Secondary Heater from engine

[noiva]

I have a "new" 1989 370LE with one of the auxiliary heaters that uses the engine coolant to heat the coach in cold weather. Mine is located about half-way back in the coach and is basically a radiator core in a housing that has a 2-speed fan switch on the dash. I just recently had a chance to use it for the first time during one of my monthly off-season runs to keep everything working. My original intention had been to disconnect the hoses at the the engine to avoid a potential catastrophe if it should spring a leak running down the highway, and I had thought I could more easily use one of the furnaces to keep things reasonably warm. I was very much surprised at the amount of heat I got from the secondary heater, and that it runs without any perceivable noise. Basically, I was getting free heat from the engine and saving propane, or gas with the generator to run electric heat. To my surprise it got so warm I had to cut it back. Now I'm thinking of leaving it connected, replacing the rusted water shut-off valve (which won't shut off now) and making sure the hoses coming in are new. Does anyone have any experience with the dependability of these things not to leak (assuming they are properly checked and maintained, of course)?
Noiva

[overlander63]

As long as it is maintained, it is relatively reliable. It would be a good idea to install manual cutoff valves on the inlet and outlet lines somewhere near the engine, in case it does spring a leak.

[noiva]

Terry,
Thanks for the tip about the dual cutoffs near the engine. I hadn't thought of that, just about fixing the rusted-open valve at the heater (inside). I could even cut the manual valves off in warmer seasons to be certain a leak didn't start without my immediate knowledge. Thanks again, Noiva

[SafeHarbor]

Hi, novia,

I used to work on an abulance doing critical transports, and we had only one shut-off on the hot side of the flow to the rear compartment. This was on Fords and an (International) Navistar, but it seemed to work fine for us.

Lamar

[StingrayL82]

My 1972 Chevrolet Suburban had the auxilliary heater you speak of and, yes, it would keep the kids quite warm in the winter. Before you replace the valve and hoses, cut them where they come out of the body and flush the core out....that's what I did with mine. Of course, it goes without saying, make sure you have a drip pan. If you pick up an LMC Truck catalog or a Chevy Duty catalog, I believe they still carry the valve you need. I know I've seen the Chevrolet auxilliary heaters and parts on Ebay from time to time as well.

Frederic

[overlander63]

If you do this, you really do need a cutoff valve on both hoses. Even if you shut off 100% of the flow, the pressure in the system will eventually force coolant backwards, still allowing a leak.

[noiva]

Larry, Frederic, and Terry,
Thanks for all the info. I had planned to do the flush when I replace the control valve on the heater. That valve is activated by a cable (similar to the old choke cables or cars and the throttle cables on lawn mowers), and actually is designed to be not only a shut-of but also a control for the amount of water (therefore heat) that goes thru the unit. As Terry has noted, I agree that shut-offs where the "Ys" are splitting off of the dash heater hoses would almost guarantee no leaks inside the coach if they were both cut off. The pressure in the coolant system could back up in the return side, it seems to me, if a valve were not put there also. At the least, it's good insurance. Thanks for the supply place ideas as well. I've been told the control valve (inside) is still available at auto supply stores (NAPA, etc.) since many older vehicles use them to control the amount of heat to the dash heaters. Once I get things apart, I'll have a lot better idea of what I'm dealing with. The system is fairly simple, but the location makes working on the controls very difficult. Like a lot of things, the guys who build them apparently don't use them Anyway, if anyone has any other suggestions I'm always open. Thanks again to you guys for the help.

Tim (Noiva)

[swebster]

Tim,
Check the hoses where then enter the coach (through the floor) for chaffing. This is a weak point in the system and will eventauly cause a leak. It's also a hard to get to item which means it's was probably not replaced when the normal cooling system and heater hoses were updated through the years so it could be very old.

You might also find they extend further back to provide hot water "on the go" through a loop in your water heater. Again, check the hoses at connections and pass-throughs. It's probably a good idea to replace these hoses and wrap them in another section of hose where they pass through the floor.

Also, definately install two shut off valves downstream of the regular heater loop so you can completely seperate the aux heater from the rest of the system. It's also a good idea to install shutoffs to your dash heater as well.

[noiva]

Steven,

Thanks for the additional suggestions, and taking the time to share them. I had planned on replacing the hoses when I do the control valve. This coach has been used so little that many items are still original. I'm working my way through the coach, and surprisingly little is aged to the point of needing replacement. I'm obviously replacing all hoses, of course, and anything else I find that is simply too old to be reliable - but it's not as much as I expected. My hot water lines have been blanked at the floor line and the water heater replaced by a gas-only unit. I plan on completely removing the plugged lines. I may even put the cut-offs for the heater in a position so they actually cut off both the dash heat and the auxiliary heat at the same time. The only drawback I can think of is that there's less versatility if one of the heaters should fail, but not the other. What do you think?

Thanks again for the help,

Tim (Noiva)

[overlander63]

Originally Posted by noiva

I may even put the cut-offs for the heater in a position so they actually cut off both the dash heat and the auxiliary heat at the same time. The only drawback I can think of is that there's less versatility if one of the heaters should fail, but not the other. What do you think?

Thanks again for the help,

Tim (Noiva)

if you did that, it would make your plumbing less complicated, but, as you pointed out, if one heater fails, you will be without heat until you can make repairs. If you put shutoffs on all 4 hoses it would allow you to bypass one or the other, but it would also make it more Rube Goldberg-like.

[noiva]

Originally Posted by overlander63

if you did that, it would make your plumbing less complicated, but, as you pointed out, if one heater fails, you will be without heat until you can make repairs. If you put shutoffs on all 4 hoses it would allow you to bypass one or the other, but it would also make it more Rube Goldberg-like.

I'm thinking this may be a case of "Less is more..." I could always add an additional set of cut-offs if one heater fails, but there would be the inconvenience of the delay to get the shutoffs and install them. Of course, this coach has so many ways to provide heat, I should never be without a source of either electric, propane, or engine-provided heat.

Tim (Noiva)