Recirc Rule of Thumb

[Mulligan Stew]

What's a good rule of thumb for when to install a recirc line in a new construction project. In other words, what is the minimum length from water heater to farthest fixture that will probably require a recirc. The point is to not over engineer.

 

[CountryBumkin]

I have not seen a spec for this, but I think it depends on a couple of factors - such as "homeowner's tolerance", water flow rate, pipe size, amount of heat lost from pipe when water is not flowing (is pipe insulated or run in an insulated space), temperature setting on WH, etc.
In my house, the furthest bathroom is about 100ft from water heater - so the wait for hot water for me can be two minutes. That's too long for me.

 

[Sponsor]

 

[Dj2]

Good answer above.
In my area, waiting 2 mins for hot water, while the cold water goes down the drain is a NO NO.
We recycle this water and use it in the garden, and that gets us a gold medal.
IMHO, a pump comes with troubles, sometimes. Many of the homeowners that I know who have pumps are not 100% satisfied.

 

[Mulligan Stew]

Thanks. I've installed recircs at the water heater, at point of use and recently I installed a sensor activated system which works with a pump at the water heater and motion sensors in the bathroom and kitchen (certified water sense system). My customers love the pumps but I'm feeling like I may be over engineering. I'd like NOT to use them if I can tell ahead of time before the sheet rock goes up. In the case I have now I've plumbed a house with kitchens and bathrooms stacked near the water heater so no need for a pump however, there is one kitchen sink that's about 50 feet away by itself. Seems overkill to install even a point of use. But it got me thinking as to what the minimum length would be to consider a pump...in this case a point of use style probably. But how many feet? 40? 50? more? Any thoughts / experience?