webasto working?

[sthomasj]

I have got a 57 foot narrowboat the heating if via a solid fuel burner and also a webasto thermo c . There are three radiators and a califier in the system . If i try to use the webasto to heat the water it is only luke warm the radiator in toilet does sort of get warm. (the califier and this radiator are on the same loop) . The radiator in the back cabin sort of gets half warm and the radiator in the front saloon never gets warm. If the engine has been running the radiator temperature does improve. I have tried bleeding the system , the webasto runs ok . Is the heater just not up to the job or could I improve its perfomance some how ? I have not run it much and its less than 6 months old.

[chris w]

Check the water pump on the Webasto is working correctly.

 

I developed the same problem as you and discovered a ball of white plastic swarf in the water pump. I deduced it had come from the original installation of the header tank when the boat builder idiotically allowed the swarf, from drilling the white plastic header tank for fittings, to fall into the tank where it eventually made its way into the water pump.

 

I removed the swarf and all the radiators and the calorifier became piping hot again.

 

Chris

[robkg]

I have got a 57 foot narrowboat the heating if via a solid fuel burner and also a webasto thermo c . There are three radiators and a califier in the system . If i try to use the webasto to heat the water it is only luke warm the radiator in toilet does sort of get warm. (the califier and this radiator are on the same loop) . The radiator in the back cabin sort of gets half warm and the radiator in the front saloon never gets warm. If the engine has been running the radiator temperature does improve. I have tried bleeding the system , the webasto runs ok . Is the heater just not up to the job or could I improve its perfomance some how ? I have not run it much and its less than 6 months old.

Hi,

 

There could be a variety of plumbing faults that could be contributing to your described symptoms. However I can suggest a couple of pointers.

 

Firstly, the water circulation pumps fitted to the heaters are very puny and will not give sufficient flow if there are more than a few elbows, isolation valves or other restrictions in the circuit.

Also the main loop needs to be 22mm copper, not 15mm. If necessary you could try fitting an external secondary pump to boost the flow.

(in my case the installation manuals failed to inform me of these requirements)

 

Are you sure that your rads and calorifier are balanced? i.e. is all the hot water taking a short cut, (e.g. through the engine block) missing out most of the items in the circuit.

 

In my experience I found the outlet temp. of the thermotop C to be disappointingly low (around 65^oC). This is significantly lower than my house central heating.

So your rads will never get blisteringly hot.

 

Good Luck

 

(As a Webasto owner you'll need it!)

[chris w]

In my experience I found the outlet temp. of the thermotop C to be disappointingly low (around 65^oC). This is significantly lower than my house central heating.

So your rads will never get blisteringly hot.

 

Good Luck

 

(As a Webasto owner you'll need it!)

If your Webasto is only outputting at 65degC, it has a fault. The software directs the water temperature to rise to 76degC and then the Webasto idles (ie: water pump but no heat) till the water temp drops to 66degC at which point the Webasto comes on at half power until the water reaches 76degC again at which point the cycle repeats. If an additional load is put on the Webasto which causes the water temp to drop to 56degC, the Webasto comes on at full power till the water temp reaches 66degC at which point it switches to half power... and so as above.

 

My rads do get blisteringly hot.... too hot to put one's hand on them for more than an instant.

 

Chris

[MIKE P]

Ditto

[sthomasj]

Hi,

 

There could be a variety of plumbing faults that could be contributing to your described symptoms. However I can suggest a couple of pointers.

 

Firstly, the water circulation pumps fitted to the heaters are very puny and will not give sufficient flow if there are more than a few elbows, isolation valves or other restrictions in the circuit.

Also the main loop needs to be 22mm copper, not 15mm. If necessary you could try fitting an external secondary pump to boost the flow.

(in my case the installation manuals failed to inform me of these requirements)

 

Are you sure that your rads and calorifier are balanced? i.e. is all the hot water taking a short cut, (e.g. through the engine block) missing out most of the items in the circuit.

 

In my experience I found the outlet temp. of the thermotop C to be disappointingly low (around 65^oC). This is significantly lower than my house central heating.

So your rads will never get blisteringly hot.

 

Good Luck

 

(As a Webasto owner you'll need it!)

 

 

Ok bled all the radiators and removed the out let pipe from the webasto and blue liquid just flowed out.(how long should i have done this for to remove any airlocks?). If it was not balanced between the calorfier and the other two radiators i would still have either hot water or radiators?). The unit is quit hot to touch but nothing else is!

 

Ok bled all the radiators and removed the out let pipe from the webasto and blue liquid just flowed out.(how long should i have done this for to remove any airlocks?). If it was not balanced between the calorfier and the other two radiators i would still have either hot water or radiators?). The unit is quit hot to touch but nothing else is!

