Electric Tankless Water Heaters - Need advice pls | GTAMotorcycle.com

Electric Tankless Water Heaters - Need advice pls

Jenerator

Jenerator

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Hi all,

At work we're putting in a gym with two washrooms (one shower, toilet and sink each) and the bossman wants electric tankless water heaters, again, one for each washroom. Has anyone RECENTLY installed one of these in this climate (Toronto) and had a positive experience? I see many that are called "whole home" but then they state they are for cottage use. We don't expect constant usage but there could be a lunchtime "rush", let's say two showers in a row for each washroom for example.

I'm trying to figure out which brand/model to install and want to see if there are any real-life experiences around here, rather than going purely by what the manufacturer says (their customer service recommended the second highest model, one for each washroom, which my boss thinks is overkill, especially since we'd also have to upgrade the electrical service for that area of the building).

Thanks.
 
kwtoxman said:
That would result in a big hit to power bills. No way I'd do electric tankless. I'd go tankless natural gas. Rinnai is a good name. Cheap brands are problematic for many.
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In an industrial application, exhaust for NG heaters may involve roof penetrations ($$) and as the showers will likely be used in times of low production, it may not have a substantial effect on the monthly bill. For a house, I am 100% with you (unless it was a very occasional use like a pool cabana).

What happens if you try to draw two showers at once through a single heater? My guess is both people have lower water pressure and not as hot as they would like, but so what, it's a quick shower at work. I doubt 2 showers would be enough to make a heater fall flat on its face and deliver cold water.
 
GreyGhost said:
In an industrial application, exhaust for NG heaters may involve roof penetrations ($$) and as the showers will likely be used in times of low production, it may not have a substantial effect on the monthly bill. For a house, I am 100% with you (unless it was a very occasional use like a pool cabana).

What happens if you try to draw two showers at once through a single heater? My guess is both people have lower water pressure and not as hot as they would like, but so what, it's a quick shower at work. I doubt 2 showers would be enough to make a heater fall flat on its face and deliver cold water.
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Definitely industrial applications are going to be different from home. But as I understand the OP the use is a gym shower/bathroom combo which sounds like it would be similar to a home install and use. As in daily (?) use. Also, my guess is that a wall vent setup would be most often used in lieu of a roof vent, though this is getting outside of my wheelhouse.

As far as capacity (e.g. two showers), that depends on what the tankless water heater is rated for volume wise. It's an easy check for gpm estimates of showers versus what the heater is rated for. And manufactures have designed tankless water systems to be modular, so a daisy chain setup is the solution for higher volume requirements.
 
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Have Navien gas heater at home, takes about 30 seconds to get hot (a little water wasted) but we can run the dishwasher, do laundry, and take 2 showers with no noticeable impact. Both showers have low flow rainshower style heads anyway so pressure changes are barely noticed.
 
No gas line nearby, boss will not pay to have one installed.

From what I've read, flow rate is largely affected by the inlet water temp, so the colder it is the slower it will be heated by the unit, thus resulting in a slower flow rate of output, which, if supplying two showers at once, could end up being a trickle. That's why I'm looking for input from those who actually have these things installed. :)
 
I have a Rinnai gas unit at home. Yes, you need to consult the mfrs chart related to incoming water temp and flow rate.

You may be misunderstanding though, the tankless water heaters do not restrict water flow at all. The temp/gpm table just tells you the flow that it can heat successfully. If you exceed this, water will still flow but will not be heated enough.

My Rinnai is rated for something like 190,000 BTU, which is why most people say that electric heaters don't work well in such a demand situation. Sounds like Scuba Steve is happy though, albeit his is a residential-back-up vs commercial use like you need.

I'm assuming that you have toilets in your business today. How do you get hot water now? Why install a totally separate system?

Assuming you have natural gas service already, paying a plumber/gas-fitter vs an electrician may be a wash. And I'd expect ongoing consumption to greatly favor gas. Just vote conservative next time and hopefully we'll avoid this carbon tax hogwash.
 
never mind heating things up...keeping things cool made my elec. bill double $ this month.

On a side note, those that have it at home, have you noticed a savings in gas cost? Is the unit mounted in the same place the old tank used to be(basement) or somewhere mid way between the outlets?
 
FLSTC said:
You may be misunderstanding though, the tankless water heaters do not restrict water flow at all. The temp/gpm table just tells you the flow that it can heat successfully. If you exceed this, water will still flow but will not be heated enough.
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I was going to mention that but the OP said he wanted input only from people who have it.
 
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Some of the electric ones have a flow valve that slows flow if the heater isn't keeping up so the water is always the same temp coming out even if the flow is reduced.

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Our old tank had died - we went tankless not really for the ongoing savings, but for the space savings. We had it installed on the basement wall near the furnace and this made space to have a really nice sauna - includes space where the old tank was.
 
