hot water on Demand

[ITD]

Originally Posted by jeffk

If I were to put a recirculating system in, I would put it on an automatic timer so that it kicked on only when I expected to use it regularly, for example for a morning shower, time it to go on about 30 minutes before you normally get up and shut off an hour later. It wouldn't be perfect but if it met your need 80%+ of the time, that would be pretty good.

At worst you could run it during the day and off at night. Or off while you are at work as well. Keeping it running all the time could be expensive.

He talked of a recirc system with a button. You want hot water, you push the button for a few seconds, then open the spigot. I'm sure the circulator pushes the hot water through much quicker than it coming out of a 1.25 gpm faucet. It sounds like a great idea, especially for an instant heater where you don't want the thing firing until you want water.

[Kamper]

net search term "water recirculator" many more responses than I am showing here



https://www.energystar.gov/products/...ulating_system


https://www.amazon.com/Watts-500800-.../dp/B000E78XHG

[jeffk]

Originally Posted by ITD

He talked of a recirc system with a button. You want hot water, you push the button for a few seconds, then open the spigot. I'm sure the circulator pushes the hot water through much quicker than it coming out of a 1.25 gpm faucet. It sounds like a great idea, especially for an instant heater where you don't want the thing firing until you want water.

An instant heater doesn't fire until you start drawing water anyway. A recirc system keeps the water in the delivery pipes hot so you don't have to wait for it to get from the heater to where you are using it. However, pumping hot water around the pipes full time is going to waste heat to keep the pipe water hot, even while you are sleeping and not using water.

As to a push button recirc system, if it hasn't been running, it is still going to take some time to heat the water in the pipes, probably just about as long as if you just turned on the faucet. The only advantage would be that you wouldn't be wasting water down the drain while it heated up. You could push the button, do something else for a minute or so, then turn the water on.

[wifi]

Hmmmm... low flow, mentioned earlier. I have an EPA "approved" low flow faucet in the bathroom sink, takes 5 mins to fill up a gallon jug. I'm really thinking this low flow "feature" is what is causing the heater to ....decide...to turn on later, as opposed to the recirc pump, which will certainly trip the flow switch instantly, when you push the button.

We should make every EPA official have a low flow faucet on an instant system

Maybe, in a few months, we can have a realistic EPA.

[jbolty]

Sort of off topic. BUT, there is nothing more stupid than a low flow faucet on a kitchen sink. If I need to fill a pot I'm not going to fill it less, it just takes longer.

[swnoel]

If you really need a recirc loop you'll need a holding tank. Why not just go with a tank from the beginning and save yourself some money! I wouldn't put in an instantaneous water heater in my home... but what do I know, except I do get tired of pissed off customers complaining about theirs!

Also beware that buying from a non certified dealer may void your warranty!

[Kamper]

Originally Posted by swnoel

If you really need a recirc loop you'll need a holding tank. ...

No. You don't.

That's the point of an 'on-demand' system. You aren't wasting energy keeping a tank of water hot.

The point of adding a recirculating system is that you don't waste water. The 'loop' runs back from near the faucet to just before the heater.

[Formula260SS]

Originally Posted by Kamper

No. You don't.

That's the point of an 'on-demand' system. You aren't wasting energy keeping a tank of water hot.

The point of adding a recirculating system is that you don't waste water. The 'loop' runs back from near the faucet to just before the heater.

Doesn't the heater need to turn on and off to keep the loop hot? Wouldn't that defeat the purpose of saving energy? We are still talking on demand systems right?

[ishoot308]

I went with an on demand system for one reason, convenience. If your thinking about an on demand system for savings, I would think twice. The energy savings of an on demand system does not justify the upfront cost. You will never make your money back in the energy savings.

For us it was a simple decision. We initially had a small electric hot water tank under our camp. Didn't have room for anything larger. We were constantly running out of hot water and it was extremely inefficient in an outdoors environment. Our plumber recommended the on demand system and he was spot on! It's a small wall mounted unit that we installed inside in our bathroom. We never run out of hot water now, it's efficient, and takes seconds to winterize. It has worked flawlessly for eight years now and we are thrilled with it!

Dan

[upthesaukee]

Originally Posted by ishoot308

I went with an on demand system for one reason, convenience. If your thinking about an on demand system for savings, I would think twice. The energy savings of an on demand system does not justify the upfront cost. You will never make your money back in the energy savings.

For us it was a simple decision. We initially had a small electric hot water tank under our camp. Didn't have room for anything larger. We were constantly running out of hot water and it was extremely inefficient in an outdoors environment. Our plumber recommended the on demand system and he was spot on! It's a small wall mounted unit that we installed inside in our bathroom. We never run out of hot water now, it's efficient, and takes seconds to winterize. It has worked flawlessly for eight years now and we are thrilled with it!

