Using a webasto to heat calorifier in summer

[Sea Sausage]

Hi everyone!

 

We bought a 60ft narrow boat which we are refurbishing and planning to live aboard. There is currently a Webasto fitted by an absolute joker so we'll be re installing it properly along with a new twin coil Surecal calorifier. So that's hot water sorted for when we're cruising and when the Webasto is running. But what about the summer months when you don't want to heat all the radiators using the Webasto? I've read in numerous places that if the flow to the radiators is stopped the Webasto will short cycle and age very quickly. 

 

Also, the Webasto is rated at 5.2KW, the manual recommends installing a system 10% greater than this, so nearly 6KW. Thats 6 average sized double panel radiators, which is about the same as my 100sqm flat. Are these diesel boilers not a bit over powered for narrow boats?

 

Thanks! 

[Tony Brooks]

Not sure exactly how its all connected but I would have the calorifier circuit in parallel with the radiator circuit so a simple shut of valve before the first radiator would allow the Webasto to heat the calorifier but no the rads. However the problem comes with reliability when you allow the Webasto to cycle so as long as you turn it off just before it goes to low heat or when the calorifier is hot enough all should be well. You will probably want it on for 30 minute or so (depending upon experience) morning and evening.

[Boater Sam]

A calorifier of decent size will soak up 6kW if the pipework is large enough, 22mm min. Yes, the Webasto will short cycle and use a lot of battery power re-igniting when the temperature gets high enough, unavoidable. Its up to you to turn it off when you ave sufficient hot water rather than let it get the whole up to maximum temperature.

Short cycling will reduce the life of the ignition electrode, the rest should be fine if the heater is serviced regularly.

 

Crossed with Tony.

Edited May 4, 2018 by Boater Sam
added

[Sea Sausage]

"Most common, narrowboat calorifiers (55 to 75ltr) will generally have a very basic copper coil inside, capable of transmitting approximately 1 to 1.5kW of heat energy into the domestic hot water"

http://www.canalboat.co.uk/canal-boats/maintenance/how-to-make-sure-your-narrowboat-is-heating-up-properly-1-4822255

Although I cant find anything written by Surecal to back this up so taken with a pinch of salt. But even doubled, so 2 to 3KW, it's still half that of the Webasto. 

 

Is it possible to reduce the heat output of the Webasto in anyway for the summer months? As it explains in the link above, you could blast a calorifier with 10KW of power, it aint gonna heat up any quicker.   

 

Edit: So I just realised there is a "part load" function with a heat output of 2.5KW which would be much better. Is it easy enough to start in this setting? I've not fired it up yet, to be honest I'm not betting on it working after seeing how it was installed ? 

Edited May 4, 2018 by Sea Sausage

[Alan de Enfield]

Leave the towel rail / radiator in the bathroom connected at all times - this will use a 'bit' of hot water and reduce cycling - it also has the advantage of being a  good drying area.

 

From what I have read (and all of ours certainly have) this seems to be the 'norm'.

 

If you are planning on cruising (or are you a static boat ?) then the engine will give you a calorifier full of hot water, if you shower, wash the pots, wash clothes in the middle of the day you will have another tank-full by evening, use the hot water in the morning, then repeat the previous day. (ours stays warm enough for a wash well into the 2nd day if not moving)

[OldGoat]

59 minutes ago, Tony Brooks said:

Not sure exactly how its all connected but I would have the calorifier circuit in parallel with the radiator circuit so a simple shut of valve before the first radiator would allow the Webasto to heat the calorifier but no the rads. However the problem comes with reliability when you allow the Webasto to cycle so as long as you turn it off just before it goes to low heat or when the calorifier is hot enough all should be well. You will probably want it on for 30 minute or so (depending upon experience) morning and evening.

Tony's point is a good one. It's poor practice for installers to put the radiators  and  calorifier in 'series'   (single pipe system) - shutting one of shuts them all off. Better it is to put them in parallel (two pipe system) so that each radiator can be controlled separately. If yours is the latter then the Webasto will heat your hot water but cut out /cycles earlier. My system with a large calorifier takes about 3 hours to heat the tank. Then I switch it off when I notice it cycling. I've not had a problem in some twenty years with the same (Mikuni) boiler.

