Junkers gas water heater not working

[chal]

My newly-acquired 1979 Westerly has one of these and it doesn't work. It is probably an original fitting. That is quite old, I know, but the boat hasn't been used much over the years and the heater seems to be in pretty good condition. Even the piezo spark device still works! I've taken the cover off and it all looks fine. The problem is that no gas is reaching the burner. There is definitely gas reaching the heater - I have checked by removing the pipe from the isolating tap just below the heater. There is also water going through the heater. The slider control at the bottom has a pilot position and the usual press-and-hold-to-light routine, but when pressed, there is no gas to ignite. Can anyone suggest anything? I don't know if there is any kind of gas shut-off mechanism incorporated into the burner as I wouldn't know what it looked like.

I would be happy to get it professionally serviced but there isn't anyone local willing to do it. A new heater would not be very expensive but a big messy job to fit and I would much prefer to get this one working if possible. Sorry, I don't have a model number (if there is one, I can't see it), nor a photo of the burner unit, though I could get one if that would help.

To save me asking another question further down the line: the issue I was expecting to find was that the thermocouple no longer worked. Can anyone recommend a universal one that would be likely to work just in case I can get the gas to light and then the thermocouple does become an issue.

Thank you!

 

[KevinV]

Deleted "helpful" suggestions.

That thing is ancient - is it really worth risking yourself and your boat for it?

New ones are not expensive.

 

[Boater Sam]

The pilot gas supply is on bypass of the main gas feed to the burner and is opened when you hold the button in at the pilot position only.
Are you sure that the button is going in far enough and not catching on the case or something?
It is possible that the tiny pilot orifice in the valve has become blocked or the actual pilot jet assembly is blocked with fluff or scale from out of the pipes.
A universal type thermocouple should be easy to find that will fit but I doubt you will need it.
These were very good heaters in their day. Junkers made most of the gas control valves for everyone at one time, as well as aircraft!

 

[wingcommander]

Best have your CO detector up n running if you fire that baby up. Just ro be on the safe side . Great water heater when working safely .

 

[Stemar]

A look at the flames will tell you if it's producing CO. A nice blue flame like this is safe.

Any yellow and you've got a problem and I'd get rid of it

 

[philwebb]

Hi chal, I think that what you will find is not working is the gas valve which opens when water flows through it. It will have some sort of diaphragm mechanism inside. The gas valve will probably be completely corroded and the diaphragm inside knackered. The chances of finding a replacement part are pretty negligible. Sorry, but it’s most likely to be junk.

 

[chal]

Thanks everyone - between the safety issue and the likely non-availability of spare parts, I think the only reasonable conclusion is that it is indeed junk and will have to be replaced. Ah well, always worth asking!

 

[Wansworth]

I have found that gas appliances Leto even for a few months tend to get clogged up

 

[Boater Sam]

If the pilot won't light that has nothing to do with the demand diaphragm, water flow rate or the main gas burner You give up easily.

 

[chal]

> You give up easily.

Ok, maybe I have, in which case: where do I start? I get your point about the pilot not being dependent on things like water flow. My initial expectation was that there was a fair chance that the pilot would light and then go out as soon as I stopped pressing the override, or that nothing would happen when I turned the water tap on, but I have no idea what I should even be looking at in terms of why the pilot will not light at all. What is stopping the gas flow to it? Something as simple as dirt maybe? Can that really stop any gas flowing?

 

[Wansworth]

We found are butane gas heaters needed a service ever winter after a summer without use

 

[wingcommander]

Your pilot injector for lpg will be very small. Ide guess marine environment , not used in a while , its blocked. Not something I would recommend anyone with limited experience to mess around with.

 

[PetiteFleur]

I had a similar problem on a gas fridge in my motorhome. Worked OK on 240v & 12v but not on gas. Utube gave the answer - the pilot jet was blocked and was easily fixed.

 

[chal]

I have had another look at the boiler and realised that the problem isn't quite what I thought. I removed the flame guard (not sure if that is what it's called, it's a small metal plate that is in front of the pilot flame and sort of directs it towards the thermocouple) so that I could get a better view of what was happening. If I move the main control to the ignition setting, press in the gas button, and hold a gas lighter (the sort that has a gas refill and burns for a long time) in front of the pilot jet, there is gas coming out and it lights. As soon as I take the gas lighter flame away, it goes out again; if I put the flame back in, it relights. I'm not sure what is happening, it's as if the pilot flame blows itself out. Any further suggestions much appreciated!

 

[Boater Sam]

Its dirty. Probably the air hole at the bottom of the pilot tube is blocked with fluff, but are you sure that the knob is going far enough in?

The pilot flame has to be directed onto the thermocouple tip, is it with the flame shoe removed?


If none of the above the thermocouple is not working

 

[wingcommander]

Could be that someone with limited experience has attempted to clean injector incorrectly and enlarged the jet, this will cause flame lift off. Could be primary air blocked. Could be corroded/ missing flame retention device. Could be one of a number of things. Best advice just get someone who knows what their dealing with .
Seriously gas can be very dangerous if not done correctly. Not trying to insult anyone. Yes I am gas safe registered. No ime not touting for work lol .
Stay safe whatever you decide.

 

[roaringgirl]

This thread scares me.

 

[Boater Sam]

This thread scares me.

Don't look then.