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Can I use the webasto when the engine is running?


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Thanks to the helpful comments on our power/battery/Sterling questions, we are getting there, but another question please, the man we bought our boat from said that we shouldn't have the Webasto on while the engine is running. I can't see that this is stated in the Webasto manual. Is that right?

 

Thank you

 

Christine

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Seems strange - but then I have a Mikuni, which, of course (!) is very resilient.

All these units Eber, Webasto Mikuni were designed for vehicle heating and so can cope with charging voltages - which is the only reason(to me) why not.

 

I assume you use the Webasto to heat the hot water as well as central heating?

We may need more info: to try to understand your statement.

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Thanks to the helpful comments on our power/battery/Sterling questions, we are getting there, but another question please, the man we bought our boat from said that we shouldn't have the Webasto on while the engine is running. I can't see that this is stated in the Webasto manual. Is that right?

 

Thank you

 

Christine

I use mine with the engine running (for central heating). Always have done.

Can't understand why you have been told not to. Might be wise to check where it's wired into just in case. Also, does it have its own diesel feed from the tank, or is it shared.

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We've not used the webasto at all yet because we've had problems with the batteries / power but the water is heated (extremely hot) by the engine, so no, it would just be for heating.

 

I will check on the other points later if it's in the manual, or on the next visit if not.

 

thank you!



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I have used my Webasto with the engine running without problems.

 

As others have said, check where the fuel supply originates. It should have a dedicated feed from the diesel tank, not be tee'd off the engine supply.

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It's OK to have a common tank feeding the engine and Webasto, as long as each device has a dedicated fuel supply. If they share a common supply, there is a possibility that one can interfere with the other.

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One reason depending on how things are plumbed could be because the engine is heating the calorifier and possibly any radiators and therefore the Webasto will go into a cycle of stopping and starting.

 

When the water arriving into the Webasto is already at a hot enough temperature the Webasto thinks it has done enough and goes into shut down mode. As soon as it has shut down it starts up again. I remember reading on here that this cycling activity is not good for it.

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I think that there might be another issue here.

 

We know that the Engine heats the calorifier. Does the Webasto also heat the calorifier? If they both heat the calorifier are they feeding into the same coil or are they on separate coils?

 

The point that I am trying to make is that the Webasto and the Engine could be feeding into the same coil, in which case the engine water pump would be working against the Webasto's pump which might not be considered a good idea.

 

I have a system where the engine pump could be working against the Mikuni so I try to make sure that this does not happen. When using the Mikuni to preheat the engine I will make sure that I switch the Mikuni off two minutes before starting the engine so that it can go through its purging cycle.

 

Niclk

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I think that there might be another issue here.

 

We know that the Engine heats the calorifier. Does the Webasto also heat the calorifier? If they both heat the calorifier are they feeding into the same coil or are they on separate coils?

 

The point that I am trying to make is that the Webasto and the Engine could be feeding into the same coil, in which case the engine water pump would be working against the Webasto's pump which might not be considered a good idea.

 

I have a system where the engine pump could be working against the Mikuni so I try to make sure that this does not happen. When using the Mikuni to preheat the engine I will make sure that I switch the Mikuni off two minutes before starting the engine so that it can go through its purging cycle.

 

Niclk

Normally marine calorifiers have 2 coils, one for the engine and one for the boiler.

 

When I picked my boat up it had just had a new calorifier fitted, and the numpty (sorry marine engineer) who fitted plumbed both coils in series, so the engine heated the rads and calorifier, and the Webasto heated the engine, calorifier and rads!

 

Edited to correct the autocorrect.

Edited by cuthound
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OK, the manual says:

 

the webasto draws diesel direct from the tank, so that sounds OK.

but the webasto does also heat the water via a twin coil calorifier. One coil heats the water, one the radiators. It is a separate coil to the engine.

 

The engine does not heat the radiators.

 

Does this help?

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OK, the manual says:

 

the webasto draws diesel direct from the tank, so that sounds OK.

but the webasto does also heat the water via a twin coil calorifier. One coil heats the water, one the radiators. It is a separate coil to the engine.

 

The engine does not heat the radiators.

 

Does this help?

Then assuming it as plumbed as per the manual (best to check), it has been fitted correctly and the Webasto can be used with the engine running to heat the radiators, as there is no point in using the Webasto and the engine together just to make hot water.

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One reason depending on how things are plumbed could be because the engine is heating the calorifier and possibly any radiators and therefore the Webasto will go into a cycle of stopping and starting.

 

When the water arriving into the Webasto is already at a hot enough temperature the Webasto thinks it has done enough and goes into shut down mode. As soon as it has shut down it starts up again. I remember reading on here that this cycling activity is not good for it.

 

 

Check for this as it short cycling is a bad thing. Usually you can hear it and will notice, but with the engine running you could easily miss it.

 

 

the water is heated (extremely hot) by the engine

 

If it's extremely hot at the taps, you should be able to adjust the delivery temperature at a mixer valve normally on the top of a vertical calorifier. The water in the tank being very hot is a good thing, because when it mixes with cold it increases the volume at the taps - effectively, it gives you a bigger tank of usefully hot water.

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Normally marine calorifiers have 2 coils, one for the engine and one for the boiler.

 

When I picked my boat up it had just had a new calorifier fitted, and the numpty (sorry marine engineer) who fitted plumbed both coils in series, so the engine heated the rads and calorifier, and the Webasto heated the engine, calorifier and rads!

 

Edited to correct the autocorrect.

