Don’t Trash That Tankless Water Heater Just To Save A Few Bucks!

A few months ago, we were called out to a restaurant (which will remain nameless to protect the not-so-innocent) in Chicago Heights, Illinois to check out a problem the owner was having with his new tankless water heater.  The heater had been installed about 3 months prior to the service call so it was relatively new.  We are usually less than confident in the installation prior to going on a call like this because we wonder why the owner didn’t call the licensed plumber who installed the new unit (installation by a licensed plumber is required by law) to make the repairs.

We could tell the minute we set eyes on the installation that it was done by somebody with the best of intentions but absolutely no know-how.  Without trying to get too technical, the venting was incorrectly installed, the water pipe was incorrectly installed, there were no shutoff or service valves for the heater and the gas line was incorrectly installed. And the owner had chosen a cheap home center brand of heater which, unfortunately, required stainless steel venting.  Often times the vent will cost as much or more than the heater.

The heater had worked for three months so the owner was convinced his Dad and cousin had installed the heater correctly.  He was convinced it must be a manufacturing defect of some sort.  Unfortunately, it’s not that simple.  As it turned out, this heater was completely shot (destroyed) because of the way it was installed.

We quoted the owner for a new heater and installation, and his reply was “That’s more than I pay the cook in a week”.  After mulling that reply over for about a millisecond and realizing the cook’s pay had about as much to do with the price of the work we proposed as the price of gasoline has to do with the cook’s pay, we continued with our explanation of the problem to the owner. The water heater was leaking from the heat exchanger due to the corrosive (acidic) condensate that was continually dripping onto it due to the lack of any drain for it.  Additionally, the condensate had leaked all over the inside of the case and had fried the circuit board and other electrical components also.

This owner had probably paid for the materials and his relatives assured him that they were capable of a proper installation.  It’s just a water heater, right?

Well the correct answer is “No. It’s not just a water heater.  It’s a tankless condensing type water heater.”  Why does that make a difference? The key is in the words “tankless” and “condensing”.

What does a “tankless” water heater mean?

Let’s tackle “tankless” first.  Because the water heater has no storage tank, it has to be able to keep up with the maximum demand put on it by the equipment or home it serves.  Maximum tankless output is determined by the size of the burner and the efficiency of the heat transfer when the heater is running.  Yes, a tankless heater as a stand-alone system is great for single family homes (the way this one was installed would not have worked in a home either).  But when it comes to a restaurant kitchen, there are other considerations.

First, just because your old tank type heater was 199,000 Btuh doesn’t mean your new tankless 199,000 Btuh is an equal swap.  Your old (commercial) 80 gallon tank type heater could produce about 160 gallons of 160 degree water in the first hour (give or take depending on incoming water temp).  And that water could be delivered at any rate you wanted.  You could use the hand sinks, lavatories, dishwasher and triple sanitation sink at the same time if you wanted.

But because you have no storage capacity with a tankless heater, you can only get the maximum output of the heater when you draw water.  So if you need more hot water than its maximum flow capability, (like trying to run all the hot water fixtures at once), it can only provide its maximum flow and will automatically cut down the flow in order to maintain the temperature you set it at.  And the maximum flow of a given water heater (assuming 199,000 btuh) is totally dependent on the temperature of the incoming water.

Think of it this way:  If the heater can heat a gallon of 40 degree water to 160 degrees every minute, then if you change the incoming water temp to 35 degrees it may only be able to heat 3 quarts of water per minute.  You still get 160 degree water, just less of it.

So let’s say a tankless heater can produce 6 gallons of 160 degree water per minute on a given day. Your restaurant dishwasher is running using 5.5 gallons per minute.  Then the pot washer opens the faucet on the triple sink to start washing pots.  The triple sink flows 3 gallons per minute on the hot side.  So what happens now?  The required load is 8.5 GPM but the heater can only produce 6 GPM.   Cold water?  Nope.  Remember the tankless heater will always produce hot water at the set point.  What it does is control the flow to maintain the set point.  So now the dishwasher gets less than its usual draw of 5.5 gallons per minutes and the triple sink gets less than its normal 3GPM.   So both appliances get less hot water.  Throw in a few more fixtures worth of usage and you can see how our restaurant owner is going to be scratching his head wondering why he is only getting a trickle of hot water all around. Just because his old tank heater had the same size burner does not mean he can replace it with a tankless of the same size.

Condensing mode on a tankless water heater

Second, it’s important that the heater run in “condensing” mode.  If you run a tankless heater at a high temperature for a long time, you lose some of the efficiency that it would have if the exhaust gasses were cooler and were allowed to condense for heat recapture.

Thinking of installing a tankless water heater?

When it comes to homes, the equation becomes much, much simpler, and the production requirements much lower, but the bottom line remains the same:  Don’t attempt to install an expensive piece of equipment like a tankless heater yourself unless you are really mechanically inclined, don’t mind reading a 50 or 60 page installation manual and follow all instructions to the tee, and have all the tools to complete the installation in a timely and quality fashion.

Skip the Do-It-Yourself!

If you are not that person described above, and you want to reap the efficiencies and money saving benefits of a professional tankless heater installation, give us a call (708) 847-7045 at Yes! Plumbing.  Our tankless experts are at the ready to provide tested top quality equipment at a competitive cost.  We serve the entire Illiana area including Schererville, Dyer, Highland, Griffith, Munster, St. John, and many towns in Illinois.

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