Sometimes you have to be in more direct control of devices when on a boat that you would in a domestic situation...

1 minute ago, Alan de Enfield said:

Leave the towel rail / radiator in the bathroom connected at all times - this will use a 'bit' of hot water and reduce cycling - it also has the advantage of being a  good drying area.

 

From what I have read (and all of ours certainly have) this seems to be the 'norm'.

 

If you are planning on cruising (or are you a static boat ?) then the engine will give you a calorifier full of hot water, if you shower, wash the pots, wash clothes in the middle of the day you will have another tank-full by evening, use the hot water in the morning, then repeat the previous day. (ours stays warm enough for a wash well into the 2nd day if not moving)

Second that - it's what we do.

[Alan de Enfield]

2 minutes ago, OldGoat said:

Sometimes you have to be in more direct control of devices when on a boat that you would in a domestic situation...

Also known as "taking responsibility for your actions - or - inactions"

[Dr Bob]

56 minutes ago, Alan de Enfield said:

Leave the towel rail / radiator in the bathroom connected at all times - this will use a 'bit' of hot water and reduce cycling - it also has the advantage of being a  good drying area.

 

From what I have read (and all of ours certainly have) this seems to be the 'norm'.

 

That's the way to do it.

[Detling]

Unfortunately mine starts to cycle after 20 mins with no radiators. Turn rads half off, open doors and windows works well, just like the stove in September chucks out too much heat but you need some on the chilly nights.

[Flyboy]

5 hours ago, Sea Sausage said:

Hi everyone!

 

We bought a 60ft narrow boat which we are refurbishing and planning to live aboard. There is currently a Webasto fitted by an absolute joker so we'll be re installing it properly along with a new twin coil Surecal calorifier. So that's hot water sorted for when we're cruising and when the Webasto is running. But what about the summer months when you don't want to heat all the radiators using the Webasto? I've read in numerous places that if the flow to the radiators is stopped the Webasto will short cycle and age very quickly. 

 

Also, the Webasto is rated at 5.2KW, the manual recommends installing a system 10% greater than this, so nearly 6KW. Thats 6 average sized double panel radiators, which is about the same as my 100sqm flat. Are these diesel boilers not a bit over powered for narrow boats?

 

Thanks! 

Why don't you just run the engine ? My calorifier will heat up from cold in just 30 mins. My engine is a Barrus Shire 45 with dual thermostats so once it gets up to 71 degrees all its hot water is directed to the calorifier. When the engine gets to 82 degrees it is directed to the skin tank. Excellent  system imo.

[Tony Brooks]

3 hours ago, Flyboy said:

Why don't you just run the engine ? My calorifier will heat up from cold in just 30 mins. My engine is a Barrus Shire 45 with dual thermostats so once it gets up to 71 degrees all its hot water is directed to the calorifier. When the engine gets to 82 degrees it is directed to the skin tank. Excellent  system imo.

I agree and the alternator charge is always good to have. However I think twin thermostats are a needless complication. Over many years I have found plumbing the calorifier in place of the cab heater as in a vehicle/digger makes no noticeable difference to engine life.

[nicknorman]

Just to mention that the heat transfer of a heat exchanger such as a calorifier coil, is proportional to the temperature difference across the heat exchanger. So quoting 1 or 1.5kw is meaningless on its own. When the water in the calorifier is the same temperature are the Webasto-heated coil, the heat transfer is zero. When the calorifier is stone cold and the webasto coil is at 80C, it’s probably quite a lot.

 

Anyway, I find we can run the heater (mikuni, in our case) for long enough to get a good dose of very hot water, with the radiator circuit just fractionally cracked, before it goes to half power. The radiators barely get warm. The water heats up quickly.

 

And this is the advantage over engine running, if there is a need for quick hot water and no need to charge the batteries - the engine takes much longer to heat the water.

 

 

[Flyboy]

15 minutes ago, Tony Brooks said:

I agree and the alternator charge is always good to have. However I think twin thermostats are a needless complication. Over many years I have found plumbing the calorifier in place of the cab heater as in a vehicle/digger makes no noticeable difference to engine life.

