Motor aid hot water heater

Postflight · 07-29-2012, 10:23 AM

I asked before about bypassing the hot water heater, or disconnecting it all together. The idea. Of having heat in the rear of the rv is great. However, the heat generated in the waterheater is toooo much.
I can't find a bypass valve for the water from the engine.
Any ideas??
Thanks

FIRE UP · 07-29-2012, 10:38 AM

Sir,
First off, I'm not chastising you in any way. But, are you really sure you're getting "heat" from the hot water heater????? I mean, in my opinion, which could be useless, I don't think anyone can feel the heat radiated from a hot water heater, at least I know I can't. They are fairly well insulated. There are multiple forms of heat to heat a water heater as you most likely know. Propane, electric assist, motor aid, and Aqua Hot.

Now, I know very little of the Aqua Hot heating system. I think it also heats the coach, if you use it that way, as well as the water heater. That would be the only form of heat that would heat the water heater as well as the coach, that I know of.

Now, I guess it is possible that somehow the heated water/anti-freeze lines that go to the water heater may be routed or, go through a section that may emit some heat into the coach, not likely though. In mine, all of those lines are clearly visible along side the engine/frame and over to the water heater. There is no portion of those that enter the cabin area/rear bedroom to radiate heat. So, just trying to help here, are you sure you're feeling "heat" from the motor aid system??
Scott

Postflight · 07-29-2012, 10:46 AM

Yes, the heater is located behind the kitchen cabinets and I can reach it. The unit after a short drive is very hot and the water coming out of there is scalding. And yes the electric and gas are off. I have also made sure the rear heat is off.
Again this is on Itasca 26P.

Hikerdogs · 07-29-2012, 01:27 PM

Quote:

Originally Posted by Postflight

Yes, the heater is located behind the kitchen cabinets and I can reach it. The unit after a short drive is very hot and the water coming out of there is scalding. And yes the electric and gas are off. I have also made sure the rear heat is off.
Again this is on Itasca 26P.

Unless your engine is overheating the maximum temp the water in the heater should get is 195*F. That's the temp the thermostat in the engine opens and the water in the heater is heated by the engine coolant circulating in a tube around the water heater. It may be that you're not used to the hot water being that hot. I know we set the temp for our home hot water heater at 160*F so it's a bit of a shock when we get 195* water in the motorhome. An easy way to know the exact temp is run some in an insulated cup then test it with a meat or candy thermometer.

Another possibly is that you have the "15 gallon" Atwood heater. If you do it isn't actually a 15 gallon tank but rather has the thermostat for the electric and/or gas heaters is set higher than the "10 gallon" models. The water is allowed to get hotter then it's supposed to automatically be mixed with cold water to only allow a maximum temperature of 180*F at the faucet when full hot water is selected. While the engine can still only heat the water to 195*F the mixing valve could be defective and not mix the correct amount of cold water allowing 195* water at the faucet.

Postflight · 07-29-2012, 01:34 PM

Well, 195 is pretty close to boiling and the cabinets (kitchen/bath) are getting that hot also. I have checked and the rear heat is not putting out any heat. I turned on to find out and if it is on you will know it.
This is why I wants to know if there is a bypass valve for the engine water to the heater.
Thanks

ga traveler · 07-29-2012, 01:38 PM

Even though your thermostat is set for 195 degrees, that is the point it is fully open. Your motorhome will run at 200 plus. Mine runs at 210. You are right, that is hot water and must be mixed with cold to be comfortable. It is simple to put a connector in the inlet and outlet line and connect the two and bypass the HWH.

Hikerdogs · 07-29-2012, 02:00 PM

There is no factory installed bypass valve or hear heat shutoff on our motorhome. If you add one I would watch the engine coolant temp gauge closely. The engine cooling system may be sized so that it needs both the rear heater and the motoraid feature to provide sufficient heat disipation on long hard pulls like mountain driving.

FIRE UP · 07-29-2012, 10:50 PM

Quote:

Originally Posted by Hikerdogs

There is no factory installed bypass valve or hear heat shutoff on our motorhome. If you add one I would watch the engine coolant temp gauge closely. The engine cooling system may be sized so that it needs both the rear heater and the motoraid feature to provide sufficient heat disipation on long hard pulls like mountain driving.

Ok Gang,
As usual, I'm always learning things here. We too have an Itasca, a 2004 36GD model with the 330 CAT. If I may ask, what "REAR HEATER" are you folks talking about? The only heater(s) we have are the heat pump, which comes on only with 120VAC and, the furnace which, is 12VDC operated. Unless they hid one on me, I don't have any rear heater.
Scott

Hikerdogs · 07-30-2012, 05:46 AM

Some models (mostly gassers I believe) come with secondary heater in the floor that uses the engine coolant as the heat source. Ours isn't actually in the rear of the coach but rather just behind the engine compartment. The engine coolant that heats the water in the water heater also runs through the heating unit in the floor. The heater has a 2 speed fan on the dash and comes in very handy when traveling in cold climates.

