• Please be sure to read the rules and adhere to them. Some banned members have complained that they are not spammers. But they spammed us. Some even tried to redirect our members to other forums. Duh. Be smart. Read the rules and adhere to them and we will all get along just fine. Cheers. :beer: Link to the rules: https://www.forumsforums.com/threads/forum-rules-info.2974/

Different type of tankless water heater question...

jwstewar

Active member
We have a Noritz whole house tankless water heater. We traded copper plumbing and an 80 gallon conventional tank for the heater and pex plumbing. Overall we have been very happy with it. It seems to save us quite a bit of propane compared to the old house and the 30 & then later 40 gallon water heaters that we had in it.

One thing that we aren't 100% happy about though is the length of time it takes to get hot water to our kitchen faucet. We made a mistake when we designed the house. Because of how the basement is laid out, it made the most sense to put the pex manifold system on the south wall of the basement. Unfortunately, what we didn't take into account is all of the water uses are on the north side of the house. I had thought about moving the heater & the pex system, but now that the basement is finished, that is kind of out of the question. So combined with the amount of time that it takes for the tankless water heater to come up to speed + the length of the line running to the kitchen sink it can take awhile to get hot water. This can be annoying if you just want a quick burst of hot water to rinse something off or even if we run a full cycle on the dishwasher. Normally we run the short cycle (35 - minutes vs. 125 minutes for a normal cycle) so it isn't a big deal, but on the long cycle we'll get a warning from the dishwasher the temp isn't high enough. We are considering getting a small point of use tankless and mounting either under the sink or in the basement right under the sink.

If we were to do this. Should I turn the hot water line off and and split the cold line and run cold to the new little buy or use the hot water line that is currently coming there and use the heaters in series and use the efficiency of the "big" propane if we are using a bunch of water vs. the relatively small electric one? I've heard of using heaters in series before to increase the flow. If we are running it enough to get the hot water to the new heater and the water is the 120 degrees that we have it set at, in theory the electric one wouldn't kick in correct?

We are thinking maybe something like this: http://www.ebay.com/itm/Stiebel-Elt...465?pt=LH_DefaultDomain_0&hash=item2c61fbda91
 
Last edited:

muleman

Gone But Not Forgotten
GOLD Site Supporter
You should tap in on the hot water line. The electric one would only be on briefly till the water from the propane gets there. You need good hot water for today's dish soaps to even begin to work in a dishwasher. I would also suggest insulating your hot water lines everywhere. This helps a lot in the time it takes for hot water to arrive at the the point of use. I prefer an indirect water heater off the boiler as it is very efficient to run and allows me unlimited hot water at whatever temp I need. With it you can also run a circulator pump to have instant hot water anywhere.
 

bczoom

Super Moderator
Staff member
GOLD Site Supporter
Interesting...

Lots of things running through my head.
- As I recall, dishwashers use very little water. Between 5-10 gallons for the entire cycle.
- Does your dishwasher have its own water heating element? Our older one does so I thought this was pretty standard.
- You said your basement is finished so moving the current HW setup isn't an option. Can you run a new 30amp service to the kitchen for this thing?
- Drawing 3KW, this thing is almost as much a power hog as a full 40-gallon electric hw tank (4KW's).
- This thing says it has a scald-guard thermostat but doesn't say there's an owner adjustable thermostat. Can you set the temperature?
- The flow rate appears really low, especially if the incoming water is cold. Figuring basement temp water incoming to this thing, it'll take 2 minutes to get 1 gallon of hot water.

Looking at all the specs on it, I'd hook it in series.

You didn't ask for this option but have you considered a small (2.5 gallon) point-of-use hot water tank? They're small enough to keep under the sink, don't require special wiring as they only draw 1400-1500 watts. Hooked up in series with your current one, you will never run out of hot water.
http://www.homedepot.com/webapp/wcs...langId=-1&catalogId=10053&productId=100094732
 

jwstewar

Active member
Muleman, no boiler as we have heat pump/propane forced air heating system.

