Hot water circulation pump

[Nasser]

Hi Guys
This is my first post
Recently shifted to a new 2 level house with central hot water system, hot water tank on the roof with circulation pump “24h timer”, noticed the the hot water pressure reduces when the circulation pump is working.
Every time I take shower I switch off the circulation pump than the hot water pressure is excellent.
Any idea why the circulation pump reduce the water pressure?

 

[Valveman]

Moving to plumbing forum where you should get more help.

 

[Sponsor]

 

[Nasser]

Moving to plumbing forum where you should get more help.

Thank you very much

 

[Reach4]

I think home recirculation pumps with a 24 hour timer would typically flow on the order of 1 gpm or less.

I think your plumbing has a restriction, and it may be more than normal. I suspect the recirculation flow pass through the restrictions. If your recirculation flow is very high, such as 5 gpm, that would add to the pressure drop of the flow to your showerhead. I think that you have recirc too fast, excessive restrictions in the piping between the two ends of the recirc connections, or both.

Will your pump adjust down to a much slower flow?

A higher recirculation flow is appropriate for a system where you push a button before using hot water. The pump quickly clears out the cooled water. It shuts off after several seconds. That kind of system is most energy-efficient. The 24-hour timer system is less efficient. Running continuously is least efficient. A motion sensor is more efficient than 24 hour time.

As a test, with the recirc pump off, how much time does it take to fill a 5 gallon bucket with cold at the tub, and how much time with hot? Roughly 60 seconds might be typical. If this is shower-only, consider the test with the showerhead unscrewed.

My comments are not based on experience. I am not a plumber.