Struggling to get the Webasto Top C to start up.

[Chewbacka]

13 hours ago, Kelbs said:

Thanks for that Rob.

 

I finished work late today and am knackered so didn't give bleeding the unit a go, however I gave it a token start up while it was going through the start up and I could hear the water pump going I gave the hot water flow pipe a wiggle around, in between the Webasto and the bulkhead, trying to move anything along. There were several big clunks which happened. I'm not really sure how best to describe it but the pipe moved when the clunk happened and it sounded like something was having trouble passing through the pipe.

 

Is this possibly air inside the Webasto trying to get out/restricting the water flow? It felt as though it was on the flow pipe (hot water leaving the unit).

 

Beau

Could that be there is no water in the heat exchanger, it fires up gets hot then a small amount of water enters which boils violently ?

 

you really need to be confident there is water in the heat exchanger and the circulation pump is pumping water.  If you are, ignore me.

Edited September 20, 2019 by Chewbacka

[Tash and Bex]

19 minutes ago, Chewbacka said:

Could that be there is no water in the heat exchanger, it fires up gets hot then a small amount of water enters which boils violently ?

 

you really need to be confident there is water in the heat exchanger and the circulation pump is pumping water.  If you are, ignore me.

It's all pointing towards a water circulation issue of some sort, definitely the first place i would look. it does sound like vaporising water on a very hot heat exchanger though.

 

The water pump is part of the initial startup sequence, it begins running as soon as 12v is applied to the "heat" demand wire, at the same time as the dosing pump starts to click, and doesn't shut down until the combustion fan does during the shutdown sequence.

Edited September 20, 2019 by Tash and Bex
expansion

[Chewbacka]

Did you ever get it working???

[Onewheeler]

I'd bet there's no dip tube inside the tank.

 

Edit: ignore that, I'd missed three pages of discussion!

Edited September 23, 2019 by Onewheeler
Idiot!

[Kelbs]

55 minutes ago, Chewbacka said:

Did you ever get it working???

Nope, still a bit of a mystery.

 

I've been away over the weekend so haven't had much chance to play around.

 

When I got back yesterday I removed the cold water return from the unit and let the water from the hot flow pipe run back through the unit.

 

I then spent a good hour bleeding all the Rads while trying to run the Webasto. I managed to get a bit of air out of the highest rad but still no joy getting the unit to run fully.

 

If I remove the 5amp fuse and put it back in then the water pump turns on and I can hear water flowing through the Rads. Once the start up sequence gets well underway, the flow pipe gets very hot, almost to hot to touch, and that heat does make it's way into the boat but the unit cuts out before anything exciting happens.

 

Just before the unit cuts out the flow pipe makes a few clunking noises and jolts about a bit. Which I am assuming is trapped air.

 

Tonight, if it's not raining, I will try disconnecting the flow pipe and turning the pump on to see if it will pump the water out of the unit. 

 

I think there must be a clump of air in the system which needs bleeding out but I can't seem to find it.

 

Any ideas?

 

Beau

 

 

[Chewbacka]

My guess and it is only that, is the air is getting to the pump which stops pumping (your pump can’t pump air) and then the water in the heater boils hence the noises, and then the overheat shuts down your system.  So somewhere before the pump there is a high loop or something which is where the air is sitting.  Not sure what others think.............

[Sir Nibble]

Does sound like a bleeding problem. It's surprising how often there's no bleed valve at high points. I added two to my own system.

[Kelbs]

42 minutes ago, Sir Nibble said:

Does sound like a bleeding problem. It's surprising how often there's no bleed valve at high points. I added two to my own system.

Each of the Rads has a bleeding valve at the top, the header tank which is at the highest point in the system has an open vent which I believe is an auto bleed. The only section which I can't bleed is the calorifier which the hot water from the webasto coils up in. 

 

I could try to draw the system out on paper if anyone thinks it would help but it would be difficult to show all the height differences.

 

 

[WotEver]

Could you not add a bleed point to the calorifier loop output pipe?

[Detling]

It does sound that the hot water cannot flow fast enough to provide a good flow of cooler water to the burner unit, this then causes a boil hence the clunks and shutdown. So though the pump is circulating water it isn't circulating enough.

 

Maybe you have a bent pipe almost closed up restricting water flow, or your pump has lost a few blades and just hasn't got the flow rate any more. 

