Tankless Water Heaters - Any Suggestions?

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So a week after the house flooded, in an unrelated incident, the water heater decided it was time to expire. It's a gas water heater, makes luke warm water but not as hot as it should be.

The water heater is in its "own" room. It is installed in the corner of the kitchen and has a wall of 3/8'' plywood around it. This takes up some valuable cabinet space.

The existing tank heater is vented through the wall pretty high up. I've taken measurements and I should be able to reuse the existing vent.

I have decided that I can go tankless to reclaim some space in the kitchen.

For usage - 2 people, 1 bathroom, kitchen and a dishwasher. I've heard that they don't always play nicely with dishwashers but I know there are some workarounds with that.

Thanks!
 
From what I was reading online, a lot of the HE dishwashers don't draw enough water for a long enough time for the tankless to kick on.
 
Make sure you have the current - or gas line for a tankless before you try switching.

UD
 
My dishwasher only has a cold fill and uses it's own heating element - so it depends on the dishwasher.
 
Originally Posted By: double vanos
First I’ve heard of them not getting along with dish washers. Care to expound on that as I was thinking about getting one too...


A friend went from tanked to tankless. The one thing they said they noticed was that hot water took a longer time to reach the faucets. Which makes sense as the tankless has to sense water movement, fire up the boiler and then heat the water all the while cold water is flowing throughout the system.

With a dishwasher using a gallon or 2 per fill, I guess it could lead to lower temps if the dishwasher also does not heat the water.
 
A recirculating pump will help latency.

Some guys run a real low speed one the guys have one on a switch.


UD
 
We like our Rani tankless. We can take two showers at the same time and do laundry with no issues. Our kitchen is at the opposite side of the house so when we remodeled we installed a Chilipepper under the sink. When we want hot water we push a button I installed under the sink and it circulates the water until it reaches temp and then shuts off. Works great and no water wasted down the drain. So when we go to use the dishwasher we just turn on the pump.
Chilpepper
 
The existing vent will likely not be sufficient and you need to run a separate air intake. And if you're going to go with a 200,000 BTU unit, the gas line will have to be upgraded to 3/4 inch. A 100k BTU will be fine on the existing 1/2 inch pipe, but during winter it may not be enough to run a dishwasher and take a shower at the same time. Or run multiple appliances.


All of that can quite costly unless you can do a lot of the work yourself and do your research.
 
Originally Posted By: UncleDave
My dishwasher only has a cold fill and uses it's own heating element - so it depends on the dishwasher.


My understanding is that this is the standard configuration....
 
I had a house with 2 water heaters I was planning to move the water 1 heater outside but on the Saturday when the water heater quit working the Renai store was closed so I went to Home Despot and replaced the tank water heater in about half an hour and that was that.
 
Originally Posted By: Virtus_Probi
Originally Posted By: UncleDave
My dishwasher only has a cold fill and uses it's own heating element - so it depends on the dishwasher.


My understanding is that this is the standard configuration....


Maybe on newer ones but the older ones were hot water fill.
 
Rinnai tank-less water heaters have a re-circulation pump on their higher end units which can be disabled if you do not want it on. We have one at the cabin and it works great.
 
Originally Posted By: itguy08
Originally Posted By: Virtus_Probi
Originally Posted By: UncleDave
My dishwasher only has a cold fill and uses it's own heating element - so it depends on the dishwasher.


My understanding is that this is the standard configuration....


Maybe on newer ones but the older ones were hot water fill.


My Bosch dishwasher has a heating element that will heat the "hot" water feed if it's not up to 140*F I believe.
Whimsey
 
I have a Takagi T-H2-DV with a concentric PVC vent termination and love it.

Yes, it does take a little longer for hot water. Some new ones do have circulating pumps built into them, but I think that is just more gizmos to break.

No problems with dishwasher or washer.
 
I replaced a direct vent Gas water heater with a Rheem tankless about 5-6 years ago.

Few things you need to know first. Does the tankless need a 3/4 inch water and gas supply? Mine did, so I upgraded that. Had my buddy help me with installing the new black pipe. I plumbed in new copper from the water main.

My tankless had a metal concentric vent that I needed to buy as well. I think the newer Rheem has two vent pipes. I also made a set of service valves for the tankless. Home depot sold a pair of service valves for $150. Buddy drilled the new 6 inch hole in the foundation for the vent pipe.

I insulated the pipes in the basement. It does take a few minutes for the water to get up to the second floor. I cheat sometimes and do a load of dishes first or start the washing machine which gets the system already producing hot water.

The thing with a tankless water heater is that you should set the water temp to a setting that you only need to use hot water and not mix in any cold water when you have a shower. If you run two showers at once the tankless will be more efficient and will produce even hotter water since the burner is firing at full capacity.

You should also read up about the "cold water sandwich" effect that you can experience with a tankless. I do like the idea of a circulation pump. I'll have to investigate that.
 
Last edited:
Originally Posted By: Smokescreen
Do tankless systems still have to purge sedimentary/other deposits?


I've seen some manufacturers recommend that you descale them once a year, involving pumping vinegar or a similar lime remover through it.
 
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