OT Tankless Water Heater

Re: OT Tankless Water Heater

johnv

Our son in Houston built a new house 3 yrs ago. The tankless is very efficient and does a good job on meeting demand. You need to size the unit for your max expected draw. Be aware that your NG supply line may not be sufficient for a high but unit, The only downside our son has is noise when it comes on(every time a hot faucet is turned on. The unit was mounted on a common wall to the house and noise is transmitted thru to adjoining rooms. Not a major noise problem just irritating at times. So think about where it will be set.

Re: OT Tankless Water Heater

johnv

Might require an expensive new service line.

Re: OT Tankless Water Heater

Barry Irby

My information may be dated, so take it with a grain of salt. You need a fairly powerful heater to produce enough water for the jetted tub. So it must have a high flow rate and large capacity burners. Some of them have 175,000 BTUH burners. The problem is if your gas line is older and sized for lets say 100,000 BTUH you may have to replace the gas line and meter.

Additionally, they may have solved this problem, but some of the bigger tankless units would not respond to a small flow of water. So if you turned on a trickle the unit would not fire and you would never get hot water.

And some of them did not respond well to power interruptions, even flickers. Power flickers tend to turn them off and you have to manually re-set them. Even though they are gas, they have some electronics that require power so you may not have hot water during a power failure.

And they have to be protected from freezing.

Re: OT Tankless Water Heater

JL

We installed two Rinnai tankless heaters for our old church - one was for the kitchen area and one for the restrooms.

The kitchen one was a high capacity and propane powered. It is mounted on the outside of the building. Not quite instantaneous - the water has to get from the heater to the faucet.

On the plus side - you can wash load after load (after load) of dishes. You can set the thermostat quite high (we set it at 150 F - and had to put warnings on the faucets). Quite a few years later and it is still going strong. You figure if it can clean up after dinner for 100 or so - it puts out a lot of hot water.

On the minus side - as it was mounted outside - you have to watch out for freezing (especially in a church, where it doesn't get constant use). YMMV of course.

Re: OT Tankless Water Heater

john in Lutz

Put a gas one in. One thing that concerned me was a requirement that be back flush every year to get rid of any hard water build up. They were instructions on how to DIY it but pretty involved. Figured you just have to pay for a service call every year. However moved before the first year up.

New service of NG

Mike L

I guess I should have said this up front. I have a brand new NG service and meter. The house I bought was all electric including heat pump. The second $500+ electric bill last winter I called and found out I could get NG for installed free, if I was replacing an electric heat pump or stove or water heater. I changed the Heat Pump. The service line is a 1 inch line with three take offs. I had them installed for water heater, fireplace and stove just in case, so there should be plenty of volume for a tankless.

Re: New service of NG

David Yoho

Mike, we've been using a Rinnai RUC98 condensing tankless on NG for about 4 years and love it. Ours will supply up to 4 things at once. The draw back to these units is it can take a while for hot water to reach a distant faucet but can be dealt with by getting their circulating types.

The NG units consume very little electricity. The installer told me I could power it from the AC outlet in my RAM truck if the power was out.

Cleaning my unit is a breeze. I paid the first year and did it myself ever since. A pair of washing machine hoses, a small submersible pump, and 3 gallons of white vinegar is all you need. Rinnai has a video out there showing this.

They run rebates frequently. We had a plumbing contractor install ours and they did a great job. Even got the rebate applied to the price.

Re: OT Tankless Water Heater

Jack Guzman from Maine

I installed one that runs on propane. I love it. My propane use nosedived dramatically. I am no longer heating water 24/7. The only down side is the wait for hot water to reach distant faucet.

Well tankless it is

Mike L

the plumber just left. The price difference was not that much ($300) plus the cost of running the gas line and exhaust. I figured I wanted to get away from the electric one anyway. I didn't ask the name brand, but it has a 12 year warranty, recirculating pump @ 9.9 gallons a minute.

Re: Well tankless it is

Yonak

Mike, how does the recirculating system work ? Do you have to be running the heater constantly ?

Re: Well tankless it is

David Yoho

Do you have to be running the heater constantly ?

No, like normal, the heater does not run until hot water is called for. The difference is a recirculating pump and sensor speed up the delivery of hot water. Once the hot water arrives to the faucet the sensor tells the pump to shut off. Rinnai has a way to circulate water to a distant faucet without the need for a dedicated return line, thus saving on installing one.

hmmm .. still not getting it.

Yonak

..So the pipe to the far flung faucet is empty and that's how it gets the hot water there more quickly that turning on the faucet ?

If I'm not mistaken, my brother's house has a dedicated heater for each section of the house.

Re: hmmm .. still not getting it.

David Yoho

The way it was explained to me was, whether the faucet farthest away utilizes a dedicated return line or the existing cold water line, a loop is created. When the demand for hot water is sensed from that faucet the pump begins pushing water there and once the sensor sees hot water the pump cuts out. I'm sure there's more to it than that but that's the main part. The water line is never empty and the tankless heater is not running full time circulating hot water in the loop. I think it gets to the faucet faster because of the pump.

I know several people that built homes in the past 5 years that installed two tankless heaters to resolve the issue.

I do know that replacing my 2-year-old electric water heater with the natural gas tankless resulted in a savings on my energy bill. The best part is not running out of hot water like would happen with the standard water heater.

