Heating options - propane, AquaHot, Primus

Topic: Heating options - propane, AquaHot, Primus (Read 1414 times) previous topic - next topic

Heating options - propane, AquaHot, Primus

November 17, 2013, 12:11:48 pm

Quote from: drcscruggs – November 17, 2013, 09:16:29 am

Yes, the grill above the front tire is the propane furnace grill and note also (harder to see) the second grill above the rear wheel on same photo. That is the second propane furnace. I have a 1996 36 u295 and I certainly don't have an issue with the propane furnace(s). I like the fact that there are 2 (as some others may only have one). They will keep you warm. People that have aqua hot (which I don't and never have) say that they love it. I frankly haven't and am happy with having not one but two furnaces. There are benefits (as I understand) to aqua hot including being more quiet to heat, using diesel, and pretty much unlimited hot water (mine also has propane hot water heater). One drawback to aqua hot is more expensive to maintain (from what I have heard about repair bills on this forum). Dave is correct and aqua hot is not usually on 295 (unless special ordered).

The new Aquahot unit is $8k plus install. Good units but a lot of $$$s
John H

Re: Heating options - propane, AquaHot, Primus

Reply #1 – November 17, 2013, 03:53:49 pm

Charles and John,
Thank you for the your responses. The main reason for the Aquahot on my end was the DW had expressed interest for the unlimited Hot water. I don't expect to be anywhere to long where we would need more heat than two furnaces can provide.

Greg

Re: Heating options - propane, AquaHot, Primus

Reply #2 – November 17, 2013, 08:12:04 pm

Quote from: GKCigar – November 17, 2013, 03:53:49 pm

Charles and John,
Thank you for the your responses. The main reason for the Aquahot on my end was the DW had expressed interest for the unlimited Hot water. I don't expect to be anywhere to long where we would need more heat than two furnaces can provide.

We have a 10 gallon (I think) 3-way Atwood water heater on our U295. We've never had a shortage of hot water for our purposes (as long as I remember to turn on the appropriate heat source when we are stopped

). We do not take long showers or run hot water for long periods of time.

We've spent a few days at a time in temperatures below 10F. The two propane furnaces were the primary sources of heat. They did fine. We burned about 6 gallons of propane per day. One could reduce fuel usage by using electric heaters.

Re: Heating options - propane, AquaHot, Primus

Reply #3 – November 17, 2013, 08:42:47 pm

Ditto with JD's experience... we also have 2 propane furnaces on our 36' and a 10-gallon two-way (propane/electric) Atwood water heater. We full-timed for a year (now we half-time)... and we've never had a problem running low on hot water. I should mention we also have a 2100XC Splendide washer/dryer (installed in 2010), and still have not had a problem with sufficient hot water.

Like JD, occasionally I forget to turn on the hot water heater electric switch (under the side of the bed, next to the circuit breaker box) when we first arrive at a campground. If I'm in a hurry for hot water, I turn on the propane switch instead, since it heats VERY quickly. Then I change it to electric.

We also did fine with cold temperatures... down to -7 (seriously!) with a little snow in Las Cruces the middle of January 2011 when we moved out of our sticks-n-bricks and started to full time:
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Re: Heating options - propane, AquaHot, Primus

Reply #4 – November 17, 2013, 09:45:23 pm

Quote from: J. D. Stevens – November 17, 2013, 08:12:04 pm

We have a 10 gallon (I think) 3-way Atwood water heater on our U295. We've never had a shortage of hot water for our purposes (as long as I remember to turn on the appropriate heat source when we are stopped ). We do not take long showers or run hot water for long periods of time.

We've spent a few days at a time in temperatures below 10F. The two propane furnaces were the primary sources of heat. They did fine. We burned about 6 gallons of propane per day. One could reduce fuel usage by using electric heaters.

Anyone have a comparison of the amount of diesel fuel the aqua hot uses. I know it temp dependent but wondered if anyone had calculated it? Sorry for the hijack

Re: Heating options - propane, AquaHot, Primus

Reply #5 – November 17, 2013, 09:48:38 pm

Bob,

When the burner is firing, it burns 1/2 gallon per hour. But since it does not run all the time, usage of 2 to 3 gallons per day is normal until the temp becomes really frigid and then 3 to 4 gallons per day is predicted.