Not a needless complication at all. All it basically consists of is removing the original thermostat housing and replacing it with a dual thermostat housing, but I know you knew that. I doubt if Barrus would have bothered if it didn't work. I've had rapid heating of the engine and calorifier for the 2500 hrs I've had the Barrus 45.

[WotEver]

12 hours ago, Alan de Enfield said:

... use the hot water in the morning, then repeat the previous day.

See if you can borrow another boater’s time machine in order to accomplish this...

[RichM]

I don't have a way to heat my 60 litre calorifier via the Eberspacher without also heating the radiators. Initially on first purchasing the boat I thought this would be an issue in the Summer months but in reality I run the diesel heater for an hour in the morning and again for an hour in the evening when the ambient temperature is cooler. This seems to work well but is dependant on your water requirements. 

 

 

[mrsmelly]

We generaly use the engine because as others have said it  heats water very quickly and as an added bonus is putting charge into batteries. However our webasto is plumbed so each radiator can  be isolated as we feel fit and valves are fitted to the system so we can have all going to the heating or all going to the cauliflower or whatever we want to each at any given time.

[Tony Brooks]

14 hours ago, Flyboy said:

Not a needless complication at all. All it basically consists of is removing the original thermostat housing and replacing it with a dual thermostat housing, but I know you knew that. I doubt if Barrus would have bothered if it didn't work. I've had rapid heating of the engine and calorifier for the 2500 hrs I've had the Barrus 45.

So two thermostats are no more complicated than just one? My view is that it tends more to marketing bull shine than a proven advantage. It seem to me some companies will go a long way to produce a marketing advantage that evaporates when it is looked at in depth. I think your post kind of proves that.

 

Only 2500 hours! How many hours do you think those old BMCs and the newer Isuzu & Kubota engines in hire boats, diggers, tractors etc have done with just a single thermostat.

Edited May 5, 2018 by Tony Brooks

[mrsmelly]

7 minutes ago, Tony Brooks said:

So two thermostats are no more complicated than just one? My view is that it tends more to marketing bull shine than a proven advantage. It seem to me some companies will go a long way to produce a marketing advance that evaporates when it is looked at in depth. I think your post kind of proves that.

 

Only 2500 hours! How many hours do you think those old BMCs and the newer Isuzu & Kubota engines in hire boats, diggers, tractors etc have done with just a single thermostat.

Single thermostats on the fords on the Nottingham Princess. 40,000 hours and counting.

[chevron]

Have installed a webasto on my boat which only heats the calorifier fitted a large 30 litre header tank to stop it cycling run the webasto for three quarters on an hour and have had no problems so far the cool water of the large header tank seems to work

[Tony Brooks]

2 minutes ago, chevron said:

Have installed a webasto on my boat which only heats the calorifier fitted a large 30 litre header tank to stop it cycling run the webasto for three quarters on an hour and have had no problems so far the cool water of the large header tank seems to work

A header tank can in no way stop a Webasto cycling. The heater WILL cycle when the heat being extracted from the water is less than the heat the boiler is putting into the water. It's running it for just 3/4 h0ur that stops it cycling. Leave it longer and it will eventually cycle.

 

At first  the cold water in the calorifier will extract lots of heat from the Webasto circuit so the Webasto runs flat out. As the calorifier warm sup it  extracts less and less heat as the relative temperatures of the Webasto water and calorifier water gets closer to each other. When they are the same almost no heat will be extracted and the Webasto will cycle to stop the water in the boiler actually boiling.

 

It's basic physics.

[chevron]

Hi Tony thanks for the reply love reading your posts and learnt so much on here.But surely if the supply tank is supplying a good supply of cold water through the webasto the system will take longer to get to temperature? Than reculculaing part warm water from a small radiator my heater tank receives all the water on the return flow into the top of the tank and takes water to supply the webasto from the bottom which has cooled off.

[Flyboy]

2 hours ago, Tony Brooks said:

So two thermostats are no more complicated than just one? My view is that it tends more to marketing bull shine than a proven advantage. It seem to me some companies will go a long way to produce a marketing advantage that evaporates when it is looked at in depth. I think your post kind of proves that.

 

Only 2500 hours! How many hours do you think those old BMCs and the newer Isuzu & Kubota engines in hire boats, diggers, tractors etc have done with just a single thermostat.

