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Webasto heater strange running


Johny London

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My Webasto runs well, and after about 60-90 mins (depending on time of year) it drops down to the slower clicking of the pump (from 2-3 a second to like 1 or something). At least it did. I always listen out for it and turn it off when it slows, so as not to get it coked up. But a few times I have gone to check on it (if there is other noise going on in the boat) and found it fallen silent.

Just now everything was quiet on the boat so I could here it really well, and it went from full chat to nothing, in an instant. I went to switch it off but then decided to see what it would do next. If I can remember the sequence: I could here the fan spinning, it increased up some, then right up for a couple minutes, then fell silent. Totally stopped. Then sped right up and the pump kicked back in slowly at first then back up to speed. So it seemed like it had rebooted. In this case it had been running for about 80 mins.

Perhaps one of the knowledgeable can enlighten me as to if this is the start of a problem or just one of its quirks. I do have only 4kw or so of rads, hence I'm always very careful to listen out for when it slows, so it is never on at half chat for any length of time and never on for more than around 90 mins anyway.

Hoping not to lose heating now!

thanks

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Sound like either the flame monitor is confused, ie. coked up, or its up to temperature and shutting down on its internal overheat stat. The fact it cycles and restart suggests there is little wrong with it.

I imagine you have checked that it has adequate electrical power to keep going?

  • Greenie 1
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I don't understand why you are shutting it down when it goes to half heat, it is supposed to do this and will run continuously.  I think you have been mis informed that it it will coke up on half heat, it won't.  I run mine all day in winter and have done so for 10 years and it's never been serviced.  If your rads. are not balanced properly and the first one is taking the heat  the heater will shut down early. Cooler water then returns from the farthest rads which restarts the Webasto. This short cycling is not good for it. My advice is balance your rads and leave it running, the thermostat will control it. 

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1 minute ago, Alan de Enfield said:

But the 'mob' says turn it off don't let it cycle so they do.

 

You and I appear to be in a minority of two.

Yes indeed, ambulances, coaches, trucks etc. run them contiuously in winter without problems. There were problems with coking up before low sulphur red diesel became the norm though. Not a lot of point in having a heating system that you have to turn off after an hour or so,

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1 minute ago, Flyboy said:

Yes indeed, ambulances, coaches, trucks etc. run them contiuously in winter without problems. There were problems with coking up before low sulphur red diesel became the norm though. Not a lot of point in having a heating system that you have to turn off after an hour or so,

I have 'done it' for years, even before low sulphur diesel, and have not had a problem. 

I have convinced myself that keeping it hot helps burn off the carbon in the combustion chamber - but I'm just a 'user' not an expert.

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51 minutes ago, Alan de Enfield said:

But the 'mob' says turn it off don't let it cycle so they do.

 

You and I appear to be in a minority of two.

The mob says don’t let it cycle but if you’ve got decent insulation then you may be getting a tad hot if you don’t let it cycle, that’s why they are not recommended for 24/7 use.    It’s good to know that the half power mode won’t coke them up as mentioned above (did they before when running on the high sulphur diesel?)

Edited by Robbo
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Reading the thread again, I notice the OP says his Webasto 'goes down to nothing ... silence'

Is that normal for a Webasto?

My Mikuni switches down to 'half' heat with no pause - I assumed that was normal for all ebersplutter devices?

 

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1 hour ago, Alan de Enfield said:

But the 'mob' says turn it off don't let it cycle so they do.

 

You and I appear to be in a minority of two.

 

Three.

 

 

7 hours ago, Boater Sam said:

Sound like either the flame monitor is confused, ie. coked up, or its up to temperature and shutting down on its internal overheat stat. The fact it cycles and restart suggests there is little wrong with it.

I imagine you have checked that it has adequate electrical power to keep going?

 

My money is on the overheat stat shutting it down. Then once cooled a little it resets and the units re-starts itself. This depends on the overheat protection being self-resetting. If the overheat protection is of the type where a button pops out and has to be re-set manually by the user however, this reason can be positively ruled out. Check what the manual says about overheat errors.

 

 

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 The Webasto manual says :-

 

When the temperature rises to reach 72° C the heater

switches to the energy saving part load operation. A rise

in temperature up to 76.5° C causes the heater to enter a

control idle period. This also happens when exceeding a

total heating operating time of 76 minutes.

After cool-down of the coolant to 71° C the heater

resumes part load operation. Another rise in temperature

to 76.5° C causes the heater to enter again the control idle

period. A drop in the coolant temperature during part load

operation due to an increased demand in heat will cause

the heater to switch to full load operation at 56° C.

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8 minutes ago, Flyboy said:

 The Webasto manual says :-

 

When the temperature rises to reach 72° C the heater

switches to the energy saving part load operation. A rise

in temperature up to 76.5° C causes the heater to enter a

control idle period. This also happens when exceeding a

total heating operating time of 76 minutes.

After cool-down of the coolant to 71° C the heater

resumes part load operation. Another rise in temperature

to 76.5° C causes the heater to enter again the control idle

period. A drop in the coolant temperature during part load

operation due to an increased demand in heat will cause

the heater to switch to full load operation at 56° C.

 

Good find. Sounds like there is a fault then. The OP says it goes from full chat to nothing. Sudden stop. It ought to ramp down to part load operation first. 

 

Maybe it is coked up after all and flame failure is occurring, and flame detection does an emergency shut off of fuel.