Re: Heating options - propane, AquaHot, Primus

Reply #6 – November 17, 2013, 09:54:44 pm

Quote from: Rudy – November 17, 2013, 09:48:38 pm

Bob,

When the burner is firing, it burns 1/2 gallon per hour. But since it does not run all the time, usage of 2 to 3 gallons per day is normal until the temp becomes really frigid and then 3 to 4 gallons per day is predicted.

I knew you knew.

Should there be a small dark spot below the exhaust pipe on the ground after several days of use?

Working backwards from some recent camping using the gen and the aqua hot that seems in the range.

Re: Heating options - propane, AquaHot, Primus

Reply #7 – November 17, 2013, 10:09:02 pm

Quote from: GKCigar – November 17, 2013, 03:53:49 pm

Charles and John,
Thank you for the your responses. The main reason for the Aquahot on my end was the DW had expressed interest for the unlimited Hot water. I don't expect to be anywhere to long where we would need more heat than two furnaces can provide.

Greg

If you find your dream coach and it does not have Aqua Hot, you can still keep the dear wife happy. Install an "on demand propane" replacement water heater. There are a couple of different models that fit into the same space as the factory unit. We did not when we replaced ours last month, due to a couple of reasons. First is we like the motoraid feature, of having hot water made off the engine while traveling when we stop or arrive. Second is we always have power when we camp, and it is included in most camping fees with the space.

An on demand working off propane did not seem to make as much sense to us. We have so far had enough hot water, with both the propane and electric turned on.

Re: Heating options - propane, AquaHot, Primus

Reply #8 – November 18, 2013, 01:57:41 am

My 95 u320 has a very rare Primus system.
Its a hot water system that heats the coach and all water needs. It also heats the front windshield/dash area and engine. Keeps the coach to 1 degree front to back and top to bottom.
Runs off of 2 propane fired boilers or electric or Motoraid.
Never runs out of hot water and silent heat.

Re: Heating options - propane, AquaHot, Primus

Reply #9 – November 18, 2013, 06:29:46 am

Bob,

A dark spot on the ground below the A-H exhaust means incomplete combustion. Is it time for your annual fuel filter and nozzle change?

Re: Heating options - propane, AquaHot, Primus

Reply #10 – November 18, 2013, 06:55:18 am

My 95 u320 has a very rare Primus system.

Sound like the ultimate system.

Will it fit in my U300???

Re: Heating options - propane, AquaHot, Primus

Reply #11 – November 18, 2013, 01:18:25 pm

JD, Thanks for the input on the 10 gallon water heater. Sounds like this opens up my options more as long as I can convince the DW that 10 gallons is plenty of water. I know it would be for me.

Patricia, Now that looks chilly! I love New Mexico. Thank you also for that info.

Dave and Dolly Cobb, I like the idea of a "on demand propane" replacement water heater. If the 10 gallon water heater is enough that sounds like it would work. Any idea on cost of that system?

Lon and Cheryl, Primus system sounds pretty awesome.

Kerry, Thank you for the update on the availability of your coach.

Re: Heating options - propane, AquaHot, Primus

Reply #12 – November 18, 2013, 10:59:31 pm

Quote from: GKCigar – November 18, 2013, 01:18:25 pm

Dave and Dolly Cobb, I like the idea of a "on demand propane" replacement water heater. If the 10 gallon water heater is enough that sounds like it would work. Any idea on cost of that system?

I paid about $600 last month for my new 3 way water heater. I think that on demand was almost $1000. Could not see the any advantage. Dolly was happy in the old coach with 6 gallons, and very happy in the new coach with 10 gallons.

That said, we did upgrade to on demand gas at the house. Dolly stands or soaks as long as she wants and has all the hot water she can ever use when home.

Re: Heating options - propane, AquaHot, Primus

Reply #13 – November 19, 2013, 01:33:40 am

Dave,
Thanks for info. Price doesn't sound to bad really. If the 10 gallon doesn't work then, well you know, "Happy Wife, Happy Life"

Re: Heating options - propane, AquaHot, Primus

Reply #14 – November 19, 2013, 01:47:03 am

The three way water heater has a lot of advantages. It heats water going down the road from the engine with it's heat exchanger and with the electric element, it needs no propane if you are plugged in. I wonder if you could put a small 12V pump in the line back to the engine and use it as a block heater in cold weather?

If you dry camp a lot, the advantage swings the other way with much less propane used with the tankless.

