Another webasto question!!

[AGlassAct]

Helped install a webasto the other day. All went well and it ‘seemed’ to function check OK. Header tank reached 70 degrees then the webasto went in to slumber mode, heat exchanger was red hot and water coming through it was a steady 40 degrees out of the pressure release valve (fitted a return circuit back into the tank when the univalve is off). Job was a good un’ - so I thought. The report now is the heater is doing it’s warm up and the header tank as it should be, as soon as the the hose reel draws water through the system the webasto header tank loses temperature and is unable to keep up - ultimately the temperature at the brush is 22 degrees maximum. No obvious air locks in the hose reel side of the heat exchanger. Battery voltage good throughout (engine running with VSR/split relay) I’ve got a couple of ideas but want to get other opinions before I jump in with yet another expensive ‘experiment’ to what was meant to be a quick install to help someone out.

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[kevinc250]

it may be as simple as having too much coolant in the stystem, from memory the pump circulates 200ml per second through the burner chamber and should raise the water temp by 7c or so on each pass it makes

if theres too much coolant in the stystem it has to have more passes through the burner to get back to the desired temp.

I think webasto state that the minimum coolant amount is 4 lites that would be the place to look at as it costs nothing to check

 

[AGlassAct]

it may be as simple as having too much coolant in the stystem, from memory the pump circulates 200ml per second through the burner chamber and should raise the water temp by 7c or so on each pass it makes
if theres too much coolant in the stystem it has to have more passes through the burner to get back to the desired temp.
I think webasto state that the minimum coolant amount is 4 lites that would be the place to look at as it costs nothing to check

That’s the kind of answers I need - thinking a bit outside the box. The header tank was quite a big one so I’ll suggest he halves the water to see if it has any affect - cheers (again!) @ Kevinc250


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[kevinc250]

just checked my temps to compare,

after filling the tank temp is 20.9c and heated water back to tank is 27.1 c so you can see theres a temperature rise of 7.2c on each and every pass through the burner, if theres too much coolant in your friends stystem its going to give those symptoms you describe

 

[Pjj]

If it’s any help I have a water temp in my header tank of 48 degrees  with two hose reels  out 100 meters  and it’s 5 degrees air temp 

 

[AGlassAct]

just checked my temps to compare,
after filling the tank temp is 20.9c and heated water back to tank is 27.1 c so you can see theres a temperature rise of 7.2c on each and every pass through the burner, if theres too much coolant in your friends stystem its going to give those symptoms you describe

He’s emptied water out and it’s made no noticeable difference. I’m flummoxed on this one. I compared mine this morning and got better results. My brush temperature was hovering around the 35 degrees mark which I would consider normal. He can’t seem to get his above 22 degrees - that’s with the hose on the reel too!!!


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If it’s any help I have a water temp in my header tank of 48 degrees  with two hose reels  out 100 meters  and it’s 5 degrees air temp 
 

I assume you have the bigger of the two Webasto’s then@pjj. What kind of temperatures do you get at the brush?


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[Pjj]

He’s emptied water out and it’s made no noticeable difference. I’m flummoxed on this one. I compared mine this morning and got better results. My brush temperature was hovering around the 35 degrees mark which I would consider normal. He can’t seem to get his above 22 degrees - that’s with the hose on the reel too!!!


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I assume you have the bigger of the two Webasto’s then@pjj. What kind of temperatures do you get at the brush?


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I have a 9 kw Grippatank one I have just checked the temps header tank 72 degrees both hoses out approx 40 meters at the brush heads temp of 52 degrees, air temperature is 7 degrees 

 

[AGlassAct]

 
I have a 9 kw Grippatank one I have just checked the temps header tank 72 degrees both hoses out approx 40 meters at the brush heads temp of 52 degrees, air temperature is 7 degrees 

Appreciate your effort [mention=2439]pjj[/mention] - that’s pretty much the same as what I get on an average day. Looks this is going to be a query to the technical department. It’s got to be a problem with the heater but have no idea where to start with it!!!

Cheers guys - I’ll put feedback up if I resolve this just in case it ever crops up again.

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[spruce]

Using a Thermo Top C @AGlassAct, the best I could get with that unit on full throttle was 35 degrees at the brush head with 95% of the hose still on the reel. That was a temperature rise from 9 degrees C to 35 degrees C = 26 degrees C. The setting on my Varistream was on 3 which delivers around 1.5lpm of flow through the 2mm jets with cold water. (TBH with warm water the flow through the system increased using the same setting of 3 on the controller, but I never thought to measure the amount of water actually being delivered. It could have been closer to 2lpm for all I know.)

