Webasto combustion fails to accur

[Kristina]

7 hours ago, matty40s said:

 

Incorrect, it MUST pump over in the tank if the owner keeps taking it off to take away for repair and then replumbing it back in again. That is why Webasto have designed and reccomend what I have suggested.

Once there are no bubbles coming through, and header tank level is stable, the lower bypass pipe should be opened up.....meaning the expansion tank reverts to just that.

It wont cause severe corrosion if the correct mix antifreeze is used, and the bypass pipe opened when ALL air bubbles are removed from system.

 

Installation guide for heat exchanger system does not show necessary bypass valve. Header tank used to feed in and out on two ends (I have been assured is one of the two options ) 

[Tony Brooks]

That diagram is for a caravan, boar or vehicle that does not use a calorifier. In a boat that plate heat exchanger would be the calorifier tank. Preferably a twin coil one with the Webasto connected to one coil and the engine cooling system to the other.

 

You can find a plate heat exchanger on a few boat heating circuits, but it is used to transfer engine coolant heat into the radiator circuit.

 

I have had a very few people send me questions about corroded heat exchangers (the boiler part) inside the Webasto type of boiler, so I would be very wary of fitting a system that has the potential to aerate the liquid in the heating circuit. I don't think the header tank movement will be the cause of your present problem but I would heed what Matty said and fit a large bore bypass to the header tank with an isolating valve.

[MtB]

Firstly I too am horrified (as a domestic heating engineer) at the drawing showing the whole of the boiler flow passing through the header tank, as this causes rapid and continuous re-oxygenation of the circulation water, which in turn supports rapid internal corrosion of any steel parts in the circuit (e.g. radiators). On a domestic house central heating considerable lengths are taken to prevent water circulating through the header tank.

 

Secondly and perhaps more importantly, if the OP has installed the system as drawn it will still work but if (as I suspect) they do not have the two fan blowers installed and have radiators instead, when the TRVs on the rad valves close down this will cause the system flow to reduce or stop. This will cause the boiler (Webasto) to probably overheat and lock out, and which seems consistent with the symptoms reported by the OP.

 

It depends on how sophisticated the temperature control in the boiler electronics is, and 'not very' is my suspicion. If there is any control at all, beyond overheat lockout. 

 

 

Edited October 7, 2022 by MtB
Clarify.

[Kristina]

4 minutes ago, Tony Brooks said:

That diagram is for a caravan, boar or vehicle that does not use a calorifier. In a boat that plate heat exchanger would be the calorifier tank. Preferably a twin coil one with the Webasto connected to one coil and the engine cooling system to the other.

 

You can find a plate heat exchanger on a few boat heating circuits, but it is used to transfer engine coolant heat into the radiator circuit.

 

I have had a very few people send me questions about corroded heat exchangers (the boiler part) inside the Webasto type of boiler, so I would be very wary of fitting a system that has the potential to aerate the liquid in the heating circuit. I don't think the header tank movement will be the cause of your present problem but I would heed what Matty said and fit a large bore bypass to the header tank with an isolating valve.

While it’s not common in boats we consciously choose this install as our friends have had this system for years on a boat. 
 
Will take into consideration fitting bypass  valve into the system

[Awayonmyboat]

All this discussion on radiator corrosion problems occurring caused by water circulating through header tanks has raised some concern about the system on my boat as I have such a header tank. In my case the header tank is sealed with a screw down cap, such that fresh air cannot freely enter it and it must pressurise when the water heats up. It is a standard tank sold for use with Webasto and Erspacher heaters.

 

My understanding from posts I found elsewhere on this site, and Webasto installation instructions, was this type of tank is acceptable and the oxygen mixing problem was only with open topped expansion tanks that had circulation through them.

 

I would appreciate expert views on the acceptability off these sealed expansion tanks so I can decide if I need to get the plumbing tools out this weekend and fit a bypass beneath it.

 

(Apologies for taking the diverting the thread slightly)

[Kristina]

30 minutes ago, MtB said:

Firstly I too am horrified (as a domestic heating engineer) at the drawing showing the whole of the boiler flow passing through the header tank, as this causes rapid and continuous re-oxygenation of the circulation water, which in turn supports rapid internal corrosion of any steel parts in the circuit (e.g. radiators). On a domestic house central heating considerable lengths are taken to prevent water circulating through the header tank.

 

Secondly and perhaps more importantly, if the OP has installed the system as drawn it will still work but if (as I suspect) they do not have the two fan blowers installed and have radiators instead, when the TRVs on the rad valves close down this will cause the system flow to reduce or stop. This will cause the boiler (Webasto) to probably overheat and lock out, and which seems consistent with the symptoms reported by the OP.

 

It depends on how sophisticated the temperature control in the boiler electronics is, and 'not very' is my suspicion. If there is any control at all, beyond overheat lockout. 

 

 

It’s installed with one fan blower and one radiator/towel rail. Will reset webasto again just in case it locked out but it didn’t seem that it overheated the time it worked after installation. Ran smoothly and was turned off on the control by us until the next day. 
the header tank has a screw on lid after system was bled Was closed so I don’t know how air would be introduced and entering into the system 

[Tracy D'arth]

2 minutes ago, Awayonmyboat said:

All this discussion on radiator corrosion problems occurring caused by water circulating through header tanks has raised some concern about the system on my boat as I have such a header tank. In my case the header tank is sealed with a screw down cap, such that fresh air cannot freely enter it and it must pressurise when the water heats up. It is a standard tank sold for use with Webasto and Erspacher heaters.