 

Do the pipes from the webasto rise to go through the bulkhead? although you state the header tank is high it is only connected to one of the two pipes through the bulkhead. On my boat the pipes do rise as they pass through the bulkhead, the return pipe has has the header tank fitted so is self bleeding the other pipe has a compression joint by the bulkhead which I crack let the air out and wait for the water to come through, if I don't no water will get round the circuit as the webasto pump is not powerful enough to push the air through.

[Tony Brooks]

Hot water out of a boiler is usually at a higher or the same level as the return so trying to bleed backwards from hot side to cold makes no sense to me. In my view you need to bleed in the direction of flow.

 

As already explained typically the Webasto is situated higher than the pipes flowing to an from the radiators so having bled the radiators there can still be air in the boiler or the pipes close to it. ALL high points in the pipework need a bleed valve so you can  release air trapped in them. Centrifugal pumps like yours can not pump air.

1 hour ago, Kelbs said:

Each of the Rads has a bleeding valve at the top, the header tank which is at the highest point in the system has an open vent which I believe is an auto bleed. The only section which I can't bleed is the calorifier which the hot water from the webasto coils up in. 

 

I could try to draw the system out on paper if anyone thinks it would help but it would be difficult to show all the height differences.

 

 

As requested days ago and when I complained about your apparent ignoring of recommendations and requests to help try to sport out your problem you were rude. Any such diagram must be accurate as far as pipe rund and angles are concerned, length of pipes are not so important.

[cuthound]

Is yours a horizontal calorifier?  If so the coils are notoriously difficult to bleed.

 

On my last share boat I had to resort to using a mains pressure hose to blast the trapped air out of the horizontal calorifier coils.

[Kelbs]

1 hour ago, Detling said:

It does sound that the hot water cannot flow fast enough to provide a good flow of cooler water to the burner unit, this then causes a boil hence the clunks and shutdown. So though the pump is circulating water it isn't circulating enough.

 

Maybe you have a bent pipe almost closed up restricting water flow, or your pump has lost a few blades and just hasn't got the flow rate any more. 

 

Do the pipes from the webasto rise to go through the bulkhead? although you state the header tank is high it is only connected to one of the two pipes through the bulkhead. On my boat the pipes do rise as they pass through the bulkhead, the return pipe has has the header tank fitted so is self bleeding the other pipe has a compression joint by the bulkhead which I crack let the air out and wait for the water to come through, if I don't no water will get round the circuit as the webasto pump is not powerful enough to push the air through.

Hello Detling,

 

The flow pipe leaving the Webasto falls from the unit to pass through the bulkhead then falls again once through the bulkhead to get to floor level where it tees off to go to the first rad (also on the bulkhead) and goes and feeds all the other rads. Before going off to feed the rads, about 40cm after that first tee on the floor level I have put in a tee which comes off to feed the Calorifier with 15mm pipe, this tee is a reducer from 22 to 15mm.

 

It certainly is getting very very hot and is probably close to, if not boiling. Would this then create bubbles in the system? And do you know why this would cause clunking in the pipe? I've been assuming that this was the trapped air.

 

28 minutes ago, cuthound said:

Is yours a horizontal calorifier?  If so the coils are notoriously difficult to bleed.

 

On my last share boat I had to resort to using a mains pressure hose to blast the trapped air out of the horizontal calorifier coils.

Its a vertical calorifier but I still don't know how to bleed it. I have a gate valve on the return coming out of the calorifier and if I open it fully it drips. I've done this a few times and not noticed any air coming out.

 

1 hour ago, Tony Brooks said:

As requested days ago and when I complained about your apparent ignoring of recommendations and requests to help try to sport out your problem you were rude. Any such diagram must be accurate as far as pipe rund and angles are concerned, length of pipes are not so important.

Sorry Tony, I've not had the time to draw out a diagram yet. There are no angles greater than 45 degrees. It seems like the water is able to pass around at least part of the system as I can hear water moving around the radiator half way up the boat. 

 

Thanks all, I very much appreciate the help and advice

[Kelbs]

I am struggling to draw out the plumbing but that's the brains of it. The Rads just tee of the flow and returns.

 

Where the pipes run off to the left of the photo (starboard) they are feeding a small rad on the bulkhead.

[Tony Brooks]

When I say angles I am talking about the angles the pipes run at compared with horizontal because I know you have some hose in the circuit and this can take a wavy path. Also with boats trimming up at the front the apparent horizontal pipes are often nothing of the sort. Any air trapped by this in the main cabin area should find its way into the top of the front most rad but if the pipes leaving the boiler slop up and then turn to go  down to cabin floor level you have an ideal area for forming air locks both in the boiler inlet and outlet side. This is why I wanted to see how the pipes run. How the pipes run before and after the boiler is not clear at all at the present.