[sthomasj]

Hi,

 

There could be a variety of plumbing faults that could be contributing to your described symptoms. However I can suggest a couple of pointers.

 

Firstly, the water circulation pumps fitted to the heaters are very puny and will not give sufficient flow if there are more than a few elbows, isolation valves or other restrictions in the circuit.

Also the main loop needs to be 22mm copper, not 15mm. If necessary you could try fitting an external secondary pump to boost the flow.

(in my case the installation manuals failed to inform me of these requirements)

 

Are you sure that your rads and calorifier are balanced? i.e. is all the hot water taking a short cut, (e.g. through the engine block) missing out most of the items in the circuit.

 

In my experience I found the outlet temp. of the thermotop C to be disappointingly low (around 65^oC). This is significantly lower than my house central heating.

So your rads will never get blisteringly hot.

 

Good Luck

 

(As a Webasto owner you'll need it!)

 

 

just thought did open all valves to max. How do I balance the system?

[chris w]

just thought did open all valves to max. How do I balance the system?

Did you dismantle the water pump for a blockage, as I suggested, while you had the hoses off? I doubt it's an airlock.

 

I don't bother balancing mine - the rads have TRV's, except the bathroom, but I leave all the rads on full.

 

To clear the system of any air, take the Webasto water pump's outlet hose off and switch on the Webasto. You should get a large surge of water after a second at which point you quickly push the hose back on to the water pump.

 

Chris

[robkg]

If your Webasto is only outputting at 65degC, it has a fault. The software directs the water temperature to rise to 76degC and then the Webasto idles (ie: water pump but no heat) till the water temp drops to 66degC at which point the Webasto comes on at half power until the water reaches 76degC again at which point the cycle repeats. If an additional load is put on the Webasto which causes the water temp to drop to 56degC, the Webasto comes on at full power till the water temp reaches 66degC at which point it switches to half power... and so as above.

 

My rads do get blisteringly hot.... too hot to put one's hand on them for more than an instant.

 

Chris

Hi Chris,

In repying to your post I am getting a distinct deja vu feeling.

I don't disagree that your description may be how yours functions, but with a different load on the heater it may behave slightly differently.

From start up:

full power until return water reaches 66degC

Heater switches to half power.

On a small load (e.g. one radiator) return water will continue to rise to 76degC at which point burner will switch off leaving circulation only.

On a larger load (5 rads in my case) then half power (2.5kW) will result in return water cooling very gradually. (rads dissipating more than 2.5kW of heat)

Eventually the return water temp. falls to 56degC at which point the heater switches to full power.

 

To summarise my heater would run continuously between 56degC and 66degC, switching between half and full power.

 

My heater categorically performed in the way I have described above. Yours may have a different logic.

 

I don't think it makes any difference, but mine was a thermotop C 24 volt.

 

Incidentally two main dealers and Webasto UK all tested my heater and none could diagnose the cause of a fault.

 

As you probably have read in other posts, due to continuous failure to function correctly I was eventually refunded my money plus costs by the dealer who sold

it to me three years earlier

[Nickhlx]

Hi Chris,

In repying to your post I am getting a distinct deja vu feeling.

I don't disagree that your description may be how yours functions, but with a different load on the heater it may behave slightly differently.

From start up:

full power until return water reaches 66degC

Heater switches to half power.

On a small load (e.g. one radiator) return water will continue to rise to 76degC at which point burner will switch off leaving circulation only.

On a larger load (5 rads in my case) then half power (2.5kW) will result in return water cooling very gradually. (rads dissipating more than 2.5kW of heat)

Eventually the return water temp. falls to 56degC at which point the heater switches to full power.

 

To summarise my heater would run continuously between 56degC and 66degC, switching between half and full power.

 

My heater categorically performed in the way I have described above. Yours may have a different logic.

 

I don't think it makes any difference, but mine was a thermotop C 24 volt.

 

Incidentally two main dealers and Webasto UK all tested my heater and none could diagnose the cause of a fault.

 

As you probably have read in other posts, due to continuous failure to function correctly I was eventually refunded my money plus costs by the dealer who sold

it to me three years earlier

#

 

If the return was not getting above 66 deg C surely the radiators were dissipating more than 5 kW, at 66 degC, preventing any further rise assuming the output of the Webasto was 5kW at that temp, or slightly less than 2.5 kW,

thereby allowing it to get to 66 deg C, but the Webasto thinking it had reached temp, shut itself back. ? Perhaps a faulty temp sensor in Webasto ? I would have thought that was easy to find though...

 

Nick

[chris w]

Hi Chris,

In repying to your post I am getting a distinct deja vu feeling.

