I was recently conducting an audit on a home when I ran across this perplexing situation, a tank-less water heater that someone installed with a reticulation pump set on a timer to run 3 hours in the morning and 4 hours in the evening. I guess the contractor has not heard of the on demand system where the homeowner can call for hot water by pushing a button and waiting a minute before turning on the water.

At least it had a temperature sensor to shut off the circulation pump once the hot water made contact with the sensor, that means that the tank-less system is only firing on and off during the timed demand period. I guess there is no way to put a positive spin on this (pathetic) installation.

We need more training out there and maybe a little more education for the homeowner so that they just don't go for the low bid, but maybe hire the contractor based on their experience in home-performance.           

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Looks like a nice install to me. Looks like they went to serious lengths to insulate the line, so how much less loss do you think your button trick would accomplish? 

There is a pretty steep chance this is a customer preference item, not a contractor education issue.  These people may not want to push a button and wait to save $50 a year.  Maybe running buttons to all their facets was impractical.  

Our job is not to enforce inconveniences upon people so they save pennies, that will turn people off.  We need to help them use less and be MORE comfortable.  That's the path to HP gaining a foothold in the marketplace. 

Was this the worst thing you could find at this house?  What was the cfm50 # and square footage? 

I don' now what school you come from but you do not install a recirculating system on a tank-less system.

you do not install a recirculating system on a tank-less system

According to who, and why? 

I come from the school that saves real energy, doesn't obsess about the small stuff, and CERTAINLY doesn't tell homeowners what they "don't" do.  

Have you ever tracked energy use?  Do you have any idea what amount of energy this circ adds?  I think if you don't know these answers you pray to the throne of dogma.  

That's not the school I come from. 

Uh really, mind explaining why you would never install an on demand one?

Hi Sean,

I am glad you asked, The whole idea of installing a tank-less (on demand) water heater is that it only runs on demand ie. when the occupants of the home are calling for hot water. installing a recirculating system that operates on a timer that calls for hot water on a timed basses even  when the the occupants are not calling for hot water is kind of defeating the purpose.

There is however a system that was designed for the on demand water heater it is called an on metlin System (Brand name).  Most users of the system use a button hard wired to the pump at the point of use or a remote control.

Then there are other methods to control the hot water. Demand pumps such as motion detectors and door switches.  I was just recently asked by a customer who had purchased a on demand system how to control it with a flow switch.  He wanted to put a flow switch into the hot water line so that when you turned on the hot water the pump would come on without having to push a button.

You could briefly turn on the hot water tap and immediately shut it off, which would activate the hot water demand system.  When you hear the pump shut off you know you will have instant hot water when you turn on the hot tap. 

Typically this would be done with a button, like a door bell button our remote control.  When you push the button the contact is made between the two wires, and when you release the button the contact is broken.  Breaking that contact is what signals the pump to turn on.

There are meany ways to set up a on demand system, the idea behind using this type of system is that it only fires when the occupants call for hot water.

Ok, so we are then on the same page then - we both have issues with the timer setup, but not the "on demand" part which does require a recirculating pump (whether by the heater, under a sink, etc...) - Heads up, you got to be careful on the wording here & other similar boards (Personally I prefer the button approach - you don't need hot water to brush your teeth, check your hair, etc...)


Alright Ted, back to your point - the issue with the timer is the water in the lines will be continuously hot (during that period) & will dump that heat straight into the house - not a bad thing during the winter, but during the summer.... Also by looking at where this heater is located & the stucco, my guess is the last thing they want is more heat in the house & the only reason they installed all that insulation is to protect the lines from the occasional days where it might drop below freezing, not to keep it "hot"

(I guess I'm not being very clear, sorry.)  

Heat into the house?  So what?  Still don't see the problem, and I don't think I will if this stays in fantasy land.  I see nobody stepping up and talking about measurements.  

How much heat? 

Good water delivery design dictates a wait of less than 5 seconds.  There is a pretty steep chance this is a customer preference item, not a contractor education issue.  These people may not want to push a button and wait to save $50 a year.  Maybe running buttons to all their facets was impractical.  

A little exaggeration might help - what are we talking about here, $2000 worth of controls to save $2 worth of energy?  

