Aquahot hot water tapers off to cold

Topic: Aquahot hot water tapers off to cold (Read 1993 times) previous topic - next topic

Aquahot hot water tapers off to cold

March 04, 2024, 09:06:54 pm

We're pretty frustrated with our Aquahot. The water starts off very hot and tapers off before going luke warm. I was pretty sure that it was the tempering valve. I did order the Watts version. When I went to replace it, it appears I had the Watts one in there already (see photo). The thing is, the adjustment knob does not fit due to space. The knob on the old one was missing. When I replaced just the guts, I had to take the knob off to put the new one in. (see other photo)

We have the AHE-100-02S model in our 1996 U320.

Burner replaced last year

Electric element replaced last year

Boiler fluid replaced last year

The hot water volume has always run less than the cold volume

I am thinking the only thing left is to flush the lines with vinegar (descale) to see if there is blockage in the hot lines. We did the descale process back when we bought it in 2017. Thoughts?

Re: Aquahot hot water tapers off to cold

Reply #1 – March 04, 2024, 09:21:24 pm

Yes sounds like it might have a lime buildup causing reduced flow.

Re: Aquahot hot water tapers off to cold

Reply #2 – March 04, 2024, 10:29:58 pm

Also the shower valve could be getting fouled too.

Re: Aquahot hot water tapers off to cold

Reply #3 – March 04, 2024, 11:14:37 pm

Viewrvs
Be careful with the vinegar flush.
I have a 98 that upon purchase required ALOT of maintenance. Did the electrical wiring, thermostats, Motor , tempering valve etc etc.....to the tune of about 6 grand. (cdn) Then I decided to flush the system with vinegar like I had heard and because of the EXTENSIVE lime etc in the system, I could not get any hot water. Tried air and everything to solve it but in the end it cost me 9 grand to get new copper tubing put in including labour etc. This was due tot he lime in the system, which had NOT been taken care of regularly.

Re: Aquahot hot water tapers off to cold

Reply #4 – March 05, 2024, 08:40:04 am

Fred, The black knob fit in the beginning and can fit now. The rubber fuel lines can be moved. If the knob hits the pan, gently lever the body of the valve up till the copper pipes go back to where they were before someone bent them down. Will not take much movement.

Test the water temp at kitchen sink. Flow the cold water and then flow the hot water. Flow rate should be nearly the same amount. Set the temp of the water with the black know to between 115 and 120 degrees F. Righty righty is cooler.

If all of this is correct and hot water cools off, get a one gallon container. Turn the water on at the flow rate you have been using and with a timer in hand put the container in the flow for 45 seconds. If the container overflows before 45 seconds, you are testing at a flow rate higher than 1.5 gallons per minute. Slow the flow rate and test temp again.

If water temp continues to cool off, your hot water coils have come loose from the heat transfer mastic. To replace the mastic is a lot of work. One of the members has done this when he replaced his fresh water coil. If this is your case, call me.

Re: Aquahot hot water tapers off to cold

Reply #5 – March 06, 2024, 06:04:26 pm

Quote from: Rudy – March 05, 2024, 08:40:04 am

Fred, The black knob fit in the beginning and can fit now. The rubber fuel lines can be moved. If the knob hits the pan, gently lever the body of the valve up till the copper pipes go back to where they were before someone bent them down. Will not take much movement.

Is it possible to put something under the copper pipes like a plastic shim or PEX tube to hold it up so the knob isn't holding the weight?

Re: Aquahot hot water tapers off to cold

Reply #6 – March 06, 2024, 06:09:59 pm

I will measure the flow of the hot and cold. I do know that the cold is much stronger at each location (kitchen faucet, bath faucet, and the bath/shower).

Re: Aquahot hot water tapers off to cold

Reply #7 – March 06, 2024, 06:11:26 pm

Quote from: Peter – March 04, 2024, 11:14:37 pm

Viewrvs
Be careful with the vinegar flush.

Peter,
I'm not sure that I understand your post. Did the vinegar flush cause damage to your copper lines?

Re: Aquahot hot water tapers off to cold

Reply #8 – March 06, 2024, 07:00:48 pm

Sent you a pm
Peter

Re: Aquahot hot water tapers off to cold

Reply #9 – March 06, 2024, 08:40:26 pm

Any solution to giving the knob room is fine. The copper pipe is twisted forcing the knob down. Gently levering the body up may restore the position of the body.

