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The video promotes hot water circulation pumps as environmentally friendly and cost effective. Installation cost of about $1000. Their reason is that you waste several gallons of water waiting for it to get hot.

One thing they did not address is heat loss in the plumbing 24 hours a day causing the water heater to fire more often. Installation cost aside it seems to me that the energy cost would be much more expensive than the water cost. (how about installing an instant water heater instead)


I would appreciate your opinion on this.

Bruce

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Bruce, the instant water heater only heats when the water is turned on through coils the water loss before you get water to the fixture is the same. A circulating pump keeps the hot water at the fixtures at all times and when installed under the slab keeps the floor warm in the winter. The pipes in the sand and all pipes insulated well the heater does not run anymore than normal. I have had one for 15 years, and changed out the pump once.

If you have the funds get a thermal camera.

Matthew,

I'm quite stumped by your reply ...

How on earth does that relate as an answer to the question posted.

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Bruce,

It's not "just the water cost".

You also must calculate in the cost to heat all that wasted water, which was once heated, and the cost to re-heat all the wasted water which will now cool in the lines.

Overall, energy-wise, I would think it would be a toss up. Giving this a value of +/-0.

Overall, water conservation-wise, it's a no brainer - install the recirculating pump. Giving this a value of +1.

End result of +1. I.e., you gain more than you lose, and, right now, there are many large areas of the southeast where water is really, really, really, important.

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Jerry,

I'll give you the South West and other water short areas like Los Vegas but my point is the heat loss in the circulation system 24 hours a day.

Without the pump you have several gallons of wasted water and the related sewage cost but I'm thinking once the water cools in the pipes over night the water heater is much better suited to keeping it warm for morning than circulating continuously. Then there is the cost of running the pump.

I'm thinking most people take 1 shower per day, teenagers excepted, then there is laundry, cooking and dishes. Heaviest use in the morning for showers, laundry can be any time etc.

I guess the question is how much heat is lost through the pipes in your home (every home is different) in a given day? Rhetorical question.

We have a water heater expert speaking at our chapter meeting next week, I'll also see what he thinks and let you know.

Thanks,
Bruce

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These circulation pumps are great, especially for medium to larger homes.

Get one with a timer and just run it in the mornings and around dinner cleanup time.

They save water, energy and time.

A return line is used for new construction which is best but if the house is finished you will need modifications or just get the circulator pump that installs under a sink. This method pushes the water back in the cold line. You will lose your cold water while it is running with this retrofit method.

The closed loop method that uses the return line will need check valves and a thermal expansion tank.

Don't solder pipes onto the pump until you disassemble the pump or the heat can damage the internal parts.

I have a few under sink 2.5 gallon heaters that are nice when the circulator is not running. If you have a large family, just leave the circulator pump on 24/7.

Isn't it needed the least at busy times? If someone else has just used the hot water, then you don't have wait around for it anyway. The time you waste a bunch of water is when no one has used it for a while and the water in the pipe has cooled off.

I recommend a timer and a thermostat for the circulating pumps. There is also a newer valve that I was interested in looking at for my house for this purpose. From what I read, you turn on the hot water at your shower, and nothing at all comes out of the valve until the water is warm. It sends the water back down the cold line until the set temperature is reached. You don't need a dedicated return line with this type of system, although I think the valves are pretty expensive. I haven't seen one in an inspection yet.

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Jim Robinson
New Mexico, USA

If you do install a pump you might opt to install it either over the existing auxiliary pan or put a separate pan below it. The can and often do leak. A dedicated circuit would be nice as well with a disconnect switch at the unit.

Aaron

I know what you mean but it just don't work that way, hot water turns luke warm real quick even in insulated pipes. The water savings is a good thing but most people have these for the luxury of having almost instant hot water.
If you have more than 3 people in the house, just let it run 24/7.

Its not really instant hot water, the loop may only run to within 4-10 feet of the fixture so a small wait is still going to occur.

Another thing to remember with the timer is that if you want 2-3 showers starting at 6am and the pump timer kicks in at 5:55am, the water heater gets a lot of cold water dumped into in while it empties the return line into the heater. So the timer needs to be set for 5:30 or 5:40 am to allow for recovery and full use of the tank.

I also have another water heater in series with the main one, it has a 220V switch and stays off unless we have company. It serves as a storage tank mostly and gains some heat from the garage in the summer. Well water is very cold and expensive to heat.

