Bosch 250 SX NG - Very Slow to Heat Water

Users who are viewing this thread

Dmmoroney

New Member
Messages
4
Reaction score
0
Points
1
Location
NY
Hello All,

As you can see from the headline, my Bosch 250 SX NG takes a very long time to provide hot water. I have a shower & sink in the bathroom, and a sink in the kitchen. At all locations the water will get hot, but it can take minutes sometimes. The kitchen takes longest, and happens to be the longest run at about 50 ft or so. The bathroom lines are around 15-20 ft. The shower does get hot quickest, and I believe it is the first run.

Has anyone experienced this? Can anyone shed some light on the issue? Again, it's not that I'm not getting hot water, it's just taking a long time.

Thank you in advance!
 

Attachments

  • 20190331_220424.jpg
    20190331_220424.jpg
    111.7 KB · Views: 426
Last edited:

Dana

In the trades
Messages
7,889
Reaction score
509
Points
113
Location
01609
The ignition delay on some tankless water heaters is pretty long, and at low flow it can sometimes even fail to fire right away. Once lit the flow can run slower, but if you're just opening up the kitchen tap to a modest flow it may take awhile to fire, since it can be too close to the flow threshold where it won't fire up at all.

Try opening up the kitchen tap to full-flow/max-hot and see if it gets there any faster.
 

Dmmoroney

New Member
Messages
4
Reaction score
0
Points
1
Location
NY
The ignition delay on some tankless water heaters is pretty long, and at low flow it can sometimes even fail to fire right away. Once lit the flow can run slower, but if you're just opening up the kitchen tap to a modest flow it may take awhile to fire, since it can be too close to the flow threshold where it won't fire up at all.

Try opening up the kitchen tap to full-flow/max-hot and see if it gets there any faster.

Thank you for the reply! So we actually open it all the way when we want hot water, and then we just wait. Sometimes it can take 3-4 minutes, fully open.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
If you haven't done an acid flush on the thing, that by itself may resolve your problem after it is done. One big difference between a tank and a tankless system is the amount of maintenance required. Unless you have very soft water, the insides of the tankless WILL start to get clogged up with minerals. If you don't have the valves installed to make circulating the acid solution through the unit to dissolve those, that will need to be added. Once you have the right setup, the actual process isn't all that hard. Most recommend that be done at least once a year, more if the water is very hard (there are limits set by the unit's manufacturer), or less often if it is very soft. If done annually, it probably takes a couple of hours. IF it hasn't been done, it may take longer. Mineral buildup can clog things up, slow the flow, lower the heat transfer efficiency, and mess with sensors.

Failing to do that can make a tankless system inoperable.
 

Dmmoroney

New Member
Messages
4
Reaction score
0
Points
1
Location
NY
If you haven't done an acid flush on the thing, that by itself may resolve your problem after it is done. One big difference between a tank and a tankless system is the amount of maintenance required. Unless you have very soft water, the insides of the tankless WILL start to get clogged up with minerals. If you don't have the valves installed to make circulating the acid solution through the unit to dissolve those, that will need to be added. Once you have the right setup, the actual process isn't all that hard. Most recommend that be done at least once a year, more if the water is very hard (there are limits set by the unit's manufacturer), or less often if it is very soft. If done annually, it probably takes a couple of hours. IF it hasn't been done, it may take longer. Mineral buildup can clog things up, slow the flow, lower the heat transfer efficiency, and mess with sensors.

Failing to do that can make a tankless system inoperable.

Thank you for the reply! I was able to find a YouTube video on how to flush the system. I'll give it a shot. Thanks again!
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks