We have a 2001 U320 and the hot water from shower, Kitchen and bath various from 79 to 81 degrees. It seems a little on the cool side to me as I need to run the shower using hot only and never have to mix in from cold to cool it down. I had it serviced 2 years ago, exercise it monthly and it runs smooth and clear at the exhaust.
Is there a "normal" temperature of hot it should be putting out?
There is a mixer valve with a thermal device that regulates the domestic hot water. Seems to me like ours is right under the pump and has a red handle. We had no hot water and had to replace it. Rudy will probably chime in on this one. He helped me with ours.
We had the same problem and replaced the mixing (tempering) valve and that fixed it. The valve is located under the fuel pump/blower assembly. Buy a new valve assembly and just transfer the guts to the old valve body. Pretty easy DIY project.
Steve
Output from the mixing AH mixing valve should be about 120° assuming your AH is up to operationg temp.
Could it be the shower valve itself?
Hot water temp at all hot water facuets, not just shower, should be 115 to 120 degrees and steady at that temp. SteveB is right that the most likely solution is new guts for the tempering valve.
To check this out, heat the heater up to temperture. When the diesel burner cycles off, heater is up to temp. Turn on a sink, not shower, hot water facuet and check the temp of the copper pipe coming from the Aqua Hot tank to the tempering valve. This can easily be to hot to hold onto. Then check the temp of the hot water leaving the heater going up into the coach. If first line stays real hot and water to coach cools off, replace the tempering valve guts.
If sink stays properly hot, then shower faucet is suspect.
To replace the guts, order a new vavle. Remove the burner from the heater revealing the tempering vavle. Loosen the knurel nut holding the old guts in the tempering vavle. Remove new guts from new valve and insert into tempering valve. Tighten knurel nut, replace burner and you are done.
Easier said than done but not to hard a task.
A tip I learned some time ago was to always use the water in your fresh water tank when you need hot water and the ambient temperature is cold. The water coming out of the ground can be close to freezing and I believe the max temp rise for the Aqua Hot is something like 50 degrees F. So, if the incoming water is 35 degrees you will probably only see 85 degree water at the faucet at full flow. If the water in your fresh water tank is 50 degrees then you will have 100+ degree water at the faucet because you are heating warmer water and mixing it with warmer water as well.
My numbers are probably not exact but I think you get my point.
Steve
Thanks all for your replys/information.. Now the problem has been identified.
FYI, I was on tank water and Aqua Hot had run a full cycle and at max.
I'll get it fixed and look forward to a "hot" shower.
Great information when you need it, great forum of Foretravelers.
One tip, make a mark on the tempering valve knob before you adjust or replace the guts. That way you know where to set it when you're done.
Some brands like Beaver and Country Coach built their own recirculating hot water plants using Webasto burners.
Why? Because of the 1.5 gallon per minute continuous hot water output. Not enough for some customers.
Beaver Marquis had four zone heating and needed to have the ability to fill a jacuzzi bath tub in their Orlov floor plan.
No way an aqua hot had the output. Plus more money to buy a aquahot versus make you own
Our older FTs are not limited to 1.5 gal per minute output.
From the user manual for the AHE-100-02S installed in my coach (or a later version) and most U320s. Unlimited hot water.
Hot Water
2.3 Using the Domestic Hot Water System
Aqua-Hot Motor Coach Heating System Owner's Manual 05/02
Page 2-3
SECTION 2: OPERATING INSTRUCTIONS
When the Aqua-Hot is at operating temperature, the domestic water is automatically heated as it is being used. Because the Aqua-Hot does not store any hot water simply open any hot water faucet and a continuous supply of domestic hot water will be present within a few seconds. This hot water feature is continuous and is accomplished by the Aqua-Hot's Mixer Valve and Intergal Domestic Hot Water Heating System. Please note that the Diesel-Burner Control Switch must be ON to get an unlimited supply of hot water (i.e. during showers).
We have no trouble doing 5 minute or more showers on 120v alone.
Anyone can misread and distort facts into anything they want.
The aqua hots temperature rise of 55 degrees over the units water inlet temp maxes out at 1.5 gallons per minute flow rate.
Past the 1.5 gpm rate the 55 degree temp rise decreases.
Only so many BTU's input in a aqua hot system. Not unlimited heat.
Webasto burner was separately purchased by the other mentioned brands to give more gpm flow or a hydro hot system.