Tankless propane/NG works great at home where gas is much cheaper than electricity. The little point of use 120V under sink heaters do work well.

Pierce

Re: Heating options - propane, AquaHot, Primus

Reply #15 – November 19, 2013, 02:06:42 am

Pierce,
Good to know about heating water on the go. I would have never known that. As you can probably tell this is all NEW to me. I am so glad that I was able to find this forum, where everyone is so willing to share there collective knowledge. Thanks again.

Greg

Re: Heating options - propane, AquaHot, Primus

Reply #16 – November 19, 2013, 08:19:21 am

Pierce

The Aqua hot does just as you say, the unit circulates hot water to the engine to pre-heat. so we have an electric pre-heat with switch on bed, and another on the aquahot. If you are plugged in, the aquahot has an electric element, that can heat the engine, or give you small amounts of hot water (say to wash hands or dishes) and then the Diesel side kicks in for a hot shower or to heat the coach

Elegant, quiet and efficient, but of course not without it's higher maintenance requirements.

HAd the usual propane stuff in my Gran Villa and U-270, worked fine. Have the Aqua-hot now, spent some $$ on it, but NEVER going back.....

Different strokes for different folks. Once my wife was in a slide coach and understood aqua-hot means endless hot water when hooked up, the decision was made..... :-)

Re: Heating options - propane, AquaHot, Primus

Reply #17 – November 19, 2013, 11:27:00 am

Greg,

If the Foretravel you purchase does not have the electric option, it can be added. Ours had one installed (don't know if OEM or added) and works great. Not nearly as fast as the gas but if plugged in, it will keep the tank hot without using any propane. Pak Hot Rod RV Water Heater Conversion Kit Fits 10 Gallon Brand New | eBay Two different brands, just one shown here.

Pierce

Re: Heating options - propane, AquaHot, Primus

Reply #18 – November 19, 2013, 11:51:43 am

When I am camped with jull hookups, I often turn on both gas an electric to the 10 gallon water heater for extra BTUs. Last week our incoming water was barely above freezing, but we never ran out of hot water for long showers. We also supplement campground water pressure with the water pump.

Re: Heating options - propane, AquaHot, Primus

Reply #19 – November 19, 2013, 09:09:49 pm

We also have 3 way 10 gallon water heater, never had an issue with the lack of hot water. When running on propane we turn it on as needed before showers and dish washing, no need to heat water all day if you don't need it.

Re: Heating options - propane, AquaHot, Primus

Reply #20 – November 19, 2013, 09:10:12 pm

Aquahot is great. If we are plugged in we use the 110v to heat water. It works for heating the coach down to about 40°. We will turn on the diesel as well. It doesn't kick in until you start using lots of water (nice shower) or it gets cold enough that the electric isn't sufficient to keep up with heating demand

On diesel we have always had enough hot water and coach heat at any temp (teens easy). While driving the engine heats the AH. The AH can pre heat the engine. Wonderful.

We really like it. I sometime wonder why they don't do in-floor heat. Then you wouldn't need fans and heat exchangers. (Quiet) You could get by with a single pump and solenoid controlled zone valves. This is how our house and my shop are heated. The house has 11 separate zones each with its own thermostat. 65° in the master BR. 73° in the master Bath for example. Perfect. And the floors are warm. Same thing in the newer all electric coaches but they are using electric heat grids embedded in the floor usually under tile. It would cost about 3/4 - 1" for a new sub floor with aluminum heat distributers for 1/2" PEX tubing. I don't know what the existing sub floor structure is. Probably part of the unibody structure so retrofit would be tough. If we both weren't 6 ft + losing an inch wouldn't be a big deal.

All that being said, we are really glad we have an AH system and as many have said, we won't be without one going forward.

Roger

Re: Heating options - propane, AquaHot, Primus

Reply #21 – November 19, 2013, 09:18:23 pm

Will both my 97 aquahot systems work like you post?

Edit:

I see from the service manual that it can.

Bob

Re: Heating options - propane, AquaHot, Primus

Reply #22 – November 19, 2013, 10:51:13 pm

Bob,

I have been using 110v with the diesel as a high demand option. It seems like it works but both are probably triggered at the same low temp point. I don't know if you can set a different low temp start point for 110v or diesel. Seems like if the system is up to temp and both sources are on it goes for a lot longer before diesel come on than when it is just diesel.