Lower hot water flow than cold water flow is a restriction in fresh water coil

Re: Aquahot hot water tapers off to cold

Reply #10 – April 20, 2024, 09:32:46 pm

I hate my Aquahot. There. I said it.

During my troubleshooting, of the temp fading off and descaling the unit, it appears gunk got in my Microphor toiulet and it is now acting up and not filling with much water.

In addition, now the AC breaker is popping for the electric element. Keep in mind that this happened last summer while at FOT and they replaced the breaker and the electric element. Now it is doing the same thing. Argh! What causes the AC breaker to pop?

I did check my fluid levels and it is not at the top of the tank. Looks to be 3-4" inches from the fill port. I could not touch any boiler fluid (turned off so it was cool) with my fingers but saw some there with a mirror. There is no fluid in the overflow tank.

The hot lines (tub, kitchen, and bath) all still have less water volume than the cold after descaling. The descaling started off with dark green fluid and specs of stuff but tapered off to a light green vinegar solution at the end.

Re: Aquahot hot water tapers off to cold

Reply #11 – April 21, 2024, 01:38:14 pm

Fred, sorry about your issues but they all seem to be previously experienced by a lot of us.

The AH tank MUST be topped off at all times. The overflow is not an indicator of a full tank. Sounds like you may have a leak in the tank to the burner if no coolant in the AH case. I did. Fixed it with stop leak.

If the tank is low the electric element may be exposed and will overheat and hopefully the breaker will trip before it boils off the H2O or fries the thermostat disk...it did on mine.

What does the aquahot have to do with the toilet? Your Microphor water level is adjustable with the controller dashpot....very small changes.

Re: Aquahot hot water tapers off to cold

Reply #12 – April 21, 2024, 02:13:33 pm

As was recommended by woody I used the stop and seal recommended to stop a leak. I was a little apprehensive at first about the product but tried it and it works exceptionally.
As stated, so important to keep the main tank up and then monitor via the overflow tank
I had major issues with my Aqua hot after buying my used coach but after some time , and a lot of money, am happy with its performance. I just did my first ever service on it this year. (Outsourced it previously) A bit of a challenge but got it done and am happy with the results and knowing I can do it my self!
Peter

Re: Aquahot hot water tapers off to cold

Reply #13 – April 22, 2024, 07:31:28 am

My Aqua Hot had frozen and burst before I bought the coach. I removed the unit and refurbished it, removing the domestic hot water coil completely. I installed a 10 gallon electric marine water heater with the auxiliary engine coolant heating option. I added an additional heat loop from the Aqua Hot to the water heater. The loop has its own pump and thermostat. Now I can heat water using 110V electricity, (powered on either shore or generator) or from the Aqua Hot, or both. The only problem I have had is I used a solar panel pump since it was small enough to fit into the AH case. I have had to replace it after 1 1/2 years use. It is just not robust enough for the application. My plan is to replace it with the same pump the AH uses the next time it fails. I will have to mount the bigger pump outside the case.

TOM

Re: Aquahot hot water tapers off to cold

Reply #14 – April 22, 2024, 08:23:31 am

What marine water heater did you use? Did you connect the aquahot in lieu of the engine loop or in addition to?

Re: Aquahot hot water tapers off to cold

Reply #15 – April 22, 2024, 08:38:15 pm

Quote from: Geodmann – April 22, 2024, 08:23:31 am

What marine water heater did you use? Did you connect the aquahot in lieu of the engine loop or in addition to?

I used this one:
11 gallon Water Heater, 120 volt | Kuuma 11841

I added an additional loop to the AH with a pump and a back flow preventer valve. I also added an adjustable t-stat on the heater to control the pump. I wired the pump into the existing switched AH supply (with fuse and relay) so the pump does not come on unless the AH is on. It all works very nicely if you have enough extra room in the bay for the heater.

TOM

Re: Aquahot hot water tapers off to cold

Reply #16 – April 26, 2024, 12:20:39 am

Quote from: Woody & Sitka – April 21, 2024, 01:38:14 pm

What does the aquahot have to do with the toilet? Your Microphor water level is adjustable with the controller dashpot....very small changes.

The Microphor was working fine before I started adding vinegar to descale the Aquahot. I'm just thinking some minerals broke loose and clogged the Microphor water supply. The toilet was flushed while the vinegar was in the system.

