Jump to content

Logic/sense check please Webasto Thermo top C


Featured Posts

Hi

i think this makes sense but wanted to just sense check it with other experienced bods please…

 

I have a Webasto thermo top C, which is rated at 2.5-5kW output. Currently connected to 3 x single panel rads with total rating 1.2kW and a redundant calorifier which is not connected to anything and is just taking up space in my engine bay. 
 

I want to disconnect the calorifier from the circuit, and replace the single panel rads with double panel rads total 2.5kW for the three rads. 
 

That’s ok in my mind, does it also sound ok to the hive mind or am I missing something? I know I’ve asked similar on here before so don’t slam me for asking again, just wanted a final sense check before I spend the £ on the rads. Thanks everyone 

Link to comment
Share on other sites

My understanding is that once a cauliflower is up to temperature, it is absorbing minimal heat from the heat source, the Webasto in your case. It is insulated, holding in the heat you have put in, so the circulating heater water going out the coil inside is at the same temperature as that going in. You don't include it in the load calculation. Just tot up the capacity of the radiators, as they are actually putting significant heat in to the boat and see how it compares with the output from the Webasto.

Link to comment
Share on other sites

Just now, Jen-in-Wellies said:

My understanding is that once a cauliflower is up to temperature, it is absorbing minimal heat from the heat source, the Webasto in your case. It is insulated, holding in the heat you have put in, so the circulating heater water going out the coil inside is at the same temperature as that going in. You don't include it in the load calculation. Just tot up the capacity of the radiators, as they are actually putting significant heat in to the boat and see how it compares with the output from the Webasto.

Interesting, so in theory I could make the change without even having to faff about removing the calorifier? 

Link to comment
Share on other sites

Just now, Balloon said:

Interesting, so in theory I could make the change without even having to faff about removing the calorifier? 

Yes. However, if it has water in it, it could slow the radiators heating the boat, depending on how it is plumbed. If it is empty, then vibration when the engine is running could fatigue crack the internal coil, leading to the circulating coolant being lost. Better to remove it. Marine calorifiers have thicker copper, or stainless steel, than most domestic ones, so there is scrap value there. Or it could be sold to another boater for their use.

Jen

Link to comment
Share on other sites

I would try and keep the calorifier if at all possible, especially if it can be connected to the engine circuit and/or has an immersion fitted. Even if it means fitting some kinda valve to isolate it from the webasto 

 

When your webasto thing packs up, it will be a great backup. 

 

Redundancy on a boat is a great thing. 

 

MtB. Will be along shortly to correct me. He normally does. 

Edited by rusty69
Link to comment
Share on other sites

Just now, rusty69 said:

I would try and keep the calorifier if at all possible, especially if it can be connected to the engine circuit and/or has an immersion fitted. 

 

When your webasto thing packs up, it will be a great backup. 

 

Redundancy on a boat is a great thing. 

 

MtB. Will be along shortly to correct me. He normally does. 

Thanks both. The calorifier is present from a previous boat layout. It would be incredibly difficult to connect it to the current layout. The domestic water plumbing goes nowhere near it now. This making it entirely redundant. 
 

I agree with the redundancy concept. We also have a solid fuel stove for heating which is usually our main source. I’m trying to make the radiators a more robust heating option for when my 11 year old is home alone as I don’t want her lighting the stove just yet. 

Link to comment
Share on other sites

The basic rule of thumb with these diesel heaters is that they need to be run hard. That means ideally you should be trying to match the radiator output to the maximum kW output of the heater, in your case 5kW. If you don't the issue is that the circulating water returns to the heater still hot, the heater then cycles down and gets coked up requiring more frequent servicing. 

 

There are other types of heat exchangers if you don't have space for more radiators, or as your were originally saying change them for double panel rads. Take the thermostatic radiator valves off the rads if you have them. They don't help. 

Edited by blackrose
Link to comment
Share on other sites

But if the old 1.2kW of radiators was sufficient to heat the boat, and you are now going to fit 2.5kW of radiators, then either you are going to have to leave all the doors and windows open and waste expensive fuel, or the webasto will still be cycling so that it is only on for about 50% of the time.

