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Noah Klein
Noah Klein,
Category: Plumbing
Satisfied Customers: 23
Experience:  Owner, Master Plumber at Royal Plumbing, LLC
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HD 200 e

Customer Question

HD 200 e
Submitted: 1 year ago.
Category: Plumbing
Expert:  Noah Klein replied 1 year ago.

Hi, my name is ***** ***** I am a Master Plumber and tankless expert.

First, do you have the same phenomenon when running water from a sink? This could be an issue with the shower cartridge.

If it is a water heater issue, I would first recommend a full descale of the unit. This should be done annually or at least biennially. Also, you should check the intake and exhaust vents and clean them of any debris. Chances are the descale will fix the problem. If you are unsure how to do a descale, it involves a special kit that you connect to the water ports under the unit. You run a solution through the heat exchanger and until all the scale buildup is removed. The kit is about $160 and the entire process is about an hour. If you do not want to do this yourself, you can hire it out. I recommend that you contact the manufacturer for a tankless specialist in your area. Unfortunately, many companies who "say" they perform a descale, do not actually know how it is properly done.

If neither of these work, you may need to have the burner removed and cleaned. This is done with an air compressor and can take some time. It also requires some technical skills. If you are not handy, you may want to hire a specialist.

Good Luck!

Customer: replied 1 year ago.
Hi Noah,
Thanks for the response, before I start with the above works I would like to clarify something.
Is there a heat sensor or regulator that holds the temp at a certain level and is there a flow switch that adjusts the heat and flow that may be old or faulty, this would cause the heater to rise in temp and then get to hot and shut off the gas.
The pressure is good and all three mixers on the line produce the same effect.
Descale would help with the temp of the water leaving the heater, but this is not a problem as it gets to max.regards
Expert:  Noah Klein replied 1 year ago.

Most tankless units have multiple sensors. The three sensors we are talking about are 1. Incoming water pressure, 2. Flow rate and 3. Outgoing water pressure.

The unit takes the incoming water temperature, calculates the BTU amount required based on the flow rate to get you the outgoing water temperature. The system verifies and adjusts the flame as needed to maintain the proper outgoing temperature.

The reason a descale is important is that scale buildup can clog the heat exchanger. Now the flow rate will change rapidly based on the scale buildup. This causes the unit to raise and lower the BTU count in an attempt to keep up with the changing flow rates. Doing a descale, cleared the heat exchanger and allows for a steady continuous flow.

Customer: replied 1 year ago.
thanks, ***** ***** town for a week but will try this and let you know.marc
Expert:  Noah Klein replied 1 year ago.

If you were satisfied with my assistance, please leave positive feedback.

Good Luck!