Webasto Thermo Top C - 15mm or 22mm pipes?

[Tracy D'arth]

I suspect that you do have stratification of antifreeze and water in the radiators and pipework which is reducing your flow. I have never worked out why antifreeze will not diffuse into water properly over a certain concentration but it wont.

 

I would try drawing some off from the  low point of the pipework and replacing it with pure water. If you can get flow in just one radiator with time running the heating it may diffuse better and let the other radiators start to work.

 

Does the calorifier heat?  You have not confirmed that there are NOT thermostatic valves fitted.

 

[matty40s]

3 hours ago, Alan de Enfield said:

 

Don't be surprised by anything with regard to boating.

 

The 'reputable well established' boat yard had 'broken the back' of someones pride and joy.

A reputable and very popular NW boat builder now in Tier 2 lifts all it's new boats(narrow and wide) onto lorries with a ramshackle selection of 4 forklifts, at least 2 of which have knackered hydraulics and cant hold their sides of the brand new boat up.

[matty40s]

3 hours ago, Sea Dog said:

There's no doubt that the pipe bore is not in accordance with the spec. However, I'd suggest that this is not the root of your problem.

I find it hard to see a heat exchanger on another system causing problems with a wrongly fitted Webasto system.

The Webasto fitting guidelines and instructions are quite clear and comprehensive, fitting 15mm from the unit onwards will not allow the unit to work properly.

I do agree with your run the system fully, and hard, on a regular basis though.

[David Mack]

8 hours ago, Tonka said:

Just found this in a Webasto installation manual.

10.3.2.2 Minimum pipe diameter
The pipe diameter of the main pipe depends on the diameter of the heating system water
connection.
Thermo Top C® 20 mm
Thermo 90 ST® 20 mm
DBW 2010/2016® 20 mm
Thermo 230/300/350® 38 mm
Pipe diameter in side branches: keep at least to the connection diameter of the heat exchangers
(heating elements, blower heat exchanger, convectors).

 

If you PM me i can send you a copy of the manual

 

Its not clear (unless its in part of the text you haven't quoted) whether these are requirements for the actual pipe bore, or just nominal pipe sizes. That said, 22mm copper has a bore in excess of 20mm, whereas 22mm plastic pipe probably has not (and certainly not through the inserts at joints).

[Grassman]

Canals are us - Thanks, I will look at getting the thermostatic valves changed as well. We just used them to turn on and off the radiators. If 'on' we always had them fully open. I have 4 double radiators and a towel radiator in the bathroom. The boat is 62ft.

 The pipes are mostly accessible as the main run is down the edge of the corridor floor on the starboard side of the boat, boxed in but easily removed. As for your other advice, I will consult my man about those points.

 

Seadog - I'm pretty sure there would be no corrosion as the radiators were new in 2018, supposedly!!

 

Matty40s & Tracy - I'm not sure. The header tank has a hose coming out of each side and both of them disappear behind some panelling in the direction of the engine bilge where the Webasto is. As for the technical aspects of your question, I will have to ask my man. By the way it is not a pressurised system if that's relevant.

 

[Tracy D'arth]

4 hours ago, Grassman said:

Canals are us - Thanks, I will look at getting the thermostatic valves changed as well. We just used them to turn on and off the radiators. If 'on' we always had them fully open. I have 4 double radiators and a towel radiator in the bathroom. The boat is 62ft.

 The pipes are mostly accessible as the main run is down the edge of the corridor floor on the starboard side of the boat, boxed in but easily removed. As for your other advice, I will consult my man about those points.

 

Seadog - I'm pretty sure there would be no corrosion as the radiators were new in 2018, supposedly!!

 

Matty40s & Tracy - I'm not sure. The header tank has a hose coming out of each side and both of them disappear behind some panelling in the direction of the engine bilge where the Webasto is. As for the technical aspects of your question, I will have to ask my man. By the way it is not a pressurised system if that's relevant.

 

If one pipe is low in the tank and the other high I am suspicious about it. We knew it was not a sealed system when you said you had a header tank.

Thermostatic valves are restrictive even when full open compared with ordinary hand wheel valves.

[Sea Dog]

15 hours ago, matty40s said:

The Webasto fitting guidelines and instructions are quite clear and comprehensive, fitting 15mm from the unit onwards will not allow the unit to work properly.