Re: Aquahot hot water tapers off to cold

Reply #17 – April 26, 2024, 12:27:05 am

Quote from: Woody & Sitka – April 21, 2024, 01:38:14 pm

Fred, sorry about your issues but they all seem to be previously experienced by a lot of us.

The AH tank MUST be topped off at all times. The overflow is not an indicator of a full tank. Sounds like you may have a leak in the tank to the burner if no coolant in the AH case. I did. Fixed it with stop leak.

If the tank is low the electric element may be exposed and will overheat and hopefully the breaker will trip before it boils off the H2O or fries the thermostat disk...it did on mine.

The tank wasn't topped off. I don't think it was lower than 3" from the top since I could see boiler fluid with a mirror. I also don't know if it just wasn't topped off at FOT when they replaced the electric element and breaker. I should have checked their work!

We replaced the boiler fluid ourselves with the YELLOW fluid. FOT and MOT only stock the PINK. Lesson learned. Only use the PINK boiler fluid going forward!

So is the electric element toast? I can top off the boiler fluid but is it already too late for that? Should topping off the fluid be my next step?

Re: Aquahot hot water tapers off to cold

Reply #18 – April 26, 2024, 08:37:05 am

Fred, remove the small cover over the electric element located below to the left of the burner. With the electric element turned off inside, remove one of the two wires on the element.. Set your VOM meter to Ohms resistance, the horse shoe symbol and check the resistance of the element by placing the leads of the meter on each connection. It should read 9 ohms. OL or very high resistance is bad element.

Re: Aquahot hot water tapers off to cold

Reply #19 – April 26, 2024, 10:08:03 pm

Thank you very much, Rudy. I will go get that checked and report back.

I have the unit off right now. I'll hold off on topping off the tank until I check it.

Re: Aquahot hot water tapers off to cold

Reply #20 – May 04, 2024, 04:21:01 pm

I did purchase a new electric element (on the assumption that the existing one is bad). The new one arrived today and the ohms reading on the new one is 9.0. Yeah! I then checked the existing one IN the unit and it reads 7.4. What would cause a nearly new heating element (replaced in 2023) to go bad so quickly?

Also, while laying in the compartment, what appears to be drops on the roof of the bay. When I wiped it, it has a yellow/green tint like the boiler fluid. Nothing on the floor of the bay and nothing on the contents on the joey bed. Could the unit have overheated and that be steam from the unit? That might also explain some missing fluid.

Re: Aquahot hot water tapers off to cold

Reply #21 – May 04, 2024, 06:30:07 pm

Would be nice to know the current draw of electric element with 7 ohms. Could be up from 13 to 17 amps.

You might look at coolant lines along the wall in the inside for a leak

Re: Aquahot hot water tapers off to cold

Reply #22 – May 04, 2024, 09:24:57 pm

Rudy,

Thanks. How do I get the current draw? I do have a clamp meter (but really never used it). Is the 7.4 ohms causing a current draw that exceeds the capacity of the 15 amp breaker? The breaker pops as soon as I turn on the electric element.

Does that ohms rating indicate that the element needs to be replaced?

Re: Aquahot hot water tapers off to cold

Reply #23 – May 04, 2024, 09:33:59 pm

Call me tomorrow after 8 am. Have the volt ohm meter handy, cover off of the burner area. and cover off of the thermostat area too. And cover off the the electric element area also. 7 one 3. 8 one 8 3234

Re: Aquahot hot water tapers off to cold

Reply #24 – May 05, 2024, 02:25:24 pm

Quote from: ViewRVs – May 04, 2024, 09:24:57 pm

Rudy,

Thanks. How do I get the current draw? I do have a clamp meter (but really never used it). Is the 7.4 ohms causing a current draw that exceeds the capacity of the 15 amp breaker? The breaker pops as soon as I turn on the electric element.

Does that ohms rating indicate that the element needs to be replaced?

Element replacement? Maybe.
@ 120v you are @ 15.4 amps.
Measure the resistance of the element. If the resistance is lower than the stated value the amperage will be higher.
Your breaker may be bad.
The breaker may be popping below the rated amperage.
Try to get an amperage reading as the breaker pops.

Volts divided by resistance = Amps.
110v / 7.8 = 14.1 amps
120v / 7.8 = 15.4 amps

14.1 to 15.4 amps is expected range when you measure..

Tim

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