Very Weak Water Pressure On Hot Water Side,Tankless Heater Not Turning On

**Najataagihe** · 03-24-2024, 03:32 PM

Originally Posted by RVing in Michigan

I have a drain valve on my water heater so I opened the ball valve and hot water shot out as expected.

https://www.amazon.com/dp/B00HJ6P0Z8...roduct_details

Is this for a tankless water heater?

**Najataagihe** · 03-24-2024, 03:34 PM

Originally Posted by Riverbug

You've verified there is no flow to any of the faucets on the hot side? Have you checked the bypass valve to see that it is in the correct position? Perhaps that would be a good place to remove the outflow water line connection and see if you get flow directly from the water heater. If so, you know it downstream of that. I would do this without the heater turned on. You just need flow, not hot water at this point.

What bypass valve?

I haven’t seen one on mine.

(This tankless mess is all new to me, so any hints are welcome!)

**Najataagihe** · 03-24-2024, 03:35 PM

Originally Posted by Viper02

might check this valve and make sure its set correctly

Thanks!

Another addition to my tankless WH database!

**Mugsysiegel** · 03-24-2024, 03:39 PM

Originally Posted by RVing in Michigan

I just had this same issue two weeks ago. No volume out any hot water faucets. I have a drain valve on my water heater so I opened the ball valve and hot water shot out as expected. I looked through my window in the basement that lets me see in the utility area- no issue visible and no kinked lines. I then knew what to look at. Sure enough, the check valve on the water heater outlet has a plastic piston with a spring and a retaining clip inside the valve. The clip had fallen off and it and the spring were missing. (obviously setting in the bottom of my heater tank) When this happened, the plastic piston gets pushed out of the check valve (with water flow) and then blocks the connector fitting. I could duplicate this event by shutting off the RV water supply, then open my tank drain to shift the piston back, then Turn the water back on. Then i turned on the hot water faucet VERY slowly and the flow was back. Put in a new check vave and all is well.

https://www.amazon.com/dp/B00HJ6P0Z8...roduct_details

@RVing in Michigan Do you also have a tankless water heater? I cannot find my check valve on my water heater even from the back.

**RiversToRidgesRV** · 03-25-2024, 11:30 AM

This happened to us on our electric water heater, the issue was the check valve attached to the output side of the water heater. I believe the valve is a one-way valve so water can't backflow into the heater.

**retired_engineer** · 03-25-2024, 06:29 PM

I asked you in your other thread on this problem if that black piece connecting the red PEX coming off of the mixing bowl and attaching to the red vinyl hose might be a check valve? Did you ever make the determination what that piece was? It's location in the plumbing would certainly fit with where I would expect a check valve.