Jenerator said:
From what I've read, flow rate is largely affected by the inlet water temp, so the colder it is the slower it will be heated by the unit, thus resulting in a slower flow rate of output, which, if supplying two showers at once, could end up being a trickle. That's why I'm looking for input from those who actually have these things installed. :)
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Flow rate is generally not regulated by a tankless water heater - the same amount of water will flow through it no matter what, and the more demand you put on it the more water that will flow through it right up until you reach the limit of the plumbing size to/from it. (Edit: If some restrict flow to keep temperatures up this sounds terrible to me - I'd rather have a high flow sorta-warm shower vs a hot dribble, no?)

What WILL change is the output temperature. If you're drawing up to the maximum GPM (gallons per minute) the unit is designed to heat you'll have a satisfactory experience. When you start to exceed that limit, simply put, the water won't be as hot as it should. When you grossly exceed it, expect lukewarm water at best.

Electric tankless heaters are not great when compared to gas - the large ones have MASSIVE amp draws, think hundreds of amps. One for your application will likely be in the 125-150 amp (at 220v) range. Unless you have this sort of wiring nearby the location for the heater it will be a costly undertaking installing the electrical setup - you're talking 8 gauge wiring if the heater itself is near the electrical panel, but possibly down to 4 or even 2 if it's some distance away, of worse yet, you may need a pony panel installed to feed it instead. All that is major electrician $$$, very likely on par with just getting a gas line run to the shower area and going with a much better natural gas heater in the end. And it'll be a LOT less expensive to run in the long term.
 
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Another option is to install the tankless gas heater near to where the gas supply is and/or where it's easy to vent, and then extend water lines to the supply and demand locations. Same if you choose the electric - install closer to the panel.
 
what if you were to plumb a 30gal holding tank prior to the tankless heaters so they are at least drawing in room temp water on start instead of 15deg ground supply?
Just thinking
 
FLSTC said:
Another option is to install the tankless gas heater near to where the gas supply is and/or where it's easy to vent, and then extend water lines to the supply and demand locations. Same if you choose the electric - install closer to the panel.
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Certainly a cheaper and better setup in the end, but the plumbing line will need to be sized accordingly if it's a long run...but in the end, PEX is cheaper than wiring or gas line, so it's certainly an option so long as people don't mind the potentially VERY long delay to get hot water. For a shower that's one thing, but for someone washing their hands after using the can, well...that's a bigger thing - it could take a minute or three to get hot water from a tankless system with a 100-200 foot run of plumbing.

crankcall said:
what if you were to plumb a 30gal holding tank prior to the tankless heaters so they are at least drawing in room temp water on start instead of 15deg ground supply?
Just thinking
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Sure, but in the end....I suspect our OP and his boss many just find that going with an old fashioned tanked system, plumbed in traditionally near the bathroom would be easiest. If volume of water is a concern given the multiple showers, buy a bigger tank, or setup two or more small/medium electric ones in series - also a very common setup where additional volume of hot water is required, and arguably (since the electrical demands of tankless are potentially a problem vs two lower amp demand traditional storage tanks, and the venting/gas issues of a gas fired tankless also present issues) may be the simplest and most realistic option.

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I have installed hundreds on tankless water heaters. Most do actually have a flow valve which will throttle the flow rate to keep a steady temperature. If the heater is installed far from the actual faucet/tub/shower, it's common to install a single loop hot water line to recirculate some hot water and keep hot supply time to a minimum.
A gas model will be much much cheaper to operate in the long term, despite install costs for a gas line and venting.

Sent from my Le Pan TC802A using Tapatalk
 
Iceman said:
I have installed hundreds on tankless water heaters. Most do actually have a flow valve which will throttle the flow rate to keep a steady temperature.
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Hmm, I stand corrected then, but is this something reasonably new? My last exposure to a tankless system that was undersized for the demand yielded a strong flow of water, but not as hot as it should have been.

I've seen the recirc line used with long plumbing draws on traditional tanks, but for a tankless system wouldn't a recirc system have the demand unit switching on and off fairly routinely to keep that long run hot? I'd think that the economics of such would completely negate any savings vs a traditional storage tank setup, no?
 
PrivatePilot said:
Hmm, I stand corrected then, but is this something reasonably new? My last exposure to a tankless system that was undersized for the demand yielded a strong flow of water, but not as hot as it should have been.

I've seen the recirc line used with long plumbing draws on traditional tanks, but for a tankless system wouldn't a recirc system have the demand unit switching on and off fairly routinely to keep that long run hot? I'd think that the economics of such would completely negate any savings vs a traditional storage tank setup, no?
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The flow valve is not new, nor is it used by all manufacturers. If a unit is designed for a recirc loop, it will have a small cushion tank and circ pump, and yes it will fire occasionally but not as much as keeping a tank hot. These are more often found in commercial units and/or extremely high demand homes.
To be fair, I left the industry fiveish years ago and newer tech has likely been developed and I wouldn't be current on it. The previous generations I installed and serviced for fifteen years.

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