This past weekend I noticed while taking a shower that the hot water seems to come and go a little bit, like not enough water can get through the aqua hot. Anyone ever experienced this before?
Keith,
It could be calcium build up in the tempering valve.
Mike
Watts tempering valve
Amazon.com: Mixing Valve, Lead Free Brass : Industrial & Scientific (https://www.amazon.com/gp/product/B00DBSPVYS/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1)
Kinda a pain to change. Would recommend just changing the guts out. I recently turned my up a little more. Helped with the fluctuation.
Scott
Maybe I'll just wait until Quartzsite and let the AH service guy do it. :)
Decided to give the system a vinegar wash. If the blue colors are any indication of gunk coming out, then I think this may have helped. Since my water pump has the quick disconnect fittings, I used an old hose that was QD on one end and threaded into the plumbing on the other end, and just dumped the threaded end into a 5-gal bucket. Filled the bucket with 5% vinegar from the grocery store and turned on the pump. Ran hot and cold from every faucet until it smelled of straight vinegar. Also ran 2 cycles of the washing machine.
After letting it sit 24 hrs, I hooked up fresh water and went around running every faucet until fresh was coming out. Several places had some dirt/rust looking particles, as well as calcium particles. The outside hot water faucet, which I did first, was quite blue initially. I'm assuming this is what was coming from the Aqua Hot as well as that faucet. Hopefully this improves the flow through the system, particularly the hot side.
I filled our water heater with 5% vinegar and then turned on the heater and let it "cook out" for 24 hours.
Really made a difference in removing or loosening up the calcium buildup. So much so that I removed and cleaned all the faucet screens.
Mine was doing the same thing. For me it was a sticky Aquahot tempering valve. Easy fix, but I had to contort a bit to get to the valve as it's underneath and behind the burner/blower. Count the turns to turn the valve clockwise (close) to stop, then open it all the way, close it again, then open it to the same number of times. Done. Zero dollah. Here's reference pics of the valve on my Aquahot. As DSD said and you can see it's a PIA solder job to R&R. In any case, the unit needs to be cold, or at least cooled off a bit to do this. Woody.
This picture do not show the blower installed that really changes everything when it's install thoroughly covering access. It is reachable to adjust and if you know which way to turn makes it doable.
Scott
When reinstalling the blower, make sure you don't pinch the photosensor wires at the top. That could cause it to ground out to the case, dropping voltage as it's returning to the control module, thusly tripping the module's failure circuit and killing combustion after 9 seconds. Ask me how I know .
Ha ha I was thinking of mentioning don't over torque hold down bolts too. I hear they are fragile
So I've heard.
(https://i.imgur.com/z53U2yy.png)
I wonder how much difference having the AH hot would make. I did not have mine hot at the time. May run some more through the hot side and see what happens. Might try heating it up too.
Bob Villa recommends heat
How to Descale a Kettle in 5 Steps (Guide) - Bob Vila (https://www.bobvila.com/articles/how-to-descale-a-kettle/)
Scott
I have never seen the technique of acidifying your hot water system in any Aquahot literature. You might want to check with Rudy before pushing any more vinegar through your Aquahot. I, for one, do not want to have to replace the coils like DSD had to do...I'm not as mechanically and facility gifted as he. Woody.
Believe it or not low coolant can cause this to a limited extent.
Thanks Mark, the reservoir is at the marks when hot and cold, but I'll check the top too.
Remove the radiator cap on top, antifreeze should be as full as you can get it. But if the level in the overflow moves during use then it is probably full
Keith
The overflow reservoir does move from cold to hot marks, but while it's cooled off, I'll check it.
If it doesn't move it is most likely low. My storage neighbor had the same no movement in his overflow tank, he was a gallon low. It works as it should now. The level should move from the cold to hot line EVERY TIME you turn the aquahot on.
Keith
I'm going to give this a go today. AH is cooled off and I pulled the side covers and can see the tempering valve. After the tempering valve, there is some other piece plumbed into the hot water line that appears to have a slow leak. It isn't mentioned in the service manual I have. Can someone identify it? Where can I get another one?
Hot water pressure relief valve that has aged out. Look online for one. It is a plumbing item used with hot water heaters.
Can be ordered from Aqua Hot but widely available from plumbing suppliers.
Thanks for the info Rudy. Bought a replacement relief valve and started fiddling with it tonight. Looks like I need to remove the burner assembly to rotate the valve to remove it. I was hoping not to have to disturb that.
