"Instant" on demand hot water units... how long to get hot water?

[88CRX]

How long should you have to wait to get hot water?

New build with a brand new instant on demand hot water unit.... it sucks (we will be replacing it as soon as it breaks) as it can take a couple minutes to get hot water at taps at the far corners of the house.

Any settings to help, should we crank the temperature controls on the unit up? Can we add an under cabinet heater to help heat the faucet water up quicker?

[jwslam]

I've noted the same issue in a new build as well. The master bath is as far as possible from the heater and takes minutes to heat up even with the unit cranked to max. I don't believe it really has anything to do with whether it's on-demand or a tanked water heater, just a fact of how such a long stretch of piping has stagnant water sitting around at room temperature.


Can we add an under cabinet heater to help heat the faucet water up quicker?
That's about the cheapest solution I can see but still doesn't help with the shower. I believe the better local ones will require 240V wiring as well.

Here's a cheaper one from HD that uses 110
https://www.homedepot.ca/en/home/p.advantage-35-kw-point-of-use-mini-electric-tankless-water-heater.1000841434.html

[88CRX]

Warming up the shower for a minute is ok (I guess).... but running tap water for a minute or two to wash your hands seems stupid.

[redevil]

Do you have a re-circulation pump on the hot water line that is on a timer? If you don't I would suggest you add one with a timer that you can have circulate before you wake up and other times such as before going to bed. This is what I have done so that the hot water has circulated in the lines and takes less time to get to the far end of the house. Also added the pump to a wemo wifi plug so that I can turn it on manually or set it on for a schedule easily.

[ExtraSlow]

Recirc pumps are the way to fix this.

[thinmyster]

I hated my on demand heater for many reasons. I switched to a tank and been happy ever since

[88CRX]

Do you have a re-circulation pump on the hot water line that is on a timer? If you don't I would suggest you add one with a timer that you can have circulate before you wake up and other times such as before going to bed. This is what I have done so that the hot water has circulated in the lines and takes less time to get to the far end of the house. Also added the pump to a wemo wifi plug so that I can turn it on manually or set it on for a schedule easily.

We have nothing. Could the pump be installed in the unfinished basement where we could add a plug/pump easily? Or does it have to be installed under the sink at the far end of the house (which would be slightly more challenging.

And I like the idea of the wifi switch.

edit: we'd need a re-circ line for this to work, correct? Shits.


I hated my on demand heater for many reasons. I switched to a tank and been happy ever since

Builder wanted to charge extra to go to tank so we declined. Will live with this on demand for as long as possible then 'downgrade'.

[redevil]

We have nothing. Could the pump be installed in the unfinished basement where we could add a plug/pump easily? Or does it have to be installed under the sink at the far end of the house (which would be slightly more challenging.

And I like the idea of the wifi switch.

edit: we'd need a re-circ line for this to work, correct? Shits.



Builder wanted to charge extra to go to tank so we declined. Will live with this on demand for as long as possible then 'downgrade'.

Should be able to add right next to it if you have a re-circulation line going back to the hot water unit from the cold line in. re-circulation pump just plugs into a regular outlet where I have it plugged into a wifi switch.

http://www.takagi.com/media/21805/Takagi-Tankless-Recirculation_Systems.png

[88CRX]

Should be able to add right next to it if you have a re-circulation line going back to the hot water unit from the cold line in. re-circulation pump just plugs into a regular outlet where I have it plugged into a wifi switch.

http://www.takagi.com/media/21805/Takagi-Tankless-Recirculation_Systems.png

Cool.

So you just add a small loop in the basement mechanical room? Then all you deal with is clearing the cold water thats in the pipe from the basement to each fixture (which is not that big of a deal).

[eblend]

edit: we'd need a re-circ line for this to work, correct? Shits.


I looked into this myself, and you don't need a dedicated line, it can use the cold water line for a return, don't really fully understand how this works, but apparently it does. There is the issue of your cold water line being somewhat warm as well and u would have to run it for a while to get the cold water. You can install this downstairs in the basement.

Keep in mind, there are various different ways plumbing can be done, and unless you have a loop system, at best it will get the hot water upstairs, but it won't be instant at the faucets, as the water would still have to travel from the second floor to the extremities of your faucets.

[killramos]

Cool.

So you just add a small loop in the basement mechanical room? Then all you deal with is clearing the cold water thats in the pipe from the basement to each fixture (which is not that big of a deal).

I think this only works if the loop is sufficiently close to the usage points. Also the bigger the loop the more energy ($) is wasted for the luxury of fast warm water.

End of the day water sitting in the pipes in one place will get cold.

The solutions all the just mitigate the issue by shortening the path between where It is warm and the usage point.