I think this is putting the cart in front of the ass.  We need to deliver to personal preferences as efficiently as possible.  Where is the questionnaire?  What was the story behind the design?  

Without any clue, obsessing on this is walking over dollars to chase pennies, and probably have a dissatisfied client.  I suspect there are REAL opportunities at this house.  I highly doubt this is one of them.  

(The expansion tank suggestion is a really good call)

Seriously Ted? 

As for the switch - try it is already included with many & up to maybe $20 worth of parts for a vacuum based system - less for a low voltage.

Math is pretty simple - QUAT & yes the numbers will vary based on house, pipe runs, type chosen, blah, blah, blah

To make it easy for you; for one persons I looked at (running continuously 24x7) - it was at least $15 a month for the pump and at least another $35 to $50 during the summer due to the heat the pipes pumped out into the space (oh & on days AC shouldn't have been needed, it was)

As for the OMG we can't expect a customer to take half a second to push a button & then wait for hot water (which they would end up doing without one), well then tie it into the light switch, a motion sensor, etc...

Just remember it is about looking at the whole picture & doing what is best for the customer based on their needs, wants, & budget - this is a pretty easy & economical fix, if you don't close your mind to it & of course have half a clue



That this system is outdoors indicates a climate that may have water conservation issues.  That may not have crossed your radar.  The awareness of the occupants regarding both water conservation and energy conservation must go into design, and from what we know, it looks like it has.  

That you can't contemplate situations where "pushing buttons and waiting" level of complexity fails doesn't surprise me.  That you don't recognize the presumption you can train or coerce behavior of unknown occupants doesn't surprise me either.  

That you jump to judgement towards a homeowner who would have this system, and compare this to a 24/7 setup, kind of does surprise me.  

I'm not an expert on hot water usage behavior, but I know some.  And the perspective they've shared makes me think pushing buttons and waiting for hot water is for us energy geeks.  Assuming it successfully transitions to a house full of adolescent children is setup for failure.  

If you disagree with this, we'll have to agree to disagree. 

Actually I could care less what climate they are in - conserving water is always good & dare I say trumps energy savings

I gave two options where they didn't have to - maybe you should quit firing away & slow down a bit

I am not saying anything about the homeowner but dealing with the system & quite honestly if I had to guess I would say it was probably the plumbers fault for not knowing or presenting other options which would have cost the same or even less to install

As for the system example - I know you to well & you wanted some numbers because if someone can't produce numbers they are clueless. Well no I don't have any for that specific setup as I don't know what it is fully, nor the pipe layout, nor their...  

Talk about presumptive... I figure out solutions that work for customers after talking with them not just assume that some cookie cutter approach will or will not work based on preconceived notions &/or lack of knowledge - this is just a picture of a bad install that wastes money with no knowledge of the HO or the full situation.

I've done the tankless with chillipepper on-demand pump, wireless controls, light switch in bathroom triggers the pump to run -- IF NEEDED.  Cost of pump $180,  cost of wireless controls $100.  That is a small amount compared to the $2000+ for a tankless.  If money was the issue,  a standard gas hot water heater,  tanked condensing heater, or heat pump hot water heater would cost less than the tankless.

As for the benefits of using on demand with an external trigger,  you can calculate out the difference in gas use.  I do not believe that particular Noritz is a full modulating heater,  thus running the recirc SEVEN hours a  day as suggested in the original story -- is likely to use about 20,000BTU/hr (minimum) or 140,000 BTU a day... which is more than ONE therm,  or about $400 a year just for gas to run the tankless....  switching to on demand switch controlled would drop that to perhaps ONE hour a day of gas for the tank to preheat the water... a savings or probably more than $300.   Payback for going on-demand is less a year or less.

And Andy Simms is correct - where  the moderating tank and or expansion tank.  Every one of the tankless heaters I've seen has specific exclusions on the warranty if you install as done in the picture.  AND THEY CAN TELL when you send in for repair, or make a claim.  All of the new tankless heaters use microprocessor control boards that can detect and keep track of run hours and modes of operation.  

At least the installation has the valves installed for flushing the heater....

I would check the Noritz installation manual. Most often whenever a recirc pump is installed on a tankless an expansion tank is also required to protect the tankless and the manufacturer warranty.


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