ᐅ A circulating pump for hot water: yes or no?

I haven’t measured it yet, but let’s say it’s about 20 seconds... although it feels much longer. The pipe runs directly from the heating system to the bathroom, which is right next door. That’s why my plumber didn’t install any extra piping there—short distances, so it wasn’t necessary.

Still, it’s quite annoying. I’ll try counting it while washing my hands this evening...

Bookstar schrieb:

It’s not about the pump’s electricity consumption, but about the heat loss from the circulation pipe!

The pump’s electricity consumption is an interesting topic because it used to be a major factor. High-efficiency pumps haven’t been standard for very long. This applies not only to domestic hot water circulation but to heating pumps in general. Many people still have this idea in the back of their minds. Inefficient pumps are often mentioned as hidden energy wasters – but this no longer applies to current models.

I also think heat losses through the pipes are often exaggerated, since the heat stays inside the house. With heat pumps, efficiency could still be discussed. In summer, of course, you want to avoid adding heat.

Tego12 schrieb:

Are you sure? Even the farthest fixture in our house doesn’t require anywhere near that... The guest bathroom nearby takes about 3 seconds.... That’s what I mean by proper planning... If done poorly, you have to compensate. I wouldn’t accept a 20-second wait time either.

Nonsense! You don’t plan based on water pipes but so that you like the floor plan. And forget the 3 seconds, 20 seconds is more realistic. In our case it’s like Basti’s solution: guest bathroom without circulation and only 4m (13 feet) of pipe. No way it’s 3 seconds. If you have three floors, circulation is mandatory. Omitting it would be a planning mistake if you expect comfort!

[NZOTE="Bookstar, post: 354957, member: 20319"]
Nonsense! You don't plan based on water pipes but rather so that you like the floor plan. And you can forget about 3 seconds; 20 seconds is already more realistic. In our case, it's done like Basti’s solution: guest toilet without circulation and only 4 meters (13 feet) of piping. There’s no way it takes just 3 seconds. If you have three stories, circulation is mandatory. Omitting it would be a planning mistake when you expect comfort!

Planning is not just about the floor plan. If it takes that long despite a very short pipe length, it’s almost certainly because a pipe diameter far too large for a guest bathroom was used, which logically extends the time until warm water arrives significantly. This is often done simply out of lack of consideration (poor planning; a guest bathroom rarely has a large rain shower that requires a matching pipe diameter…). Detailed information can be found in the pink forum.

That you shouldn’t base your entire floor plan solely on water piping... Yes, you can misunderstand anything if you want to.

Nevertheless, I expect an architect to optimize the entire design, not just the floor plan (especially if, as I believe some here do, there are certain standards for ecological building). For me, a beautiful house is much more than just a nice floor plan.

Tego12 schrieb:

This obviously significantly increases the time it takes for hot water to arrive. It is often done simply because it is not properly considered (no proper planning; in guest bathrooms there is rarely a large rain shower that requires an appropriate pipe diameter...). I

This is the point where circulation becomes mandatory—not just figuratively. Due to stagnation and the risk of bacterial growth. If I remember correctly, no more than 3 liters (0.8 gallons) of hot water should remain in the pipe. This corresponds to running the tap for about 20 seconds with typical pipe diameters. It should not take longer than that.

Tego12 schrieb:


Read the pink forum about this (the home technology section has all the experts), where it is consistently advised against due to the increased risk of Legionella bacteria and energy waste (heat loss is significantly higher than the small amount of electricity used by the pump). It doesn’t break the bank, but many people also consider environmental friendliness when building a house. With good planning (short distances and properly sized pipes), the water heats up very quickly even without it.

Strange logic... Legionella bacteria form in lukewarm stagnant water, but a heat pump operates at around 40°C (104°F), which poses a very high risk for Legionella, so a circulation pump should definitely be installed.