Now to find the power circuits to the unit to kill it before I try removing the burner. AC and DC power, right?
I guess I'll be able to get to the tempering valve easier once the burner is out though.
You don't have kill the power, just remove the burner 2 bolts just loosen them and you can swing them out of the way, and set the burner out of the way.... I forget the size,and a 12" 1/4" extension will be needed... . Do not overtighten the bolts when you go back together with it. Might as well replace the nozzle and clean the burn chamber while you got it out...
Keith
Turn electric element and diesel burner switches to off. Run hot water till it cools off. Remove the burner for access. Remember when re-installing the burner to not over tighten the two J-bolts that hold the burner to the heater. They just need to be snug, not tight.
With burner out, turn off fresh water pressure pump and turn off the shore water hose. Remove the relief valve and replace. Use thread sealer or paste. Turn on water pressure and check for leaks. Install burner and you are done.
# 10mm socket for the two nuts.
Thanks Richard, Rudy and Scott. It really is as simple as it appears. I figured for sure there was something I could break when taking it apart. So far so good. Replaced the valve and reinstalled the burner. Letting it heat up now.
Also did Pyolet's "turn the tempering valve" trick a few times while it was easy to access. Looks like it's only about 1 turn from closed to open...is that right? Mine is set at maybe 3 o'clock from fully in (clockwise) about 5-6 o'clock and fully open about 1 turn counter-clockwise (6 o'clock).
Ran the AH last night until it got up to temp and shut off. No leaks. Checked the temp at the kitchen faucet, 121*F, so it looks like I'm good there too.
Slightly off topic, but still related to the AH, while it was hot I decided to test all zones for heating since we're eventually going to get some cooler days (still in the low 80's here - it's NOVEMBER!) at some point.
- Zone 2 - bedroom, has one heat exchanger under the bed and works fine.
- Bathroom has it's own t-state and works fine. One heat exchanger with a branch that feeds the toilet room.
- Zone 1 - front living area. There are two heat exchangers, one under the stove and one in the pedastal for the table. Both work good. I also had air coming out of the dash vents, but ambient temp only.
Is there another heat exchanger in the dash? If so, is there any reason it would not get heat while the other exchangers in the front area do?
1 Yes
2 Not that I an think of. Ours takes a few minutes (almost when it cycles off) for the heat to come out. I thought it was due to the radiator in the dash is down stream of the primary as they are in series.
Mike
Maybe I just didn't give it long enough. Maybe ran it for 2 minutes in each zone. I'll give it a bit more time next time. Thanks Mike!
My 96 U320 has three heat exchangers in the dash:
AC evaporator
Coach heat exchangers, 1 for engine supplied heat and 1 AquaHot supplied heat.
I've been thinking about this. If you are using your water pump and have an accumulator then the water pressure in your system varies as the pump cycles on and off. The OEM shower valve controls the rate of flow and the relative mix of hot and cold water. It is not an automatic mixing valve that controls the mix of hot and cold to maintain a set temperature. You could change out the whole shower valve to do that but then with most of these valves you have no volume control.
The AH mixing valve is more automatic, mixing cold water and the AH hot water (it could be as much as 180°] so that hot water coming out of the mixing valve is no more than 120°.
At the shower you mix hot and cold water based on where you set the knob. If the pressure varies in the water system and there is more resistance in the hot water side then at lower system pressure less hot water will mix with cold water and when the pressure goes up more hot water will mix. If the total volume setting is low this temperature variation should seem less.
The AH mixing valve may need replacing but the hot side is whatever comes out of it. The more likely place for a hot water side restriction is at the Manabloc or the shower valve itself. Make sure the shower valve is clean and all of the screens etc in the shower head and hose are free of crud.
We recently did the vinegar soak and flush. Lots of blue stuff coming out, that is mostly vinegar reacting to the copper. And lots of small bits of stuff. After you are done with that check all of the screens again. The screen at the vacuum breaker on the shower hose was completely clogged up, no water got through. I called Moen and the sent me 2 new screens free of charge.
Check the easy stuff first.
Good thoughts Roger. I did the vinegar wash two weeks ago, so I hope that flushed out system and maybe these issues will no longer be present. I had removed the shower head from the hose for this. I also did the AH tempering valve full closed/full open cycling a few times while I had the burner out, and reset for 121*F at the kitchen sink. Hoping to get away this weekend to give it a test run.
Between moving the tempering valve and the vinegar treatment, it seems to have eliminated the surging hot water issue.