I don't disagree that your description may be how yours functions, but with a different load on the heater it may behave slightly differently.

From start up:

full power until return water reaches 66degC

Heater switches to half power.

On a small load (e.g. one radiator) return water will continue to rise to 76degC at which point burner will switch off leaving circulation only.

On a larger load (5 rads in my case) then half power (2.5kW) will result in return water cooling very gradually. (rads dissipating more than 2.5kW of heat)

Eventually the return water temp. falls to 56degC at which point the heater switches to full power.

 

To summarise my heater would run continuously between 56degC and 66degC, switching between half and full power.

 

My heater categorically performed in the way I have described above. Yours may have a different logic.

 

I don't think it makes any difference, but mine was a thermotop C 24 volt.

 

Incidentally two main dealers and Webasto UK all tested my heater and none could diagnose the cause of a fault.

 

As you probably have read in other posts, due to continuous failure to function correctly I was eventually refunded my money plus costs by the dealer who sold

it to me three years earlier

I have the Webasto ThermoTop C 12v model. I don't have 5 radiators like you, but I do have 3 rads plus a calorifier and my radiators get so hot that it is impossible to touch them for more than a moment. My temperature switching points are as I stated, which correlates with the workshop manual. Did you ever experiment by turning off any rads to see if that made a significant difference?

 

Chris

[robkg]

#

 

If the return was not getting above 66 deg C surely the radiators were dissipating more than 5 kW, at 66 degC, preventing any further rise assuming the output of the Webasto was 5kW at that temp, or slightly less than 2.5 kW,

thereby allowing it to get to 66 deg C, but the Webasto thinking it had reached temp, shut itself back. ? Perhaps a faulty temp sensor in Webasto ? I would have thought that was easy to find though...

 

Nick

Hi Nick,

 

With the heater running at full power (5kW) the return water would gradually increase in temp. i.e. rads were dissipating less than 5kW.

But as the return water reached 66 degC, the heater would switch down to half heat mode (2.5kW). The return water would then gradually cool

suggesting that the rads were dissipating more than 2.5kW.

 

Should this cycle be incorrect for a Thermotop C then I agree, it should be easy for either a main dealer or the manufacturers to acertain but they both maintained the unit was faultless.

It took another (non inland waterways) Webasto main dealer to discover that the unit had a fault (repeated erroneous flame failure cut outs) although he was unable to determine the cause.

 

 

 

I have the Webasto ThermoTop C 12v model. I don't have 5 radiators like you, but I do have 3 rads plus a calorifier and my radiators get so hot that it is impossible to touch them for more than a moment. My temperature switching points are as I stated, which correlates with the workshop manual. Did you ever experiment by turning off any rads to see if that made a significant difference?

 

Chris

Hi Chris,

In answer to your question, yes I did run the heater on one rad. only. Under those conditions the heater behaved differently.

i.e. Full heat up to 66 degC, switch down to half heat but water temp. continues to rise up to 76 degC, at which point heater switched down to circulation only.

Water then cools to 56 degC when burner would fire back up on full heat. And cycle began again.

[chris w]

Hi Chris,

In answer to your question, yes I did run the heater on one rad. only. Under those conditions the heater behaved differently.

i.e. Full heat up to 66 degC, switch down to half heat but water temp. continues to rise up to 76 degC, at which point heater switched down to circulation only.

Water then cools to 56 degC when burner would fire back up on full heat. And cycle began again.

That last bit is not correct operation. Once the heater enters its idle mode @ 76degC, it cools to 66degC at which point it switches back on at HALF power and the temperature rises to 76degC again at which point it idles back down to 66degC and so on.

 

The heater will only cool to 56degC (and hence come on at FULL power again) if a large cooling load is put on the system, such as opening a cold radiator valve.

 

Chris

[robkg]

That last bit is not correct operation.  Once the heater enters its idle mode @ 76degC, it cools to 66degC at which point it switches back on at HALF power and the temperature rises to 76degC again at which point it idles back down to 66degC and so on.The heater will only cool to 56degC (and hence come on at FULL power again) if a large cooling load is put on the system, such as opening a cold radiator valve.Chris

Hi Chris,

 

The heater will only cool to 56degC (and hence come on at FULL power again) if a large cooling load is put on the system, such as opening a cold radiator valve.

 

Categorically NOT in my case.

 

Your information is very interesting. 

Does your heater often (or ever) switch from half power to full power?  It was when doing this that the glow pin/flame sensor on my heater used to cool sufficiently to cause the control software to incorrectly think that the flame had extinguished and consequently shut the heater off.  This would occur approximately once per hour throughout the time I had the heater (from new).

