Aquahot -- is this the best it will do??

[rv rick]

We recently bought a 2010 Winnebago Tour 42AD coach with the Aquahot 450 for heat and hot water. The hot water part works great, but the heat seems pretty weak.

This morning, it was about 50 degrees outside and the inside coach temp was 57. I started the heat (using both electric and Diesel heat on the Aquahot -- electric was on all night, so the boiler was hot) and ducked back in the warm bed. An hour later, I got up and found the temp in the coach was 67 and the Aquahot outlet register temps were running about 130. The Aquahot seems to be full of boiler antifreeze and the hot water is very hot. This did not impress me very much -- I think I could have done as well with my 110v space heater.

We fulltime in the coach and will be in colder temps than this -- based on this performance, I would hate to be in 20 degree weather!

My question to those with the Aquahot is - is this performance normal? Does your system really heat the coach? Finally, we only have 5 registers in a 42' coach (3 front zone, two back zone). Is this what other folks have?

Many thanks for your input.

[Oldkarphart]

Sounds like your zone check valves might be stuck (common problem with little use). Tap on the brass check valves on top of the unit with a small hammer or screwdriver while the unit in running in all zones....this should do the trick.
Make sure the ratio of boiler antifreeze is correct, heretell this will cause the valves to stick also.

[radams]

I've never been too impressed with the air heating capability of mine either. If you've got 130F at the registers I would say the solenoid valves and pumps were functioning properly. You did have both thermostats on "furnace" mode, right? The 450 is Aqua Hots's smaller unit with a burner producing 50,000 BTU's and the electric element adding another 5500 or so. You've got a lot of cubic feet of space in that coach and I'll bet it's going to take a while to heat it up.

The limiting factors of the system are the 55,000 BTU's heat source, the size of the heat exchangers at the registers, and the relatively weak 12VDC fans pushing the air. These coach builders should really be putting the larger Aqua Hot unit in coaches of your size. The 450 was originally designed for use in 30 to 40 ft. coaches and they didn't have the number of slides, or the size slides, the newer coaches have.

There's not much you can economically do about it now though.

[Roger Berke]

Your Aqua-Hot should heat up your coach much faster than you report. We have a 42’ coach with the full size Aqua-Hot unit. It will warm up the coach in about 20 minutes… so warm you have to open up the windows to make it comfortable.

Where are your heat exchangers located?

Are you getting heat out of every heat exchanger?

130 degree heat from the heating register is a little low. Should be more in the 150-160 degree range.

- Roger Berke -
Moderator - http://www.Forum.RVHydronicHeaterRepair.com

[rv rick]

Thanks for the replies

I did verify each register is active and sending out heat in the 130 degree range. I also checked that I am getting airflow out of the register, so I believe that the fans on the register are working, although the amount of air flowing out is not very impressive.

The registers are located just below the cabinets: two in the front area of the coach, 1 in the middle, and one in the end/bedroom area. There is also a register that feeds three small outlets in the bath area. They do very little and I did check to make sure the air hoses feeding the outlets are not kinked.

I am afraid that the system seems to be working as designed, however, it is just not putting out enough heat to do the job. I am surprised that this is the system of choice in larger coaches -- my older 40' coach with two small propane furnaces did a great job.

If I can't get this working better, I will need to investigate propane or catalytic heaters.

[Pairajays]

Originally Posted by rv rick

We recently bought a 2010 Winnebago Tour 42AD coach with the Aquahot 450 for heat and hot water. The hot water part works great, but the heat seems pretty weak.

This morning, it was about 50 degrees outside and the inside coach temp was 57. I started the heat (using both electric and Diesel heat on the Aquahot -- electric was on all night, so the boiler was hot) and ducked back in the warm bed. An hour later, I got up and found the temp in the coach was 67 and the Aquahot outlet register temps were running about 130. The Aquahot seems to be full of boiler antifreeze and the hot water is very hot. This did not impress me very much -- I think I could have done as well with my 110v space heater.

We fulltime in the coach and will be in colder temps than this -- based on this performance, I would hate to be in 20 degree weather!

My question to those with the Aquahot is - is this performance normal? Does your system really heat the coach? Finally, we only have 5 registers in a 42' coach (3 front zone, two back zone). Is this what other folks have?

Many thanks for your input.

Vehicle Systems, manufacturer of the AquaHot, is a great company. Why not give them a call and tell them your situation. I'm sure they will be very helpful.

