AquaHot Burn percentage as a function of outside temp

[Gary.Jones]

I am wondering if any of us are OCD enough to have done an analysis of the performance of our AquaHot 450s? By this I mean (and I have not seen this in the AquaHot manual (based on my failing memory)) out of lets say an hour of operation at 40 degrees outside, what percentage of the hour (or number of minutes) is the exhaust blower on, and what percentage of the hour is the diesel burner burning?

I know that the nozzles are rated at ~ 1/3 gallons per hour, but don't now what percentage of the hour the AquaHot burner is burning as a function of temperature. Now, I am assuming that there is no way to know that universally because that will be a function of a lot of coach-specific factors, but have any of you taken a stopwatch to the actual performance of your 450s in a 45B lets say (as a function of temperature) and know the data?

Gary

[Cruzer]

Never checked it that close but I do know that the Entegra's insulation level makes it run half as much as in our previous coach. The Aqua-Hot does have an hourmeter which is tied to the burner circuit. The meter runs whenever the burner motor is active. That will be mostly burn time although there will be a bit of purge cycle at the beginning and cool down cycle at the end of the burn so it won't be an exact .35GPH reading.

There are lots of variables, such as ambient temperature, wind, humidity, amount of sunlight, etc. Also, if you are plugged into shore power the electric element will reduce the runtime of the diesel burner. Likewise if you use the fireplace for additional heat. The biggest reason I see for heat loss in an Entegra is those two piece front windshield shades. I installed the one piece MCDs on our last coach and it made a huge difference in dealing off any cold from the windshield. The two piece shades on the Entegra are not the optimal design but are necessary due to the design of the Travel Supreme dash - which I hope gets changed in the future. I'd love to redesign that.

[Gary.Jones]

Thanks Mark..... I was not aware of the "burn meter" so that will be a resource.

I thought that maybe I was the only one sufficiently OCD to have done measurements ( ), so the ambient temp this morning in Indiana was right around 40 degrees (they were predicting high 20s to low 30s last night (don't think it got there)), so all of us at Camp Entegra were running AquaHots, so decided to take the stop watch out and do measurements.

Now, I also had the AC heating element on, so these will be low figures. Also,ambient is 40 degrees. Inside temp is set to 70 degrees

Pre-ignition blower run was ~ 10 seconds.
Ignition and continuous burn was 2.5 minutes one time, and 3.5 min second time
Cool down (burner off and only blower running to cool down), 2.5 minutes
Elapsed time between burner cycles was 7.5 minutes

Therefore for two cycles, the elapsed times for two complete cycles was: 12.5 minutes for one cycle and 13.5 minutes for a second cycle. Out of the two cycles, the burner was ignited and burning diesel for an average of 3 minutes (2.5 and 3.5 minutes respectively). Extrapolating, for these circumstances then, the burner was fired for 3 minutes out of each 13 minute cycle, or was burning ~ 23% of the time. Again extrapolating, that would be ~ 23% of an hour at 40 degrees, and a burn rate ( ~.3 gph x 23%) of less than .1 gallon per hour (.075 gallons).

Someone check my math.

I'll go this again without the AC heater "on" and looking only at diesel burner

Gary

[hawgguy]

I rekon the fuel consumption is more a factor of duration of operation. Which would be a fixed 1/3 GPH.

The duration of operation is determined by outside ambient temp and preference of inside temp which are not fixed and subject to variance - particularly the latter.

[hawgguy]

Originally Posted by Cruzer

The biggest reason I see for heat loss in an Entegra is those two piece front windshield shades. I installed the one piece MCDs on our last coach and it made a huge difference in dealing off any cold from the windshield.

I usually don't bother with my Magne Shade during the winter months. Maybe I need to rethink that. I wonder if there would be an insulation value with it in place?