With this heater it's not necessary to run the gas furnace or the generator & heat pump to keep the entire coach warm while on the road.

cbeierl · 07-30-2012, 10:11 AM

As far as I know the motor-aid 'rear heater' (separate from the motor-aid water heater) isn't on any of the Winnebago DPs, just some (all?) of the gassers.

John Mo · 07-30-2012, 10:28 AM

My 35J gasser also has motor-aid and I can confirm that the kitchen cabinetry gets very hot during a day on the road. I suspect it has more to do with the insulation of the coolant lines run to the hot water tank than heat escaping the tank itself as the cabinet doesn't seem to get hot when parked and running electric or Propane to heat the water. Also, water remains hot for a surprisingly long time after all heat sources have been turned off, so I think the tank itself is well insulated.

My coolant temperatures have run as high as 210+, so I think hot water from the tap could easily be near boiling at times.

DancinCampers · 07-31-2012, 08:22 AM

On my previous Adventurer the coolant ran thru the aux heater, then the water heater before returning to engine. If yours runs similar, just cut the water heater in and out hoses and splice them together. If you splice them with a ball valve, you could shut off water to the aux heater during summer, open during winter.

FIRE UP · 07-31-2012, 08:54 PM

Quote:

Originally Posted by cbeierl

As far as I know the motor-aid 'rear heater' (separate from the motor-aid water heater) isn't on any of the Winnebago DPs, just some (all?) of the gassers.

Chris,
Is there a name for that particular option, just like "motor aid" for the water heater? Would it be called "Motor aid-Rear heat" options or something like that?
Scott

jimmyjnr · 07-31-2012, 09:06 PM

Winnebago had failed to connect our rear heat and water heater circuit , the feed and return rubber loop from the engine needed to be cut and connected to the solid alloy pipe work to rear of coach.
It was an option , so I suspect your engine cooling system is sized to work without the motorsid option

Beabop · 07-31-2012, 09:10 PM

I have motor aid to the water heater, no floor heat as we had in the Adventurer. think only gassers have floor heat.

cinbol · 09-10-2012, 09:09 AM

Quote:

Originally Posted by Postflight

I asked before about bypassing the hot water heater, or disconnecting it all together. The idea. Of having heat in the rear of the rv is great. However, the heat generated in the waterheater is toooo much.
I can't find a bypass valve for the water from the engine.
Any ideas??
Thanks

Thanks for raising the question - I have read thru the thread and this is just what I was looking for. Our HW tank is underneath the kitchen counter next to the sink (partitioned off) - above it is our "silverware" drawer - upon arrival at our destination we always find the eating utensils very warm and anything in the cabinet under the sink is as well - have learned not to leave any trash from spot to spot - we also have warming issues in the bathroom under-sink cabinet (shared wall to where the HW heater is)- same thing - everything gets warm. We would also like to find a way to by-pass when needed. thanks for the tips.

Postflight · 09-16-2012, 01:31 PM

Well, after using our unit for a while, I have found that at campsites with the gas or elec heat on, my cabinets get quite hot. So, I think most of my heat is coming from the lines from the water heater. I am going to insulate them and see if that brings down the temps.
Again, this is on gas engine models. But I still think having engine temp water running through there is looking for a leak with that high of water.
Bob
Itaska 26P

Hikerdogs · 09-16-2012, 03:09 PM

Our coach is almost 12 years old and has over 100,000 miles on the odometer. We have never had a problem with a water/coolant leak of any type. The hoses used on the motoraid heater are made of the same material as all the other engine coolant hoses.
If they were made of the same material that automotive coolant hoses were made of 40 years ago I would agree they were a leak waiting to happen. The material has improved a hundred fold between then and now. I would bet the hoses could go another 100,000 miles and still be in good shape.

Mr_D · 09-16-2012, 03:18 PM

Quote:

Originally Posted by Hikerdogs

Some models (mostly gassers I believe) come with secondary heater in the floor that uses the engine coolant as the heat source. Ours isn't actually in the rear of the coach but rather just behind the engine compartment. The engine coolant that heats the water in the water heater also runs through the heating unit in the floor. The heater has a 2 speed fan on the dash and comes in very handy when traveling in cold climates.

With this heater it's not necessary to run the gas furnace or the generator & heat pump to keep the entire coach warm while on the road.

Our 2000 DSDP had a rear heater, our present 2002 doesn't due to the bedroom slideout configuration, other models could have them and they were DP's so it's not limited to the gassers.