Tankless Water Heaters

[calmloki]

We have some old duplexes with 30 gallon gas water heaters in the bathrooms: guess that's not kosher any more. Very limited room available, so i've been looking into options - one option would be to delete a section of kitchen cabinet and rewire and plumb for undercounter 40 gallon electrics. Another option is to mount a gas sealed combustion tankless WH in the bathroom in the original WH location. Downside is it will require chimney upgrades and new gas line - the tankless units take 190k BTU at max vs about 30kBTU for the old WHs. Tankless electric WHs require 2 or 3 huge supply cables and 2 or 3 60amp 240v breakers per heater; read major breaker panel upgrade. An outside mount gas tankless WH maximises room inside, doesn't require a chimney, but does require freeze protection housings for the lines, replumbing gas and water lines, and supplying a 120v receptacle at the heater to run the ignitor (Bosch makes what they call a hydro-powered ignitor, no need for a power circuit, but costs about $200 more than comparable heaters).

The gas-fitters, plumbers, and electricians are hurting my feelings really bad. Like $4250 for a small Rinnai WH, installed outside, no repairs to the interior where the old WH gets removed. It has to be inspected, and it's a rental, so i have to go with licensed workmen and don't get to do it myself. That's about $3000 for labor. Talking a new heater location right next to the crawlhole, a roomy crawl, just weatherized last year, so nice new groundcover and insulation all up in place, 15' to the gas meter and 7' to the water line connection points straight in from the crawl hole.

So. Before dropping more than 10 months of a unit's rent on a single water heater installation - is anybody out there using a tankless? Gas or electric? Happy with it? Capacity and make of your unit? Our little duplex units are tiny one bedroom, shower only, bathroom sink, kitchen sink, the end - no dishwasher or washing machine.

 

[REWahoo]

You might find some information in this thread: http://www.early-retirement.org/forums/f27/tankless-water-heater-anyone-24886.html

 

[Rich_by_the_Bay]

Have a propane Rinnai which replaced a big tank in the attack (talk about an accident waiting to happen...). Set at 130 degress, we have no problem with cool water surprises. I think Consumer reports had something on them in the last couple of months.

We like it. No problems in 4 years, can run hot water all day if we want, no problem with multiple water users at the same time. They are cheaper to run power-wise, at least the gas is, compared to electric, so some recovery of your investment there.

 

[calmloki]

Tanks! (note to self...) here's a nice interactive graphic of operation of a tankless attached. Rinna Tankless: Inside the Box Operating Animation

 

[Rambler]

We have two tankless WHs in our home. I went with a larger Bosch...wanted the hydrostatic igniter (which is only in the smaller unit) but was worried about having multi users on at the same time. Turns out that the smaller unit would have been fine. Building code prevents using water lines that are significant enough in size to be a problem. We went with two WHs because of the size of the house...one supplies each end. I didn't want to run cold water for 5 min from one end of the house to the other waiting for hot water for a 3 min shower.

In general I am very happy with the WHs. I have not run into this myself, my I was told by my sis who stayed with us a few nights, that the shower would get hot and cold. I have not been able to reproduce it, but I suspect it has something to do with not having enough water flow for my big WH to stay engaged...i.e., it may have been cycling on and off.

Also, consider carefully before putting it in the attic. My big Bosch does not like to come on after sitting for three months. When we go home for Christmas, or for the summer (from apt in Asia, where we have a Rinnai), it takes several attempts to ignite. If it does not ignite after 3 attempts, it will not ignit until reset. This WH resides in our attic and is very easy to access thru a door in DD's closet, so we are OK. But, I don't think you want to drag your ladder out to go thru a ceilling access when your tenant complains about no hot water, and sure as heck they're not going to do it either...

My opinion is to go with the hydrostatic igniter Bosch, in the same closet as the current WH.

One final point: do you pay the gas and water, or does the tenant? If you do, you will find your gas and water bills going up, since those endless showers are sure nice on a cold winter morning...and tenants who don't pay for those separately will quite quickly learn to enjoy your new water heater...long showers...at your expense, where otherwise a depleted tank WH would convince them otherwise quite quickly.

R

 

[Bimmerbill]

I have a Noritz and like it a lot. Consumer Reports just did an article on saving energy and I was suprised that the tankless water heater didn't save more money than they reported. I like the fact that if I'm not using hot water, I'm not paying for energy. But I guess the high purchase and installation costs are a high hurdle to payback.

 

[two4theroad]

We installed a Bosch AquaStar Propane unit in our remodeled house in 2002 because the "endless hot water" appealed to us. It DOES live up to that claim but we have constant issue with "too much hot water."
The main drawback of the unit to me is that I can't take a regular hot shower. The water is always too hot, even after turning the unit down to its lowest setting. If I try to reduce the temp by reducing the hot water flow with the shower spigot, the flow goes totally cold. Also you can't set the flow low for rinsing dishes by hand or any other job requiring a minimal flow. The aforementioned low flow switch kicks in and cuts off the gas.
Because of this I have seriously considered removing the unit and converting back to the old 40 gal heater but cost and inconvenience (the hot water heater closet was converted to my walk in pantry) have kept me from following through. The cost alone for converting from tank to tankless sounds like a major expense when installing it in a small rental unit.
I would go with the undercounter unit in the bathroom and build a cabinet around it. That is what we did in my mother's efficiency rentals.
Just my 2 cents worth.
2fer

 

[cute fuzzy bunny]

Great idea if you have a space or location problem (I'm not thrilled with 50 gallon tanks in attics and upstairs closets). I dont think there are many situations where theres an actual cost savings in equivalent use. Maybe if you're a very light user of hot water and only at one or two times per day. A high efficiency, highly insulated storage tank model is pretty tough to beat.

But I think in some situations people replace older, low efficiency, low insulation tank heaters with a high efficiency tankless and see a savings there. Problem is, thats not apples to apples.

There are a lot of threads on the pro contractor sites like hvac-talk and terry loves plumbing forum. I havent seen many of those go in a direction favorable to tankless.

Any chance of building a little water heater shack on the outside of the house on the other side of that wall (where you were proposing a tankless)? Insulate the walls of the shack but not the wall between it and the home. Between the heat from the burner and water tank and the seep through the wall, that might do well in even below freezing situations.

 

[calmloki]

....
Any chance of building a little water heater shack on the outside of the house on the other side of that wall (where you were proposing a tankless)? Insulate the walls of the shack but not the wall between it and the home. Between the heat from the burner and water tank and the seep through the wall, that might do well in even below freezing situations.

The shed idea is a good one that has been kicked around - one shed/duplex. Downside is room (back of the duplexes is about 5') + yet more permits + concrete pad + building. End up with the same plumbing & gas line labor cost issues so the question is whether the difference in cost of two tankless vs. two tank type WH is less than the cost of the building. Thinking the cost difference is maybe $700/heater max, so can i put up a shed for $1400 or less including permitting? Pretty skinny call, and the afore-mentioned lot-line issues come into play.... I really hate to take storage space away from the tenants, which is a big reason against the undercounter kitchen electric WH.

 

[cute fuzzy bunny]

The cost depends on if you do it yourself or contract it out. Pouring a small pad and doing a 3 wall attached 'shed' with a small roof is pretty small potatoes. You might even buy a prefab unit meant for attaching to a house for $300-400.

One thing to throw out there on the gas tankless units and their location inside a dwelling. They sound like a rocket motor when they go off. Basically they're going to have the same sort of sound levels as a gas furnace. I see a bed pretty close behind the existing WH...

I put one in my wifes old house, in an exterior closet just outside the kitchen. The first time it went off I jumped a foot. And that was through an exterior wall...