Link to comment
Share on other sites

8 hours ago, ditchcrawler said:

I haven't got a clue what your previous thread was, maybe a link to it would give a clue what you are planning

It was basically just this one, but with fewer specifics. I don’t think it’s particularly illuminating

7 hours ago, blackrose said:

The basic rule of thumb with these diesel heaters is that they need to be run hard. That means ideally you should be trying to match the radiator output to the maximum kW output of the heater, in your case 5kW. If you don't the issue is that the circulating water returns to the heater still hot, the heater then cycles down and gets coked up requiring more frequent servicing. 

 

There are other types of heat exchangers if you don't have space for more radiators, or as your were originally saying change them for double panel rads. Take the thermostatic radiator valves off the rads if you have them. They don't help. 

I was aware of the getting coked up issue, and glad to hear that I can go all out with the radiators. I wasn’t sure how much I should account for the calorifier but good to hear from Jen that I can basically disregard it. I’m also going to be exchanging the TRVs for regular valves when I make the swap of the rads. 

2 hours ago, David Mack said:

But if the old 1.2kW of radiators was sufficient to heat the boat, and you are now going to fit 2.5kW of radiators, then either you are going to have to leave all the doors and windows open and waste expensive fuel, or the webasto will still be cycling so that it is only on for about 50% of the time.

The old radiators were only sufficient to top up the heat output from the stove, which is at the other end of the boat. I want to be able to get the boat reasonably warm with just the radiators, without the stove, so that when my 11 year old daughter is home alone after school this winter (she wasn’t last winter), she will be warm enough without having to light the fire. I don’t want her lighting the fire alone just yet. When I’m home and the stove is lit we probably won’t have the radiators on. 

Link to comment
Share on other sites

2 hours ago, Balloon said:

I’m also going to be exchanging the TRVs for regular valves when I make the swap of the rads

There's a lot of good stuff on this forum re Webasto Thermotop C. Use the search.  I didn't fit any valves to my 5Kw of rads and the system worked well.

Link to comment
Share on other sites

Like hot air balloon 

and knackered from carrying big heavy double panel radiators in the humid weather 

Just now, rusty69 said:

Are you high balloon? 

 

3 minutes ago, Balloon said:

Thanks all for your advice. All seems to be working well! Now to get down from my glycol antifreeze fume induced high…

 

8A806AF6-98C6-454F-99D9-EB3DD593BE09.jpeg

  • Haha 1
Link to comment
Share on other sites

6 minutes ago, Balloon said:

Like hot air balloon 

and knackered from carrying big heavy double panel radiators in the humid weather 

 

 

8A806AF6-98C6-454F-99D9-EB3DD593BE09.jpeg

I'm not surprised you're hot air balloon if you have been testing the heat output of those rads. 

 

Looks good though. 

Edited by rusty69
Link to comment
Share on other sites

1 minute ago, rusty69 said:

I'm not surprised your hot air balloon if you're have been testing the heat output of those rads. 

 

Looks good though. 

I put it on for 20 mins with all the hatches open just to check everything was tickety  boo

Link to comment
Share on other sites

1 hour ago, system 4-50 said:

I wanted to see his pipework, not his plumbing!  

 

Is it still only one rad?

I’m a she 😝 and I have three rads but a bit dull to show them all. They look the same as one another. 
 

what aspect of my pipework are you interested in? You probably won’t like it. It’s 15mm plastic speedfit. But it’s what was there when I got the boat and I’m not changing it now

Link to comment
Share on other sites

19 minutes ago, Balloon said:

I’m a she 😝 and I have three rads but a bit dull to show them all. They look the same as one another. 
 

what aspect of my pipework are you interested in? You probably won’t like it. It’s 15mm plastic speedfit. But it’s what was there when I got the boat and I’m not changing it now

My likes & dislikes are unimportant, it is what matters to you that counts!  My interest is in how you have connected the pipework to the rads wrt valves & pipe expansion as per:

https://www.canalworld.net/forums/index.php?/topic/105439-webasto-central-heating/#comment-2440293

and I'm just nosey!

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.