[benyl]

I think this only works if the loop is sufficiently close to the usage points. Also the bigger the loop the more energy ($) is wasted for the luxury of fast warm water.

End of the day water sitting in the pipes in one place will get cold.

The solutions all the just mitigate the issue by shortening the path between where It is warm and the usage point.

Yeah, we have a re-circ line and I disconnected it. Fucking useless with long runs. Water temp varies wildly and indirectly heats your house in the summer.

I should have built a manifold for hot water where each washroom has a direct line to the boiler so that it is the shortest possible. Next house I guess.

[kenny]

As eblend mentioned if you didn't get a recirculation line installed during the build, you can use the cold water line. You'll need the hot and cold lines furthest away from water heater T'd off to a pump. It'll move the room temp water in the hot line back down to water heater via the cold water lines. The drawback to this is that your cold lines will be room temp (possibly even warm momentarily) if that matters to you.

You would have to make sure the pump is moving enough water to trip your flow sensor though or it'll never heat the water.

[88CRX]

I'll have to do some timed tests.

Powder room (which is right above the mech room) VS ensuite sink (which is as far as possible away) to see the difference.

Suppose there are 2 issues, the time for the unit to heat the water AND the time to clear the line of cold water to hot.

[kenny]

I'll have to do some timed tests.

Powder room (which is right above the mech room) VS ensuite sink (which is as far as possible away) to see the difference.

Suppose there are 2 issues, the time for the unit to heat the water AND the time to clear the line of cold water to hot.

The recirculation pump really needs to be plugged into a smart outlet to function properly without wasting tons of $. My builder had the recirc pump set to turn on every morning but trying to set other times where we would want hot water right away was tough. Now, it is all based on activity around the house (motion in washrooms, first activity in morning, etc). If the hot water line is cold, it takes just under a minute for hot water to circulate with the pump I have.

[88CRX]

The recirculation pump really needs to be plugged into a smart outlet to function properly without wasting tons of $. My builder had the recirc pump set to turn on every morning but trying to set other times where we would want hot water right away was tough. Now, it is all based on activity around the house (motion in washrooms, first activity in morning, etc). If the hot water line is cold, it takes just under a minute for hot water to circulate with the pump I have.

Sorry but do you have an on-demand hot water system or do you have a tank?

[mr2mike]

Tankless... have fun with the constant de-scaling services... Never going tankless.

[88CRX]

Tankless... have fun with the constant de-scaling services... Never going tankless.

Is that major issue with a water softener as well?

[Euro838]

Tankless... have fun with the constant de-scaling services... Never going tankless.

I think the warranty is void if you do not install a water softener. I have tankless and water softener and have had zero issues. Shower takes about a minute or so to warm up in the morning and if the water is in regular use, taps don't take too long. I like it better since I would normally have 2 hot water tanks in my place.

[kenny]

Sorry but do you have an on-demand hot water system or do you have a tank?

I have a tank.

[88CRX]

I have a tank.

OK. And are you at a full minute to get hot water after motion is detected and you pump kicks on or a full minute after you turn the tap on and let it warm up?

[kenny]

OK. And are you at a full minute to get hot water after motion is detected and you pump kicks on or a full minute after you turn the tap on and let it warm up?

One minute from motion/pump activation for our ensuite taps.

[mr2mike]

Is that major issue with a water softener as well?
Water Softner should fix that de-scaling. However, I know of some condos that only have the tankless. Seemed like a good idea at first.

[jwslam]

So without a dedicated return line, are there any negative effects when the pump is running and I open a cold water tap?

[suntan]

So without a dedicated return line, are there any negative effects when the pump is running and I open a cold water tap?

Yes. Since hot water is mixing with the cold line, the water will be warm initially.

[speedog]

Could it be as simple as smaller house equates to shorter runs? All of our hot water runs are easily under 20 feet, takes virtually no time to get hot water at any tap, bungalow for the win.

[88CRX]

Could it be as simple as smaller house equates to shorter runs? All of our hot water runs are easily under 20 feet, takes virtually no time to get hot water at any tap, bungalow for the win.

Good point... We'll demo the second floor of our house!

Classic Sdog.

[speedog]

Good point... We'll demo the second floor of our house!

Classic Sdog.

Whatever, many people live in a home that has many more square feet than they really need which will equate to linger runs. Now I'll grant you that bungalows just are not a thing anymore and even less so in the burbs but they do have their advantages.

[killramos]

This is the same issue as HVAC in new bigger taller homes. One utility room hidden off in a convenient basement corner really isn't sufficient without expensive mitigation solutions put in place.

Problem would be easily solved with a second hot water heater upstairs to shorten the runs.

None of this shit was an issue with a central utility room in older bungalows, which used to be the standard fare. Higher density requirements mean building up and more compact and that comes with constraints. This basically equates to a design flaw that people are seldom willing to pay to deal with on spec homes.

speedog isn't wrong.

