Heater info

[LopezMike]

My 1971 25 Caprice has what I believe to be the original heater. It has no numbers and the only place it names the manufacturer is on the plastic relay cover on the top. It looks rather like a V1 buzz bomb engine and certainly sounds like one.

Does anyone have any of the following info?
1. Original model number so I can do a search.
2. An owner's manual.
3. A wiring diagram for it.

It works fine except for one glitch that has just started up. On shut down once in a while it cools down and then keeps on blowing cool air. Indefinitely. A good rap with the knuckles wakes it up, so to speak.

I suspect it has to do with the microswitch under the plastic cover. A mechanical adjustment perhaps.

Help!!

Mike

[WillieC]

I have that info! Somewhere. I just overhauled the ebersprechensiedeutscher unit last year.
Sounds like a stuck relay. Give me a couple days. I'm in the middle of projects.

[LopezMike]

Overhauled it? Wow! You are brave.

I've been looking at it as if it were unexploded ordinance. Listening for ticking noises.

Looking forward to your finding any stuff you have.

Mike

[WillieC]

It's pretty basic. I'll fill you in. (I installed a push button that interrupts fuel flow to give the glow plug time to warm up. Fires a whole lot easier. Could have done it with relays, but I could also install a whole new propane ducted furnace and flux capacitor.)

[LopezMike]

Not a bad idea. How long do you hold the push button down?

If it's for a relatively fixed time interval I can conjure up a time delay relay.

I've pulled the beast out and made a start on the schematic. The Bosch numbers on the two steel case relays don't get me anywhere on the web. I can reverse engineer them after some bench work with an ohm meter. Once I really understand the circuit I might be tempted to replace the whole set of relays with modern and available ones/ Maybe even a couple of sockets so its' easy to swap them out.

After this is all over I suppose it would be worthwhile to post a document to the files section here.

I wish I knew of a way to quiet the beast down.

Thanks,

Mike

[LopezMike]

Willie (and anyone else who might know!),

How long should this heater cool down after the thermostat shuts it down? Mine has always gone on for quite a while. In fact my intermittent failure now is just an extension of what was happening anyway.

There is an adjustment screw on the microswitch that (I think) senses the combustion chamber temperature. I'm going to bolt it all together tomorrow and time it and then turn the screw to see what happens.

Why does this all remind me of the Bob Newhart routine about doing bomb disposal over the telephone? "Ticking faster now? Turn it the other way! Hello? Hello? . . . ."

Just to put me through more agony, I see that WallMart online is selling a heater this size for $145. Hmm.

Mike

[WillieC]

Let's try this. I have several pages and the phone and computer may turn them all around and they may be illegible. I can clarify where necessary.

Let's begin!

IMG_3562.JPG

IMG_3563.JPG

IMG_3564.JPG

IMG_3546.JPG

IMG_3547.JPG

IMG_3548.JPG

IMG_3549.JPG

IMG_3550.JPG

IMG_3551.JPG

IMG_3552.JPG

IMG_3553.JPG

IMG_3554.JPG

IMG_3555.JPG

IMG_3556.JPG

IMG_3557.JPG

IMG_3558.JPG

IMG_3559.JPG

IMG_3560.JPG

IMG_3561.JPG

I think I will post this before it gets lost. Sorry about the quality.

[WillieC]

I also just found another page on the boat tucked away in an important place, a schematic showing the two relays installed, as seen in the mess I started with. For the life of me I saw no reason for two relays, so I deleted one and ended up closely following one of the schematics in the photocopied brochure.

Note, I eliminated the thermostat that is still on the boat. I figured I'd turn it on when the Starfleet Commander tells me to and off when I wanted to. I am the thermostat.

Taking it apart and cleaning it up is not too tricky. There are a gasket/asbestos seal or two you need to be careful with. Mine was pretty carboned up, and I was too chicken to try burning it all out, so I did a bunch of scraping. I may need to revisit this step.

To your questions:

I hold the NC button down for 15 seconds or so. I think it helps.

You might be able to decipher my pinouts of the relays on "As installed early 2020".

The glass rod in the thermal switch (TS) is what operates the microswitch. It lengthens as it heats up and changes the state of the contacts as it operates. That is what shuts the fan down as it cools off. The red light comes on when running normally, i.e. when the glow plug goes out and the safety switch loses power to its coil as the glass rod lengthens.

The plastic encased doothang is the safety switch (SS), the coil of which heats up in parallel with the glow plug. If the chamber where the glass rod is does not get hot, the coil in the Safety Switch heats that little plastic compartment and will open the NC contacts which kills the whole thing. It auto resets when it cools. Lots of moving parts, all fairly straightforward.

Sorry for any confusion, hope some of this helps.

[LopezMike]

Wow! I am so going to come and visit with you and we are going to a copy center!

For what it's worth, I pulled the unit, made a first start on a schematic and re-installed it. Then turned the microswitch adjustment screw 1/4 turn CW and it shortened the cool down time from 5 minutes (sometimes forever!) down to 2.5 minutes.

However, I found a new Webasco Chinese knockoff on the web for around $100. I'm going to buy it and give it a try. It throttles down after startup to regulate the temperature rather than just being and on and off proposition. And I'll have this one for a spare.

Thanks again. If we venture south across the straits later this year well have to meet somewhere convenient.

Mike

[nebulatech]

Just spitballing, temperature sensors are usually based on resistance. Is it possible there is some creeping corrosion in your wiring that is increasing resistance? I once fixed a 12v Alder Barbour cold plate refrigerator simply by spraying CorrosionX on the wire terminals...

[WillieC]

I pondered the Chinese knock off heater. Do tell how it installs and performs.

[LopezMike]

The sensor in the old heater is a glass rod that gets longer when hot and triggers a microswitch. There is a screw that moves the switch by a very small amount to set the point between running and not running the fan. Turning it 1/4 turn CW did the trick.

As you say, the newer units probably use a thermocouple that puts out a small voltage and is prone to trouble with bum connections.

The new heater will be here in a couple of weeks. I hope it's quieter. It's supposed to use less current by running the fan slower when full output is not needed. The YouTube videos speak of some variability in fan noise due to quality control issues. Several suggest that the motor bearings are poor quality or even shipped without grease. All of which I can fix. I have a small shop where I've built prototype scientific instruments for many a moon. Machine shop and electronics. All the way from foundry to programming.

Caprice is reaching the point where I cannot fit any more fancy stuff. Once I get this furnace issue tamed and the right thermostat for the compressor fridge I will be lost for projects. Like a dog newly de-fleaed. "What do I do now? Anyone know how to polish props?"

Wife laughing in the background. "The lawn you fool!"

Mike

[WillieC]

The weeds! The kitchen! The peeling paint! Fool indeed.

[Dieselram94]

I’m very interested to see pictures of your install!!! Please post some as you go. My boat has never had a heater, where did the original one exhaust too? Are you planning to use the same hole for the new ones exhaust?

[tribologist]

Lol! Got a suggestion.. go to one of the Facebook chinese diesel forums and ask how to run it on waste oil…. Then run for cover.. I got one of those heater bolted to the back door in the garage. They are pretty good! I had to get a new pump on mine. Some pumps lack screens. There are some different Controls. Some better than others.. i got the wrong one. No timer or thermostat on mine. Just a remote.