[Ann n Gene]

Cruzer, do not understand your statement about the shades needing to be two piece because of the Travel Supteme dash. The early Entegras had the same dash and used the one piece MCD front shades. I had one and loved it. I think the reason for the change was a perceived problem that one piece was too heavy and could fall down. When MCD installed these at the factory they used 5 brackets across the front and solved the problem. I think Entegra elected to go with the two piece because of pet owners request so one could be raised enough for the pets to see out. I much preferred my one piece shade to today's set up ether two. All JMHO


2016 Cornerstone 45B
Formerly 2011 & 2013 Anthems and 2015 Cornerstone
2014 Lincoln MKT towed

[voltdoc]

Originally Posted by Ann n Gene

Cruzer, do not understand your statement about the shades needing to be two piece because of the Travel Supteme dash. The early Entegras had the same dash and used the one piece MCD front shades. I had one and loved it. I think the reason for the change was a perceived problem that one piece was too heavy and could fall down. When MCD installed these at the factory they used 5 brackets across the front and solved the problem. I think Entegra elected to go with the two piece because of pet owners request so one could be raised enough for the pets to see out. I much preferred my one piece shade to today's set up ether two. All JMHO


2016 Cornerstone 45B
Formerly 2011 & 2013 Anthems and 2015 Cornerstone
2014 Lincoln MKT towed

We have the one piece shade and we have 2 cats that like to sit up on the dash. When we lower the shade we pull it back towards the inside of the coach and let it drape over the front of the dash. That leaves a gap at the bottom to the right of the console with enough room for kittys to get on/off the dash yet still maintains complete privacy for us. It also eliminates the gap in the corners that we would have otherwise. Doesn't seem to affect heat loss.

[Smitty77]

Not an Entegra owner, and have a single element HydroHot -500xx series.

You've mentioned many of the variables that makes duration of diesel run also such a variable! I'm not aware of any usage meter on our HydroHot, so I basically estimate usage, and crank it into a spread sheet I have that uses 30% of a gallon, which I was told by several Aqua/HydroHot techs was more accurate for my specific unit.

When staying in a park with the HydroHot on electric, I use 1 1/2 hours of diesel run time per week. If not running electric, say dry camping, I use 2 1/2 hors per week. (If we have our daughter with us, or I the we've run a few loads of wash with no electric on. I'll bump that up a bit time wise, based upon my 'SWAG' of actual usage.

Generator values are fixed, via hours, but also a bit variable based upon load. So I have two values, one with 'full load', one with 'moderate load'. And if we used say 15 hours during a week, I'll spread those 15 hours by my 'SWAG' between the full and moderate levels. I use 35% of a gallon for moderate, and 55% of a gallon for full load.

If I'm plus or minus 30% on being accurate on all of these values, I'd be very happy! But, over the years I do feel it is good as reference on determine actual coach MPG, vs the Silverleaf's stated MPG, when doing calculations manually. (Well, not manually, also on my spread sheet!)

This is always good 'Hmmmmm!' dialog around the campfire...

Best to all, and have really enjoyed walking thru a few Entegra's - enjoy your rides!
Smitty - SOB!

[DSL417]

JMHO, two piece shades from the one piece starting 2014 directly related to the change of the front shade to United...and likely cheaper. And JMHO, they look BAD (maybe the ONLY thing I think looks bad about Entegra!). And if they did it for pets, I guess requests associated with pets rate more than owner requests in other areas!

[DSL417]

I have a feeling that running the generator more often in slightly below 40 degree temps (like I did overnights for five days dry camping last weekend) to drive the electric heat registers drove diesel usage much more than the AquaHot. of course, it is not a fair measure because other things drew on the batteries, but those five days dropped fuel milage on that tank by 1 mpg (so I think that means I used somewhere between 8-14 gallons of diesel during those five days). I'll live with that given what we saw and did during those dry camping days Beyond that, my mathematics skills fall short of where this discussion has gone thus far:0

[Mr_D]

I like the single piece MCD's we have but would like the two piece units for the cats. As it is I have to leave the shade and sunscreen up about 6" so the cats can see out, and of course that leaves less than total privacy for us.

