Webasto and Calorifier sizing

[Ex Brummie]

Telford vented cylinders are only grade 3 which is too low for normal boat pressure systems, especially when engine heating is used.

[Tracy D'arth]

16 hours ago, matty40s said:

 

 

 

 

These are not suitable for a boat with a positive pressure pump, they are sold as vented i.e. open vent domestic hot water systems operating at very low pressure.

[IanD]

18 hours ago, Colin Brendan said:

I suppose a starting point would be what are surecals coils rated at? Can't seem to find that info.

Or:

• does anyone have a thermotop C?
• How big is your Calorifier?
• How long before you can have a shower?
• Do you have to keep a rad on in summer to stop it short cycling before you get a shower out of it?

 

I've been through exactly this discussion with my boat. Going by Dave Jesse's measurements the standard Surecal coils only deliver just over 1kW, he measured a temperature rise of 16C/hour for a 55l Surecal:

 

https://www.perseverancenb.com/post/how-to-measure-the-calorifier

 

To speed up water heating from both generator and diesel boiler (both can put out more than 10kW) I'm having a custom calorifier made by coppercylinder.co.uk which has two large-area finned coils rated at 5kW each (and extra-thick 60mm lagging to keep it hot overnight). These are probably too big for a Thermotop C, but they'll do any size you want. The only problem is -- of course! -- the cost, over £1000 for mine... 😞

Edited January 27, 2023 by IanD

[ditchcrawler]

2 hours ago, Loddon said:

20Ah is 6% of my nominal battery capacity hardly a problem when the overnight capacity is only down to 89%🤔

As it happens I shower in the evening when the water is hot from our days boating😱 

We shower in the morning and its still hot from the days before boating but this of course assumes you go boating.

1 hour ago, Tracy D'arth said:

 

 

 

 

These are not suitable for a boat with a positive pressure pump, they are sold as vented i.e. open vent domestic hot water systems operating at very low pressure.

I got the pee taken when I pointed that out

[David Mack]

45 minutes ago, ditchcrawler said:

We shower in the morning and its still hot from the days before boating but this of course assumes you go boating.

And also assumes your calorifier is well insulated, and preferably located in a warmish cabin rather than a freezing engine space.

[ditchcrawler]

16 minutes ago, David Mack said:

And also assumes your calorifier is well insulated, and preferably located in a warmish cabin rather than a freezing engine space.

In the warm yes, well insulated, not as good as it could be. I really should get a can of spray foam.

[GUMPY]

4 hours ago, ditchcrawler said:

We shower in the morning and its still hot from the days before boating but this of course assumes you go boating.

You haven't had to deal with the amount of hot water C uses when washing up cold water doesn't get a look in 

[blackrose]

On 26/01/2023 at 19:38, Colin Brendan said:

 

B: Allow the Webasto to run in summer without rads for 30 mins without short cycling (I will stick a rad on if I have to but would prefer not).

 

Personally I'd run a webasto for at least an hour before switching off. They don't like being run for short periods, so perhaps a bigger calorifier would be better.

Edited January 27, 2023 by blackrose

[ditchcrawler]

22 minutes ago, Loddon said:

You haven't had to deal with the amount of hot water C uses when washing up cold water doesn't get a look in 

I do the washing up in the evening on the boat she does all the cooking etc.

[Colin Brendan]

7 hours ago, ditchcrawler said:

We shower in the morning and its still hot from the days before boating but this of course assumes you go boating.

I got the pee taken when I pointed that out

I'm sorry - I don't understand what you mean by 'this assumes you go boating'? Could you explain?

[Colin Brendan]

2 hours ago, blackrose said:

 

Personally I'd run a webasto for at least an hour before switching off. They don't like being run for short periods, so perhaps a bigger calorifier would be better.

Good to know - how big is your webasto and how big/what brand is your calorifier, and do you leave a rad on in summer?

Edited January 27, 2023 by Colin Brendan

[magnetman]

9 hours ago, Colin Brendan said:

I'm sorry - I don't understand what you mean by 'this assumes you go boating'? Could you explain?

 

He is referring to the engine cooling circuit heating the calorifier. If you are someone who moves the boat every day (going boating) then provided you have a well insulated calorifier you will virtually always have hot water as a byproduct of using the engine a lot. 

 

If on the other hand you like to stay moored and only move occasionally then this byproduct of engine running is less available. 

 

Lots of different types of boat owners about. Of course winter does change the story somewhat but you did refer to using a Webasto to get hot water in summer. 

 

Presumably this is on a non grid connected boat. If it was connected to shore electricity then perhaps an immersion heater would be better. 

 

 

 

[blackrose]

9 hours ago, Colin Brendan said:

Good to know - how big is your webasto and how big/what brand is your calorifier, and do you leave a rad on in summer?

 

My Webasto is the Thermotop 5 kW. My calorifier is 60 litres but I've no idea what make as it was already on my boat when I bought it.

 

I can get hot water after about half an hour with the Webasto on, but I think that's just water at the top of the (vertical) calorifier, I think it takes an hour to heat it fully. I run mine with 4 x 2000 btu rads. In summer I won't use the Webasto and I'll use my instant gas water heater now that expensive shore power isn't a good option.