Edited February 16, 2009 by robkg

[chris w]

Hi Chris,

 

The heater will only cool to 56degC (and hence come on at FULL power again) if a large cooling load is put on the system, such as opening a cold radiator valve.

 

Categorically NOT in my case.

 

Your information is very interesting. 

Does your heater often (or ever) switch from half power to full power?  It was when doing this that the glow pin/flame sensor on my heater used to cool sufficiently to cause the control software to incorrectly think that the flame had extinguished and consequently shut the heater off.  This would occur approximately once per hour throughout the time I had the heater (from new).

My heater NEVER goes into fast mode other than for the first 15-20 minutes of initially switching on OR if I switch off the rads (to heat the calorifier faster) and later switch the rads back on.

 

Chris

[canalchris]

If your Webasto is only outputting at 65degC, it has a fault. The software directs the water temperature to rise to 76degC and then the Webasto idles (ie: water pump but no heat) till the water temp drops to 66degC at which point the Webasto comes on at half power until the water reaches 76degC again at which point the cycle repeats. If an additional load is put on the Webasto which causes the water temp to drop to 56degC, the Webasto comes on at full power till the water temp reaches 66degC at which point it switches to half power... and so as above.

 

My rads do get blisteringly hot.... too hot to put one's hand on them for more than an instant.

 

Chris

Glad to hear of someone else who seems to be happy with webasto, mine has been on the boat four years and runs the same as yours chris.

[chris w]

Glad to hear of someone else who seems to be happy with webasto, mine has been on the boat four years and runs the same as yours chris.

Yep... I service mine once every 6 months and it runs like a dream.

 

Chris

[robkg]

Yep... I service mine once every 6 months and it runs like a dream.

 

Chris

Hi again,

there clearly is a different logic sequence used in our two heaters. My heater when running on circulation only, would always relight and run on full power,

or put another way would never ignite straight in to half power. Although explaining exactly why my heater never functioned correctly is largely academic now I no longer have it,

I still would be interested to find out. The dealer who sold it to me maintained that the sequences my heater went through were impossible and would not accept any evidence to the

contrary.

 

Does anyone know of someone who fundamentally understands these heaters and may be able to shed light on the differences in the software logic.

In my experience this would not include two of the countries main dealers or Webasto UK.

 

The only obvious potential differences are that mine was a 24v unit and I am guessing yours is 12v, or the age of the heaters. Mine was purchased in August 2005.

 

P.S. I apologise to the OP for hijacking this thread.

[tosher]

Yep... I service mine once every 6 months and it runs like a dream.

 

Chris

 

The next time you do it Chris I'm sure many of us Webasto owners would really appreciate a few pictures, I certainly would. Thanks

[chris w]

The next time you do it Chris I'm sure many of us Webasto owners would really appreciate a few pictures, I certainly would. Thanks

I'll do that. I plan to do it again around April time. and I shall happily post some photos.

 

Chris

 

The only obvious potential differences are that mine was a 24v unit and I am guessing yours is 12v, or the age of the heaters. Mine was purchased in August 2005.

 

P.S. I apologise to the OP for hijacking this thread.

Mine is 12v and was fitted at the beginning of 2007 so is now 2 years' old

 

Chris

Edited February 18, 2009 by chris w

[sthomasj]

Just cleaned out my webasto after seeing how easy it was thanks to Chris W (loads and loads of build up). All the rads warmed up for the first time this year ! It did take about 3 hours though but the boat was very cold . When disconnecting the outlet pipe to remove air locks in the unit the flow was by no means gushing out , more of a steady stream. Do you think the fuel pump may be lagging?

[Nickhlx]

Just cleaned out my webasto after seeing how easy it was thanks to Chris W (loads and loads of build up). All the rads warmed up for the first time this year ! It did take about 3 hours though but the boat was very cold . When disconnecting the outlet pipe to remove air locks in the unit the flow was by no means gushing out , more of a steady stream. Do you think the fuel pump may be lagging?

 

 

Chris W did a magnificent write-up for us Webasto fans on servicing and maintenance, and I saved it for future use somewhere... I will try to find it and PM you with it or e-mail if you like - in the meantime, have a search for these words on this forum....

 

Nick

[Canalwatcher]

Chris W did a magnificent write-up for us Webasto fans on servicing and maintenance, and I saved it for future use somewhere... I will try to find it and PM you with it or e-mail if you like - in the meantime, have a search for these words on this forum....

 

Nick

 

It's a pinned topic under "Boat Building and Maintenance"

 

Mick

[Nickhlx]

It's a pinned topic under "Boat Building and Maintenance"

 

Mick

 

 

Thanks for that, Mick - no need to search now

 

 

Nick