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-   -   Dishwasher or Supplemental Water Heater? (http://www.houserepairtalk.com/f11/dishwasher-supplemental-water-heater-7974/)

RickR 11-14-2009 11:48 AM

Dishwasher or Supplemental Water Heater?
 
Hello,

I looked through some of the threads here and you look like a bright bunch, so here's my question.

I have a very poor floorplan in my house, which results in the kitchen sink/dishwasher being caddy-corner from the water heater. The full run for the piping goes from the water heater in the garage, up the internal wall, through the attic, down the external wall on the opposite side of the house, then finally into the kitchen. This results in two major problems:
1) It takes a lonnnnnnng time for hot water to reach the kitchen.
2) As the weather outside gets colder, the water in the lines cools down during the dishwasher's wash cycle. So even if I run the sink to get hot water to the kitchen prior to running the dishwasher, by the time it runs the rinse cycle it is using cool water again.

So my question is this, should I be looking at a new dishwasher with internal temperature controls/monitoring? Or should I be shopping for a supplemental tankless/small-tank water heater for in the kitchen? And do you have a suggestion for the best model of whichever you propose?

Thank you so much!

travelover 11-14-2009 04:47 PM

The simplest solution would be a dishwasher with its own heater. I can't recommend one, but you might find something at Consumer Reports or similar at the library (they have back issues).

The small local water heater would work, too, but would take up space under the counter and waste electricity when not needed. Too bad you can't insulate the pipes, but I can see where the one in the external wall would be inaccessible. I think a tankless model would be very expensive.

A third alternative is to crank up the temperature on your water heater, but scalding hazard might ensue, as discussed in another thread.

RickR 11-14-2009 09:49 PM

Earlier I talked to one of the fellas at HD who suggested one of these: WATTS Hot Water Recirculating Pump with Timer - 500800 at The Home Depot

Anyone here have an opinion? It looks easier to install than the mini water heater and cheaper than the high-end dishwasher. I also like the timer feature, so unlike the secondary heater, I could turn this off for 18 hours each day. On the downside, it is the same price as the small water heaters and it doesn't look like top-quality construction.

Nestor_Kelebay 11-14-2009 11:32 PM

Where would be the disadvantage in putting a hole right through the exterior wall of your house so that the water supply line from the heater in the garage to the dish washer would be much shorter?

Also, putting pipe insulation on the water supply pipe between the heater and the dish washer will help tremendously in preventing the hot water from cooling down during the wash cycle.

RickR 11-15-2009 12:25 PM

Quote:

Originally Posted by Nestor_Kelebay (Post 36777)
Where would be the disadvantage in putting a hole right through the exterior wall of your house so that the water supply line from the heater in the garage to the dish washer would be much shorter?

Also, putting pipe insulation on the water supply pipe between the heater and the dish washer will help tremendously in preventing the hot water from cooling down during the wash cycle.

Putting a hole through the exterior wall would not make the run any shorter. Straight-shot they two are about 120' apart with the dishwasher on the North wall and the heater near the south wall.

I was talking to one of the guys up at HD who suggested this as a possible solution:
WATTS Hot Water Recirculating Pump with Timer - 500800 at The Home Depot

Any opinions on this?

RickR 11-15-2009 12:31 PM

Quote:

Originally Posted by Nestor_Kelebay (Post 36777)
Where would be the disadvantage in putting a hole right through the exterior wall of your house so that the water supply line from the heater in the garage to the dish washer would be much shorter?

Also, putting pipe insulation on the water supply pipe between the heater and the dish washer will help tremendously in preventing the hot water from cooling down during the wash cycle.

There would be no advantage to running another line outside the kitchen wall since the dishwasher and heater are at opposite ends of the house. The dishwasher is near the northeast corner of the house and the heater is near the southwest corner of the house. Straight-shot the run is about 120'.

As another alternative, one of the guys at HD suggested the WATTS Hot Water Recirculating Pump. (I would link to it, but the rules forbid it. You can find it by searching "Recirculating" on the Home Depot website.) I'm torn on this product. Cons: it's nearly the price of the small water heaters. It looks cheaply built. Pros: I can install it myself. It has a timer, unlike the water heater. It's cheaper than a new high-end dishwasher.

Any thoughts on the semi-recirculating pump? I guess I should also mention, we nearly don't use cold water, so the delay in cold water wouldn't be an issue.

travelover 11-15-2009 02:41 PM

Nestor is right that insulating the pipe would help a lot and would cost the least. Can you access the line in the overhead run?

Costco has those recirculating pump at a good price - often in the store. Running the pump would cost less in electricity than an electric point source heater.

Costco - Watts Premier Hot Water Recirculation System

Wuzzat? 01-20-2010 06:19 PM

Quote:

Originally Posted by Nestor_Kelebay (Post 36777)
Where would be the disadvantage in putting a hole right through the exterior wall of your house so that the water supply line from the heater in the garage to the dish washer would be much shorter?

Also, putting pipe insulation on the water supply pipe between the heater and the dish washer will help tremendously in preventing the hot water from cooling down during the wash cycle.

"the only state in the union where "he needed killin" is a legitimate defense in court."

Can you provide a link for this? :cool:

subzero 01-29-2010 03:24 AM

The other alternative is to crank up the temperature on your water heater.

Wuzzat? 01-29-2010 08:28 AM

Quote:

Originally Posted by RickR (Post 36761)
Or should I be shopping for a supplemental tankless/small-tank water heater for in the kitchen?

A 1 kw tankless heater would raise 1 GPM of water by only 7F.

If you have:
-50' of 1/2" ID pipe full of cold water you'll need a WH with a half gallon tank.
-to raise the temp. of this water by 80 Fahrenheit degrees it will take 100 w-h of energy.
-a half hour before the rinse cycle comes along you'll need a heater with 200 w of power.


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