Webasto thermo top c only warm

[mick55]

I should have added, run the system flat out for about three hours, testing for an hour or so is useless, it needs a long run time to see what the system is doing, heating from stone cold takes time, at least one of the rads should be too hot to touch for any length of time, you may have had a new ECU fitted, but even Webasto are not immune to zero hours failure of components, trust me I know only too well.

[pgrange]

4 minutes ago, mick55 said:

You say it ramps up well past 50, what water temperature is the WTT actually showing on the graph? after an hour it should be showing 84 at full load before going down to part load, even if the flow is not good, at least some part of the system should be getting hot enough that you cannot keep your hand on it, the whole of the system cannot run lukewarm after an hour of full load, it is just not possible on a small system such as yours.

That's exactly my issue. If all rads are open it's lukewarm after an hour of running and it struggles to get above 35. One rad on it'll run hot, very hot. The more rads come on line the cooler the water temp gets. 

[Mike Adams]

1 hour ago, pgrange said:

am guessing that the temperature monitoring uses a thermistor and between ECU or thermistor I would suspect the thermistor first, if indeed a thermistor is used. If so is there any chance of you measuring its resistance across a range of temperatures and then comparing it with Webadto data ------------ if you can find it.

The temperature sensor is on the ECU circuit board and is held against the burner housing by a spring clip and screw. There seems to be two devices used, one having two pins and another 3. Can't see any numbers on them. One could be the sensor and the other a cut out

[pgrange]

3 minutes ago, mick55 said:

I should have added, run the system flat out for about three hours, testing for an hour or so is useless, it needs a long run time to see what the system is doing, heating from stone cold takes time, at least one of the rads should be too hot to touch for any length of time, you may have had a new ECU fitted, but even Webasto are not immune to zero hours failure of components, trust me I know only too well.

OK thanks for that. I'll give it a go ?

[mick55]

Let me know how it performs after an extensive run, some part of the system should get hot if the heater is performing correctly, you may have a circulation problem, but this cannot be ascertained until you have run it for a prolonged period, if it is a circulation problem, this can only be addressed once you know the heater is operating correctly

I have been installing these heaters for quite a number of years and have some expertise in the repair and diagnosis of them, and that is how I make my living, happy to help if I can.

Hope these comments assist.

[pgrange]

27 minutes ago, mick55 said:

Let me know how it performs after an extensive run, some part of the system should get hot if the heater is performing correctly, you may have a circulation problem, but this cannot be ascertained until you have run it for a prolonged period, if it is a circulation problem, this can only be addressed once you know the heater is operating correctly

I have been installing these heaters for quite a number of years and have some expertise in the repair and diagnosis of them, and that is how I make my living, happy to help if I can.

Hope these comments assist.

Mick I'll let you know. Really appreciate your help. 

 

Many thanks 

 

Peter 

[David Mack]

On 04/12/2019 at 15:51, pgrange said:

I ran only 1 rad upto 50 deg then opened the 2nd rad. Immediately the temp drops to 40 deg then after some time the temperature climbed and topped out at 47 deg. Opening the towel rail the temp dropped again and when the calorifier was opened the temp dropped to 35 deg and couldn't climb any further.  The rads have been balanced.

 

If you can't get the rads up to temperature how can you have balanced them?

My approach to balancing rads (on a domestic hot water system) is to open all the rad valves (inlet and outlet) fully, run the system for a while then slowly turn down the lockshield valves on the hottest rads (usually the ones closest to the boiler), which forces more water through the cooler more distant rads, until all are running at more or less the same temperature. If you have themostatic valves, remove the head unit during balancing, so that the actual valve is fully open.

[Detling]

For comparison my 2011 webasto thermo top C running 3 rads and a cauliflower gets then all hot in under 20 minutes and after 40 goes into low power mode for about 10 minutes and then settles down to 10 full blast 10 low power. All the rads  are to hot to hold, but can be touched so 70-75 degrees.  I think the slowdown low power mode is triggered by the return flow temperature which in the OP's case is not going to hot enough as the rads don't get that hot.

If the output hot flow is not hot enough (you should be able to tell by feeling the output pipe) then the question is where is the 5 kW of flame heat going, assuming the beast is running hard, it could be that it never leaves low power mode thus only outputting 1.5 kW or so.  On mine at full power the tick of the fuel pump is slightly over 1 pulse per second, on low power mode about one tick every 2 seconds.

Another possibility is a fuel line partial blockage. After the very cold weather a few years ago my webasto refused to run and on checking the fuel system the water separator / filter was full of a white diesel wax like soft candle wax, cleaning this out made it run fine.