Sorry but you are wrong, I have owned several single thermostat engines and they don't warm up the engine and calorifier anywhere near as fast as a twin thermostat set up. So I think I have proved the advantage. Your hypothesis is pure supposition. I presume you've never owned a twined thermostat engined boat so have no first hand experience. You say two thermostats more complicated than one, please explain why you think this is so? I can see no reason that two thermostats would be less reliable than one, most will last the life of an engine. Failure of either would be no different than on a single thermostat engine. 

[Tony Brooks]

1 hour ago, chevron said:

Hi Tony thanks for the reply love reading your posts and learnt so much on here.But surely if the supply tank is supplying a good supply of cold water through the webasto the system will take longer to get to temperature? Than reculculaing part warm water from a small radiator my heater tank receives all the water on the return flow into the top of the tank and takes water to supply the webasto from the bottom which has cooled off.

Unless you are circulating the Webasto water through the header tank, and that is not a very common way of doing it, then the only exchange of water between the tank and boiler will be from the boiler circuit during warm up because of expansion and from the header tank during cool down because of contraction.

 

If you are circulating the water through the tank then you in effect have another small radiator and that will tend to reduce cycling. It all depends upon your setup.

[Tony Brooks]

10 minutes ago, Flyboy said:

Sorry but you are wrong, I have owned several single thermostat engines and they don't warm up the engine and calorifier anywhere near as fast as a twin thermostat set up. So I think I have proved the advantage. Your hypothesis is pure supposition. I presume you've never owned a twined thermostat engined boat so have no first hand experience. You say two thermostats more complicated than one, please explain why you think this is so? I can see no reason that two thermostats would be less reliable than one, most will last the life of an engine. Failure of either would be no different than on a single thermostat engine. 

That rather depends upon if the boats had bypass stats or ordinary thermostats in them. My single stat Bukh is getting well  towards hot - including the calorifier in under half an hour.

 

This is the situation you have. In the early stages of warming both stats will prevent any coolant circulating apart from if the first one from the engine is a bypass stat or any flow through a bypass port. During this stage no heat will go to the calorifier so its the same for a single or twin stat boat.

 

At some point the calorifier stats will open and direct coolant to the calorifier but the same thing happens on a single stat boat if the single stats had the same temperature rating as  the one on a twin stat system so very similar but I agree on a twin stat boat as no coolant can get to the skin tank the calorifier will warm up to some degree faster but the engine will not and on both systems the temperature gauges should give similar readings. Some marinisation use a cooler than "normal" thermostat to help  minimise the scalding danger from the calorifier. The question is how much faster and from observations I do not think it is particularly significant.

 

Once the second stat opens then  both systems should preform similarly.

 

I simply can not comprehend how someone can believe two mechanical devices will be as reliable as one. I also believe needing two different temperature thermostats must ee a complication but each to their own.

[Flyboy]

28 minutes ago, Tony Brooks said:

That rather depends upon if the boats had bypass stats or ordinary thermostats in them. My single stat Bukh is getting well  towards hot - including the calorifier in under half an hour.

 

This is the situation you have. In the early stages of warming both stats will prevent any coolant circulating apart from if the first one from the engine is a bypass stat or any flow through a bypass port. During this stage no heat will go to the calorifier so its the same for a single or twin stat boat.

 

At some point the calorifier stats will open and direct coolant to the calorifier but the same thing happens on a single stat boat if the single stats had the same temperature rating as  the one on a twin stat system so very similar but I agree on a twin stat boat as no coolant can get to the skin tank the calorifier will warm up to some degree faster but the engine will not and on both systems the temperature gauges should give similar readings. Some marinisation use a cooler than "normal" thermostat to help  minimise the scalding danger from the calorifier. The question is how much faster and from observations I do not think it is particularly significant.

 

Once the second stat opens then  both systems should preform similarly.

 

I simply can not comprehend how someone can believe two mechanical devices will be as reliable as one. I also believe needing two different temperature thermostats must ee a complication but each to their own.

Sorry you've still got it wrong so have a look at these extracts from the Barrus Shire manual. I will be very surprised if  Barrus have got it wrong.