Turn on all your faucets on hot and the shower and after the coils run out of hot water the temp will start to fall.
Beavers used a Parr water pump capable of much higher water flow than a normal rv water pump.
And used a residential high flow shower head in most models
Here you go.
Here's what the 'guts' of the tempering valve look like.
Someone posted the Aqua hot bearing numbers and I can't seem to find them--Could I get a re-posting
Thanks
Chris
Chris,
608RS
I buy SKF rather than the cheaper skate board bearings that you will find.
Mike
Before replacing the tempering valve, try exercising it. Make sure you mark the current position of the valve knob. Rotate the knob its full range back and forth a couple times, then try Rudy's temperature test again.
Bob is not the one distorting the facts here.
Roger Berke & Rudy have both stated that the Aqua-Hot units in our older coaches are rated for a 55 degree temperature rise at 1.5 GPM. Running the numbers confirms that the diesel burner doesn't suppy enough energy to heat incoming very cold water (such as coming from a city water tap) to 120 degrees at flow rates significantly above 1.5 GPM. Incoming water at moderate temperature and with one shower flowing is no problem, but the Aqua-Hot simply cannot continuously suppy hot water at higher flow rates under all circumstances.
Half the facts don't make a complete conclusion.
Yes you can pick and choose your facts any way you want to make whatever case you want. So if you are connecting to very cold city water or well water you may not get a continuous supply of 120 degree water. If you are using water out of your tank that has been sitting there for a while you probably will. If you are parked somewhere in sub freezing weather maybe not. Maybe you have un-wisely selected a 3 gal per minute shower head, probably not.
Deep well water might be 40-45°. Our well water in MN is 45° +/- 1 or 2 degrees all year round. They are commonly used in geothermal heating and cooling systems. Most city water is amost always warmer than that. So 55° increase is going to be at least 95° at 1.5 gal per minute. You are probably not going to be showering with all hot water so some mixing is going on which means you are not using 1.5 gal per min or hot water but maybe 1 gal per min or maybe less in which case the temp rise will be greater. Which means you will use less hot water giving you even more temp increase.
You can use your AquaHot anyway you want and perhaps find a situation where you can reach its limit. CaFlashBob was implying that the AquaHot in our Foretravels is inadequate. Out of context this is misleading to someone looking at a Foretravel with an AquaHot when for almost everyone with an AquaHot in almost every circumstance it provides continuous hot water for the way we use it.
This is exactly what you did when you gave the impression that our Aqua-Hot units will continuously supply well over 1.5 GPM of hot water under all circumstances. Bob was correct in stating that their specifications do not state that.
I spent a conserable portion of my Foretravel manager years long ago discussing the various defrugalities of the systems installed in the owners coaches. We all learned together. No harm. No foul.
The details is where the rubber meets to road as it is.
Having lived with the way back when early rv systems like three way Dometic's and six gallon water heaters and being a winter dry camper if required the finite details on exactly how the systems work on our coach is important.
The idea that it is optimized as equipped for four season dry camping with backups for almost every system in it is important to us in shaky town.
Not so important to most. They are used to power poles or run the gen and nice weather.
Quote from Rudy about 10 months ago.
The water heating spec for the Aqua Hot heater is 55 degree temp rise at 1.5 gal per minute flow. In cold climes, you may be ingesting really cold ground water such as perhaps 40 degrees. Add 55 to that and you are not happy but the heater is working correctly.
So one can fill the onboard fresh water tank, turn the basement thermostat up to full hot and leave overnight. Next morning you have warm enough water via the fresh water pump to have a nice shower. You can possibly slow the water flow down giving it more time to pick up heat as long as you enjoy the show flow.
Keep the fresh water tank topped off as adding 20 gallons of cold to 80 that is warm works better than the other way around. Electric is not rated to provide hot water for showers. You always need the diesel burner and electric element if plugged in. Diesel burner is needed in temps below 45 degrees for interior heating as well as hot water.
There could be a mixing valve issue as mentioned also. To test, turn hot water on till it is just warm or cool. Place your hand on the pipe from the tank to the mixing valve. If real hot, mixing valve. If not real hot, incoming water temp and/or to fast water flow. You must be at the heater reaching under or around the burner to do this test.
Hope this helps.