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Thanks for the replies (I wasn't notified there had been any until just the last one!?)

 

I don't have a header tank - it's a pressurised system, so I guess I could check it's not going over pressure (the gauge is in the engine bay though... who put it there?). I'd be very disappointed if it was coked up as I have treated it very well, (unlike my batteries) though of course it must be considered. Is there a procedure for getting the coker upper thing out? I'd been meaning to ask about that routinely anyway, as I hear people do just clean them up themselves. 

 

So I have: Coked up / Overheat / Over pressure / control idle for the 76 mins thing.

 

Could it be that last one? Because it is cold out now, the heater is still at full chat to the 76 mins deadline and thus goes completely off (control idle). I'll like that idea best - then it's not broken!

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My heater, this is not pressurised, started tripping after I bled the rads, and failed to top up the header tank. I would not run for long, before stopping and then restarting.

I pulled a water hose back from the heater, let some water out, and then refitted the hose quickly, and all was ok after that. it is getting a bit ‘nippy’ out now so good luck with this.

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  • 1 month later...

Hi guys. I've recently finished my (recon)Thermotop C install and have been running the unit occasionally over the last 2 weeks. Mine takes about an hour up to temp and after about 70 mins it stops roaring. The fan and I assume circulation pump continue. After about 5 mins it falls silent then it starts up again and runs again at full load ( fast ticking fuel pump). So far I've only let the second phase continue for about 30 mins before switching off. It has Never, as far as I can tell gone into half load. It's all or nothing or so it  seems.  Sounds similar to Johnnys issue though he states that his did go into half power mode. I know we both bought from the same eBay seller. I will message the seller who I assume is the refurbished and ask if he can shed any light.

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I think we had the answer to this, must have been in another thread. The Webermaster shuts down after 72 mins regardless of half or full power, then restarts. That's how it is configured to run. I've had mine on a lot lately because I have the power to run it (mains hook up) - even after two or three restarts it's staying on full now just because it's so cold the boat sucks all the heat from the rads (ie higher temperature differential =  better heat transfer).  

The jury seems to be out as to whether half power cycle is a bad thing or not nowadays.

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5 hours ago, Johny London said:

I think we had the answer to this, must have been in another thread. The Webermaster shuts down after 72 mins regardless of half or full power, then restarts. That's how it is configured to run. I've had mine on a lot lately because I have the power to run it (mains hook up) - even after two or three restarts it's staying on full now just because it's so cold the boat sucks all the heat from the rads (ie higher temperature differential =  better heat transfer).  

The jury seems to be out as to whether half power cycle is a bad thing or not nowadays.

Ah that's interesting. So you reckon it's behaving this way because of the cold. When I first ran it  2 weeks ago the weather was milder but I think (wouldn't stake my life on it) it was doing the same. ?‍♂️ It was all new to me then so maybe not. Certainly runs exactly as you describe Johnny at the moment so I feel reassured that all is ok. Once it's hot it certainly kicks some heat out! As I write my feet are on a rad but I have to keep taking them off as they're burning! I feel proper civilised now ?

 

P.s. managed to fix my leaky ball valve compression joint without removing heater Though I did manage to get the electrical connections off (with a struggle). Only one weeper left now and its a bloody towel rad tail  where it screws into the rad with ptfe. I hate those type of rad tail. I put about 23 wraps on it and it still flipping leaks! There's sooo much slop in the threads! All the tails on my main rads have a rubber seal which is how they should all be in this day and age!

Edited by Motters79
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Compression joints on copper pipe:

Clean the pipe and the olive until bright.  The dark colour that gradually develops on copper pipes is copper oxide and is harder than pure copper and does not "merge" so well. Take it off.

Wire wool is good for this though it is unpleasant to use. Ensure that no fragments get in the pipe by inserting a bit of kitchen roll into it before you start.

 Clean off the oil from the pipe that comes from the wirewool.  It is not good for rubber bits.

Wrap 3-4 turns of PTFE tape around the thread, not the olive, in the correct direction so that it does not unwind as you tighten it.

Assemble the joint hand tight, taking care that the olive is seating correctly and the pipe is fully home. 

Tighten the joint further with tools as necessary.  Use tools for both sides of the joint.  Remember the number of flats used.  Dismantle your first joint to check that the olive can't move and is slightly deformed into the pipe, and redo with more flats until right.  You now know the number of flats needed for this make of joint when doing the others.

You should not expect any of your joints to leak.  

If you get a very tiny leak it will usually stop within 48 hrs without further intervention.  Bigger leaks may be overcome with an extra nip with a spanner.

 

BSP joints eg the tail into a radiator, are different.  Use Loctite 55 string as per the manufactur's directions and it will seal reliably everytime -  unless you are trying to mate two wrongly-sized components together!  PTFE tape works but only sometimes.

 

Well, it worked for me (other methods are available).  I use JG push-fit now.

 

(This post has been checked for humour and other faults but the use of anti-humour (the black ones) goggles is recommended.)

 

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21 hours ago, system 4-50 said:

Clean the pipe and the olive until bright. ... 

Wire wool is good for this though it is unpleasant to use.

Those green plastic kitchen scourer pads are excellent for this job.  I always keep a few in my plumbing box, having been taught this trick 20 years ago.

 

Less bits fall off and you don't get punctures in your fingers which is helpful when working with flux. 

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