"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.

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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.

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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.

[88CRX]

This quote is hidden because you are ignoring this member. Show Quote

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.

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]

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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

Is that major issue with a water softener as well?

[Euro838]

This quote is hidden because you are ignoring this member. Show Quote

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]

This quote is hidden because you are ignoring this member. Show Quote

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

I have a tank.