Axiom Home Page Forums General Discussion The Water Cooler Tankless water heater?

Guys, Adrian's furnace thread just reminded me there's a whole panel of people right here willing to share their knowledge on all sorts of topics, so here goes:

My water heater is getting old and my local service dude mentioned the tankless idea as an eventual replacement. I have absolutely zero experience with the tankless heaters. I get them in concept but I don't know where to start to figure out if it would be worth the switch for my family of 5. I am on natural gas as my fuel source. Thoughts? Things to consider?

Thanks!

Shawn, where are you?

Dan, I don't know much, but share a somewhat recent experience.

We had our water heater replaced by a plumber that we trust, and I thought it would be a good idea to go tankless. He doesn't like tankless here in NH, because the incoming cold water temps are so cold that the units don't hit anywhere near the efficiency that they do in warmer climates.

If there is some truth to that, Ottawa's climate should prove more a factor than NH's.

Dan, i have had a Bradford White tankless water heater for a couple years now and have no regrets whatsoever. However, I'm a single homeowner and don't use much water.

Some things to consider are the size of your house, having a family of five, and water consumption. Because instantaneous water heaters only function when there is a call for water (specifically hot water), they have a limit on the amount of hot water they can supply at one time. For example-if someone is having a hot shower, and you are doing a load of laundry with hot water, you may not get any hot water if someone wanted to do the dishes at the same time. I haven't done any research in a long time, but I'm pretty sure the water heaters are rated on the projected demand per household, and the size of the house.

Something else to consider is that they are extremely efficient in the sense that they don't rely on a constant energy source to keep them running, like a contemporary water heater, but, they are extremely inefficient to run, and that's where questions arise i.e. if there's a large family that will rely on a lot of hot water, they technically might not be that efficient. My water heater puts out more BTU's than my furnace.

Another thing is when you turn on the hot water tap, you won't get hot water right away, and you may have to wait up to 30 seconds or possibly even more if it's a large house.

As Adrian said, Shawn is the expert, as it's his field of work, but hopefully I have provided you with some information that you previously didn't know.

If you have any other questions, ask away, and I'll help as best I can.

Cheers.

I vaguely remember my boss saying something about his tankless water heater not providing enough hot water on the spot for he and his family of four.

That's all I know.

I can't disagree with any of the above.

A friend built a new ~2,400 SF house a few years ago. They needed TWO tankless water heaters and she's still not "happy". Technology may have improved since then.

IIRC tankless water heaters seem to be most successful when used in specific locations of the house in conjunction with a "big white tank" heater for everything else.

A fancy shower or soaking tub might get its own tankless heater, or "the bathroom at the far end of the house" where it might otherwise take 5 minutes for the hot water to work its way along the pipe and out the low flow faucet.

For a family of 5 with natural gas I would go with a conventional water heater.

Disclaimer - I learned everything I know about tankless water heaters off the internet

My new house is 2600 sqft, 2 story and we have a hybrid system. The Rinnai tankless feeds into a 40 gallon tank which has a temp sensor on it and a pump that circulates the water through the Rinnai when the temp in the tank drops to low. We also have a circulation pump just for the water lines in the house to cut down on how long it takes to get hot water at any of the taps. This system works very well for us; after a few months of figuring out how to get the settings just right. The line between the tank and the heater has a filter in it, the purpose of it is to prevent the heat exchanger on the tankless side from clogging up.

Thanks for all the input guys, that really helps. My main 2 reasons for thinking about this was for the efficiency and the space savings in furnace room (I have a fairly small house).

Cam - with a family of 5 and regular baths/showers for the kids I think I may hit those inefficiencies with it running fairly often.

Jason - the hybrid system sounds like a great idea (never heard of that concept before) but there goes my space savings if I need a secondary tank anyway. And having 2 tankless systems just doesn't make sense cost wise for me.

Mark - good point on the temp of the incoming cold water, mine in Ottawa is quite cold, even in the summer if you let it run long enough.

So so far based on what I'm learning I am leaning away from the idea, but have not ruled it out yet.

I wonder if there's any calculators out there that let you figure out what the best option is for you?

Well, and how long will it take to recoup the increased initial capital investment?

We could put a team of gov't statisticians together, maybe a panel of 8, to do a study for the next 6 months to see how much you'll save on your water bill.

OK! Now we're talking!