 

Straight away I cans see an air trap with a sloping pipe to the left of the expansion tank and have a suspicion it may be the cold feed to the boiler.

Edited September 23, 2019 by Tony Brooks

[Kelbs]

9 minutes ago, Tony Brooks said:

Straight away I cans see an air trap with a sloping pipe to the left of the expansion tank and have a suspicion it may be the cold feed to the boiler.

Thats the hot water pipe coming from the calorifier, not part of the radiator system. I don't seem to have any air trapped in that system, possibly because the expansion tank holds pressure?

[Tony Brooks]

1 hour ago, Kelbs said:

Thats the hot water pipe coming from the calorifier, not part of the radiator system. I don't seem to have any air trapped in that system, possibly because the expansion tank holds pressure?

The domestic water system uses a positive displacement pump so providing the pump valves are in good condition it will pump and thus purge the air.

[grahame r]

In your original post you mention Spencer, is that Spencer of Spencer and Victoria fame at the Boatyard? If so, he know's everything about everything and certainly has the diagnostic software to tell you if the unit is faulty and the experience to bleed the system properly. Enjoyable as it is to pontificate on this problem, winter is coming!  

[MtB]

10 hours ago, Kelbs said:

 

 

 

 

 

This photo alone jumps out at me as illustrating the installation has not been carried out with any appreciation of air locking. There is no air vet to let the air out of the calorifier coil so this circuit is never likely to work unless the pump happens to have the power to shove the water through and clear the air. 

 

I note OP is on the K&A and so am I. Happy to call in for a quick look and see if I can pin down the problem if the OP wishes, and is anywhere near me the Hungerford end, rather than Bristol!

 

 

 

 

[Kelbs]

8 minutes ago, Mike the Boilerman said:

 

This photo alone jumps out at me as illustrating the installation has not been carried out with any appreciation of air locking. There is no air vet to let the air out of the calorifier coil so this circuit is never likely to work unless the pump happens to have the power to shove the water through and clear the air. 

 

I note OP is on the K&A and so am I. Happy to call in for a quick look and see if I can pin down the problem if the OP wishes, and is anywhere near me the Hungerford end, rather than Bristol!

 

 

 

 

I hadn't considered air being trapped and thought it would always make it's way up to the header tank.

 

Where would I put a bleed valve on this pipework to help bleed the coil?

[Chewbacka]

I noticed in your photo of the coolant header tank there is another job for later - for an lpg bubble tester to be an acceptable bss method for lpg leaks it must be in the gas locker.  Assuming you wish to use it for that purpose needs relocating.

[MtB]

1 minute ago, Chewbacka said:

I noticed in your photo of the coolant header tank there is another job for later - for an lpg bubble tester to be an acceptable bss method for lpg leaks it must be in the gas locker.  Assuming you wish to use it for that purpose needs relocating.

 

I wasn't going to mention that until the Eber is working!!

 

 

[Kelbs]

2 minutes ago, Chewbacka said:

I noticed in your photo of the coolant header tank there is another job for later - for an lpg bubble tester to be an acceptable bss method for lpg leaks it must be in the gas locker.  Assuming you wish to use it for that purpose needs relocating.

The gas locker is just the other side of the bulkhead. I was advised that it would be fine here and the bss seemed fairly vague. Will move if needed before I get the bss.

[MtB]

4 minutes ago, Kelbs said:

the bss seemed fairly vague

 

The BSS is very specific, it MUST be inside the gas locker!

 

But the BSS is unnecessarily strict on this in my opinion. There is no 'real life' risk in it being there so don't worry about it until BSS time.

32 minutes ago, Kelbs said:

I hadn't considered air being trapped and thought it would always make it's way up to the header tank.

 

Where would I put a bleed valve on this pipework to help bleed the coil?

 

Replace the top elbow just to the left of the red-handled gate valve with a tee, with the spare branch pointing UP, and put an air vent in the UP pointing bit. 

 

 

[Kelbs]

6 minutes ago, Mike the Boilerman said:

Replace the top elbow just to the left of the red-handled gate valve with a tee, with the spare branch pointing UP, and put an air vent in the UP pointing bit. 

 

 

Brilliant, thanks Mike. I'll pick the bits up on my way back from work.