Cold water in hot water pipe

  • Erstellt am 2017-01-03 10:52:13

Bremen_83

2017-01-03 10:52:13
  • #1
Hello everyone,
you are my last hope. Throughout the entire house, we only have a water temperature of about 22°C left. Two different sanitary master companies have unfortunately not yet found a solution.

The following situation exists:

    [*]A year ago we bought a single-family house (built in 1982). At that time, we already noticed that the hot water temperature at all taps was only a maximum of 40°C, although 60°C was present in the hot water storage tank (in the basement). The temperature was still sufficient for showering, so initially other repairs and renovation work had priority.
    [*]Four months ago, I briefly turned off the water to replace the angle valve on a toilet. After turning the water back on, we suddenly only had a maximum hot water temperature of 22°C at all taps. Now showering in winter is no longer fun! Apparently, something in the pipes got clogged or opened due to the pressure drop and subsequent buildup. This condition still exists today.

The house installation is as follows:

    [*]Heating + hot water storage tank in the basement
    [*]Hot water circulation pipe exists
    [*]Taps in the basement: shower in the sauna room, washbasin in the utility room
    [*]Taps on the ground floor (EG): washbasin and toilet in the guest bathroom, on the other side of the building there is a washbasin in the kitchen
    [*]Taps on the upper floor (OG): 2x washbasins, bathtub and shower in the bathroom
    [*]Unfortunately, we do not have an exact laying plan of the pipes

Of course, we have already started various attempts to solve the problem – together with specialist companies:

    [*]The circulation pipe only delivers lukewarm water. The circulation pump + check valve were replaced with new components. Additionally, a shut-off valve was installed in the circulation pipe in the basement. However, no improvement could be observed. Simply shutting off the circulation pipe also did not lead to an improvement.
    [*]All mixer taps were checked and all angle valves were turned off. Nevertheless, only lukewarm water could be drawn, no matter which tap was opened again.

However, we have made an interesting observation:

    [*]When the hot water line is opened in the guest bathroom, water initially flows with a temperature of 22°C. But when hot water is turned on at any other tap (in the basement, ground floor, or upper floor), suddenly we have 60°C hot water, the circulation line finally delivers hot water, and cold water flows simultaneously from the hot water line of the guest bathroom. It cannot be due to a defective mixer tap in the guest bathroom; turning off the angle valve of the cold water line in the guest bathroom also leads to no change.

So it seems that cold water is being forced somewhere into the hot water line. But where??? We have checked all accessible components. Could it be that a check valve was installed in the floor or wall back then that is now defective?

A specialist company will come by soon with a leak detector to better understand the position of the pipes.

Do you perhaps have any other suggestions and ideas?

Many thanks in advance!

Best regards and happy new year
Jörn
 

Knallkörper

2017-01-03 13:50:09
  • #2
My theory is also: At one point, cold water pushes into the circulation line. This point is near your guest bathroom.

Maybe the cold water pushes through a fitting into the circulation line.

Example / thought experiment: You have a shower fitting with a connection for the shower hose. But instead of a showerhead, you have connected a water hose, with which you fill your pool outside. There is still a shut-off valve in the hose because you want to be able to turn off the water outside. The shut-off valve in the hose is closed, but you leave the shower fitting open, out of convenience. The mixer is set to a medium temperature.

Consequence: If water is drawn from the circulation line elsewhere, cold water flows through the fitting into the hot circuit.

If this suggestion does not help further, I would get a measuring device yourself to measure the volume flow in a pipe. This way, you can find out where water flows and where it does not.
 

wrobel

2017-01-10 22:53:11
  • #3
Hello Hello

What comes to mind quickly:
defective check valves in shower thermostats
or on the domestic hot water mixer of a solar storage tank

Olli
 

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