Dan

Our Masonic Lodge had an oil fired hot water heater coupled with a large insulated tank that was installed back in the 70's, which was fine back when fuel oil was as cheap as a bottle of soda. The problem was in the last several years, we were spending a lot of money, $675 - $800+ per summer just keeping the hot water hot. Oil fired furnace was turned off during the summer months.
We opted to go with an on demand propane fired hot water heater. It was just under $2,000. One of our members is a licensed installer, so we had no additional cost other than a small amount of supplies for the hookup.
We only use our kitchen 30-35 times per year, so the increase in propane use was negligible. We do have a commercial dishwasher, but it is a low water use model.
Even with the fluctuation in fuel prices, we felt we did recoup our costs in only a little over 3 years. I do realize our case is quite unique, but depending on use, cost recovery is possible. I also agree that convenience is often the driving force to using on demand system. It was for us as well.
Dave

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[ishoot308]

Originally Posted by upthesaukee

Our Masonic Lodge had an oil fired hot water heater coupled with a large insulated tank that was installed back in the 70's, which was fine back when fuel oil was as cheap as a bottle of soda. The problem was in the last several years, we were spending a lot of money, $675 - $800+ per summer just keeping the hot water hot. Oil fired furnace was turned off during the summer months.
We opted to go with an on demand propane fired hot water heater. It was just under $2,000. One of our members is a licensed installer, so we had no additional cost other than a small amount of supplies for the hookup.
We only use our kitchen 30-35 times per year, so the increase in propane use was negligible. We do have a commercial dishwasher, but it is a low water use model.
Even with the fluctuation in fuel prices, we felt we did recoup our costs in only a little over 3 years. I do realize our case is quite unique, but depending on use, cost recovery is possible. I also agree that convenience is often the driving force to using on demand system. It was for us as well.
Dave

Sent from my GT-P5210 using Winnipesaukee Forum mobile app

You definitely recouped your costs and you have given a great example of a perfect use and reason for on demand! No doubt you saved a ton especially where you had no install costs!

I should of been more clear in my post, it was geared more towards average homeowner daily use...

Dan

[Kamper]

Originally Posted by Formula260SS

Doesn't the heater need to turn on and off to keep the loop hot? Wouldn't that defeat the purpose of saving energy? We are still talking on demand systems right?

With the push-button system the water only circulates when you want it to. The on-demand saves energy and the circulator saves water.

[TheProfessor]

Originally Posted by Kamper

With the push-button system the water only circulates when you want it to. The on-demand saves energy and the circulator saves water.

So you have to push a button on the circulator?
Where is the button?

If the shower is at the other end of house, there is cold water in the pipe. Pushing a button some place still has to heat up that cold water in pipe.
So apparently one is still using fuel to heat up the cold water in pipe.
6 or one and a half dozen of the other.

But let the engineers here explain all.

[Patofnaud]

Originally Posted by Formula260SS

Doesn't the heater need to turn on and off to keep the loop hot? Wouldn't that defeat the purpose of saving energy? We are still talking on demand systems right?

With a recirc pump on a traditional hot water tank/boiler/reserve (you can just repurpose an old circulator pump), and a check valve that taps in close to the end of your run, recirculates it back to the input side of your hot water source.

That way you save water (and some power) because now you can prewarm up your pipes at a push of a button, and cycle water from the heater to just before your shower/back room sink back to the water heater getting it up to temp BEFORE you turn the shower on and 'let it warm up' for 10 mins.

[Sunset point]

I also had the dilemma last year of what to do for hot water. My space was limited under the house and the existing hot water tank was 18 gallons 120 volt. I decided to take a chance on an electric on demand system leaving the existing 18 gallon tank in place. My plan was the on demand system could boost the temp from the 18 gallon tank as it was slowly hetting colder. Well one year later the system made it through the winter. When its just me i dont turn on the 18 gallon tank and rely solely on the on demand. Last week it was set at 138 degrees and i noticed the shower going warm and cold so i turned it to 120 and now its perfect. I do have a low flow shower head. The only scenario where it couldnt keep up was a shower and two sinks all needing hot water. I heard lots of skepticism on these initially but for a camp they may not be a bad idea if you have the necessary power. I draw water from the lake, so if you have a well the entering water temp would be colder. I also didn"t want to have propane cylinders on my dock as im on an island. The unit is also warrantied for life for whatever thatvis worth. If the 18 gallon tank goes i may consider just going with the on demand electric entirely after another year of use.

[ITD]

Originally Posted by jeffk

An instant heater doesn't fire until you start drawing water anyway. A recirc system keeps the water in the delivery pipes hot so you don't have to wait for it to get from the heater to where you are using it. However, pumping hot water around the pipes full time is going to waste heat to keep the pipe water hot, even while you are sleeping and not using water.

As to a push button recirc system, if it hasn't been running, it is still going to take some time to heat the water in the pipes, probably just about as long as if you just turned on the faucet. The only advantage would be that you wouldn't be wasting water down the drain while it heated up. You could push the button, do something else for a minute or so, then turn the water on.

I don't know a lot about these heaters but I thought the selling point was tankless instant hot water, maybe not. A circulator would get hot water through the pipe much quicker than a low flow faucet.

I just checked out the Rinnai site and they have a heater with a built in recirc pipe, to keep the water in the pipe hot.