Tankless Water Heater

[Texasmark1]

Thinking about converting to a different "tool" for heating household water, 2 occupants.

Currently running a conventional 30 gallon, 30kBTU Propane burner, 3 ? OD double wall vertical, roof exhaust vent pipe, 75' ⅝ copper tubing to the tank/regulator, Fisher controls R632-JFF 750,000 BTU/Hr. rated regulator, 0.4 psi, 7/32" orifice.

Dishwasher, gas range and maybe 40kBTU of space heaters in the winter plus 2 bathrooms, also pulling on the 75' (from source) distribution point. A second line from the regulator same pipe, 120' long to a gas clothes dryer.....obviously everything won't be running simultaneously, maybe half or less usually.

Rating on the new tankless heater is 140k BTU/Hr for up to 6.8 gpm flow. Vent outlet is 4 ?" diameter and seems to be flanged so that my vent pipe will sit on it comfortably.........length about 10'.....problem carrying fumes from a 140k burner vs the 30k burner on a regular water heater?

For you users or knowers, am I opening a can of worms? If you just want to wash your hands at the sink, maybe using a quart or so of hot water, does it have to turn and off. Mfgr. didn't specify the size of the SS tank. Said it would last a lifetime....beats my 6 year average with current heaters on my high Alkaline (butttt soooo soft) water.

Thanks

 

[circus]

Simple is better. My brother had one that needed service about once a year. The complexity to make it idiot proof required trained techs $$$ to fix it. Finally just installed a cheap electric heater and planned to change the anode every 5 years or so. Didn't save a dime.

 

[Steve@Advance]

I will highly discourage a tankless water heater for anything but point of use.

I installed one for a friend of my wife. She bought it, against my recommendation, all I did was install it.

Very unhappy with the results. There was no "blending just a little hot" with the cold. It took a significant flow to turn on the burner. It would go from cold to too hot, no happy medium. It was worse in the summer when only a little hot was needed, not going to happen.

The tank may be lifetime guaranteed, but they are far from maintenance free. They have to be acid cleaned to keep the efficiency and flow. Not an easy job.

It does have to turn on for every use. It stores no hot water.

I would recommend a top end gas tank type heater. Probably have to go to a plumbing supply and pay dearly, or research online, find a better deal.

Then buy a solenoid operated drain valve, put it on a timer to keep the sediment flushed. Maybe 5-10 seconds once a day.

 

[Steve@Advance]

PS

I realize you probably want to stay with propane, but another alternative is an electric Rheem Marathon heater. All fiberglass tank, stainless fittings, uses standard elements and thermostats. Lifetime tank guarantee.

I've had one for about 5 years now, installed 2 others, all working perfectly.

 

[Bob Harvey]

Am thinking about one (propane) for the wood fired hot tub at the summer cottage that I manage. The owners are only here (from England) for the summer. Problem is no fires in the summer - in fact fire ban was announced last week. Probably use it during initial filling, then a circulating pump and filter.

 

[Two Dogs]

Just one word from experience. DON'T!

 

[Texasmark1]

They must use Gorilla Glue on the threads of those anodes. I had one I used for several years, the requirement dissolved, I was going to store it for future use elsewhere but wanted to know the anode condition......no go. Course little did I know how heaters have doubled+. Had I known that it would still be here

Thanks folks for your replies

 

[MarkB_MI]

I'd be concerned about supplying around 200K Btu/hr through a 75 foot long 5/8" copper line. Which is roughly the same as a 1/2" pipe. I'm thinking 3/4" ID minimum.

 

[MarkB_MI]

Reference this table:
Propane gas pipe sizing

 

[Texasmark1]

Thanks Mark. I was looking for a chart like that and some conversions therein.

 

[Billy Shafer]

I agree with Two Dogs. Don't waste your money. I worked for a shop that had one. Power bill went up. Water never did heat properly. Water became maybe hot. It went to the trash dump. Had a regular heater put back in.The place we bought it from. No longer sells them. To many returns and complaints.