Jim E

[BigSkyBob]

Our 40' coach has 4 slides and we have the 450 DE like yours. It was in the high 20's in vegas several mornings last winter and the water even froze in the hose feeding the coach. I use a 1500 watt electric heater at night but turn on the diesel burner in the mornings as it is usually about 55*. It generally takes about 30 minutes to get the temp up to 70* so your unit has a problem somewhere. You can feel the feed line and return line at the back in the boiler to see if that's working as it should. Check the outlet line temp to make sure it's about 130*. If the temp is less than 130* it can be adjusted using the mixer valve on the back of the boiler. We have six registers feeding warm air into the coach including a full size in the bath. I've been in temps as low as 10* and my Aqua-Hot warmed the coach with no problem and would cycle on and off. Could there be a problem with the thermostat? I mean does your diesel burner run continuously?

[Arch Hoagland]

Is there a return air filter that could be clogged up?

You mentioned low air pressure out of the registers.

[MONGO MAN]

Originally Posted by BigSkyBob

Our 40' coach has 4 slides and we have the 450 DE like yours. It was in the high 20's in vegas several mornings last winter and the water even froze in the hose feeding the coach. I use a 1500 watt electric heater at night but turn on the diesel burner in the mornings as it is usually about 55*. It generally takes about 30 minutes to get the temp up to 70* so your unit has a problem somewhere. You can feel the feed line and return line at the back in the boiler to see if that's working as it should. Check the outlet line temp to make sure it's about 130*. If the temp is less than 130* it can be adjusted using the mixer valve on the back of the boiler. We have six registers feeding warm air into the coach including a full size in the bath. I've been in temps as low as 10* and my Aqua-Hot warmed the coach with no problem and would cycle on and off. Could there be a problem with the thermostat? I mean does your diesel burner run continuously?

The tempering/mixer valve at the rear of the boiler is only for the domestic Hot Water at the faucet - not the room heat.

[Pairajays]

Go here Forums Roger Burke owns this site and he knows everything there is to know about AquaHot.

Jim E

[radams]

You know, it might be instructive to find out what heat exchangers Winnebago is using and what the heating capacity is of each. Just ask them what the BTU output of each is when using 130F hot water. I have read where others switched to the Aqua Hot exchangers to improve their system. Maybe they did that to get more heat capacity and/or air flow. Knowing what you have now versus the AH's would tell you if there was room for improvement. I didn't see any capacity charts for the AH exchangers on their website but maybe Roger Berke could help with that. Secondly, you might ask what the fan capacity is for each unit in SCFM's. If the fan isn't moving the air much it can't dispense it very well. I'm not suggesting you should have to go through all this but that it might give you another possible solution.

[radams]

FWIW department, I just talked to Lonnie (great guy) at Aqua Hot and here are the specs on their heat exchangers

http://www.aquahot.com/eSource/ecom/...-IIIforweb.pdf

Note that the BTU rating is based on 180F water temp so you'll need the same for whatever Winnebago is using. Also shows you their fan capacity.

[rv rick]

These are great ideas and I really appreciate the input. I will do some double checking on this. This is our first Aquahot and I need to learn the new system. Sounds like I need to focus on the system circulation, so will move forward on that front.

I can say that the constant hot water is wonderful!

[Roger Berke]

I had the pleasure of meeting Rick and the opportunity to check out his Aqua-Hot for proper operation.

I found that his Aqua-Hot was working up to specifications. The coolant temperatures were all within standards, all of the zone pumps were working properly, and sending hot coolant as designed to the interior heat exchangers.

I was getting around 145 degrees warm air from the interior heat exchangers. Rick was using an infrared thermometer, which does not measure air temperature as accurately as my digital thermometer.

I think what is wrong is that his coach manufacturer did not allow for return air for the heat exchangers that were inside of the coach. The Aqua-Hot installation manual is very clear that mounting the heat exchangers without sufficient ventilation will severely reduce their overall heating performance (heat output). The return air registers must be the same size, or larger, than the outlet-air registers.

Aqua-Hot supplies a “kit” to coach manufacturers that includes the Aqua-Hot, fittings, circulation tubing, filters, etc. It is up to the coach manufacturer to install the unit following the very detailed installation manual provided by Aqua-Hot. These manuals are online, here: https://www.aquahotparts.com/eSource...t/Manuals.aspx

- Roger Berke -
www.Forum.RVHydronicHeaterRepair.com