Hot Wallas

[TyBoo]

The other day the 1996 vintage Wallas 95D shut down on its own and when I tried to restart it smelled like electronic parts burning and went right into shutdown mode.

I pulled the stove out an turned it over to look at things. There was no visible sign of burning or shorting. I cleaned all the contacts for the plugs on the circuit board and hooked it back up. It fired right up and seemed to work fine. It was even igniting faster and getting up to operating temp quicker. Now, however, it only burns on high and the rheostat doesn’t seem to change the temp. The fuel pump is pulsing faster than it had been and does not slow down when the knob is turned down. I shut off the lid fan for a few minutes to listen to the fuel pump while I fiddled with it and the stove shut itself down presumably due to high heat (as it should, I think). It fired back up the next several times no problem except the inability to adjust the temp.

The hottest spot on the ceramic top I have found is about 1050 degrees where it was always 800-900 before. It’s on now while we are out fishing and roasting us pretty good, but Lois likes it and doesn’t want me to shut it off yet.

The last time I sent it to Scan Marine for service it cost me something over $600 and some parts were replaced with used since they can’t get new parts for the old thing. So sending it back again isn’t a good option and I intend to replace it with an Espar before too long.

In the meantime I would like to see if I can figure out the temp control problem. It seems to me I read somewhere about an adjustment for the pump speed but I cannot find the info anywhere now. Does anyone have any experience with this? I am planning to junk the thing anyway so I guess I can’t screw things up too much beyond burning up the boat.

Thanks.

[thataway]

Just off the cuff, the "Temperature control" is a rheostat. You should be able to check the resistance, with any ohm meter. Hopefully the specs are on the case of the rheostat. It may have shorted--and thus giving full current all of the time to the pump. I believe it is what controls the "flow rate"--since it is a solenoid piston pump...that would make sense. By increasing the resistance, you would slow down the pump. Scan Marine, might give you the specs on the rheostat you have. Either replace it--(if bad) or put more resistance in series, and see if it decreases the pump speed--and thus the heat.

[ssobol]

This video shows how to adjust the pump cycling.

https://www.youtube.com/watch?v=IW9QvCzEfZU

First thing to check is that the rheostat is good and the wiring to the remote panel is ok. A bad connection to to the rheostat will probably make the pump either run at maximum or minimum. It appears that it'll be maximum.

[TyBoo]

Thanks, gentlemen. I am going down to the boat in a little bit and will check the rheostat and it's wiring a little closer. I will also check the resistance and see if it varies.

I watched that video a couple times yesterday while I was out fishing but couldn't really see what the guy was doing there. The first thing he points at has what looks to be a slotted screw on it? Is that maybe an adjustment of some kind? I did see something similar with my head under the counter and flashlight yesterday but the srcew did not seem to want to turn and I didn't want to reef on it it. That seems to be what I recall way deep in my old man's memory hearing about years back. I will study on it some more today and look more closely at the video.

Thanks again, and if you don't hear from me tonight watch the NW Oregon news for stories about marina fires.

[TyBoo]

I should also mention that I have a line on a used Espar unit that was taken out of a truck. I might grab the thing and hook it up on the bench in the shop to see what it sounds like and how much it blows. It would be nice to have ducted air for the berth and the windows.

Even used the Espar isn't cheap. Still many times less than a new Wallas though. Maybe I can bribe the old geezer who has the thing with some imported beer and some smoked/canned sturgeon or something and get him to at least meet me half way for delivery.

[localboy]

Mike, my only input is the muffler makes a big difference in exhaust noise. I installed it and wrapped it in muffler insulation. I didn’t want to be a nuisance to neighboring boats. I also sprung for the air intake silencer in hopes of quieting the cabin too.

I could see the benefits of hot air across the windshield. If you figure out how to do that easily, I’d be interested in seeing how you engineered it.

[TyBoo]

Thanks Mark. I am not sure what all is coming with the used Espar unit. Maybe I ought to buy some more beer just in case it has a muffler option.

Well - no fires at the Warrenton marina today. So that's good.

I checked the function of the rheostat and found it to vary the resistance between 0 and 100 ohms. All the connections are good. I also found the adjustment screw the guy in the video was pointing at. It is a little bitty thing I didn't see yesterday. It had to turn a long ways to make any difference but if definitely changed the pulse speed, or the duration between pulses, of the pump. I screwed it righty tighty a ways first and it speeded the pump up, so I backed it off 15 whole turns beyond its original setting and it reduced the pump cycling by about a third, meaning a second and a half between pulses instead of less than a second. The stovetop reached about 850º at the hottest spot which is about 200º less than before. The rheostat still does not seem to have any effect on the pump speed, but we always ran it on high anyway so if it stays heating to this temp it's good by me.

Speaking of the rheostat, it has a connection to the center of three terminals which I believe makes it technically a potentiometer and puts it a ways out of my range of understanding. Too much electronic stuff for a simple oil stove.

The stove ignited quickly and fired right up again. It would be working well if it wasn't for the control problem and the intermittent problem of it not completely shutting off after cool down. It has done that occasionally for as long as I have had it despite a couple trips to Scan Marine. I have a main switch hidden away that I use to kill it completely when that happens, and it happened again today. I am guessing that some poor connections at the plugs caused the intial problem (this time!) and cleaning all of them with some acetone and a brush made thing work better. Maybe whatever component it was we smelled burning is the cause of the control problem.

Sturgeon fishing again tomorrow so watch the news for stories of a boat afire on the Columbia River estuary