But first, let's form a sub-committee to decide what to name the committee!

Ok. I think the first thing we should do is go on strike.

I'm glad this thread was started. It made me think. My hot water heater just goes about its job, never complaining, just providing hot water day in and day out. I almost take it for granted. Everyone should pause a moment this time of year, and give...

Oh, it says "tankless". Never mind, as you were.

A friend of mine is a plumber and he said you should consider the age of your home with respect to the size/material of the water lines. He also mentioned that with a large family (he has 3 kids)he didn't recommend the tankless systems. My neighbour did a full reno (demo down to the studs) and installed new water lines with a tankless system. He is quite happy with it however there are only two adults in the home.

We've Had our tankless for several years now and are very happy with it, It does take running the water a little longer to get it to heat in certain showers, but we have 5 bathrooms in a 5,000 sq ft home. The water also gets much hotter than it did with our previous water heater. The big bonus for us was in our propane savings, the unit has more than paid for itself. Remember a tankless heater only turns on when a hot water spigot is opened where a conventional heater is always running.

Michael, do you have a different experience with the hot water when the incoming water supply is colder?

I have considered tankless and anyone that I talked with that had tankless - including a family of 6 (4 girls) were all quite happy with theirs. The caveate is that they all had Propane / Natural Gas. The one thing I have not seen specified here is whether or not the tankless systems being discussed are Electric or Gas? The scuttlebut down here is that no one with Electric is happy.

The guy in reference to my reply is using electric.

Thanks for the laugh Chris!

Again, thanks for all of the comments everyone. While discussing this with my wife last night she pointed out we actually almost never run the dishwasher and take a shower and ... For whatever reason the water pressure in my house is not great so we actually avoid concurrent water usage out of habit.

Argon - it is natural gas supplied.

Cheers!

Michael, that's one area that I have not been able to figure out - if the savings on natural gas will offset the increased price of purchase & installation.

CB,
I was more asking if some of the various comments where others were lees than pleased could be tied to electric in-line heaters as opposed to gas?

Tom, the only difference I've seen is that the water will take longer to heat up during the winter, particularly in the baths with the longest supply line from the tank.

Dan,
I'm not an expert but I would assume the size of your house would make a big difference. Our old water heater had to do a lot of work to keep the water in our house warm, I'm sure in part due to having so much line to accomidate 5 bathrooms,I would still have to run the water to get it hot, and in certain rooms it would never get as hot as I wanted, it wasn't uncommon for us to also run out of hot water. The tannkless never runs out of hot water and you can set the temp. up to 130 F. That being said I think you would still realize a savings in a smaller home due to the fact it uses gas on demand. And if you like scalding showers like I do it's the way to go.

Things must be OK for you, Michael.

My showers generally need to be cold.

Lol

Oops wrong thread.

I have recently installed a rinnai tankless water heater. I like the fact that I never run out of hot water, but I don't think that the heater lives up to its stated 7.5 GPM. When the washer draws hot water I get almost nothing in the shower. It's only been a few months so It is still too early to tell if I'm glad I went this route. The one thing I do like is the space savings which was important to me.

That could also be due to the design of the water lines and the washer has a more direct route instead of being fed off a manifold to equalize the flow to all lines.

Oh, another good point Jason. I am in an older bungalow and there is definitely differences in flow patterns/routing to different taps. No central manifold here.

Thanks for the info Listener - keep me posted as you get more experience with your system.

Jason

I never experienced the problem with no water in the shower when I had the old heater. At the time I had the heater installed I also had a pressure reducer installed. I guess my pressure used to be between 125-150psi. It is now reduced to 95psi. Perhaps that is why I did not experience the problem before.

We are on a well and I recently worked on my pressure. It was fluctuating from 18 psi (a mere dribble) to around 45 PSI. My fiddling got it from 33 - 60 psi and we think we are in heaven. I have a pressure washer that can't hit 150 psi? Sounds like that would peel the skin off?

Sorry to add what seems to be an opposing opinion, but, then, as said, other attendant systems have a great affect on the outcome.

We have a small house w/ forced hotwater bsbd. The tankless sytem that was here when we bought was tied into the furnace/heat system. When the heat was on in the house, both the pressure and the delivery of hot water were compromised.

We switched to (elec) hot water 3 years ago (60gal).

We've been much happier. Or, since the comparative is disappearing, "more happy."

Keep Happier Alive!