I have no difficulty with that - mines an Eberspacher, but the guidance is much the same. As I said, however, mine (and all/most/many fitted in a build by Simon Piper) is done in ⅝" coolant hose and 10mm plastic with no issues in the real world. Not great practice maybe, but mine has given 12 years of fault free service and is certainly not a recipe for a perforated heat exchanger. 

[Duck-n-Dive]

Both Webasto and Eberspacher need a good circulation to get rid of the hot water that they are generating., so you need to keep the flow going.  If they don't have enough load, they will start and stop which will reduce the life dramatically.

1. Ideally the main flow should be in 22mm with 15mm T to each radiator.

2, Remove all thermostatic valves and leave all of the valves open

3, Make sure any branch through the calorifier is fitted with a 3/4 closed isolator to reduce the flow throught the coil.

4. Make sure the header tank is in the Return to the webasto, not the flow.

[Detling]

Mine has plastic 22 mm off the rubber, splits within a few inches into 15 to calorifier and 22 to rads once through bulkhead that splits into 2 x 15 one port side one starboard both have 2 rads. No trouble.

[Grassman]

On the basis that I'm not going to be able to get anything done now until well into January or longer, my man is going to drain the system tomorrow and re-fill it with the recommended 25/75 mix, and will mix it properly before putting it in. At least it might get it working again so as we can use it in the meantime until I can get the pipework issues resolved. Previously it's taken 12 months until it's b*ggered up the Webasto so hopefully a few weeks shouldn't do any harm.

 

You've all been so great sharing your expertise and advice so I won't forget to let you know in due course how I get on and what the eventual outcome is whenever that will be.

[Tracy D'arth]

13 hours ago, Detling said:

Mine has plastic 22 mm off the rubber, splits within a few inches into 15 to calorifier and 22 to rads once through bulkhead that splits into 2 x 15 one port side one starboard both have 2 rads. No trouble.

So yours has two 15mm circuits effectively, I suspect that Grassman has only one long run of 15mm to carry the water.

[robkg]

A possible solution to poor flow problems is to fit an external pump to boost the flow.  It can be wired in parallel with the switched supply to the Webasto unit so that it doesn't need switching separately.  I did this to my installation several years ago with dramatically improved results.  This may be an easier fix than replumbing the whole system.

[matty40s]

On 21/12/2020 at 20:26, Detling said:

Mine has plastic 22 mm off the rubber, splits within a few inches into 15 to calorifier and 22 to rads once through bulkhead that splits into 2 x 15 one port side one starboard both have 2 rads. No trouble.

That is quite normal.

Congrats.

[matty40s]

16 minutes ago, robkg said:

A possible solution to poor flow problems is to fit an external pump to boost the flow.  It can be wired in parallel with the switched supply to the Webasto unit so that it doesn't need switching separately.  I did this to my installation several years ago with dramatically improved results.  This may be an easier fix than replumbing the whole system.

Why should you have to post fit another pump to a system that has been installed incorrectly to rectify.

You shouldn't,  unless you cant get the original plumbing changed to correct standard and are engaging brain to try to sort expensive and complicated piping fixes with another solution.

Good luck, but the Webasto, Eberspacher and Mikuni are specified with quite strict air intake, exhaust , coolant piping and fuel supply specifications to suit.

If these aren't met then it's not down to them.

[robkg]

5 minutes ago, matty40s said:

Why should you have to post fit another pump to a system that has been installed incorrectly to rectify.

 

I'm not suggesting you have to fit an external pump, I'm just being pragmatic in that this could be a solution if attempting redress from the installer fails.

[Grassman]

Thanks for the latest replies.

 

robkg, I'm loathe to fit an external pump because it would mean something else draining my batteries even if it's only a slight draw.

 

Update - Yesterday we checked again the strength of the coolant which confirmed it was 50/50%. We completely drained the system and some came out in globs which confirms the instructions that it should me mixed beforehand and not to rely on it mixing while traveling around the system. We re-filled with our pre-mixed 25/75 strength, bled the system using one of those impeller pumps that attach to a drill, and made sure that all the radiators had no air in them and were full.

 

We then turned the Webasto on and all radiators heated up over the whole of each one's area, not just the bottoms like before. There was no excessive smoke, just a little coming out of the exhaust for the first few minutes, and no reduction of the level in the header tank.  We ran it for 12 hours with no problems so far.

 

This of course is only a temporary measure to get us over the Xmas shutdown period until I can sort it out with the installers, because the fundamental problem of the small pipes and all the other issues remains the same. I will only be having it on in the daytime so that I can keep an eye on it.