 

Theodora has two coils but one is not used. Your engineer might have been a numpty but it depends what his goal was. In my boat I could see a good reason for connecting the other coil in series with the first. It would double the heat transfer area and allow the Mikuni to heat the tank rather more quickly. With the single coil connected the Mikuni heats the water from a bit warm to good for a shower in something like 10 minutes. It then goes on to low power because its temperature is high. With the second coil fitted it would remain on full power for longer so heating the calorifier hotter quicker.

 

Are your engine, rads and calorifier coils all in series? If that's the case then I would agree with you that the engineer was a numpty. I plumbed Theodora to have the engine, mikuni and rads all in parallel and the circulation controlled by valves. This means that the Engine can heat rads and/or calorifier, the Mikuni can heat engine and/or rads and/or calorifier. This is really convenient and allows great flexibility.

 

Nick

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Eberspacher and webasto are commonly used to preheat engines in cold environments so can be used at the same time.

I think the most relevant point above is that the engines running temp may make the unit go into snooze mode regularly or even constantly, which affects the long term efficiency of the unit. (They need to be run on high mode for minimum 1/2 to 3/4hour to burn off built up carbon deposits)

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Theodora has two coils but one is not used. Your engineer might have been a numpty but it depends what his goal was. In my boat I could see a good reason for connecting the other coil in series with the first. It would double the heat transfer area and allow the Mikuni to heat the tank rather more quickly. With the single coil connected the Mikuni heats the water from a bit warm to good for a shower in something like 10 minutes. It then goes on to low power because its temperature is high. With the second coil fitted it would remain on full power for longer so heating the calorifier hotter quicker.

 

Are your engine, rads and calorifier coils all in series? If that's the case then I would agree with you that the engineer was a numpty. I plumbed Theodora to have the engine, mikuni and rads all in parallel and the circulation controlled by valves. This means that the Engine can heat rads and/or calorifier, the Mikuni can heat engine and/or rads and/or calorifier. This is really convenient and allows great flexibility.

 

Nick

Yes when we picked DQ up after monies transferred, I was surprised to find the radiators getting really hot despite the Webasto being switched off! As it was a hot a June day, I had no option but to turn off each radiator. That first night on board was really uncomfortably hot.

 

A little investigation found everything connected in series, so I checked with the builder to see if it had been designed that way. It hadn't so I replumbed it when changing the antifreeze in the central heating system.

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Do I get this right?

 

Many narrowboats have a calorifier with two coils. The heat source is connected to one and the radiators to the other. This means that to heat the radiators the water in the calorifier must be hot so that it transfers its heat to the radiators. So the heat flow is Heat source (Engine or boiler) ---> Calorifier water ---> Radiators.

 

If this is the case then turning on the rads means that they cool the calorifier. Is that what is wanted? It also means that to heat the interior of the boat the calorifier must be heated first.

 

I am sure that people have told me that this is the arrangement on some boats. Why? What are the advantages?

 

Nick


(They need to be run on high mode for minimum 1/2 to 3/4hour to burn off built up carbon deposits)

 

That figure is interesting. I suppose that it might apply to Mikuni. Is it published, Matty, or learned from experience?

 

N

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Hi Nick,

 

No you haven't got that right ?

 

Coil 1 is part of the engine cooling circuit and heats the calorifier and nowt else.

 

Coil 2 is heated by the boat's heat source which also heats the rads. So effectively it's plumbed as just another rad in a simple installation.

 

Tony

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Do I get this right?

 

Many narrowboats have a calorifier with two coils. The heat source is connected to one and the radiators to the other. This means that to heat the radiators the water in the calorifier must be hot so that it transfers its heat to the radiators. So the heat flow is Heat source (Engine or boiler) ---> Calorifier water ---> Radiators.

 

If this is the case then turning on the rads means that they cool the calorifier. Is that what is wanted? It also means that to heat the interior of the boat the calorifier must be heated first.

 

I am sure that people have told me that this is the arrangement on some boats. Why? What are the advantages?

 

Nick

 

That figure is interesting. I suppose that it might apply to Mikuni. Is it published, Matty, or learned from experience?

 

N

A normal installation on a modern narrowboat will have a coil from the engine heating the calorifier, and a coil from the eberspacher/webasto/mikuni heating the calorifier and generally heating some radiators in that circuit. The units do not especially like to heat JUST the calorifier and it is normal to leave a single (bathroom or towel rad) open in summer to take some heat.

individual boats might be designed by their owners to operate differently - someone who cruises a lot all year round may have the radiators heated by the engine for example.

my experience is not only my own boat, which has been in place for 14 years and used almost daily for 9 and now replaced this week, but also looking at all the boats coming into the workshop who have issues and talking to eberspacher/webasto service agents who deal with faults daily.

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Neil Smith, on 06 Apr 2016 - 10:46 PM, said:

You should never shut off any radiators or even fit thermostatic rad valves with a webasto as it restricts the flow and leads to cycling on and off.

 

Neil

(Thank heavens I don't have a Webasto....)

 

Seriously it's not a matter of which manufacturer of that sort of heating - it's more that they all need some form of 'heat sink' to work reliability. It (ought not to) / matters not how you close that heat sink down - the fact is that you shouldn't.

 

I have thermostatic valves - installed mainly because they're easy to turn on/off if you need to change the heat pattern to dry wet clothes for instance. I do have a reserve heat sink as the bathroom radiator is always on as is the calorifier. We have four large radiators and the heater never has a problem overheating the boat.

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