Bruce, I will concede the saving water and time.
But a circulator pump will not save any energy, there will be an increased energy use when you factor in the cost of running the pump.
But the larger energy cost will be the loss of heat in the lines which could be quite substantial. There is no way that the cost of water will ever give a ROI for a circulator system.
They are a great convenience, but not a money saver unless you are paying LOTS for your water and very little for your energy.

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Jim Luttrall
Mr. Inspector.net, Inc.
Allen, Texas 75002

Some homes will have a cost savings depending on many variables. Many factors apply making monitoring/calculations near impossible but....

Anyone who has closely watched an outdoor spa heat up after draining and refilling knows this: The time it takes to heat water from 60 to 80 is much longer than from 80 to 100. I have monitored this many times even on a 6kw electric spa, it is way longer.

Taking this knowledge and applying it to a water heater is very much the same. You let that tank get that extra cold water sent in while you are waiting for it to reach the fixture and the time to heat it goes up. Is it more than the heat loss from the circulator pipes? Hard to prove either way.

I could put a timer on my water heater and see how much it runs and then check again without the pump in use but other variables might change such as the number of showers and the temperature of the water coming in from the 80 foot pipe under the garage slab and driveway slab. Could be an interesting experiment.

While you have standby losses from the hot pipes, even if insulated, the "loss" is into the thermal envelope of the home, which helps heat the home, so it isn't a total loss. Without a circ., you have to run the hot water for 30 seconds or more to get really hot water. That means wasting a few gallons of water. Also, as the water leaves the tank, cold water refills it and sooner or later, it will fire, thus using more energy. No free ride. If a tank has a circ. pump and fires as water is drawn off, it doesn't have to fire as much to maintain temp. on a gallon or two whereas it will fire much longer when a larger chunk of the tank is drawn off. Here, I'm speaking of a boiler with an indirect tank, which is much more efficient holding heat (1/4 of one degree per hr.)

I spoke with the Buderus rep. about my new boiler and he swears the energy loss is negligible with a recirc. as long as you insulate the pipes.

Bob

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disgusted with some people on this forum. Out of here!

Bob,

I've had many homes where that "30 seconds or more" was "more" ... as in "more like 5 minutes", some even "more like 15 minutes" - not guessing, timed it with my watch.

That's A LOT of water, and wasted heat to heat that water, and waster heat to re-heat the replacement water.

Yep. Same here.

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Jerry Peck, Construction / Litigation Consultant
Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )

Anyone who has closely watched an outdoor spa heat up after draining and refilling knows this: The time it takes to heat water from 60 to 80 is much longer than from 80 to 100. I have monitored this many times even on a 6kw electric spa, it is way longer.

I don't think a BTU know's how hot the water is when the water is being heated. If you place 16 ounces of water at 59°F into a stovetop pan and turned on the gas burner, it would take one BTU to raise the temperature of the water to 60°F. As more BTUs continue to flow from the gas flame, the water will eventually reach the boiling point of 212°F.

Physics does support that idea, but remember, the heating element is immersed in the cold water of spa's and water heater's therefore causing the heating elements performance to diminish. The stove burner is not affected as much by the load that is not engulfing the source.

I have observed this slow heating of cold/cooler water in spa's for years after draining and refilling, have owned a few over the last 18 years. One was a 240V 6kw heater and the other is 120V 1.5kw heater, they both do the same thing and it is not just a little difference, its major. The only reason I can think of is the cold water effect on the immersed element.

I don't want to get too technical (we need a thermodynamics professor here) but a BTU is a BTU and a calorie is a calorie. Considering that the water chemistry is the same, it takes the same amount of energy to raise a given amount of water at the same pressure 1 degree.

Here is what I am curious about. What is the actual cost of a circulation pump.

Installation cost around $1000.00.
Timed operation cost of the pump
Heat loss in the pipe both supply and return as opposed to without a pump having a slug or cold water entering the heater while waiting for hot water to get to the fixture and them cooling off after use.

I'm thinking it may be much more cost and energy efficient to plump the home with only 1 cold line and have a small on demand unit for each area of use in a new build only of course. It would be a much higher install cost but over the long run of 20 years I'm thinking it would be a great savings but I don't know how much.

What's your opinion?

Bruce

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