 

My understanding from posts I found elsewhere on this site, and Webasto installation instructions, was this type of tank is acceptable and the oxygen mixing problem was only with open topped expansion tanks that had circulation through them.

 

I would appreciate expert views on the acceptability off these sealed expansion tanks so I can decide if I need to get the plumbing tools out this weekend and fit a bypass beneath it.

 

(Apologies for taking the diverting the thread slightly)

So it is effectively a sealed system? With a pressure release valve in case it over pressurises? In which case I would not worry. The simple remedy if it is not a sealed system is to fit a large bore bypass valve before the tank, connecting the expansion and vent pipes together so that the water flows through the valve and not through the tank. Closing the valve when filling will allow the vent to get rid of the air. Once filled and vented, open the valve fully.

2 minutes ago, Kristina said:

It’s installed with one fan blower and one radiator/towel rail. Will reset webasto again just in case it locked out but it didn’t seem that it overheated the time it worked after installation. Ran smoothly and was turned off on the control by us until the next day. 
the header tank has a screw on lid after system was bled Was closed so I don’t know how air would be introduced and entering into the system 

Because the expansion bottle has air in it, the water circulating picks up the air. It is not a sealed system with a pressurised expansion vessel and PRV.

[matty40s]

12 minutes ago, Awayonmyboat said:

All this discussion on radiator corrosion problems occurring caused by water circulating through header tanks has raised some concern about the system on my boat as I have such a header tank. In my case the header tank is sealed with a screw down cap, such that fresh air cannot freely enter it and it must pressurise when the water heats up. It is a standard tank sold for use with Webasto and Erspacher heaters.

 

My understanding from posts I found elsewhere on this site, and Webasto installation instructions, was this type of tank is acceptable and the oxygen mixing problem was only with open topped expansion tanks that had circulation through them.

 

I would appreciate expert views on the acceptability off these sealed expansion tanks so I can decide if I need to get the plumbing tools out this weekend and fit a bypass beneath it.

 

(Apologies for taking the diverting the thread slightly)

Nothing wrong with your system.

The Webasto tank we are talking about has the inlet/outlet entering at the base, not a lot of oxygen gets mixed in, and it is by far the quickest and most thorough method of bleeding the bubbles from the system on commission, and then after work carried out. 

By opening the bypass valve, this then becomes a system exactly the same as yours, and has a pressure cap.

Edited October 7, 2022 by matty40s

[cuthound]

19 hours ago, Cheshire cat said:

Is high sulphur diesel still out there?

 

BT had loads of it in the late 90's, some some gas oil was so old the content was 5% sulphur. It was soon to become illegal to use it, so I managed a project for a company to collect it, filter it, dilute it with ULSD, add lubricity additives and sell it back to BT at a slightly lower cost than buying new USLD.

 

Since 2010 all diesel for non road machinery has to have sulphur content of 0.001% or less.

 

 

 

18 hours ago, nb Innisfree said:

I don't think high sulphur is actually illegal for off road use, but I might be wrong. 

 

It has been since the end of 2010.

 

https://www.crownoiluk.com/news/sulphur-limits-on-fuel-explained/

Edited October 7, 2022 by cuthound
To insert spaces between merged posts

[Kristina]

On 07/10/2022 at 07:49, Tony Brooks said:

That diagram is for a caravan, boar or vehicle that does not use a calorifier. In a boat that plate heat exchanger would be the calorifier tank. Preferably a twin coil one with the Webasto connected to one coil and the engine cooling system to the other.

 

You can find a plate heat exchanger on a few boat heating circuits, but it is used to transfer engine coolant heat into the radiator circuit.

 

I have had a very few people send me questions about corroded heat exchangers (the boiler part) inside the Webasto type of boiler, so I would be very wary of fitting a system that has the potential to aerate the liquid in the heating circuit. I don't think the header tank movement will be the cause of your present problem but I would heed what Matty said and fit a large bore bypass to the header tank with an isolating valve.

It was the god damn cheap pump, finally got it working. Lesson learned. So you recon it’s worth fitting  bore bypass to the header tank in the near future. The header tank we have is is the same as what Awayonmyboat has talked about with a cap on top two hose barns on bottom and should pressurise as water heats up

[Tony Brooks]

34 minutes ago, Kristina said:

It was the god damn cheap pump, finally got it working. Lesson learned. So you recon it’s worth fitting  bore bypass to the header tank in the near future. The header tank we have is is the same as what Awayonmyboat has talked about with a cap on top two hose barns on bottom and should pressurise as water heats up

 

If the cap is airtight then the amount of air the water can absorb will not be very great, but I have my doubts that it will be airtight because as it heats up the tank may balloon by the expanding coolant and air and/or as it cools down the tank may collapse. If it is sealed the same could apply to the heat exchanger unless you have some flexible hose in the circuit. If you do then that would tend to collapse. I suspect the cap may have a breather in it. I can't really advise because I have always avoided such heaters so have no experience

 

The fact that Mike has confirmed what Tracy said makes me think the bypass and valve would be a good idea.

[Kristina]

50 minutes ago, Tony Brooks said:

 

If the cap is airtight then the amount of air the water can absorb will not be very great, but I have my doubts that it will be airtight because as it heats up the tank may balloon by the expanding coolant and air and/or as it cools down the tank may collapse. If it is sealed the same could apply to the heat exchanger unless you have some flexible hose in the circuit. If you do then that would tend to collapse. I suspect the cap may have a breather in it. I can't really advise because I have always avoided such heaters so have no experience

 

The fact that Mike has confirmed what Tracy said makes me think the bypass and valve would be a good idea.

Yeah there’s a bunch of flexible hose in the circuit. 
anyway will take into account in the future