Webasto Top C

[Matt R]

 My heating system is a Webasto Thermo Top C, it runs x2 radiators and x1 towel rack (rad)... System uses a 50/50 mixture of antifreeze & water to run through the rads. The system is connected also to a colirifier to heat water... Currently my webasto was reconditioned as the inner burner was clogged with burnt fuel. Im guessing when the boat was taken from the water it drew dirty fuel from the bottom of the tank. Webasto has been reinstalled by myself in the engine bay, all pipe work is 22mm with 15mm T offs to rads so within recommended frame work. Webasto turns over using when using control unit an fires up, inline fuel pump seems to work... Could feel coolant/water circulation through pipe work to unit. Webasto goes through start up process makes all usual noises but eventually sounds strange. Slight smoke from unit near exhaust and unit gets hot as hell. I dont trust leaving it on in this state. Even bled rads and air seems to be released. Right now i am confused with the whole set up and dont undertand why it is not working. 

I thought could be electrical related issue but usually a webasto would not even fire up if it doesn't receive its 12v's so again this is why I'm stumped... Any ideas or know anyone good with these systems? Getting to winter soon and would be nice to have the rads working 

[Tonka]

Which part of the country are you?

[Matt R]

Staffordshire, penkridge to be exact

[Matt R]

Why

[Tonka]

Evesham Marine do webasto servicing but not sure if they will go to Penkridge

[Tracy D'arth]

Air lock in the pipework stopping circulation.  Or a valve closed when it was removed and not opened.

Edited September 13, 2023 by Tracy D'arth

[Matt R]

Any idea how to loose a potential airlock in the system? Im not a plumber, lol. And value, what kind of valve are we talking about... I didnt switch any value while removing the unit for refurbishment purposes... Only thing switched was the fuel line off so didn't leak diesel everywhere... 🫡

[Tonka]

Just now, Matt R said:

Any idea how to loose a potential airlock in the system? Im not a plumber, lol. And value, what kind of valve are we talking about... I didnt switch any value while removing the unit for refurbishment purposes... Only thing switched was the fuel line off so didn't leak diesel everywhere... 🫡

Did you drain the pipework before removing unit

[Matt R]

Yes i drained all but the radiators

[Tracy D'arth]

50% antifreeze is too strong, it does not take away the heat as well as 30% concentration. Sounds illogical but it is true.

[Matt R]

Hmmm, okay well im guessing its not quite 50 50 anyway as i only topped up last time in the header tank with a mixture of 50 50.. Whatever was in the system already... Mainly water i assume... I would say its more like 60, 40 in essence... Cant be 100% but when i drained it off the mixture was not dark blue... Lighter shade... Anywayz.. Real annoying

[cuthound]

6 hours ago, Matt R said:

 My heating system is a Webasto Thermo Top C, it runs x2 radiators and x1 towel rack (rad)... System uses a 50/50 mixture of antifreeze & water to run through the rads. The system is connected also to a colirifier to heat water... Currently my webasto was reconditioned as the inner burner was clogged with burnt fuel. Im guessing when the boat was taken from the water it drew dirty fuel from the bottom of the tank. Webasto has been reinstalled by myself in the engine bay, all pipe work is 22mm with 15mm T offs to rads so within recommended frame work. Webasto turns over using when using control unit an fires up, inline fuel pump seems to work... Could feel coolant/water circulation through pipe work to unit. Webasto goes through start up process makes all usual noises but eventually sounds strange. Slight smoke from unit near exhaust and unit gets hot as hell. I dont trust leaving it on in this state. Even bled rads and air seems to be released. Right now i am confused with the whole set up and dont undertand why it is not working. 

I thought could be electrical related issue but usually a webasto would not even fire up if it doesn't receive its 12v's so again this is why I'm stumped... Any ideas or know anyone good with these systems? Getting to winter soon and would be nice to have the rads working 

 

When I filled Webasto central heating with a 50/50 mix of water and antifreeze, I found the radiators wouldn't heat up.

 

I diluted the mix to 25% antifreeze/75% water and the radiators immediately got hot.

[Matt R]

Webasto serviced again, Coolant good mixture, pipes all connected as should, webasto bled, rads bled, fuel pumping, webasto in out water/coolant pipes rearranged aswell as webasto repositioned. Still smoke on start up this time from top of air intake tube connected to webasto... Any ideas 

[Midnight]

Probably an air lock. Happened to me. I disconnected one of the pipes that connects to the unit and bled it that way.

 

 

 

Edited September 23, 2023 by Midnight

[Tractor]

The water pipe feeding the rads, not the pipe connected to the pump, slip this of slightly until you get a slight spill of water, and push back, secure with hose clip.

If header is up to level, this ensures no air in the heat exchanger.

 

[Tracy D'arth]

When I fit diesel heaters I incline them otherwise there is an air bubble in the heat exchanger that is tricky to remove.

[RAP]

Interesting? Any pics of your inclined intstalls?

[Tracy D'arth]

27 minutes ago, RAP said:

Interesting? Any pics of your inclined intstalls?

Sorry,no.

[blackrose]

9 hours ago, Midnight said:

 I disconnected one of the pipes that connects to the unit and bled it that way.

 

 

 

 

I bled mine the same way.

On 13/09/2023 at 13:39, Matt R said:

 My heating system is a Webasto Thermo Top C, it runs x2 radiators and x1 towel rack (rad)...

 

Currently my webasto was reconditioned as the inner burner was clogged with burnt fuel. 

 

I think the Thermotop C is a 5kW heater. Do your 2x rads & towel rack + pipework roughly add up to 5kW? They'd have to be pretty big rads. Balancing heater output with radiator output is what you should be trying to achieve in the installation, otherwise if the rads are significantly less then the coolant ends up returning to the heater warm or hot and the heater starts to cycle down and the burner gets coked up. Webastos need to be run hard.

 

Could this be why it was clogged up last time?

 

Don't include the calorifier in your kW output calculation because once it's hot it's no longer taking any of that 5kW heat from the boiler.

 

Also if your rads have thermostatic valves get rid of them. They just unscrew. They don't help because they shut the radiator off when the room gets warm leading to the same effect on the boiler as not having enough rads.

Edited September 23, 2023 by blackrose