Contractormag 2382 Hotandcold

What could possibly go wrong? Pt. 2

May 7, 2015
After gathering the system deficiency  information from the occupants, a good expert will then review the physical installation The contractor had attempted to install a larger pump to move more water to a particular zone This mechanic’s efforts were well intentioned, but his basic knowledge of how things hydronic work was sadly lacking Two thermostats were not interlocked, so most of the time the heating system was running trying to warm the floors, and the cooling system was running trying to cool the air

Last month, we started a series of articles on my experiences as a former expert witness on hydronic heating systems. This is part two of that series.

After gathering the system deficiency  information from the occupants, a good expert will then review the physical installation. As I sat in the mechanical room making schematic drawings of the system layout, I kept thinking to myself, “What could possibly be wrong with a system that was this pretty …”

In reviewing the history of work that had been performed on the system, as well as the history of complaints, I found that the contractor was trying his best to get a handle on the situation and satisfy the consumer. He wasn’t ignoring their complaints, but it seemed like every time he’d try something else, another problem would crop up that he didn’t anticipate. The original complaint started out as a bedroom, which was the farthest remote zone from the physical plant that had trouble achieving set point when it got  cold outside.The system for the radiant distribution was set up with one single mixing station to satisfy the needs for low water temperature operation. Floor finishes for this system varied from hard, bare concrete and tile to a heavily padded, thick carpet in the master bedroom, the problematic cool zone.The contractor had attempted to install a larger pump to move more water to that particular zone. It was a high head, high flow pump. When that effort didn’t satisfy the consumer’s wishes, he installed another pump on the return, thinking that a push- pull arrangement was necessary in order to overcome the high- pressure drop of that particular zone, which was piped in 3/8". Most of the basement was done with 1/2" tube. When additional flow didn’t do the trick, he started reconfiguring the system to allow a higher temperature of water to go to this problematic zone. In fact, he took this zone out of the low temperature zones and set it up to operate with the hot water baseboard and fan coil unit zones. And he kept his push- pull, high- head pumping arrangement intact.

This is where the second part of the complaint raised its ugly head, that being an overheat condition in the areas served by the higher temperature water. What the heck, if a little pump does a little good, then a bigger pump will do a LOT of good, no? ... Simple mechanic thinking.

As I sat there, reviewing the original mechanical engineering drawings, and comparing them to my “as built/modified” drawings, it became apparent to me that this mechanics efforts were well intentioned, but his basic knowledge of how things hydronic work were sadly lacking. Some of it had to do with consumer expectations (the consumer wanted warm floors in his bedroom ALL the time, but didn’t want the space so hot that good, comfortable sleep was disturbed).

That’s a tough one to satisfy, and in this case, the floor was running continuously, trying to satisfy the call for heat from the heating thermostat. Right next to the heating thermostat was a cooling thermostat. The cooling system was installed by another company. These two thermostats were not interlocked, so most of the time, the heating system was running trying to warm the floors, and the cooling system was running trying to keep the air temperatures down, and the utility company was the only winner.

So in an effort to satisfy the consumers wishes for a warm floor, the mechanic kept changing system configurations, and adding pumps to the mix. As I sat there drawing out the system, it suddenly dawned on me that he had three high head, high flow circulators in series. Having pumps in series causes their head (pressure generation capability) to be increased. This is what led to the second complaint of overheating conditions in the balance of the system.

The higher temperature zones were being controlled by a conventional, commonly used zone valve, with a “close off” against flow pressure factor that was significantly exceeded by the pumps in series. So regardless of whether the zone needed heat or not, when the remote bedroom called, all other zones saw such a drastic pressure differential across their valves that they began acting as inadvertent pressure-activated bypasses.

The woman of the house threatened her children with their lives if they even thought about touching any thermostats, and in fact had requested bids for locking thermostat aspirator boxes for all the thermostats in the house to keep them from possibly adjusting the thermostats. The kids swore that they never touched the thermostats, and in fact had resorted to opening and closing their bedroom windows in an effort to control their bedroom temperatures, which were part of the baseboard zones. Another win for the utility company …

I had this mental picture of the lady of the house walking around with a huge ring of keys on a retractable key fob, kind of like Schneider from he old TV show One Day at a Time. The out of control heating system also caused her to seek out a good hormone therapy expert because she thought she was going through early menopause due to hot flashes. After I corrected all the deficiencies in the system, she fired her hormone therapist.

The actual root cause of these issues had nothing to do with the original design of the system, except that the design engineer didn’t take into consideration the fact that the consumers wanted plush carpeting and padding, so it felt like they were walking on clouds when they got out of bed in the morning. The contractor was actually partially guilty because like all radiant flooring contractors, he’d oversold the concept of “warm floors.” To compound these problems, the crawl space directly below the master bedroom had no fiberglass insulation in the floor joist bays, compounding the backward or downward loss of heat from the radiant panel. This ventilated crawl space was running at around 80°F. There are a lot of lessons to be learned from this problematic installation that we will try and cover in this series of articles moving forward.If you are not yet a member of the RPA, please check us out and join our efforts to promote the use of radiant heating and cooling systems by joining our organization. Tune in next month as we continue our journey into what can happen if we are not in total control of these wonderful comfort systems. Until then, Happy Hydronicing!

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