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Circulation pumps, not point of use or tank-less water heaters save water
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Editor, Manteca Bulletin,

There has been much discussion about tank-less heaters and point-of-use heaters at sinks in an effort to save water.  Here are the simple facts:

Tank-less heaters do not save any water.  People get hung up on the term “tank-less”.  When you get right down to it, tank-less heaters have the same amount of water flowing through it as a tank style heater: One gallon of cold water in equals one gallon of hot water out. Why would you think a tank-less heater would magically use less water?  In fact, I could easily argue that a tank-less heater will use more water because of the delay in start-up time.  The only savings with a tank-less heater is in gas usage. Comparing purchase and installation price of a tank-less heater to gas savings, payback is generally over 10 years down the road, assuming that you haven’t had any trouble with the heater.  By the way, “instant on” also means “instant off”.  If the power goes out, you have no hot water— instantly.

Point of use (POU) heaters do save water, but the price can be high. All residential versions are electric, and have small reservoirs just like a large water heater.  Save water, but drive up your electric bill? No thank you.  None of the POU heaters will support showers, dishwasher, or laundry, so a large volume heater would still be needed.  If you design a home with a tank-less heater, and POU heaters at sinks, you will add $4,000 or more to the purchase price of the house, and repairs or replacement downstream will be costly.  Do you like ceramic pedestal style sinks?  Where are you going to put that ugly little heater box with all the pipes attached?

Here is a practical solution that can be applied right now to any house with a conventional tank style heater.  If the City Council wants to consider a rebate program, this would be an excellent candidate for the program:

Grundfos is a manufacturer of circulation pumps.  They have a pump (UP Comfort Series, model UP15-10SU7P/TLC) that mounts on top of an existing tank style water heater.  The pump comes with a special circulation valve that mounts on the farthest faucet away from the water heater.  With the pump running, hot water will slowly flow to that farthest faucet and ultimately through the valve.  It creates instant access to hot water on any faucet along the way.  When the pump is running, there is virtually no purging of cold water.  The pump has a timer so it can be set to operate only during those times that hot water is needed (showers, etc).  The only problem is that it uses the cold water pipe to return water back to the water heater.  If the pump is on, and no water has been used, you will probably get warm or hot water from the cold side of faucet for a short period of time.  That means some purging may still occur on the cold side of a faucet, but far less than what is going on now.  Cost?  The pump kit can be purchased on-line from Grundfos for $230, or purchased locally (Standard Plumbing) for $250.  It will take a plumber about an hour to install. An electrician might be needed if there is no outlet near the heater.  And yes, it is always recommended to get a permit to do such work.   Once installed, it is a simple matter of setting the timer to match your family lifestyle.

With the timer properly set, this pump could conserve hundreds of gallons of water per month just in one household, regardless of when the home was built.

A few words of caution:  

• This pump will not work with a tank-less heater.  It moves 1/3 of a gallon of water per minute, which is far under the flow sensor limits of a tank-less heater.  

• If faucets have not been used, and hot water has been moved into the cold water pipe, it could present a scald issue for kids and elderly.  Supervision would be recommended until the entire family is acclimated. It is generally recommended to set the pump to cycle on and off every 15 minutes or so during those times that hot water is needed to prevent such problems. Some adjustments of water temperature during showers may be needed as well.  

• If the pump is not running, all faucets will function as they did before, and will require purging of cold water.

Make no mistake, demanding tank-less heaters and POU heaters at sinks on new construction is a huge mistake.  It will only drive up the cost of a house, increase the electrical power bill, and increase problems downstream. 

The pump described above can only be looked at as an enhancement to an existing home.  If the City wants to seriously consider Code changes for new construction, a properly designed circulation pump system is the way to go.  It represents very little electrical usage, an almost negligible  increase in gas usage, and with a properly set timer, would result in very little water waste.


Greg Henry