[speedog]

This is the same issue as HVAC in new bigger taller homes. One utility room hidden off in a convenient basement corner really isn't sufficient without expensive mitigation solutions put in place.

Problem would be easily solved with a second hot water heater upstairs to shorten the runs.

None of this shit was an issue with a central utility room in older bungalows, which used to be the standard fare. Higher density requirements mean building up and more compact and that comes with constraints. This basically equates to a design flaw that people are seldom willing to pay to deal with on spec homes.

speedog isn't wrong.

Even in non spec homes, it would be very rare to find a secondary water heater or furnace. Due to my current profession, I have been in several hundred new homes over the past few years and I can count on one finger the number of homes that had a secondary water heater. Secondary furnaces, only once as well and in the same home.

[JRSC00LUDE]

Seems to me, the secondary water heater should be the electric instant one and it should be in the en suite.

Edit - I showered every day in Asia with a little wall mounted electric water heater and never got electrocuted. Worked great. Why can't we just have those?

[speedog]

Seems to me, the secondary water heater should be the electric instant one and it should be in the en suite.

Edit - I showered every day in Asia with a little wall mounted electric water heater and never got electrocuted. Worked great. Why can't we just have those?

It is often very odd where someone will scrimp to save a few bucks when building a home, appearances almost always win out over practical and very nice to have features like a secondary water heater. Floating shelves, it's absolutely amazing how many of these I've installed - recently I did a cabinet install at a new home in Elbow Valley which had what I would consider a barely upgraded from base level kitchen, the door hinges and drawer slides were absolutely the lowest grade available in a home that is probably worth north of $1.5 million. Why wouldn't they have spent the extra $4-600 to have top notch slow close hinges and self closing slides, I just don't get it.

[FixedGear]

I'm not an expert, but I'd think this has more to do with the plumbing (water velocity, distance from heater, etc) than the heater. I used to have on demand water heater and it worked very fast. Now I'm in a small 2 br house built in the 1930s, with a giant hot water tank, and it takes 2-3 minutes to get hot water in the shower which is literally 10 ft from the water heater. :rofl:

[rage2]

Edit - I showered every day in Asia with a little wall mounted electric water heater and never got electrocuted. Worked great. Why can't we just have those?
Fuck do I hate those things. Zero water pressure.

[JRSC00LUDE]

Fuck do I hate those things. Zero water pressure.

But they work was the point haha, I'm sure there's a bigger/better one than the typical!

[88CRX]

I'm not an expert, but I'd think this has more to do with the plumbing (water velocity, distance from heater, etc) than the heater. I used to have on demand water heater and it worked very fast. Now I'm in a small 2 br house built in the 1930s, with a giant hot water tank, and it takes 2-3 minutes to get hot water in the shower which is literally 10 ft from the water heater. :rofl:

Yea I'll have to time the sink right above the mech room vs the furthest ensuite sink and see if its a run length issue or on-demand unit issue.

If all else fails we'll find a bungalow to purchase.

[jwslam]

So without a dedicated return line, are there any negative effects when the pump is running and I open a cold water tap?

Yes. Since hot water is mixing with the cold line, the water will be warm initially.
I meant wrt the hydraulics since the pump is still pushing and the CW line now is reversing flow.

[cycosis]

Mine is great, got it standard with my jayman home. There’s the odd time where it takes a little bit to get warm but most of the time it’s pretty quic and there is never temperature fluctuation.

[Maxt]

It is often very odd where someone will scrimp to save a few bucks when building a home, appearances almost always win out over practical and very nice to have features like a secondary water heater. Floating shelves, it's absolutely amazing how many of these I've installed - recently I did a cabinet install at a new home in Elbow Valley which had what I would consider a barely upgraded from base level kitchen, the door hinges and drawer slides were absolutely the lowest grade available in a home that is probably worth north of $1.5 million. Why wouldn't they have spent the extra $4-600 to have top notch slow close hinges and self closing slides, I just don't get it.
Starter mansions... Its all about building as much finished square feet for a certain budget... My latest house is like this, huge but built with some of the cheapest shit possible which I am slowly upgrading, as opposed to my old house which was only 1200 sq ft, but was built with some of the best materials of the time...
Here's Rinnai's add a loop system with thermal valve control so its not on, all the time.
https://www.rinnai.ca/gas-water-heating/tankless/accessories/recirculation-solutions
The other factor that adds to the slow times is the low flow fixtures. At one commercial place that has one, it was taking 2-3 minutes in the morning to get water back to their staff sink, so I drilled the holes out in their faucet aerator, its under a minute now. so what you save in gas, you can now spend on water :banghead: