Another tankless task...or why I take three minute showers

[nnarth212]

Howdy all, found this fourm while snooping for a solution to my three minute showers. pleased to see an active forum on these and other issues. Greetings!


So, fairly certain my flow is too low when taking a shower to keep the thing lit. But what’s the best solution?

Reading the link below (2nd post) I may try lowering the temp on the unit. However is there a more elegant solution? I am having my Takagi relocated this Tuesday due to other construction and have the opportunity to add a recirc pump, but where, and how are these best activated?

https://terrylove.com/forums/index.php?threads/water-going-cold-with-takagi-tankless.34628/

LONG story short, I know this system could be better designed by someone more experienced than myself.

THE DETAILS: 1800 SF old crumbling victorian in process of a DIY restoration. Tankless serves single kitchen sink, DW, and single full bath.... which is furthest from the unit. Shower must be full hot or the hot goes cold. It is new 3/4 inch copper from the WH to the kitchen sink where the full bath plumbing circuit takes off in crusty old 1/2 pipe thats needing replacing, which is in the future....

Any way, happy Sunday tinkering and best regards from sunny SF.

 

[Dana]

Howdy all, found this fourm while snooping for a solution to my three minute showers. pleased to see an active forum on these and other issues. Greetings!


So, fairly certain my flow is too low when taking a shower to keep the thing lit. But what’s the best solution?

Reading the link below (2nd post) I may try lowering the temp on the unit. However is there a more elegant solution? I am having my Takagi relocated this Tuesday due to other construction and have the opportunity to add a recirc pump, but where, and how are these best activated?

https://terrylove.com/forums/index.php?threads/water-going-cold-with-takagi-tankless.34628/

LONG story short, I know this system could be better designed by someone more experienced than myself.

THE DETAILS: 1800 SF old crumbling victorian in process of a DIY restoration. Tankless serves single kitchen sink, DW, and single full bath.... which is furthest from the unit. Shower must be full hot or the hot goes cold. It is new 3/4 inch copper from the WH to the kitchen sink where the full bath plumbing circuit takes off in crusty old 1/2 pipe thats needing replacing, which is in the future....

Any way, happy Sunday tinkering and best regards from sunny SF.

Which model Takagi, and what is the temperature setting? The most elegant solution is usually to simply turn the temperature down, increasing the flow through the tankless, but there are limitations. When the incoming cold water temperature is high enough it may still have problems with flame-out or poor temperature regulation, depending on the minimum firing rate of the tankless. Some shower mixers and anti-scald features can also have functional difficulties when more than 95% of the flow is from the hot side too.

Recirculation pumps can be controlled in a number of ways. The most energy efficient approach is a demand switch, where the hot water is called by pushing a button. Others simply have a temperature sensor at the furthest fixture that turns on the pump when it gets too cool, then turns off once the hot water arrives. Some of those are programmable to only do that during certain hours of the day to avoid standby losses.

CA plumbing code and Title 24, as well as the IRC 2018 requires that both the supply and return plumbing be insulated on recirculation system. CA code minimum R value are based on the pipe diameter (and the CA plumbing code requirements differ from Title 24- go figure!), whereas the IRC calls out R3 minimum, independent of size. Other hot water pluming (not on the recirculation loop) only 3/4" or larger pipes aren't required by the IRC to be insulated- I'm not sure how it breaks down in CA.