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Hot Water pre-heater, under counter

I seem to remember an episode on Ask This Old House about an under counter water pre-heater. If I remember correctly, this was installed to eliminate the few minutes of cold water that comes out of the hot water side when it is first turned on. I think the solution was an under counter heater that acted like an instant hot water heater but was thermostatically controlled to shut off when hot water from the tank reached the faucet.
I was searching the web for something like this but all I am finding are circulators.. Am I remembering an episode correctly or should I look at taking a vacation?

Thanks for the info!!!!!!

Re: Hot Water pre-heater, under counter

I think you are referring to the episodes where a circulating pump is in stalled to keep the water circulating not a heater.

Re: Hot Water pre-heater, under counter

JLMC is correct.

Since the water sitting in the lines between the hot water heater and the faucet gets cold, these systems periodically circulate the standing water to keep it hot.

The upside is that it avoids dumping perfectly good water down the drain, but at the cost of higher fuel costs when the water heater is activated more.

Most of these systems cost several hundred dollars & involve an in-line circulator pump, and often an expansion tank to prevent pressure buildup.

Google "waiting for hot water" to get numerous sites.

If you need additional sites, Google "hot water recirculating system"

Grundfos and other companies manufacture these systems.

If you want to try a diy option, some people simply pipe in a loop back to the hot water heater in the longest line of their hot water piping.

Since hot water has the tendency to rise up in the supply piping, the water crculates by itself, if it is piped correctly.

Google "passive hot water recirculation" (with and without the quotation marks) for sites.

Another option for some houses, is to simply relocate the hot water heater so that it is in the cellar directly under the kitchen/bath, so that there is a minimum of piping between the heater and the taps.

This will not work for any 2nd floor taps or showers.

Sometimes it helps in a minimal way to insulate the HW piping with foam insulating strips that are easily installed.

Re: Hot Water pre-heater, under counter

Greetings! I have been looking for this device for a number of years.I saw an article about it but have not been able to find it. I am hoping t may be out there now. here is what I remember.

1.) The device had 5 heater elements within it.
2.) When the hot water is turned on all 5 elements heat up.
3.) Via a thermostatic control, each of the 5 elements will shut down as the hot water arrives, until the Hot water fully arrives, at which time te entire unit shuts down (HWT set to 120, preheater set for 115)

I see from this post, I was not the only one who had some introduction to this product. Can anyone please let me know if they have ever heard of this and where it might be acquired? Thanks!

Re: Hot Water pre-heater, under counter

Try searching "Point of Use Tankless Instant Hot Water Heaters." Some are small (can handle about a gallon per min) and fairly inexpensive. I've seen the device you described on another home show but this is the closest I've actually been able to find.

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