Question about Amtrol ST-5-C THERM-X-TROL ASME Expansion Tank, 2 Gallon

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When the water stops flowing, there is a sharp-thud sound presumably in the unit.

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If your thermal expansion tank is older than three years, it is probably time to replace it. There is a diaphragm inside the tank that goes bad over time. Before replacing this tank, if you have recently purchased a new washing machine, this may be the problem if it does not have hammer arrestors on it as well.

Posted on Nov 18, 2009

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SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

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Posted on Jan 02, 2017


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What could be wrong?

Give more detail on issue. It just stopped working one day? But was fine until then? How old is unit? Are you sure gas is turned on to unit? Etc. good people on this site to help, but give them the complete picture. Good luck.

Mar 20, 2015 | Water Heaters

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About every two weeks we have no hot water pressure. Cold water has pressure but not hot water.

Hi Nancy, What you have is called a VAPOR LOCK, What you can do is just what you are doing , But let's add a step to your wounderful job you are doing so far. Ok, yes OPEN your HOT FAUCET , DO Your steps but OPEN the RELIEF VALVE ( BLOW-OFF ) At heater unit. That's the TUBE that points to the floor by itself, OPEN UNTIL WATER comes out and your BANG sound happens,(may want to spin up slightly to put bucket under pipe) RELIEF VALVE pipe. This should help your problem. May need to repeat a couple of times in a row to complete your task. Hope this was helpful - Bill.

Jan 17, 2015 | Water Water Heaters

1 Answer

No hot water from kitchen tap

The hot side of the faucet is most likely plugged with something that came up thru the water system. The average thankless waterheater requires at least 1/2 to 3/4 gpm flow rate for the unit to sense flow and turn on. If there is not enough flow it will not fire and heat the water. Not sure about this particular unit but a few require at least one full gallon per minute flow. So chances are that if you fix the faucet, you fix the hot water issue at the same time

Jan 09, 2014 | Rinnai Water Heaters

1 Answer

The thermal cutout, on the left side, pops up when water stops flowing through the unit. The modules are Polymer. I can press the button, have tons of hot water as long as the water is flowing through...

The left canister probably has a grounded element in it, which will keep power going after the water is off. Either that or you have a bad triac on your control unit

Nov 03, 2013 | Bosch PowerStar AE115 Tankless Water...

1 Answer

Model PTG-42PVN

According to the symtoms...sounds like you have a problem with the flow control valve. If less than 3 yrs old, contact Rheem Customer Support at (800-432-8373) and they can an authorized tech in your area to service the unit.

If the unit is out of warranty, I reccommend you still call customer support to find a local technician. Unless you're highly technical/mechanical, this is not a problem you should attempt yourself.

Thanks for trying


Jan 30, 2010 | Rheem Paloma PTG-74PVN / RTG-74PVN...

1 Answer

Bosch Aquastar 2400E LP Does Not Heat Water

Sounds like the water flow sensor and servo, may just need cleaning, get it checked out by a Bosch agent

Nov 10, 2009 | Bosch AquaStar 2400ES-NG

1 Answer

Temperature fluctuates while flow remains constant.(within the pump cut in/out settings) Max temp obtainable 43c

This sounds like a common problem with tankless type water heaters. The modulating burner has a set Btu range it can operate within, a maximum and minimum. With very low flow rates and very low temperature rises, the burner has trouble maintaining a steady output temperature because the btu load drops below the heater's minimum input. Typically the machine will overheat the water beyond it's setpoint, the burner will cut out, and then re-ignite once the output temperature has dropped low enough.
The solution to stopping this behavior is to simply increase the water flow through the device (i.e. higher flowing fixture or larger pump). This type of problem is exaserbated with recirculation systems that bring a very high water temperature to the unit.
Higher end tankless brands have a lower minimum input btu and thus fewer problems with this.

Aug 17, 2009 | Bosch Water Heaters

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No hot water after installation and powering up

All water valves open? Unit will flow approx 3/4 gallon prior to starting. If flow is good, check the flow switch to see if it is closing. If flow switch is closing and unit still not firing, assuming gas pressure is good; Nat 3.5''w.c., LP 10" w.c., loose wiring at board, ignitor. Sounds like something simple overlooked.

Jul 12, 2009 | Rheem Tankless Hot Water Heater...

1 Answer

Do i need to have a flow stop istalled in my cold water in line?

Yes you'll still need a flow stop unless it is already install in the outlet pipe going out out the heater..

Apr 01, 2009 | Rheem RTG-74DVP Direct Vent Liquid Propane...

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