Boiler Struggles

Planning for the boiler install has taken quite a bit of study. Similar to installing the radiant system itself that required learning about pex, radiant pipe layouts, Manual J, heat loss calculations, flow rates, btu’s per square foot, etc. etc. the boiler installation is another full university course worth of study. Besides the Uponor manual that I have already described, and of course the Challenger Installation Manual, I have been looking at other boiler install manuals, pump manuals, do it yourself postings, and helpful heating websites. I will create a list of these and add them to a resources tab. It is about time I list the resources that I have used for this project in its own area.

Much of the installation is quite straightforward, until it comes time to actually perform the pipe additions and tightening required. There are so many devices to connect to the hot water heater or the boiler connection pipes that the total installation becomes a bit fuzzy and difficult to assemble. And of course since the fittings to the boiler are compression fittings, they require two wrenches to tighten as per the instructions. However,  when I tried sending water through the system, I found that they leaked badly and the inside connections leaked too . After search the internet to figure out where I had gone wrong, I realized I had overtightened the compression fittings, a common error, and despite using two wrenches, had loosened the fittings inside the boiler! So yet again, after fitting all the connections together several times and taking them apart, I had to disassemble the entire pipe installation to begin to fix the leaks.

Here are some diagrams of the hot water connections from the Challenger installation manual.

Challenger Boiler DHW Piping for Install

Challenger Boiler Domestic Hot Water piping with customizations drawn in to represent my system.

Interestingly only number 7, the mixing valve, was included with the boiler. And there was a 1/2″ size ball valve that I can’t figure out how to install since the 1/2″ hot and cold water pipes connected to 3/4″ pipe with the included compression fittings, so I bought 3/4″ shut off valves. (Update: the 1/2″ ball valve was for the gas supply.) Of course I didn’t realize there was a mixing valve included either so I had purchased one but I think I will use the included one in the setup. I bought two used Taco I-series valves from ebay and think their setup may be more complicated than the manual valve.

Challenger Boiler System Pipe

Challenger Boiler System Pipe 1st install drawing with customization for my system.

There are far fewer connections required for the boiler plumbing. The instructions require a primary/secondary piping arrangement. Interestingly, some of the professional forum posters believe this P/S system is unnecessary with a condensing boiler, but the installation instructions requires primary/secondary. I thought this first drawing represented a P/S system, which basically means there is a loop that just circulates the hot water and a secondary system of loops that feed the zone valves (or secondary circulators if those are used instead.) We have Honeywell zone valves on our existing system. Originally, I planned to put the primary circulator pump on the hot side even though the Challenger instructions have it on the cold side, but when I read more I realized it is the secondary circulator pump that should be on the hot side.

Challenger Boiler System Pipe No. 2

Challenger Boiler System Pipe No. 2

The second drawing is very similar to the first except that I included temperature and pressure gauges on the return pipe. I read that it is useful to have but also read that they are not necessary because anyone can feel a 10 degree or 20 degree temperature difference just by touching the pipes. But the pipe is supposed to be insulated and I think it takes a professional experience to “feel” for the difference so I opted for gauges. The above drawing still does not have two “closely spaced tees” in the primary loop. The return and supply pipes on the existing system are about 11″ apart. That is within the maximum distance allowed, but the rule of thumb is 4 times the diameter of the pipe being used or 12″ maximum. I’m using 1″ pipe up to where it connects with the existing 1 1/4″ pipe so the ideal distance for the two tees is 4″. To accomplish that I will have to install the primary loop something like the drawing below.

Challenger Boiler System Piping for Install 3rd drawing

Challenger Boiler System Piping for Install 3rd drawingse

This last layout diagram has a connecting pipe between the hot and cold connections to the secondary loop. The Uponor manual leaves this connection out because condensing boilers do not need the return water to be warm enough to prevent condensation. When the cooler water enters a traditional hot water boiler, as with a glass of ice water on a warm day, the water will condense on the warm boiler which is a problem for traditional boilers. A condensing boiler takes advantage of this phenomenon to extract extra heat from the condensing water and increase the efficiency of the boiler, it is not a problem for a condensing boiler to receive cooler water. In fact it makes it operate more efficiently if the temperature difference between incoming and outgoing water is closer to 20 degrees (known as delta T of 20) versus 10 degrees which is often recommended for traditional boilers. If this short connection is installed, it allows warm water to flow throughout the primary loop, warming the water that enters the boiler. So it doesn’t really make sense to me for the Challenger instructions to include this connection. Should it be there or not?

These struggles are just the tip of the iceberg in the effort to learn enough to install the condensing boiler myself. Others would prefer to leave this learning to the professionals or they might not appreciate that there is so much to know to do the installation correctly. But I want to learn as much as possible with this project as I am planning to support others who are working on green remodeling. So where to turn?

I actually signed up for a Triangle Tube training that occurred right in Arvada-one of the few training sites in the country. I did this as a green building advisor, as individual owners of these boilers are not allowed to take this professional course. The course was two days and I got a lot of information about the larger versions of Triangle Tube boilers and their control systems. Only at the very end of the two days was this newer model discussed. The trainer had installed the boiler for his daughter for a year and showed the actual inside of the aluminum exchanger after a year’s use.

The system is much less complicated than the larger boiler and he recommended just using smaller pumps with a single loop system instead of a primary/secondary setup. I was the only woman in the class and the installers who attended were very skeptical of any use of Manual J for calculating boiler requirements. They said in a strong wind those calculations would go right out the window! My questions and research were very much pooh poohed and I felt a bit out of place in the classroom, but I was able to gather many notes and information about boiler installation. They talked about a very scary story of a family who recently died in a vacation house from the boiler fumes. They were not specific about how it happened but it was not a Triangle Tube boiler.

This entry was posted in Condensing Modulating Gas Boiler, House Systems, Radiant Heat. Bookmark the permalink.