Hydro Hot Challenged

[Bob Jae]

Les what the low cut off does it shut off the coach heating zones if they are running so that the hot water gets the priority so that you have a hot shower.  If the heating pumps are not running it should make no difference.

[Les Brandt]

I can't get my "large frame" under my coach to get to the back panel. It sits too low where I park it and it's either dig a trench in my driveway, build ramps or take it to my Aqua Hot shop. I'm leaning towards the latter at the moment.

[Karl Welhart]

Les,

I think your HH is located in the same place as mine.  I can easily get to mine by airing the bags and opening the LR slide.  Then I crawl in behind the propane tank and have plenty of room to unscrew the panel to access the mixing valve.

Karl

[Les Brandt]

So I mangled to get the back off my Hydro Hot unit and tried to adjust the mixer valve. It wouldn't move and I was scared of breaking it with force. When I look at the numbers on it it shows 1 and 2 on the back face. Should this be set higher to have hot water longer or does this just affect the temperature of the hot water?

I started the diesel burner. When I ran the tub, hot water came at first then the burner cut off and the water gradually got to warm and then cold, then the burner cut in again.

[Edward Buker]

Les,

That mixing valve just affects the water temperature to the faucets. It is possible that the knob on that unit might lock and have to be pulled upward to release it to turn. Not sure but worth a try. The red direction would be hotter as it points out. The valve may be defective if it cannot/will not move. The version I have is a different brand and a kit can be installed without removing it, not sure on yours. You might call the maker of your Hydro Hot to see what is possible with that mixing valve.

It sounds to me like your unit does not allow the burner to run long enough. There is usually a couple of button thermostat that controls the firing of these units and those may be out of calibration with age. A recording of the temperatures as to what happens boiler temperature wise when the burner goes on and off using an inexpensive IR gun would be a good place to start. Also some mixing valve in and out temperatures as you run water to see if the incoming hot water is hot enough and if the mix is bad or if the water coming in is not hot enough to begin with and mimicking the boiler temperature performance.

I have not owned a Hydro Hot and do not know what their limitations are but there should be some folks that have been there before and can steer you a bit with this.  Hope this helps.

Later Ed

[Karl Welhart]

Les,

Ok, (Orman, please do not read this post) I had the very same problem and this solution is NOT recommended by the Aqua Hot people.  Take a rubber hammer and tap the top of the mixing valve.  After a few taps, try to turn the knob.  If it is still stuck, try again....  It would be best to have the hot water facet running while doing this procedure.  Good luck.

I think someone said that you do not have a stir pump.  Not sure if that is true, but you should determine if your model does have one and if so, then make sure it is working.

Karl

[Orman Claxton]

Les
You are not likely to be able to turn the mixing valve by hand, I use a pair of pliers to turn by rocking the valve , it will be hard to break free, may have to try Karl's solution
Also,
send me your E Mail

[Les Brandt]

You mean I have to crawl under that thing again? LOL

I'm still eating gravel from removing the back cover yesterday!

[Orman Claxton]

Les
Post a picture of the front of your H/H, including the lower left

[Les Brandt]

Hi Orman,

The coach is already at my mechanics getting other work done. Here is a photo I had on file. There is no stir pump on this unit in the lower right. Robert Jae already had me check this and there is only a bolt where the stir pump is on other units. We confirmed on Roger's Aqua Hot site that this unit does not have a stir pump.

I sent you an email Orman.

[Karl Welhart]

Les,

That is very strange that you do not have a stir pump.  The function of the stir pump is to circulate the coolant in the tank for even heat around the fresh water coil.  This helps reduce the problem you are having with not getting more even hot water flow.  

Not sure if this stir pump can be added but maybe it would help. The stir pump does not really help much if the zone heating pumps are working.  Therefore,, this stir pump is only necessary when the system is only being used for domestic hot water needs. I think getting the mixing valve to work will also be helpful.

BTW, your unit looks just like mine.  However, I have a stir pump...

Good luck,

Karl

[Les Brandt]

This is off a website. Refers to my HHE-500-4m

Model HHE-x00-04x    Webasto 2010 - Uses ethylene glycol coolant
Open zone pumps (no plastic cover)
Engine preheat pump is PLX-CM3-P71
Check valves are outside of the case.
Has large radiator cap.  PLX-403-000
Must use plastic float (PLX-01G-ML7) (or float sensor - ELE-200-001-HYD).
NO drain valve
NO stir pump
Uses ‘clip on’ Low Temperature Cutoff Thermostat - ELE-LTC-505
Electric system uses ELX-228-1A1 - Relay, SPST, 12 VDC/30 Amp. Neutral wire is switched through relay and high limit. Upgrade kit available, here: ELE-630-002-HYD
Exhaust pipe connects in different location than models starting with 06x model.
Set fuel pressure on Webasto to 135# instead of the 'standard' 145# (exhaust different)

[Les Brandt]

Like my slide and leveler issue....Sad to say, I've given up!

As much as I like to try to do things myself and get the satisfaction of doing a repair and learning, It goes in the shop Monday. I'm on holidays as of Friday and I'm out of time and over frustrated.
Ain't nothing a few G's can't do!
I'll let you guys know what it was after I recover from the bill for this as well.

[Les Brandt]

Update:

Per my previous post from last fall. Got the coach out of the shop. Had hot water but it started to run cold after a bit. Had to turn off the hot water and let the system heat up again.

Fast forward to Now:

Now that its spring, I got underneath the Hydro Hot and pulled the back and managed to get the mixing valve to loosen full motion I turned on the Hydro Hot system and still run out of Hot Water after a short bit.

I need some help diagnosing this as I can't afford another trip to the shop like the last time. My butt is still puckering from the last bill.

As mentioned earlier, mine does not have a stir pump. Could it be the low temperature sensor just ahead of the mixing valve?

[Bob Jae]

Les take a look at this document   http://www.aquahot.com/eSource/ecom/eSource/staticpages/documents/Lack%20of%20Continuous%20Hot%20Water%20Troubleshooting.pdf

See if that helps.

Good luck