Not able to drain Truma heater (1 Viewer)

[solaris]

A repeat of last year’s problem. Then I changed the automatic dump valve for a manual one, which made no difference. Opened it this weekend and about a litre drained into a bucket, with all taps opened. If I turn pump one, there’s still water in the main tank, it pumps out of the dump valve but stops when pump turned off. An airlock seems obvious problem but system works fine rest of time. Live in the sticks so could drive around to see if I leave a trail of water, when the monsoons have stopped. Oh and reversed into bucket at end, 0.99p B&Q jobbie 15 years old which naturally shattered. Just not made to last.
Thanks in advance

 

[Jake Royd]

I wonder if the system is furred up with calcium/limestone deposits?
It maybe worth thinking about descaling it with white vinegar?

 

[daveandsan]

I dumped my water heater today with all the taps open and thought that there wasn’t much water come out.
I just remove the shower head and attach a small air compressor using one of of those tapered attachments they use for blowing up plastic balls, just push it into the shower hose.
I always drain my main tank first, that’s just got a bung in the bottom of tank.

 

[donkey]

Not sure what the issue is. "there's still water in the main tank".
You are never going to drain the main water tank via the system drain valve.
It is only designed to drain the hot/cold pipework.
Anything below the valve level will need to be drained via the tank drain tap.

Geoff

 

[solaris]

Thanks for your comments. To respond to your thoughts:

Van is 2018, I have flushed the system about 2020 with proprietary cleaner. Mentioned water in tank as have an underslung tank with submersible pump with non return valve. Was trying to demonstrate that water flows freely through the Truma and the non return valve means water from Truma cannot drain back into tank. When freezing weather is forecast I also open cold tank drain tap but as I discovered last year this still leaves water in Truma, found out on refilling when system came up to pressure far too quickly. Like idea of blowing air through shower.

Because we use van all year I tend to drain Truma between trips in winter for safety and also have a heater in the van.

You have all given me ideas to consider, thanks again.

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[GeoffnDee]

solaris It may be worth checking if there is another (inline ? ) non-return valve fitted near the Truma boiler water supply inlet , as , if there is one fitted in this location this could be the cause of it not fully draining down , as they normally do , with the taps being left open, with the pump turned off , to allow air in for the Truma to drain .

 

[Engineer999]

I drained down the fresh water tank and opened the Truman drain on the water heater over the weekend. All the taps, including the shower, were open half way between hot and cold and a flood of water ensued from beneath the van. However after that had finished and I was moving around the van removing and cleaning the carpets, a second wind of water started draining from the heater, I presumed an airlock - perhaps the OP needs to rock the van to encourage this?