DETAILS: Sometimes, it’s the little things…

Written on: May 8, 2013 by Wayne Lawrence

Hello again! This month I thought to share two insufficient hot water calls I was sent to investigate. They both had similar problems, but with different types of equipment. I had written about “Insufficient Hot Water Problems” in the November 2012 issue, and “How to Clean an Indirect Water Heater’s Coil” in the December 2012 issue. The two calls that follow are worth sharing due to the fact there were problems with both from the first day of the installations, and I was again faced with customers who were convinced they were sold defective equipment. Sometimes, little details missed cause big headaches later!

#1: The troubled tankless

I received this call after a defective boiler block replacement. A boiler section was defective, and a new block was replaced under warranty, reusing the existing tankless coil and oil burner. 

“I can’t take a shower now”, the customer exclaimed. I asked, “Was there a problem before?” He tells me, “No, it happened right after the boiler replacement!” I look at the system, and find the installer just cut the coil piping above the mixing valve, leaving all else intact, and after reinstalling, sweat couplings were used to reconnect the water lines. All was put back just as before. So I check that the aquastat probe is all the way into the well, review the temperature settings, run the boiler to limit, and have him run the hot water at the kitchen sink. 

Scalding hot water at first, for a few seconds, then I could hold the hot water line in my hand right at the coil! The burner didn’t even start! 

“You need a coil cleaning,” I told him, as I was convinced the coil wasn’t producing. He said, “No way, I just had it cleaned last year, and I’m not going to pay for another cleaning!” He goes on to demand, “I want a new coil!”

I now call the office, and ask to check the past service history. I find this account had been complaining of “insufficient hot water” for years. Some people get me nuts. With an hour now wasted due to him not telling me this had been a constant problem, I get on the phone again, and set up a new coil replacement. Upon the replacement, here is what I found: the coil was piped backwards! Very easy to do, because in these days of cutting corners—meaning saving money—the “super expensive stickers” that used to identify “in and out” or “cold and hot” on the coil plate were not only missing on the existing coil, but on the new replacement coil I took out of the box! 

Here’s what happened: the cold inlet water was sent to the outside of the coil first, it picked up heat, and came back through the inside of the coil close to the aquastat probe. The aquastat reaction time is now slowed. I then find, when removing the problem coil, that boiler sealant was used to slow the section leak on the old boiler. You can never forget the odor of “stop leak.” The sealant had coated the heat transfer surface of the existing coil. Past service history is so important in properly troubleshooting! 

The new coil was installed using a trick I was shown by my friends, Tom and Bob from Napco Oil. (They rescued me from a life of working on garbage trucks in the ‘80s by introducing me to this trade, and started me out helping on installations.) I measured from the face of the boiler block (See Figure 1) and stretched the coil to go through all the sections (Figure 2). 

[EDITOR’S NOTE: ALL FIGURES APPEAR AT THE BOTTOM OF THIS PAGE]

I made sure to mark the inlet cold water side, to send the cold water to the inside of the coil first (See Figure 3). All was put back together, using anti-seize on the bolt threads (I’m sure we’ll see this customer for a coil gasket replacement in a few years, and I’m sure he’ll try to get that for free as well!) and the best part, we haven’t heard from him since! I was on a call today and saw a coil with the proper markings, so for you youngsters, these are the stickers I was talking about! 

#2: Directly becoming aggravated by his indirect!

This next customer was very agitated. “The salesman told me I would never run out of hot water again,” he tells me as I hear the Taco 400 auto vent on the boiler hiss behind me. I look at the boiler and see 210° on the temperature gauge, check and find the limit set to that temperature on the 4081B aquastat as well. 

I now look at the aquastat on the indirect and find it set to 160°. The customer told me he runs out of hot water all the time. He had a 40 gallon indirect, and replaced it with a 60 gallon, only to have the same problem! He says, “They keep adjusting the temp settings each time I call.” 

I run the water at the sink and find it’s scalding hot. It was a warm day, and I go back down to the boiler to check the supply and return temps to the indirect coil. I find the coil and tank need to be flushed due to poor heat transfer, and I perform the tank flush as described in the December 2012 issue. This tank was really dirty! 

It was then that I saw the cause of his complaint. The way the circulators were piped on the return was the cause of the problem with both his old 40 gallon, and now his replacement 60 gallon indirect. This was an old converted gravity system with 2″ piping and large radiators. Five returns into inch and a quarter piping, with a B+G 100 circulator pushing against a Taco 007 circulator with undersized ¾” piping from the indirect coil. They piped the circulators facing each other! When the thermostat called, the B+G was overpowering the Taco 007, and the indirect couldn’t recover due to the reduced flow (Figures 5 and 6). 

There was no priority for the indirect, and when the room thermostat called, the boiler temp dropped quickly due to the missing boiler by-pass piping that should be on all converted gravity jobs. So out of my van comes my “get me out of trouble friend,” Mr. RIB relay*, and we make the indirect a priority, solving the circulator piping problem on the return, and letting the indirect recover (see Figure 7). A reset of the 4081B to 180/150° on the boiler, and 120° for the indirect appears to have put this call to rest. I don’t like to set any water heater above 120° for fear of an injury; if the customer wants it hotter, let them adjust it.

 Well, that’s it for now; hope to see you in Hershey, PA at the OESP show! 

Stay safe, Wayne

*Relay In a Box: http://www.functionaldevices.com/building-automation/relays.php

FIGURE 1: Click for larger image

FIGURE 2: Click for larger image

FIGURE 3:COIL INLET
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FIGURE 4: Click for larger image

FIGURE 5 BOILER RETURN: Click for larger image

FIGURE 6: BOILER RETURN CLOSEUP
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FIGURE 7: Click for larger image