I imagine every coach is different. Try it out in yours, see how it works for you. I figure if I am plugged in I am goimg to use it.

If I need to run the generator to boost battery voltage, I always turn on the 110v option for the AquaHot. Charging batteries doesn't use much of the generator capacity so you might as well heat water (and run AC if it is hot).

A bunch of complex systems. Lots to learn.

Roger

Re: Heating options - propane, AquaHot, Primus

Reply #23 – November 19, 2013, 11:47:07 pm

Quote from: Home2fromHastings – November 19, 2013, 10:51:13 pm

Bob,

I have been using 110v with the diesel as a high demand option. It seems like it works but both are probably triggered at the same low temp point. I don't know if you can set a different low temp start point for 110v or diesel. Seems like if the system is up to temp and both sources are on it goes for a lot longer before diesel come on than when it is just diesel.

I imagine every coach is different. Try it out in yours, see how it works for you. I figure if I am plugged in I am goimg to use it.

If I need to run the generator to boost battery voltage, I always turn on the 110v option for the AquaHot. Charging batteries doesn't use much of the generator capacity so you might as well heat water (and run AC if it is hot).

A bunch of complex systems. Lots to learn.

Roger

Here is the only reference in the shop manual I down loaded a while ago on page 87

Please note that the 120 Volt-AC Electric Heating Element is the Aqua-Hot's secondary heat source for heating both the interior and/or the domestic hot water during low heating de- mand situations (such as when moderate ambient temperatures exist and/or when there is a low demand for domestic hot wa- ter).
If the 120 Volt-AC Electric Heating Element is not providing enough heat, turn the Diesel-Burner on, in conjunction with the 120 Volt-AC Electric Heating Element.

I will see if the manual mentions different temp sensors for the system but I bet there is one only.

Edit:

Looking at the available shop manuals that may or may not be the correct ones for our coaches it seems the diesel low cut on thermostat is a 175 degree unit.

The electric is 185-190. Both high cutoffs I think are the same at 200 degrees.

So they seem to let the temp drop more before the heating element comes on in diesel probably as it energy input is so much higher.

So the tank is always between 185 and 200 on electric and 175 and 200 on diesel.

Both systems seem separate except for a stirring pump for the diesel side that circulates the hot antifreeze from one side to the other in the tank. Out and back in the other side.

Do not see such a thing for the electric.

So unless my quick study is incorrect the fastest heating would be to turn on both switches.

Both would heat until 200. After that if the electric was off the system would let the tank temp drop to 175 before turning on the tank re circulation pump and burner.

At 185-190 the electric would turn itself back on. Rudy would of course know better.

So it seems to heat to 200 then shut off then when the electric hits 185-190 it cuts back on and if the temp drops below 175 the diesel comes on.

Maybe if the tank temp never gets to 175 it never comes back on?

So both heat to get to 200 but the electric only keeps it going unless it gets to 175 again.

Seems like a well designed system to me. As nighttime temps drop it will add the higher input automatically or as needed.

Glad you mentioned how you use yours. I learned something today. Good day.

Separate high limit safety switch cutoff on the diesel side at 230. One at 200 a second one at 230.

Bob

Re: Heating options - propane, AquaHot, Primus

Reply #24 – November 20, 2013, 04:57:23 am

Quote from: Bill Chaplin – November 18, 2013, 06:55:18 am

My 95 u320 has a very rare Primus system.

Sound like the ultimate system.

Will it fit in my U300???

It does not take up that much room. Two boilers (about 12" x12" foot print each), a 12v circulating pump. Problem is the full length wall baseboard heat exchangers that runs full length on both sides of the coach. There is also heat exchangers in the dash, entrance step,and in the cargo bays. You also need the control center. It is NOT as easy to operate as a Aqua-hot system, but, it works GREAT. It draws very little 12v electric power, and the pump will run down to 9v.

Bluebird used this system. I get VERY VALUABLE info from the Wonderlodge/BlueBird Forum.
I have only read about one other Foretravel that had this installed. It was a 95 U320 that the owner of Justin Boots ordered. Foretravel wanted a system that would heat the hot tub that was installed in his coach.

The Primus systems are no longer made. Parts are available, from Dupree. Some Primus owners have converted to a Wabasco diesel system. They can use the Primus heat exchangers and then substitute the Primus propane boilers for the Wabasco diesel boiler.

Good luck with your project.

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