BC, that is what we are running into with the dishwasher. It uses so little water, it doesn't keep enough water flowing to keep it hot. This is a Bosch Dishwasher. Supposedly super efficient. So efficient it doesn't even have heated dry.:sad::hammer: I thought that was standard, but nope. We were so concerned about quietness and cleaning rating and then finally looks to even consider that - frankly just thought it was standard and didn't need to. For almost $1000 for a dishwasher, you would think the thing could dry them too.:yum:

Was trying to stay tankless just because of the size. With how little water this thing actually needs to heat until the propane gets its hot water there, I don't need a lot of water, just need (or want) it quick, I'm not overly concerned about efficiency. Obviously don't want to waste energy that was the point of the tankless in the first place, but for just a few minutes a day, probably not a huge concern either.

I have a small area right under the kitchen sink in the finished area of the basement. It is the wiring closet for the electrical of the house. The panel, network, and phone connections are all there. I can easily do a bit of plumbing work and wiring to get what I need up to the kitchen sink. Just not enough room to move the manifold, heater, 2 water filters, and the water softener to there.

BTW, I still need to do more research before I buy any unit. At this point, not ordering the one I posted a link to, just something "like" it. Probably would look at another Noritz or possibly a Bosch. Though, Bosch may not be on the list either given our less than thrilled experience with our dishwasher and our wall oven and the fact their customer service line either out and out lied to me or were just plain idiots on the cook top and caused us to be without a cooktop for several weeks when we moved into the house.
 

waybomb

Well-known member
GOLD Site Supporter
Have had a Rheem 195,000 btu tankless for 4 or 5 years now. Love it. For the dishwasher, the reality for us is that we usually rinse stuff off before putting it in the dishwasher. We do this with the faucet in "hot", and by the time the last dish is in the washer, the hot water is there. Start the dishwasher up.

But on our dishwasher, even if the dishwasher is filled with cold water, the dishwasher adds time to the cycle as the coils heat the water in the washer. It wont start until water reaches "x", whatever that is.
 

bczoom

Super Moderator
Staff member
GOLD Site Supporter
Mrs. JW must do dishes differently then Mrs. Zoom. Mrs. Zoom goes through a ton of water cleaning all the items before they go into the dishwasher.

I was thinking about going tankless myself until I saw the electric requirements (I have an all electric house). They start at 13KW's and go up to 30KW's. OUCH! Hell, I couldn't even have hot water using the genset unless I powered down the rest of the house. Can't do it at the bunker either since that has a demand meter so it slams us hard on the rates. That would be like starting a 10-15hp motor. Last time we did that (and let it run for 10 minutes), our electric bill literally doubled.
 

bczoom

Super Moderator
Staff member
GOLD Site Supporter
Have had a Rheem 195,000 btu tankless for 4 or 5 years now. Love it. For the dishwasher, the reality for us is that we usually rinse stuff off before putting it in the dishwasher. We do this with the faucet in "hot", and by the time the last dish is in the washer, the hot water is there. Start the dishwasher up.
Natural Gas?

But on our dishwasher, even if the dishwasher is filled with cold water, the dishwasher adds time to the cycle as the coils heat the water in the washer. It wont start until water reaches "x", whatever that is.
That's what I was mentioning thinking they all had that option. I do like that it's optional. Not sure whether it's that option or the hot drying option but one of them melted my fine collection of Justice League and Eat-N-Park cups as well is my favorite soup bowls (made by a company called Miracle Whip). :sad: I keep both settings off now... :unsure:
 

muleman

Gone But Not Forgotten
GOLD Site Supporter
Once in a while the heated drying element gets turned on in ours. It is hell on tupperware. Just one more reason we are switching to corning glass containers as the others get scratched and yucky.
 

waybomb

Well-known member
GOLD Site Supporter
Yes, 195,000 btu NG heater.

In the house in Poland, we have a mechanical tankless heater. Works ok, but the Rheem with its electronic controls and all, the temperature stays consistent at a very low flow or with a few faucets running, including the whirlpool that has 3/4" pipes going to its faucet.

I was worried that getting a heater that could fill the tub while washing dishes, clothes, and taking a shower would be way too variable when just barely running a sink faucet. I was told the electronic controls and design were much advanced compared to what we had in Poland. So I went with it. And the guy was right.

Had an electric water heater prior to the tankless. My electric bill was about double what it is now that my heater is gas. And I have not even noticed an increase in the gas bill. I think it has paid for itself already.
 
Top