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Webasto Central heating


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6 hours ago, WotEver said:

It’ll make no difference which line you put it in. If it’s closed then there will be no flow through the cauliflower loop wherever you put it. 

“Balance the system
Balance the radiators with the lockshields and remember to fit a lock shield / balancing valve to the Calorifier coil outlet pipe.”

 

Again taken from the Webasto manual. I imagine its there to restrict the out flow and keeping the hot coolant in the coil for longer?

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1 minute ago, Greenhorn said:

“Balance the system
Balance the radiators with the lockshields and remember to fit a lock shield / balancing valve to the Calorifier coil outlet pipe.”

 

Again taken from the Webasto manual. I imagine its there to restrict the out flow and keeping the hot coolant in the coil for longer?

The hot coolant won’t be in the coil if the outlet is closed: no flow. 


And if the valve is say half closed then there’ll be half flow - whichever leg it’s in. 

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I am a registered heating engineer and although commonly seen adjacent to domestic heating system header tanks any sort of shut off valve between a header tank and system is not allowed. The header tank serves three purposes, supply of water, expansion and contraction and a route for boiling water and steam to escape under fault conditions. Suppose the internal thermostats on Webasto fail and it raises water temperature above 100 degrees and someone has shut off the isolation valve to header tank. The increase in pressure in the sealed system will allow the water to exceed 100 degrees without boiling, however if a joint fails or rubber hose slips off the whole volume that is above 100 degrees will instantly flash into steam, this will result in a volume of water/steam increase of 1600 times instantaneously. Not good, there are photos on the web and at training colleges of houses blown to bits by poorly installed unvented hot water cylinders. 

There should be no valves between the feed tank and the boiler. I know this is a boat installation but the laws of physics are the same. 

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8 minutes ago, plumbob said:

I am a registered heating engineer and although commonly seen adjacent to domestic heating system header tanks any sort of shut off valve between a header tank and system is not allowed. The header tank serves three purposes, supply of water, expansion and contraction and a route for boiling water and steam to escape under fault conditions. Suppose the internal thermostats on Webasto fail and it raises water temperature above 100 degrees and someone has shut off the isolation valve to header tank. The increase in pressure in the sealed system will allow the water to exceed 100 degrees without boiling, however if a joint fails or rubber hose slips off the whole volume that is above 100 degrees will instantly flash into steam, this will result in a volume of water/steam increase of 1600 times instantaneously. Not good, there are photos on the web and at training colleges of houses blown to bits by poorly installed unvented hot water cylinders. 

There should be no valves between the feed tank and the boiler. I know this is a boat installation but the laws of physics are the same. 

the isolation valve mentioned is between the two pipes going to the header tank, closing the isolator forces all the flow through the header tank, both the flow and return are still open to the header tank. Domestic header tanks usually only have one pipe and that should never be isolated.

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16 minutes ago, plumbob said:

... any sort of shut off valve between a header tank and system is not allowed.

Then it’s a good job that he hasn’t put one there :)

 

(Other than the two adjacent to the heater itself of course.)

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Yes i agree i have just looked at the image in the post again using a different browser as the one on my usual one was distorted and did not show the valve location clearly. There would be no issue with the installation as shown but i would put the header tank as close as possible to the boiler

 

Yes the two adjacent to the boiler need to go as they can isolate the boiler from the feed tank

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8 minutes ago, plumbob said:

Yes the two adjacent to the boiler need to go as they can isolate the boiler from the feed tank

I would imagine that their only purpose would be to permit the boiler to be removed for servicing and would otherwise never be closed. 

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Welcome to the world of plumbing, where every small job turns into a s**t storm of complications. An old lady asked me recently to change a tap on a basin, simple you would think. 3 hours later i had cut the top off the tap with an angle grinder and used a hole saw to frill out the stem of the tap as the original installer had glued it in with some sort of  solid adhesive. Everything in plumbing gets complicated.

I would agree about the valves but the usual cause is someone else who did not fit them turning them of trying to isolate something else

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I come from a petroleum engineering background, mostly maintenance of RAF fuel installations. people have been known to open or close valves that Should be well left alone (unless when servicing for example). A simple lockable valve handle and strong cable tie is something I’ve had to do before and after hearing concerns about valve placemat on here I’ll make sure to do this on the boat also. 

  • Greenie 1
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