 

[Texasmark1]

"Fixin" to check out the Rheem Marathon. Thanks

 

[petehall]

I agree with everyone
I had 2 high dollar instant heaters in my house
I went back to regular propane tank heaters
So frustrating trying to control the shower temp !!!
Maybe they have perfected them ???????

 

[504]

I have had two,one gas that back drafted when the furnace came on and froze it. I switched to an electric,three 50 amp breakers to run it. The gas worked better and faster.The newer ones are freeze proof,the heat will come on if it gets too cold. A lot of people complain that the water is either too hot or too cold,the owners manual(both of mine) says to restrict the flow out of the heater,I used a 1/4 turn ball valve so I can hold the water in the heater a little longer. We have been in this house 17 years,mostly just two of us,the most was 6 living here,and we do not run out of hot water.

 

[dcarp]

We put one in on the outside of the house, so it is vented directly. It is under cover from a carport. It has a digital control box mounted on the inside of the house to set your upper temperature limit. We have had this one for 4 years with zero problems.

 

[CenTex Farmall]

We've been using tankless water heaters for about 15 years now. We have the same problem with water eating anything that is not brass or copper.

First one was a Bosch with natural draft vent. It made its own electricity and if you had water flow and propane then you had hot water. It worked fine in the garage in place of the tank water heater. Later I moved it outside on the wall but in its own box to protect it from weather and freezing. After a couple of years it started to go schitzo on us and required frequent fiddling to keep it going.

I replace it 4 or 5 years ago with a Takagi model and it has worked very well. It's made to live outside, has a powered vent and protects itself from freezing. It's one of the smaller models but will run both showers at once.

The temp on the Takagi is set on an inside control panel. The water temp is very stable and doesn't fluctuate, even with people turning other sources on and off. The Bosch was pretty good but would occasionally fluctuate a few degrees up or down but nothing drastic. With the Bosch you could turn on a trickle of water and not trigger it. The Takagi is more sensitive and will fire up with just about any water flow above a drizzle.

On both I have hot water in the same time it took with the old one in the garage.

What I did with propane was run a two stage setup with one regulator at the tank and then a second step down at the house. I haven't had any issues with this setup, lines are sized according to BTU at given pressure. The BTU ratings on these things are for maximum demand at a maximum temp differential between set point and incoming water temp, i.e. the thing makes the fire bigger or smaller as needed and mostly it's smaller.

They both have very efficient heat exchangers. On the Bosch you could get reach right above the heat exchanger with the cover off and even with all that fire burning under it you could hold you hand in the exhaust.

During the summer (not running central heat) you can't even tell any gauge movement on the propane tank from May through Sept.
They definately save on fuel, fwiw.

 

[Ian Beale]

Around here Rinnai is one of the goto brands. Needs an electrical connection though.

We got there after working out that solar was a very expensive hobby. No problems in a few years of use.

 

[1130Leo]

I had a bosch, hated it. Many people I know have the Reni brand, they like them.

 

[1948CaseVAI]

I read a couple of plumber forums and the pros call then "thankless" water heaters. Of course the pros like them because each one is a reliable annual service call.

 

[BigPapa53]

(reply to post at 23:58:10 05/20/19)

We just went with a Rinnai and we, too, are very happy with it.

We'd always had electric and we were fixing to have to replace our 5th one in 35 years. We added a room on the house and we thought we could put a conventional gas water heater in a hall closet but codes said no, so then we were going to put it in the crawl space but it wasn't high enough. I was against it but it was really our only option if we wanted to go NG.

The only issue we've had was getting it to come on when turning on the hot water at the sink in the new bathroom and a bathroom we remodeled. I finally figured out it was because both the faucets we had installed were Delta "ECO" models, designed for low flow. I called Delta to ask about modifying the faucets for more flow and was told that the flow restriction is in the aerator. I changed out the aerators and no more issues.

Water temps are good and consistent and our cost for hot water has definitely gone down.

-Scott

 

[Texasmark1]

Just curious, how do Solar Panels stand up to hail? How heavy are they per area? How do you replace your shingles with solar panels? How prone are the attachment points to leaking?

 

[buickanddeere]

You will be happier with a tank LP heater . And install a 1 or 2 gallon 120V tank heater under the kitchen sink .