The latest episode of "Ask This Old House" showed Rich Trethewey installing a Taco D'Mand hot water recirculating pump.
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As usual, the show doesn't give enough information, so it's hard to say whether they used the 006 or the 008. In any case, the pumps are about $400.
What do you think about these units? Are there cheaper ones? I was never in favor of them until I saw that you press a button when you're ready to use hot water.
My kitchen is a long way from my hot water heater. This device would be very handy unless it causes diseases or something.
What parameters was that based on? Like RBM said, I think those are just nuts. First, if you're comparing using a push button type pump with no pump at all, the savings in gas is minimal.
With no pump, you have to heat enough incoming cold water to replace the water that is in the hot water pipe between the water heater and the point of use. That's not a lot of water. With a pump, you have to heat enough returned water to replace the water that is in the hot water pipe. So, the difference is in heating a gallon or two of water either from about 45F or about 65F. The other small savings would be in the cost of the gallon or two of water that goes down the drain.
My whole gas bill in summer, which is just for the water heater, is only $17 or so.
If you're comparing a push button system to one that already has a pump and keeps it circulating 24/7, then it would be more substantial, but still, those numbers are hard to believe.
The biggest drawback to these systems, which I bet TOH never mentioned, is that unless you install a seperate return line from the points of use back to the water heater, the stale, tepid water is going back into the cold water line. There it will be available for anyone who draws a glass of what they think is cold fresh water. That person could be at the point-of-use where the pump is or anywhere else along the path of the cold water pipe going back to the water heater. Meaning if you're drawing a pitcher of water to mix the kids some Koolaide in the kitchen, you could be in for a surprise. Before installing one, I'd analyze what else is on the cold water line and figure out hot to install a new line if necessary,.
In addition. no one (including ATOH) ever mentions the cost of running power for the pump.
On the ATOH episode in question, there was clearly a brand new receptacle shown inside the vanity where the pump was placed.
Depending on the current electrical situation and homeowner's skill level, the installation of the receptacle could add significant cost (percentage wise and payback wise) to the installation.
That's a good point. I guess in some cases you could manage to get the pump cord to a nearby outlet without it looking like hell. But as you say, in the ones I've seen installed, they always seem to have that receptacle right there in the vanity. Another problem could be if you don't have a vanity, ie pedestal sinks.
I was going to mention pedestal sinks (since I have one) but I chose not to.
That adds another level of complexity since you now need to figure out where to put the pump (in a closet? in the basement?) and then figure out how to plumb it so that it turns off when hot water is at the sink (not just at the pump) and run the wires for the push button or hope the remote (Honey, where is the remote for the sink?) can turn it on and...and...and.
Could be. I don't see how pushing a button when you enter a bathroom is much different than turning on the hot water tap. Factor in the cost of the pump, the cost of installation, the cost of operation (electricity) and the cost of maintenance and it doesn't seem terribly efficient to me, at least at the rate I pay for water v. electricity.
Actually, now that I think about it, having to push a button to call for hot water is an extra step. If you just turn on the tap when you enter the room, you're done. No button pushing, no mechanical pump to wear out or consume electricity. The tap's turned on already. As someone else noted, the "idling" heat of a pump loop helps heat the house in winter, and that make it harder to calculate its true benefit. I still don't know what the real numbers are concerning lifetime operating costs. I suppose it comes down to how many seconds you're willing to wait to have hot water, how long the run is to the water heater, how much clanging the pipe make at 3AM when you're washing your hands, etc. I can't really see it saving any money. They must do something because so many people install them. But then again people buy billions of dollars of worthless diet supplements . . .
I'm seeing more and more preposterous claims on ads lately, as in the Honda MPG ratings that they've been sued for inflating. It's always a good idea to examine them fully and try to confirm where the real numbers are. Wireless doorbells, for instance, seem to have a multiplier of at least 2X when it comes to stating their range. (-: Battery life is another statistic inflated to almost meaninglessness.
What they do and why people install them is they can eliminate waiting for hot water to arrive at a point-of-use that's a long distance from a water heater. It's a solution to a large house where the water heater is in the basement at one end and you have a bathroom on the second floor at the other end.
I agree that any cost savings in energy and water are likely to be small and could easily be exceeded by the cost of the pump, installation, etc.
a passive gravity system will do the same silently and transparently. And the only cost is the extra tubing from that point back to the heater. It's such a duh solution, I can't believe EVERY house doesn't have it.
The difference though is that a passive system is losing heat through those pipes 24/7 whether water is being used or not. How much that amounts to I don't know. If they were well insulated it might not amount to much and could be a good system.
It's such a miniscule amount. I doubt a person would see a difference in the gas bill. I mean we all could do without air conditioning also, but most people don't.
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