If you reduce the flow to the brush head you will get hotter water provided the Thermostatic regulator valve is set for higher.

But it works the other way as well. The faster the flow of water through the heat exchanger, the lower the temperature will be at the brush head.

 

[AGlassAct]

We tried all that@spruce - the guy has his flow on 30 all the time (which is pretty low) and even when we decreased the flow it made little difference. I didn’t install a thermostatic valve - just a pressure release valve which was set to circulate water back in to the main tank when the feed to the brush was off. My webasto will happily sit at 40 degrees until the battery gives up so I know it’s achievable. I’m now thinking either the burner needs replacing, the unit needs decoking (which I did before we fit it but couldn’t remove a lot of the build up because I didn’t have/know of the appropriate chemicals) or the PCB has a fault. I have emailed technical services but will more than likely get fobbed off to dealers who won’t want to offer constructive advice unless it’s sent to them for repair. The confusing (and frustrating) thing is it’s functioning to the letter - up to the point the secondary circuit is activated (pole) and then it can’t keep up. I would have told the guy to scrap it by now as I really don’t have the time to keep messing about with it - but it’s really bugging me (I need to find a fix otherwise my OCD won’t let up!!).


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[scottish cleaning service]

It seems like a process of elimination by replacing one part at a time to see the fault.

 

[AGlassAct]

It seems like a process of elimination by replacing one part at a time to see the fault.

What a daft comment? I’ll just replace the PCB at £80 - just in case. I’ll just replace the burner assembly at £170 - just in case. I’m all for process of elimination Scottish but I don’t have a store room full of webasto bits to throw at it, plus this whole process is to help assist someone else who doesn’t have the knowledge and technical background to ask the questions himself. If I had the time and the heater was sat in my garage I’d quite happily swap bits over from the two other heaters I have but the obvious route for a broader solution was to ask the knowledgeable experienced webasto users on here first.


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[spruce]

What a daft comment? I’ll just replace the PCB at £80 - just in case. I’ll just replace the burner assembly at £170 - just in case. I’m all for process of elimination Scottish but I don’t have a store room full of webasto bits to throw at it, plus this whole process is to help assist someone else who doesn’t have the knowledge and technical background to ask the questions himself. If I had the time and the heater was sat in my garage I’d quite happily swap bits over from the two other heaters I have but the obvious route for a broader solution was to ask the knowledgeable experienced webasto users on here first.


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Before using the hose reel, your friend needs to run the Webasto through its start up cycle to its shutdown cycle and see what's happening.

Here's a copy of the startup and run procedure from Webasto. He could print this off and tick each phase off as it completes. One of the things we were taught in the motor trade was to always confirm and identify the customer complaint before doing any mechanical repairs.

Functional Description
Switch ON
Upon switching the heater on by the rocker switch or the optional timer, the ceramic igniter pin, the combustion air fan
and the circulation pump are activated.

After 30 seconds the fuel metering (dosing) pump starts operation and combustion air fan operation is suspended for 3 seconds.
Subsequently the combustion air fan speed is increased in two ramps within 56 seconds to nearly full load operation.
After a stabilization phase (constant speed) of 15 seconds the combustion air fan speed is again increased in a ramp
within 50 seconds to nearly full load.
After reaching full load fuel delivery, the ceramic igniter pin is deactivated and the combustion air fan operation is
increased to full load.
During the subsequent 45 seconds as well as in normal operation the ceramic igniter pin functions as a flame sensor to
monitor the flame condition.
Once all these events are completed, the heater begins the automatically controlled heating period of operation.
In case of a no flame condition or a flameout, a restart is automatically initiated. If the no flame condition persists, fuel
delivery is stopped and the heater enters an error lockout with a cool-down of the combustion air fan.
A flameout during normal combustion operation causes an automatic restart.

Heating Operation
When the temperature rises to reach 161° F (72° C) the heater switches to the energy saving part load operation.
A further rise in temperature up to 171° F (77° C) causes the heater to enter a control idle period. This also happens
when exceeding a total heating operating time of 76 minutes.
The circulation pump and the operation indicator light (if equipped) remain on during control idle.
After cool-down of the coolant to 160° F (71° C) the heater resumes part load operation. Another rise in temperature
to 171° F (77° C) causes the heater to enter again the control idle period. A drop in the coolant temperature during
part load operation due to an increased demand in heat will cause the heater to switch to full load operation at 133° F
(56° C).
Should the coolant temperature however not drop within 15 minutes during the control idle period to below 160° F
(71° C), a subsequent drop in the coolant temperature below 160° F (71° C) causes the heater to perform a regular
starting sequence into full load operation.

