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Webasto running cool when calorifier added.


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Morning all,

 

I'm new to canal boats and am fettling a 62x12 widebeam.  I fired the heater up (Webasto 4.5kw) for the first time and it ran beautifully and warmed the 6 radiators up a treat, really warm. 

The water was cold, so after a bit of pipe tracing I located the gate valve to the calorifier and opened it.  I could feel the hot water from the Webasto going into the tank so waited patiently.

 

After about half an hour the radiators were much cooler, in fact just warm.  I expected that the calorifier might rob a bit of heat from the rads but not that much.  After another hour I had warm water and warm radiators, nothing hot enough to be of any use.

 

Engine heats the water fine, although the coil in the calorifier is separate to the Webasto so probably not relevant.

 

Is a 4.5kw heater enough for so many rads, calorifier and a big boat? When I shut the calorifier off the rads warmed up again to a proper temperature.  I suspect the unit's not big enough to run everything? ambient temp was about 6 degrees on the day I tested it.

 

Any ideas or anything I've missed?  Thanks in advance,

 

Pete

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13 minutes ago, Pete1987 said:

I suspect the unit's not big enough to run everything?

I think you may have answered your own question.

 

That is a big boat to heat.

 

Work out the actual surface area of the radiators, you can then calculate the total 'watts' and you may find that your 'number' is around 5Kw + which it can cope with, but when you add in the  calorifier it is just too much for the heater.

Is the heater operating on 'high' continuously or does it drop back to 'low' ?

have you got the room thermostat turned down / up ?

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Worth remembering that the calorifier will only take heat (and thus cool the rads) whilst the water is heating up. Once the calorifier water is up to temperature all the heat will go to heating the rads. You don’t say how big the calorifier is, but perhaps it is quite big, and will thus take a fair while to heat up.

 

Anyway my suggestion, as mentioned previously, is to only slightly open the gate valve to the calorifier. That way, most of the heat will go to the radiators. It will of course take longer to heat the calorifier, but it will get there eventually.

 

I would say that 4.5kw is about right for a 62’ narrowboat. Definitely on the thin side for a 12’ wide boat, but if it is just background heating (supplemented by a solid fuel stove etc) then it will be fine.

 

What you certainly don’t want is an over-powerful heater as it will get everything up to temperature and then start cycling on and off. This is really bad for the longevity of this type of heater.

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Thank you all for your replies. Interesting suggestion about partially closing the gate valve, as when I tested it I opened the valve fully. 
I’d rather have hot radiators and warm water, as that can always be topped up by using the immersion heater. 
I was hoping to get set up so that the webasto can come on with the timer for a couple of hours from 4am so we can wake up to warm rads and hot water for showers. I’ll keep experimenting with the valve and give it a bit more time. 
If it’s not big enough to do everything I’ll let the webasto get just the radiators red hot then use the immersion for water. 

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3 hours ago, Pete1987 said:

Thank you all for your replies. Interesting suggestion about partially closing the gate valve, as when I tested it I opened the valve fully. 
I’d rather have hot radiators and warm water, as that can always be topped up by using the immersion heater. 
I was hoping to get set up so that the webasto can come on with the timer for a couple of hours from 4am so we can wake up to warm rads and hot water for showers. I’ll keep experimenting with the valve and give it a bit more time. 
If it’s not big enough to do everything I’ll let the webasto get just the radiators red hot then use the immersion for water. 

 

I trust you will only try the bit in red if you are on a shoreline or whatever solar you are producing covers the immersion heater electrical load.

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10 minutes ago, Tony Brooks said:

 

I trust you will only try the bit in red if you are on a shoreline or whatever solar you are producing covers the immersion heater electrical load.

Yes Tony, if we’re out and about the main engine gives loads of hot water. 
I’m just aware we need a good, reliable hot tank of water to get three of us through the bathroom in the mornings. 

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Easy to say and difficult to understand why folks have problems - but I fitted a Mikuni heater (FWIW is doesn't really matter a jot on the label and to some extent the actual manufacture of the heater unit) and it runs the cauliflower (a 'big' vertical domestic version).

 

On startup from 'cold' the heater churns away for 1/2 -1 hour and everything is a bit tepid for a while. Thereafter the radiators start to warm up progressively, with the bathroom twin panel pleaantly warm followed by the three cabin heaters.

Once the base load is completed the whole boat is toasty.

 

'We' forget that the ebersplutter / Mikuni / other heaters were only designed  to prevent vehicles from freezing up and provide some heat for the drivers / passengers while the vehicle started moving. Thus I think its a miracle that these units will provide a heating solution for folks in a boat, reasonably reliably  without  folks complaing that 'they don't work' 

 

If 'you' adapt a device to do something outside its basic design concept, you have to accept that there may be some compromises....

 

 

 

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14 hours ago, Pete1987 said:

Morning all,

 

I'm new to canal boats and am fettling a 62x12 widebeam.  I fired the heater up (Webasto 4.5kw) for the first time and it ran beautifully and warmed the 6 radiators up a treat, really warm. 

The water was cold, so after a bit of pipe tracing I located the gate valve to the calorifier and opened it.  I could feel the hot water from the Webasto going into the tank so waited patiently.

 

After about half an hour the radiators were much cooler, in fact just warm.  I expected that the calorifier might rob a bit of heat from the rads but not that much.  After another hour I had warm water and warm radiators, nothing hot enough to be of any use.

 

Engine heats the water fine, although the coil in the calorifier is separate to the Webasto so probably not relevant.

 

Is a 4.5kw heater enough for so many rads, calorifier and a big boat? When I shut the calorifier off the rads warmed up again to a proper temperature.  I suspect the unit's not big enough to run everything? ambient temp was about 6 degrees on the day I tested it.

 

Any ideas or anything I've missed?  Thanks in advance,

 

Pete

It could be that the heater has been plumbed in incorrectly so check the installation manual if you have one. You may find that the return pipe from calorifier has not been plumbed in to the return pipe correctly, to near the heater.

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4 hours ago, Pete1987 said:

Ex Brummie, sorry to sound a bit thick, can you explain? Do you mean that the rads will be deprived because the calorifier will gobble up all the heat?

Water is very lazy and will take the easiest route in the circuit, so restricting the flow to the calorifier will still allow hot water to return to the webasto and make it short cycle.

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