Dishwasher Woes

I live in a small one level condo on a slab foundation. It takes several minutes to get hot water at the kitchen sink, since it is located in a peninsula, and the supply lines run through the slab. When the dishwasher runs, I always run the tap until hot. The problem is, when the dishwasher goes to refill, it fills with entirely cold water. I try to run the hot water each time I know the dishwasher is about to refill, but this wastes a lot of water, and my time. The water heater (electric) is located in the attic. I am considering either installing a hot water recirculating system, or a point of use tank type water heater, like the Bosch Ariston 4 gallon model. Neither bathroom takes a particularly long time to get hot water, so I am leaning away from the recirculation idea. Would you guys recommend I go the small tank type water heater route, or recirculate? Which would likely use less energy? Should I install a small tank type heater inline with the hot water supply?

Thanks for the opinions/suggestions.

A tankless point of use water heater is probably the easiest, possibly least expensive. The main amount of work is in adding a dedicated breaker, wiring etc. They are reasonably inexpensive, and you could possibly get by (after a little research) with a single phase 30 amp breaker. Either way, single or double phase you are only using electric when on demand, verses a recirc pump which would always run (in the time allotted) and also require additional electric and piping. Just research the amount of gallons your dishwasher uses per minute and find a "point of use" tankless water heater that can at the least meet this demand.

I was trying to avoid having to run a new circuit. It would be very difficult to get wiring to the sink location. The Bosch Ariston is a tank type 4 Gallon model, and it is 110 volt. It has a recovery rate of 7 Gallons per hour. My dishwasher uses 6.1 Gallons total for the normal cycle. The cycle takes 1.5 hours to run, and that consists of 2 washes and 3 rinses. Do you think that will be sufficient? The only 110 volt tankless water heater I saw will not have enough flow. There is a 6 gallon model available as well, but would take up a lot more room under the sink.

Does the DW have a heat option? Many do, if so, it's only telling it to heat the water! Most people don't have the recommended DW hot water temp, so heaters are not uncommon and actually required to get a good cycle.

On any tank type heater, you only get about 70-80% or so of its capacity before it cools off because of the cold water coming in. So, it's likely you'd still get some lukewarm water during the wash. With the recirculation systems, you could put it on a switch and only run it when you were running the DW. They don't really use much electricity, the pump is generally only a 1/25-Hp motor or maybe about 30w.

I found out each fill of the dishwasher takes 1.2 gallons. Wouldn't the tank likely have enough time to recover between refills?

It would cost less to replace the dishwasher with a unit that heats the water. Some dishwashers have a button for that.

1. In my opinion the Ariston heaters are the least desirable of any unit.
2. "Point of use" heaters, unless they have "HUGE" input wattage, have much to restricted flows to even consider for a dishwasher.
3. A small wall hung 2 gallon 120v heater inline with the hot water pipe will pretty much take care of your problem. And should fit into the sink cabinet better than a 4 gallon one.

hj, what would you recommend for this small heater, as far as brand/model?

hj said:

1. In my opinion the Ariston heaters are the least desirable of any unit.
2. "Point of use" heaters, unless they have "HUGE" input wattage, have much to restricted flows to even consider for a dishwasher.
3. A small wall hung 2 gallon 120v heater inline with the hot water pipe will pretty much take care of your problem. And should fit into the sink cabinet better than a 4 gallon one.

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