Navien NPE-240A2 Slow Heat Time

[Halexh]

Hello all,

I recently moved into a brand new 2 story house that has a Navien 240A2 in it. In the morning it usually takes 4 or more minutes for water to become hot in one of the locations that may be furthest from the water heater (not 100% if it is the furthest). I have read quite a few posts on here, as well as the manual trying to deduce how to fix it, but I still don't know what to do. I will be honest, a lot of the threads go way over my head in regards to plumbing language. That being said, here is some more information and photos:

It is currently set to Internal Recirculation, with a subsetting of Always (as opposed to Intelligent or Weekly - See page 84 of the manual). The temperature is set to 130F. With this setting I would expect the water heater to keep the water internal to the water heater (as well as the water in that small tank in the photo) always at 130F. Therefore whenever I request hot water, the only delay is from emptying the old cold water in the pipes. Maybe 30 seconds? Is this interpretation correct?

Another question I had: from the photos, it looks like a external recirculation pipe is installed, and I could utilize this feature in the water heater. From my understanding, all this buys me is keeping the water in the pipes at the requested temperature in order to remove that ~30 second wait time at the cost of more gas. For me, this seems silly since gas is more expensive than water. Correct me if I am wrong here please.

Thank you

 

[Fitter30]

Theres some additional settings starting at page 88 to enter menu page 89 for the hot button

 

[Sponsor]

 

[Halexh]

Theres some additional settings starting at page 88 to enter menu page 89 for the hot button

I am not sure what you are getting at here. The description for the hot button you are referencing says:

Number of stop function occurrences by temperature gap between supply and return water

But the Hot Button is some optional addition to the system that I am 99% sure is not installed in my house. See this for more details on the Hot Button.

 

[Breplum]

It is not clear to me what you are wanting. The four minutes it takes to get to the farthest outlet is only 'fixable' if you set it to run for external recirc (which it is indeed piped for). You don't necessarily know how they piped the hot water loop and it may be that even though a plumbing fixture appears close it could be on the END of the hot loop.
If set for internal recirc then the mini tank is kept to whatever the setting is. Confirm that the mini tank is hot by tripping the t and p valve and feel it to confirm that it is instantly hot when tripped.

 

[Halexh]

It is not clear to me what you are wanting. The four minutes it takes to get to the farthest outlet is only 'fixable' if you set it to run for external recirc (which it is indeed piped for). You don't necessarily know how they piped the hot water loop and it may be that even though a plumbing fixture appears close it could be on the END of the hot loop.
If set for internal recirc then the mini tank is kept to whatever the setting is. Confirm that the mini tank is hot by tripping the t and p valve and feel it to confirm that it is instantly hot when tripped.

Let's assume the mini tank is hot and the water within is kept at the desired temperature. Are you then saying roughly four minutes is normal for the hot water to reach it's destination? The house is 3400 square feet. Why would it take four minutes for the water to travel the distance of the pipe?

 

[Reach4]

Let's assume the mini tank is hot and the water within is kept at the desired temperature. Are you then saying roughly four minutes is normal for the hot water to reach it's destination? The house is 3400 square feet. Why would it take four minutes for the water to travel the distance of the pipe?

4 minutes sounds like an estimate.
If you turned on the faucet to about 1/2 gpm of hot (with or without cold added in), and the path was 90 ft of 3/4 inch pipe, that could explain 4 minutes.

But then at 1/2 gpm, I wonder if the tankless WH would turn on.

 

[Halexh]

4 minutes sounds like an estimate.
If you turned on the faucet to about 1/2 gpm of hot (with or without cold added in), and the path was 90 ft of 3/4 inch pipe, that could explain 4 minutes.

But then at 1/2 gpm, I wonder if the tankless WH would turn on.

That four minutes is an estimate, but it's a conservative estimate. And this is with the shower turned on, completely to the hot side.

 

[Bannerman]

The mini tank that Breplum refers to, is not the small tank shown in the photo, but is a small tank that is internal within the WH. The tank shown in the photo is only utilized to absorb thermal expansion since water will expand when heated.

Every time any hot water faucet in your home is turned on, you will be paying for the gas to heat that water even as the water flowing from the faucet remains 'cold'.

The cold water flowing to drain while you are waiting for hot water to arrive, is water that had been previously heated. If for example the 4-minutes of flow to drain equals 8-gallons, then that will represent the cost of heating 16+ gallons of water since the wasted 8-gallons will be replaced with an additional 8-gallons of heated water.

Suggest reprogramming the WH initially for Intelligent External Circulation which will allow the WH to determine your hot water usage patterns over a 1-week period to establish when circulation will be beneficial. Once your usage patterns become known, that will become the circulation schedule it will use.

While Intelligent circulation will reduce water waste and gas consumption by only circulating based on your usual usage patterns, installation of the Hot Button capability would maximize savings and would provide greater flexibility for hot water useage that is outside of your usual schedule.

Since hot water is often not needed immediately upon entering the bathroom, kitchen or laundry room, by activating the Hot Button when entering the room, that will likely allow sufficient time for the pump to operate so hot water will be nearby in time for when it will be actually needed.

 

[Halexh]

The mini tank that Breplum refers to, is not the small tank shown in the photo, but is a small tank that is internal within the WH. The tank shown in the photo is only utilized to absorb thermal expansion since water will expand when heated.

Every time any hot water faucet in your home is turned on, you will be paying for the gas to heat that water even as the water flowing from the faucet remains 'cold'.

The cold water flowing to drain while you are waiting for hot water to arrive, is water that had been previously heated. If for example the 4-minutes of flow to drain equals 8-gallons, then that will represent the cost of heating 16+ gallons of water since the wasted 8-gallons will be replaced with an additional 8-gallons of heated water.

Suggest reprogramming the WH initially for Intelligent External Circulation which will allow the WH to determine your hot water usage patterns over a 1-week period to establish when circulation will be beneficial. Once your usage patterns become known, that will become the circulation schedule it will use.

While Intelligent circulation will reduce water waste and gas consumption by only circulating based on your usual usage patterns, installation of the Hot Button capability would maximize savings and would provide greater flexibility for hot water useage that is outside of your usual schedule.

Since hot water is often not needed immediately upon entering the bathroom, kitchen or laundry room, by activating the Hot Button when entering the room, that will likely allow sufficient time for the pump to operate so hot water will be nearby in time for when it will be actually needed.

Thank you very much for that long explanation. That definitely helps me understand things better. Regarding the intelligent setting for external recirculation, wont I basically be paying more gas to keep the water in the pipes heated as well? Obviously the cost comes at the benefit of not having to wait for water?

Maybe the fair middle ground is to use the time of day setting, so that the water is hot before the shower gets turned on each morning?

 

[Bannerman]

Maybe the fair middle ground is to use the time of day setting, so that it gets setup before the shower gets turned on each morning?

Intelligent mode will automatically recognize the time(s) when hot water is utilized each day so as to cause the water to circulate in preparation of those times, without you needing to program the time of day setting.

When the hot water is circulated in preparation for only when hot water will be actually used, there won't be much if any additional gas consumed. You are currently needing to preheat the water in the pipes before you are able to begin showering. With the pump automatically circulating hot water through the pipes just before you usually want to shower, the water nearby to the shower will be already preheated so your wait time should be greatly reduced, and far less water should be wasted.