inches in quite literally minutes with ease and no previous knowledge outside of a quick training session.
Always look to see what new innovations are on the market. I recently had the pleasure of visiting a manufacturer who is making pre-assembled primary/secondary headers in stainless steel. Not only does it look stunning, but it is also surprisingly cost-effective and much faster than piping a primary/secondary yourself.
As for the topic of closely spaced tees, they have been used for longer than I have been alive. They can be harmless in the right application, but technology has evolved, and it does require some thought and at times can be a problem. Look at the example below and see if you can decipher the problem.
During the winter, the system worked perfectly, but the building owner complained that all summer long the front lobby radiators were smoking hot. Look at the way that the indirect is piped in. It works great in the wintertime, but all summer long, we are pumping heat all through the secondary piping and can end up with heat going out into the building if thermal traps and check valves are not being used. This is exacerbated by an external control that was bringing pumps on; and although the boiler was off due to reset heating, the heat from the indirect was getting pumped around the building.
The other thing I want to note is the potential temperature drop across the loads. The last load return water is coming back at 115.8F. What would happen if we had installed a hydronic heat pump only capable of producing 130F water? The complaint will be that the emitter on the far right of my drawing will have water temperatures that are too low to heat the space and the end user will be cold.
Imposing our own budgets
This is a topic I discuss frequently while doing training. When it comes to hydronics, we sometimes instinctively rule out more expensive options because we think we won’t get the work or the homeowner won’t want it. Let the customer decide. Sometimes paying more upfront will result in paying less each month for the life of the home.
Don’t imply your own budget constraints on the consumer; give them options so they can choose. I know that I myself am quite guilty of this and actively work to not put my own budget limitations or design preferences on consumers/contractors/engineers that I have just met.
Air & dirt elimination
Air vents and high-efficiency air separators are not the same. When I started working at Eden Energy Equipment and met Bob ‘Hot Rod’ Rohr, it was my first introduction to a high-efficiency air separator, and I felt like I had been punched in the gut. I learned more in an hour talking to Bob than in five years of working in the field.
We sometimes wrongly assume that when we commission a system and purge out the obvious air, our job is done. The reality is that as the water heats up, we are going to be squeezing out the entrained air in the system.
Often, I will hear that dirt separators are not getting used because the contractor has never had a boiler heat exchanger fail or they are putting in potable water.
Scale will coat your heat exchanger and cause blisters and failure. Before that happens, it is also negatively impacting your boiler’s efficiency because that sludge gets baked right into the heat exchanger impeding heat transfer. I’d suggest paying for the dirt separator, which protects your boiler from not only failure but a drop in fuel efficiency or paying for more fuel for the life of your new boiler and crossing your fingers it does not fail.
Boiler plant strategy
Often, we see designs done where a building needs 500,000 btu/h and the designer will spec a single boiler to cover the load. In many scenarios, two smaller boilers are better than one. Immediately out of the gate, two boilers give you redundancy and no fear of leaving a building completely without heat.
A few years ago, I worked on an apartment facility project. The boiler we took out was an old 500,000 btu/h boiler. We replaced it with two boilers that could meet the required capacity. By doing this, we not only gave them redundancy but we also increased the turndown ratio. Now in the shoulder seasons we can lower our firing rate to as low as 10,000 btu/h. While in the dead of winter, we utilise the full power of both boilers.
We also do this exact same thing using a hydronic heat pump with a backup electric or gas boiler to cover the domestic hot water and the coldest years of the day.