Switch Off
When turning the heater off the combustion process terminates and cool-down commences. The circulation pump
and the combustion air fan first continue operation to cool the heater down (cool-down) to be automatically switched
off afterwards.

NOTE
The cool-down time and the combustion air fan speed depend on the heater operating condition at the time of deactivation.
Cool-down time is 175 seconds when deactivated in full load operation and 100 seconds when deactivated in part load operation.
Dependent on the software variant implemented in the control unit there might be deviations from those cool-down periods.

If the Webasto is following these processes then its working correctly. If its shutting down prematurely then the issue is inside the unit.

What diesel is your friend using in his heater?

Also, if your friend isn't allowing the Webasto time to heat the internal water circuit up before cleaning then the Webasto is never going to heat up if he starts it and gets on to cleaning straight away. The heater just isn't capable of doing that. (These 'cabby' heaters are sturdy little things and my gut is telling me that this is where to look to solve the problem. It will be an operator issue rather than an issue with the boiler.)

When its used as a parking heater in cold countries, the unit initially runs and warms the engine coolant up to 30 degrees before it activates the internal ventilation fan to defrost the windscreen. If the owner has the vehicles fan on full, then the heater isn't going to raise the coolant temp much above 30 degrees  as the cabin heater matrix and blower will be zapping the heat generated. If the coolant heat drops to below 30 degrees then the Webasto will switch the vehicles heating fan off again.

Depending on where the Webasto is situated, the heat from the exhaust will help to warm the engine bay up.

Another solution is to swap your heater with his and see if this solves the problem. If its the same then the issue is not with the heater.

 

[kevinc250]

I was thinking about this last night and i'm more in agreeance with spruce as it could simply be user error the burners working as it should so the problem must be a minor one,sorry that I can't give a technical answer

 

[Pjj]

If I have read it right you should let it warm up before using it then ??? We turn ours on and use it straight away within 5-8 muinits it’s very hot water that you cannot put your hand under, we have never experienced any of the issues mentioned in this post . I assume that the correct size of heat exchangers are used and it’s a 9kw not a 5 kw ?. 

 

[AGlassAct]

That’s how I always use mine. It’s started up before I go out (either on the pre-programmes timer or I manually go and switch it on) so by the time I’m at the first job the preheat has been done and the secondary circuit is ready to roll. That’s how I showed him how to use it and explained the different phases of the process - we even checked the temperature of the header tank when the unit started to wind down and it was 72 degrees. The unit is doing everything it should - until it’s asked to maintain the heat with the secondary circuit in play.
Road diesel (white as they say) is the only fuel the heater has seen since I’ve been involved - and looking at the combustion chamber photos before a give it an initial clean - I’d say it’s probably only been run on Tesco’s finest. I got a reply from webasto today - just a link to the 78 page technical manual and a good luck basically. I’ve got the webasto back now so will give it a full de-coke and inspection, replace all the gaskets and try another PCB. I’ve convinced myself it’s the PCB !!!@pjj - it’s the 5kW one, the one you have is a different beast altogether. @spruce - what’s the best chemical to remove old built up carbon deposits? Any recommendations? I’ve brought some brake cleaner to try as that’s been recommended on some of the boat forums as well as running the heater on pure paraffin which should burn off the deposits as it naturally burns at a higher temperature - I’m a bit dubious though!!!!


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[spruce]

That’s how I always use mine. It’s started up before I go out (either on the pre-programmes timer or I manually go and switch it on) so by the time I’m at the first job the preheat has been done and the secondary circuit is ready to roll. That’s how I showed him how to use it and explained the different phases of the process - we even checked the temperature of the header tank when the unit started to wind down and it was 72 degrees. The unit is doing everything it should - until it’s asked to maintain the heat with the secondary circuit in play.
Road diesel (white as they say) is the only fuel the heater has seen since I’ve been involved - and looking at the combustion chamber photos before a give it an initial clean - I’d say it’s probably only been run on Tesco’s finest. I got a reply from webasto today - just a link to the 78 page technical manual and a good luck basically. I’ve got the webasto back now so will give it a full de-coke and inspection, replace all the gaskets and try another PCB. I’ve convinced myself it’s the PCB !!!@pjj - it’s the 5kW one, the one you have is a different beast altogether. @spruce - what’s the best chemical to remove old built up carbon deposits? Any recommendations? I’ve brought some brake cleaner to try as that’s been recommended on some of the boat forums as well as running the heater on pure paraffin which should burn off the deposits as it naturally burns at a higher temperature - I’m a bit dubious though!!!!