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Rudy Legett
1995 U320 M11 400 hp
Exactly! The Aqua-Hot models in our older coaches are great units but there are real-world conditions where they cannot continuously supply the hot water needed for a comfortable shower.
Unfortunately for those who prefer insults over facts and physics even great systems such as our Aqua-Hots do have their limitations!
The Aqua Hots in the newer coaches are smaller and only have 2 zones. Our older coaches have more hot water than they do.
I'd like to bump this as cold weather is upon some of us.
It's a good idea to use water from the fresh water tank rather than much colder water from the campground if you like hot showers.
I find this works with my 10 gallon propane water as well.
The hot water heating spec for the Aqua Hot heater is "55 degree temp rise at 1.5 gallon per minute flow rate".
So 40 degree ground water will only get to 95 degress at 1.5 gallon per minute, cool shower. Plus a fancy shower head flowing faster than 1.5 gallon per minute equals cool shower.
I agree using fresh water tank water helps provide hot shower in cold weather. Plus refilling water tank each evening, not letting the fresh water tank get nearly empty, letting the new water warm up over night keeps tank temp up too.
I presume that 55 degree rise requires all of the BTUs being used to heat water, none wasted on interior or engine heating. And also requires electric plus diesel.
I learned this from Mark, our tail gunner tech rep on the Alaska Motorcade. That's when I started using tank water even with my conventional water heater. Well water piped through 40' of permafrost is a bit clilly.
Tom, Not knowledgeable enough to say how much interior heating demand would impact water heating. The large heater in Unicoaches is normally able to heat water and interior at same time. Not true for the 400 series in a Nimbus.
Frigid conditions and cold ground water certainly challenge water heating
Electric element is 5,000 btu's. Diesel is 50,000 as far as I know.
A owner spent a full winter in Montana with foam around the coaches skirt with an aquahot U320. Plugged in also.
I think they added extra insulation in the windshield and window areas.
Heated water hose and running off internal tank I think.
What and how the Aqua Hot works for you depends on where you are and how you use it and what your expectations are.
We have used our coach in a wide range of outside temperatures for more than 9 years. Often below freezing. We are comfortable heating the bedroom to 60 degrees and the living room to 68 degrees. We will turn down the thermostat to 64 in the living room over night. Unless it is less than 40 degrees we are on electric only. In the morning the LR temps go from 64 to 68 in minutes. And since the electric was on all night it is hot. No problem taking a shower at any time. And two in a row is OK. And the heat is on in the bathroom.
We do not use the blower and heat exchanger in the dash, a simple switch to turn it off. Much more uniform heat in the LR. The other fans run longer but not as often.
Your experience may be different. You may want to heat the whole coach to much higher temperatures. Maybe you want to take long showers. What you want it to do for you and what your expectations are dictate what it will do.
All of these stories about your big AH not heating the coach and letting you take a shower just are not our experience. I don't think ours is any different, it is just how we use it.
Has anyone put in a 240 volt element in a Aqua-hot. At 240 volts a 2500 watt element could be put in.
Not wanting to cause any conflict, not asking about inlet water temp verses tank water temp. Not asking about water hot enough to shower. Here is the questions:
Is the Aquahot systems on all the Foretravel coaches 600D or equivalent? If not, what is the difference. I have seen 450D's and 600D's. Not sure what the 55 degree temperature rise Rudy commented on would be associated with which one or even a different one. Is there a higher temp rise or flowrate for the 600D's?
Newer Aquahot's use double electric elements.
specs for 450D here: http://www.aquahot.com/products/RV/450D.aspx
600D here: http://www.aquahot.com/products/RV/600D.aspx
Note as Bob said 2 electric elements in the 600D and a higher Continuous, Tank-less Hot Water 2.0 GPM
450D a single electric element and a Continuous, Tank-less Hot Water 1.5 GPM
No. Depends on the year/model of coach.
Current model, new, large coaches have 600D equivalent. IC has a 400D, maybe (believe that is a smaller model with no engine preheat).
Older coaches can have a roughly 450 equivalent or a Hydrohot (I believe that's what was used in some Nimbus coaches). In between 2006 and 2014 or so it's going to be coach-specific what they might have put in.
Thanks to all that responded. I was interested in knowing if what Rudy said about the 55 degree increase at 1.5 GPM was an Aquahot absolute or varied with model. Now I know that statement was directly associated to older discussed system.