Possible cheaper fixes for quicker water

Bill Tindall, E.Tn.

It took what seemed an eternity to get hot water to my daughters guest bathroom. They were contemplating various expensive solutions. I noted that it took an unexpected amount of time to fill a glass from this sink faucet.

I just tested in our house and unrestricted it takes 1.5 min to move water about 30' at 60 psi inlet pressure. Unrestricted means the faucet is not flow restricted.

In the case of daughters house she had three problems, all easily remedied. I upped the inlet pressure from 40 to 60 psi. The cut off below the sink was restricted. And finally the residents of water starved CA mandate our faucets in water blessed TN deliver some piddly amount of water per minute. Take the faucet apart and rip out the restriction.

What can't be easily fixed is a hot water heater not centrally located or the mistake I have seen made of running 3/4" line to sink faucets. 30' of 1/2 pipe contains about 4 gallons of water that has to be displaced to change from ambient to hot. It will take a flow restricted faucet several minutes to pass this amount.

how....

Bill Tindall, E.Tn.

....does a pump get water through a pipe any faster than inlet water pressure? Before I bought a system I would need to understand how it worked and that how it worked made sense for my needs.

Re: how....

David Yoho

Bill, I wish I had answers for you. I'm sure a qualified installer would be able to explain it all. Our tankless does not have a circulation pump. The upstairs bathroom in the hall is the farthest point from the water heater but sees very little use these days. The rest of the faucets, dishwasher, washing machine, and our upstairs bathroom get hot water fairly quickly. The garage wash sink and washer being the closest get it almost immediately.

Before I bought a system I would need to understand how it worked

I agree with you. In my case, since we were not utilizing a circulation setup, I didn't question it much more than the general info given.

Here is the idea of how it works

Mike L

I did a little Google Search to find out. I have a pretty good idea of how they work in my head.

https://www.pickhvac.com/tankless-water-heater/is-a-recirculating-pump-worth-the-money/

I have done all of that

Mike L

When we moved here in Aug 2019 the second thing I did was to get rid of all the flow restriction devices in the faucets. The pressure here is on the low side most of the time anyway and they needed to go. They are all 1/2 copper lines running to the faucets the only 3/4 copper line is at the water heater.

Thanks

Thanks, explained it well

Bill Tindall, E.Tn.

The "smart" system that circulates in the AM, for example, and off at 3 AM makes sense. Continuously circulating seems like trading storing hot water in a highly insulated tank vs essentially storing it in a line that is going to loose heat readily if copper and not insulated. Personally trading all that complexity to save a minute shaving (which is now occasionally ) is not one I would make. In my hands complexity breaks would would lead to more annoyance than waiting a minute for hot water.

Good info

David Yoho

Okay, I understand it better now. For me, the wait for hot water to our most used faucets is not long enough to cause me to need a pump. On those faucets I actually think it's pretty quick. Since our upstairs hall bath is used so infrequently now, it doesn't matter how long it takes.

One feature I do think is important in choosing a tankless is the condensing vs. non-condensing type. Condensing units are more efficient and should last longer.

A Tankless Tale

David Yoho

This topic made me recall a recent event involving hot water. The short version is - one day while outside I noticed the brick on the lower left corner of where our crawl space door is was wet. I figured there was a leaking pipe since there are several just inside the opening. I was not prepared for what I saw when I opened the hatch!!

Removing the door revealed a steamy, wet, sauna-like mist across the entire crawl space. Our crawl space is an enclosed one with blown insulation on the foundation walls and a heavy plastic vapor barrier on the ground. The air handler for he first floor has a vent at the supply duct that supplies conditioned air to the crawl space so it's cool in the summer and warm in the winter.

I knew instantly I not only had a leak but a hot water leak. The bad part was the leaking pipe was spraying and it was all the way at the opposite end from the crawl space door. A few trips under the house, a Shark Bite "T" and it was fixed. It took a week of running fans under there to dry everything. No real amount of water sitting on the vapor barrier - just a few puddles. After drying I treated the wood and other surfaces with a mold killer / inhibitor and all is well.

Not sure just how long the pipe was leaking but one thing is for sure. It sprayed hot water until I shut off the water. That tankless was sending 120-degree water relentlessly!!

We talked about under the house

Mike L

but I want it were I can see it. So it will be in the same place as the tank one that is coming out. Inside the garage to the left of the door leading into the house. That should make it easy to get adjusted the first time and do maintenance on it.

Re: We talked about under the house

David Yoho

I agree. Ours is in the laundry room where the old electric water heater was. My wife's aunt lives in Tallahassee, FL and hers is on the outside on the back of the house. A buddy nearby installed two. One in the garage and a second under the house toward the other end of the house.

Re: A Tankless Tale

Barry Irby

Mine wasn't tankless, but in my rental house the pop off valve failed and was spraying hot water into the crawl space. The tenant was complaining to the agent about the high cost of electricity and water. The agent thought they were just b*tching. I finally got a letter form the Building Official about the water running into the street. (A mosquito problem). When I got there the water had been running for months. The floor joists were warped and rotting and the plywood subfloor delaminated, (about ten sheets) and the particle board underlayment turned into sawdust. A few thousand dollars later we installed a new water heater.

I asked the agent why she never told me and she said she thought they were just b*tching.

You don't want a water leak, but you REALLY don't want a hot water leak.