 

If I were doing it from scratch I'd fit a 100 litre calorifier if one was available, also in your situation without rads perhaps you could run a webasto with a larger calorifier for an hour without it cycling down and coking up. You basically need to roughly match the kW output of the Webasto with the kW output of whatever it's heating including pipe runs. If the heat has nowhere to go the antifreeze/coolant in the system returns to the webasto hot and that's when it cycles down and cokes itself up. They like to be run hard. 

Edited January 28, 2023 by blackrose

[magnetman]

I wonder if one could put a pwm speed controller on the Webasto water pump and slow down the flow rate to get more heat into the calorifier and stop the Webasto cutting to the lower power setting too quickly. 

 

It might have the opposite effect. I had a Mikuni but I can't remember if the water pump speed was varied by the control unit. 

 

I think the pump speed might have been constant whereas the air fan and fuel injection speed were varied. 

[David Mack]

34 minutes ago, magnetman said:

I wonder if one could put a pwm speed controller on the Webasto water pump and slow down the flow rate to get more heat into the calorifier and stop the Webasto cutting to the lower power setting too quickly. 

Won't make any difference. If the water flow is slower not only will the circulating water spend longer in the calorifier giving up its heat, but it will also spend longer in the webasto being heated up. Which means it will be hotter leaving the webasto, and the internal thermostat will cut to the lower power setting.

Edited January 28, 2023 by David Mack

[ditchcrawler]

11 hours ago, Colin Brendan said:

I'm sorry - I don't understand what you mean by 'this assumes you go boating'? Could you explain?

I go boating, ie, the boat moves for a few hours every day so the calorifier is reheated every day.

[Colin Brendan]

On 28/01/2023 at 10:28, ditchcrawler said:

I go boating, ie, the boat moves for a few hours every day so the calorifier is reheated every day.

I live on the boat so moving it every day of the year would be a bit impractical tbh - I don't want to have to move the boat just to get a shower really... unless that is what you are suggesting? For a moment there I thought this was one of those passive aggressive posts about different lifestyles and 'proper' boating - but glad we cleared this up - wouldn't want to derail my honest question with that nonsense!

[GUMPY]

1 hour ago, Colin Brendan said:

I live on the boat so moving it every day of the year would be a bit impractical tbh - I don't want to have to move the boat just to get a shower really... unless that is what you are suggesting? For a moment there I thought this was one of those passive aggressive posts about different lifestyles and 'proper' boating - but glad we cleared this up - wouldn't want to derail my honest question with that nonsense!

So you're a towpath shuffler then

Edited January 29, 2023 by Loddon

[Tony Brooks]

I guess the need to shower in the morning after no more than 30 minutes means that the OP has the wrong boat. As someone earlier said, a decent instant gas water heater (with change over valving) would tick all the boxes performance wise, but may be a bit cool in the depths of winter. Otherwise, I think that a large vertical calorifier may well do the job because the top will get hot from a Webasto in half an hour, but how far down the cylinder the usable hot water will reach is pen to question, so it may have to be a short or tepid shower.

[MtB]

2 hours ago, Colin Brendan said:

I live on the boat so moving it every day of the year would be a bit impractical tbh - I don't want to have to move the boat just to get a shower really... unless that is what you are suggesting? For a moment there I thought this was one of those passive aggressive posts about different lifestyles and 'proper' boating - but glad we cleared this up - wouldn't want to derail my honest question with that nonsense!

 

Ah yes, the canals were built for housing. I forgot. 

 

 

[Guest]

24 minutes ago, MtB said:

 

Ah yes, the canals were built for housing. I forgot. 

 

 

 

Actually they were. So working on the canals could be combined with living on them.

🙄🙄

 

[David Mack]

2 hours ago, M_JG said:

 

Actually they were. So working on the canals could be combined with living on them.

🙄🙄

 

That's how it worked out in the later days of carrying, but when the canals were built I think far more boatmen had homes on the land.

[Colin Brendan]

Wow - there's a lot of judgement going on here without anyone really knowing me or what I do! What a friendly community! Mods - you must be proud of this environment that seems to encourage such a discriminatory and tbh bullying attitude! Who would have thought I only came on here to ask a question about Calorifiers!

 

[ditchcrawler]

5 minutes ago, Colin Brendan said:

Wow - there's a lot of judgement going on here without anyone really knowing me or what I do! What a friendly community! Mods - you must be proud of this environment that seems to encourage such a discriminatory and tbh bullying attitude! Who would have thought I only came on here to ask a question about Calorifiers!

 

And you received advice, how you boat effects how your water is heated, no one has said you are right or you are wrong in what you do.

[Colin Brendan]

36 minutes ago, ditchcrawler said:

And you received advice, how you boat effects how your water is heated, no one has said you are right or you are wrong in what you do.

Really

 

On 29/01/2023 at 20:54, Loddon said:

So you're a towpath shuffler then

Let's be real here - not exactly neutral language

 

On 29/01/2023 at 21:29, MtB said:

 

Ah yes, the canals were built for housing. I forgot. 

 

 

followed by a bit aggressive sarcasm after judging me (and obviously finding me wanting!) And it all started because you couldn't help turn my rather non-offensive question into an opportunity to assert your dislike of anyone who doesn't conform with your idea of propriety with this comment below - what a lovely bunch! And despite whatever you may believe you still don't really know anything about me and how I live on or use my boat. You should be very proud. 

 

On 27/01/2023 at 15:42, ditchcrawler said:

We shower in the morning and its still hot from the days before boating but this of course assumes you go boating.

I got the pee taken when I pointed that out