 

We've highlighted another possible contributory factor in that from where the main pipes enter the cabin, the first 10 feet of pipework is tucked under the gunnel which is above the height of the radiators, and then drops down into the first radiator which is in the bathroom. It could easily have been channelled along the floor and out of sight inside cupboards/lockers so why they did this I don't know. On the basis that air will always find the highest point, this obviously reduces the effectiveness of any bleeding of the system.

 

As well as the wrong pipes, those other issues that we've discussed shows that the whole installation was a poor and carried out by somebody who didn't really know what they were doing, which was surprising considering it was done by a well know and reputable boatyard. 

 

Thanks again for all your help, you've been brilliant, and unlike what often happens on here where people seek help and then never come back and say how it turned out,  I definitely will keep you informed and let you know how I get on when I do battle with the installation company in a couple of weeks time.

[Sea Dog]

3 hours ago, Grassman said:

We've highlighted another possible contributory factor in that from where the main pipes enter the cabin, the first 10 feet of pipework is tucked under the gunnel which is above the height of the radiators, and then drops down into the first radiator which is in the bathroom.

As I mentioned earlier, my Eberspacher is not plumbed in accordance with the manufacturer's recommendations, being done in ⅝" hose and 10mm plastic pipe. In addition, the ⅝" hoses from the engine 'ole to midships is run under the gunwale similar to yours.  Neither affect the operation.  Now, that's not to say you shouldn't get it plumbed iaw the installation instructions if you can, but I'd suggest you've solved your main issue by replacing the "coolant" which was undoubtedly causing an issue.  

 

Therefore, when you "do battle" with the installer as you put it, you may consider not dying in a ditch over a complete rebuild if they offer another resolution you might find acceptable should you re-evaluate your system performance now and find it works well. I still have little doubt that your perforated heat exchanger is due to corrosion, not caused by the below-spec pipe sizing.

Edited December 24, 2020 by Sea Dog
Changed "iaw" auto correct error

[TheBiscuits]

58 minutes ago, Sea Dog said:

I still have little doubt that your perforated heat exchanger is due to corrosion

 

Especially as we now know that the antifreeze containing the corrosion inhibitor wasn't mixed correctly.  The heat exchanger could well have been in plain water for most of it's service.

[Grassman]

Interesting thank you and I understand where you're coming from. What we did with the coolant yesterday has obviously got it running again but the fundamental problem is still the main pipes circuit, and so long as I can get that sorted I'll be reasonably happy. Webasto say in their manual that it should be 22mm and so do half a dozen Webasto marine agents I've spoken to, and that is where I will be coming from when seeking redress from the boatyard.

 

The section of pipework being too high is just one of many instances of poor workmanship by the company, which collectively might have contributed to the problem.

[Grassman]

After all your help and input I promised that I'd let you know the outcome.

 

It's good news. The company who installed the heating system have agreed to change all the pipework to 22mm (except the individual feeds to each radiator) and to rectify those other issues I've mentioned. This will also involve re-routing the section of pipe that ran above the height of the radiators to a much better way, which should now contribute to helping it flow better.

 

I mentioned previously that they were a reputable company and fair play to them, the gaffer came out, looked at the job and readily agreed to rectify all issues that I'd mentioned. I feared I'd have a battle on my hands but thankfully that's not the case and we have now fixed a date for it to be done.

 

Thanks again everybody, your help has been immense. 

[Alan de Enfield]

9 minutes ago, Grassman said:

Thanks again everybody, your help has been immense. 

Thanks for the update, its nice to know there are some reputable companies around who stand by their work.

[Boatingbiker]

Good news Grassman, 

[Tonka]

Great news. Thank you for the feedback. 

[Tracy D'arth]

52 minutes ago, Grassman said:

After all your help and input I promised that I'd let you know the outcome.

 

It's good news. The company who installed the heating system have agreed to change all the pipework to 22mm (except the individual feeds to each radiator) and to rectify those other issues I've mentioned. This will also involve re-routing the section of pipe that ran above the height of the radiators to a much better way, which should now contribute to helping it flow better.

 

I mentioned previously that they were a reputable company and fair play to them, the gaffer came out, looked at the job and readily agreed to rectify all issues that I'd mentioned. I feared I'd have a battle on my hands but thankfully that's not the case and we have now fixed a date for it to be done.

 

Thanks again everybody, your help has been immense. 

Thanks for the update, so there is a god?

[Sea Dog]

Result!  Good companies are the ones who respond this well to their rare slips.