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I 'nicked' this a few years ago

View attachment Servicing a Webasto Thermo Top C Diesel Boiler.pdf

Personally I would be very cautious about using cleaning chemicals.

This document by Chris Wyles is copyrighted and not to be reproduced except for private use. It was available on the boat forum for general download (not a clue which one now) so I believe its ok adding these servicing instructions to this post. I'm not and never have been a member of any of those boating forums. This servicing manual was available for any Tom, **** and Harry to download.

? ? The short form for Richard was censored.

 

[AGlassAct]

I have that document already@spruce - but thank you. The one I have is no where near as coked up as the one in the guide but I’d hoped to remove most of the deposits so I can rule it out. Here’s the combustion chamber before I had a go at it the first time

I asked a friend of mine (who does car valeting and oven cleaning) if he could recommend a product - he gave me alloy wheel cleaner which is basically hydrochloric acid, as you know that doesn’t mix well with aluminium!!!!!


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[spruce]

I have that document already@spruce - but thank you. The one I have is no where near as coked up as the one in the guide but I’d hoped to remove most of the deposits so I can rule it out. Here’s the combustion chamber before I had a go at it the first time

I asked a friend of mine (who does car valeting and oven cleaning) if he could recommend a product - he gave me alloy wheel cleaner which is basically hydrochloric acid, as you know that doesn’t mix well with aluminium!!!!!


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Thats not bad at all tbh.

 

[Pjj]

That’s how I always use mine. It’s started up before I go out (either on the pre-programmes timer or I manually go and switch it on) so by the time I’m at the first job the preheat has been done and the secondary circuit is ready to roll. That’s how I showed him how to use it and explained the different phases of the process - we even checked the temperature of the header tank when the unit started to wind down and it was 72 degrees. The unit is doing everything it should - until it’s asked to maintain the heat with the secondary circuit in play.
Road diesel (white as they say) is the only fuel the heater has seen since I’ve been involved - and looking at the combustion chamber photos before a give it an initial clean - I’d say it’s probably only been run on Tesco’s finest. I got a reply from webasto today - just a link to the 78 page technical manual and a good luck basically. I’ve got the webasto back now so will give it a full de-coke and inspection, replace all the gaskets and try another PCB. I’ve convinced myself it’s the PCB !!!@pjj - it’s the 5kW one, the one you have is a different beast altogether. @spruce - what’s the best chemical to remove old built up carbon deposits? Any recommendations? I’ve brought some brake cleaner to try as that’s been recommended on some of the boat forums as well as running the heater on pure paraffin which should burn off the deposits as it naturally burns at a higher temperature - I’m a bit dubious though!!!!


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Ok, I had this discussion with Oliver before I bought mine , he said that the 5kw will give hot water in the summer and warm in the winter as it’s not powerful enough to raise the temperature of the water that’s only a few degrees above freezing. As a side point they also do the wabasto in 12,14,16,18 kw versions as well a mate of mine fits them in boats for central heating systems now that would be an intresting application for wfp ???

as for cleaning depending on the size of the parts ultrasonic cleaning will remove all the carbon and won’t damage the item being cleaned 

 

[AGlassAct]

 
 
Ok, I had this discussion with Oliver before I bought mine , he said that the 5kw will give hot water in the summer and warm in the winter as it’s not powerful enough to raise the temperature of the water that’s only a few degrees above freezing. As a side point they also do the wabasto in 12,14,16,18 kw versions as well a mate of mine fits them in boats for central heating systems now that would be an intresting application for wfp [emoji23][emoji23][emoji23]
as for cleaning depending on the size of the parts ultrasonic cleaning will remove all the carbon and won’t damage the item being cleaned 

The webasto will break down into small enough bits - I can rig up a DIY ultrasonic cleaner easy enough, but what would you put in it solution wise? On my list so far are coke, brake cleaner and possibly paraffin. The ideal would be to get it vapour or soda blasted but no one near me does it.


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