[Gary.Jones]

Maybe the highjacked MCD shade sub-thread could wander off to another place

After months of having front night shades that dont work and were rolled up and held with rope and clothes pins, I am so happy that mine are working again that I don't care if I burn more diesel or less...... but I can get into bed in my undies without everyone seeing me

Gary

[CampDaven]

Originally Posted by Gary.Jones

I am wondering if any of us are OCD enough to have done an analysis of the performance of our AquaHot 450s? By this I mean (and I have not seen this in the AquaHot manual (based on my failing memory)) out of lets say an hour of operation at 40 degrees outside, what percentage of the hour (or number of minutes) is the exhaust blower on, and what percentage of the hour is the diesel burner burning?



I know that the nozzles are rated at ~ 1/3 gallons per hour, but don't now what percentage of the hour the AquaHot burner is burning as a function of temperature. Now, I am assuming that there is no way to know that universally because that will be a function of a lot of coach-specific factors, but have any of you taken a stopwatch to the actual performance of your 450s in a 45B lets say (as a function of temperature) and know the data?



Gary

My 450 burns .3 gallons per hour of burn time. It really works great, and I don't care how much diesel I use. My DW likes 72F. No discussion is required.
But back to your question:
Temperature cannot be a function of burn time, rather a reason for burn time; longer or shorter. Temperature plus wind speed (WCF), and R-value plus leakage, against total CF of RV air volume, and so forth....would make an interesting formula. And if the cat is hogging one of the heat registers, all bets are off!
BTW, I have found that burn times are noticeably longer if the burner nozzle is worn, and/or if the combustion chamber is caked with soot. I test the burner nozzle by putting blank white paper about 3 inches in front of the exhaust. If it shows spattering, the nozzle is spitting more than misting, which makes soot, et al.
I PM mine annually to ensure the most efficient burn. I can't control fuel useage any better way.

[Gary.Jones]

Outside temperature in Middlebury last night was 28 degrees when I checked it this morning. Conditions were the same. Temp inside the coach set to 70 degrees, both diesel burner and AC heater element "in-line". Under 12 degree colder conditions than first reported, the #1 Zone interior "radiators" are running all the time. Forgot to say yesterday, but the basement thermostat was also set on "7" during all the readings, and again today still set at "7".

Here is the data on the AquaHot. With those conditions, the blower turns on and blows for 10 seconds at the start of the cycle, then the diesel burner (Wabasco) ignites and burns for 4 minutes, followed by a 2.5 minute cool down phase with the burner off and the exhaust fan blower running, and then a 3.5 minute interval where it is all off, before the cycle repeats itself. So, comparing to when the temp was 40 degrees, at 28 degrees, the total cycle shortens from 13 minutes to 10 minutes. The burn time is at 4 minutes out of the cycle of 10 minutes, or it is burning diesel 40% of the time. At a nozzle burn rate of .3 gallons per hour, then I am burning diesel 24 minutes total out of each hour. 24 minutes is 40% of the whole hour with a nozzle burn rate of ~ .3 gallons per hour, that means that I am burning ~ .12 gallons of diesel per hour to stay warm. Lets say at a diesel price of $3.00 / gallon, I am burning .36 gallons of diesel per hour, then it is costing me roughly $1.08 per hour to keep the coach warm on diesel. That is pretty good both from a cost standpoint and a consumption standpoint. However, given a 24 hour day, that would be $26 a day and consume 8.6 gallons of diesel per day, constant temperature. (Of course, it would not likely have to run as much during the "heat" of the day during sunlight hours, but this should be worst case)

I am interested just because it is interesting to note how much it is costing and what is the consumption on my coach in certain prototypic situations. I want to check the same data in the same conditions but much lower interior temperature (such as maybe 55 degrees) if I needed to leave the coach unattended for a while with the AquaHot providing the heat. Also, again, the coach is connected to 50A power so the AC heater element is "on" in the AquaHot, but the temp is below what the heat pumps will handle so they are off and the AquaHot is on and doing the heating. This is all unique to me and my coach but thought the data might be interesting to others. Paraphrasing what Gene says, "Just my humble data".

Again, someone else check my math and see if my data and extrapolations makes sense.

Cheers

Gary