[pgrange]

Evening everybody 

 

After 3 hours. All rad and the calorifier fully open on both flow and return. Calorifier 3/4 open on flow and 1/4 on the return. 

 

Peter 

[Detling]

As stated earlier you do not need to throttle both the flow and return to a radiator or the calorifier coil. the flow will be limited by the smallest valve hole. if you have one at 1/4 open, as long as the other is more than 1/4 then flow is 1/4 of the maximum.  Does the temperature in your screenshot refer to the output water temperature?, the return water temperature?  the case temperature? or cooling air temperature?. If as you suggest it is the output water temperature then your webasto is not running at full power.

 

[pgrange]

17 hours ago, Detling said:

As stated earlier you do not need to throttle both the flow and return to a radiator or the calorifier coil. the flow will be limited by the smallest valve hole. if you have one at 1/4 open, as long as the other is more than 1/4 then flow is 1/4 of the maximum.  Does the temperature in your screenshot refer to the output water temperature?, the return water temperature?  the case temperature? or cooling air temperature?. If as you suggest it is the output water temperature then your webasto is not running at full power.

 

Tbh Detling I'm not sure what that temperature refers to but I'm leaning towards the return temp. I've been playing around with it again this morning. Bringing each rad online and tweaking the return valve. I now have the towel rail and the bedroom rad nice and hot. The front and calorifier are still only warm. 

[David Mack]

20 minutes ago, pgrange said:

Tbh Detling I'm not sure what that temperature refers to but I'm leaning towards the return temp. 

If the return temprature is 35 degrees - around body temperature - and the thing is putting out 5kW, then the outlet pipe should be too hot to touch! If it isn't then the heater is not running at 5kW.

[mick55]

19 hours ago, pgrange said:

Evening everybody 

 

After 3 hours. All rad and the calorifier fully open on both flow and return. Calorifier 3/4 open on flow and 1/4 on the return. 

 

Peter 

After three hours running the temperature should be far higher than 36, around 80 would be more like normal, that heater is not burning at full load.

[mick55]

I would do a fuel dosing test to see if the pump is delivering sufficient fuel.

[pgrange]

2 minutes ago, mick55 said:

I would do a fuel dosing test to see if the pump is delivering sufficient fuel.

Mick 

 

Can I run the fuel pump component test in WTT to determine whether I have sufficient fuel or not. How much fuel am I looking for? 

 

Thanks 

[pgrange]

36 minutes ago, David Mack said:

If the return temprature is 35 degrees - around body temperature - and the thing is putting out 5kW, then the outlet pipe should be too hot to touch! If it isn't then the heater is not running at 5kW.

Dave 

 

Thanks for the reply. 

 

I'll check how hot the outlet pipe is. The bathroom rail was hot to touch this morning, a lot hotter than previous. 

[mick55]

Turn the heater off, remove fuel pipe to heater and put into a small container, start the heater and in one start cycle it should pump 10ml of fuel until it shuts down.

How much fuel did it pump?

[pgrange]

1 hour ago, mick55 said:

Turn the heater off, remove fuel pipe to heater and put into a small container, start the heater and in one start cycle it should pump 10ml of fuel until it shuts down.

How much fuel did it pump?

OK thanks Mick I'll give that a go and report back. 

[Detling]

If the dosing pump is the normal one you will hear it ticking at, full wack about 1 tick per second if running slower you will not get full power. If the fuel line has an obstruction which restricts the flow you will not be getting the correct amount of fuel per tick.

[pgrange]

20 hours ago, Detling said:

If the dosing pump is the normal one you will hear it ticking at, full wack about 1 tick per second if running slower you will not get full power. If the fuel line has an obstruction which restricts the flow you will not be getting the correct amount of fuel per tick.

Had a listen to it this morning and yes its clicking away 1 a second if not slightly faster. I'll check the actual amount of fuel it delivers tomorrow when I have more time. 

[pgrange]

Just on a side note I read a post on here from some time back that rang bells. Direct from the heater I have 2 T joints which go to my calorifier, one flow one return. Could it be that the heated water is going to the calorifier coil and back to the heater still hot before its had a chance to get to the front of the boat? . The calorifier valves were originally wide open. I have throttled them back as per sea dogs recommendation but I'm unsure by what amount or the method. 

 

Thanks Peter 

[David Mack]

Your rads/calorifier are clearly not properly balanced. I commented on this in post #32.

[landartisan]

Hey pgrange

 

did you ever find a solution to your problem? I’ve got the same heater installed and it’s only putting out about 18c after several hours of runtime. Curious to know if you can help me out as there’s not much info available online for this issue. Thanks