Webasto header tank

[ditchy]

So I went around to help a friend out today as the top of one of their radiators was cool. When their Webasto is running. I started to bleed the radiator and air was coming out.

 

I asked where the header tank was and the owner wasn't sure. Then after a thorough look I couldn't identify where it was.

 

The boats a wide beam (irrelevant). The Webasto water hoses go from the unit itself in, then out of the calorifier then through the bulkhead to inside the boat, presumablyto all radiators.

 

I'm wondering is it possible to set this up as a sealed system and how to top it up if this is the case.

The whole of the inside perimeter shows no sign of a header tank or expansion vessel. Do I need to look harder. I told the owner not to bother to turn the Webasto on tonight and that I would return tomorrow. This is so that I could look into it further and prevent any damage.

Any advice or information will be appreciated. Thanks

[Loafer]

The radiators should be bled with the system switched off, and no pump running.

 

There should be a header tank, but could be anywhere in the system so you'll have to search for that.

For the time being, if you can bleed all the radiators until water runs out of the top hole, then there's enough in the header tank. Try that first, then you can at least run it again while you look for the header tank.

[NB Lola]

Loafer, is on the money, only bleed with it switched off.

[ditchy]

Yes. Ive bead it with pump off. It seemed to not have enough pressure to release all the air out. I stopped before water spluttered out. 30 -40 seconds

[Loafer]

Yes. Ive bead it with pump off. It seemed to not have enough pressure to release all the air out. I stopped before water spluttered out. 30 -40 seconds

 

That sounds like not enough water in the system then. Try longer with the bleed valve, you aren't doing it any harm. Also, find the header tank!

 

Unless I'm missing some other method of maintaining a head of water, in which case that isn't working either.

 

ETA The header tank HAS to be accessible, it's a regular boat servicing thing.

We need more expert opinion as to whether you should fire it up or not. I suspect 'no'.

Edited December 18, 2015 by Loafer

[ditchy]

Thanks loafer. This is what I'm thinking. It needs to be some where and I'd assume it must be the highest point too. I was wondering if these ever had the option to have no header and too.

[Loafer]

Can't imagine a boat system without a header tank, meself. It's probably lurking behind a pull-out panel, or a bedroom cupboard, at around chest height.

Is it outside?

[fretman]

on a lot of boats, mine included, the header tank for the engine is also the header tank for the heating sysytem

Edited December 18, 2015 by fretman

[Sarah and Ian]

Any outside lockers it could be in?

[Tony Brooks]

I have seen that type of boiler on boats that have been plumbed like a domestic combi-boiler with an expansion - cum top up pressure vessel, one even had two. It may be like this. look for one or two accumulators that are not connected to the doemstic water system. How you top the system up with antifreeze mixture is another thing to consider.

[NB Lola]

When I made my mistake of bleeding with pump on, the, now I know, inevitable happened and the header tank gushed forth, depositing my anti freeze treated water all over the place.

[davidc]

on my last boat which had which had a similar system the header tank was built in to the side of the engine space and the actual filler come dipstick was on the cruiser floor to wards the side

you can just see it poking up under the rear right seat

hope this helps

Edited December 19, 2015 by davidc

[NMEA]

It may well be a closed loop system, the current Webasto preferred method above header tanks and the way I have done it for some years unless specifically asked not to. If so there will be a filling loop with a pressure gauge close to it, this should be pressurised to 1 bar cold before, during and after a full bleed. Your description of the pressure being enough to expel some air and then stop would support that but not absolutely confirm it. It is however true that some boat builders try to hide the header tank in very difficult to find locations, I recently took over 30 minutes to find one, simple methodical following of the plumbing will eventually reveal whichever method has been used. Probably time for a coolant change too as if it had been done recently the owner would surely know where the header tank / filling loop is. As for running the Webasto, if the water pump does not make horrid noises indicating an air lock in the heat exchanger it would probably be OK to run it if it was monitored.

[ditchy]

Hi and thanks for all the input. I found it. Very well hidden behind a very shallow false pillar. Topped the tank up. Bled the system. Hey presto. That's it! I was sure it had to be a sealed system... Thanks guys for the fast replies.

[NMEA]

Pleased you found it!

It is quite worrying that some owners are not made aware of these essential bits of information by the previous owner or builder and given a handbook if relevant, the header level, or pressure on closed systems should be part of a weekly check routine which will give a heads up to any developing issues and one wonders what other important or even vital system checks owners are not made aware of. Not everybody is a long time boater or indeed of a practical bent and there are more and more inexperienced liveaboards coming along every week. Looks like an opening for Haynes

[Loafer]

Blimey! A satisfied customer. We should have him stuffed!

 

Glad it all worked out, Ditchy! Warm Christmas.

[Joe the plumber]

One question.

 

Where did the water that has been lost from the system go? Central heating systems shouldn't consume water.

 

If it needs topping up again soon, I'd have a good look to see if there's a leak somewhere.

[Robbo]

One question.

 

Where did the water that has been lost from the system go? Central heating systems shouldn't consume water.

 

If it needs topping up again soon, I'd have a good look to see if there's a leak somewhere.

vaporation from the header tank (especially if open topped)

[NMEA]

vaporation from the header tank (especially if open topped)

Quite so, especially those Mickey Mouse things with a loose flat lid that many boat builders use. But in this instance it is an unknown and the original presented issue was a cold radiator top and the header level was not checked before bleeding operation started. This can be caused by build up of gasses which are a by product of corrosion and why in post #13 I recommended a coolant / inhibitor change especially in this instance as the owner was blithely unaware of the service requirements or even the importance of checking the header or indeed even its location. Exhausted inhibitor is something I come across on a very regular basis as far more owners do not change the coolant at the specified intervals than do. Many systems I see don't even have a drain down point! Come on, admit it (even to yourself) how many of you have 3 + year old coolant in your heating.

I don't have shares in an Antifreeze manufacturer by the way.

[ditchy]

One question.

 

Where did the water that has been lost from the system go? Central heating systems shouldn't consume water

 

If it needs topping up again soon, I'd have a good look to see if there's a leak somewhere.

Very good point... Keep an eye on it

[IanM]

When I made my mistake of bleeding with pump on, the, now I know, inevitable happened and the header tank gushed forth, depositing my anti freeze treated water all over the place.

 

You're not the only one to have done that