Fully emptying Truma boiler

[PG’s trips]

6 weeks ago I thought I had fully emptied the Truma boiler heater by pressing the ‘wee’ blue valve frost protection thingymebob. But when I happened to put the hot water tap on today, with 12volt on, water starting coming out the boiler emptying place under the MH (valve is still open). So was there was still water in the Boiler system???? Can anyone explain why that was? I had also emptied the fresh water tank and pretty sure I had left taps on until they ran empty as part of winter prep. Bit worried given frosts last few nights. Have I missed something. How can I be sure the boiler is now totally empty? Thanks.

 

[two]

Water trapped in the pipework.
You should open the taps to let air in and avoid the possibility of it freezing in the tap (expensive).
So long as most of the water is out of the boiler, that's OK. It'll have room to expand if it froze.

 

[autorouter]

How can I be sure the boiler is now totally empty?

There's only two ways to be sure. One way is to blow all the water out. I cut the hose from the tank, and inserted a tee-piece, with a shutoff tap and schrader valve (tyre valve) in the branch. I used a small car tyre compressor, the digital type set to cut off at 20psi so as not to overstress the pipes or the boiler. Don't forget the toilet flush line, and leave mixer taps open at midpoint so the hot and cold pipes are both open. If you want a professional system that does the same thing, Floe can supply them.

The other solution is to used food-grade antifreeze, which is available but not very popular this side of the Atlantic.

 

[mike mcglynn]

I have seen the water system emptied with the use of a balloon ,just blow it up and place over taps then open taps.

 

[PG’s trips]

On reflection, I perhaps didn't fully empty the system by only having the taps on the cold rather than midway when emptying. So will try that again today. Still learning !

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[two]

The point is to avoid leaving any trapped water in your system.
Blowing air through will not rid all water but should make sure that there isn't a 'slug' left in pipework anywhere. But pipework can expand rather than rupture and is cheap to repair if it did. The boiler, pump, taps and filter are the things to let water out of. The boiler is expensive. The others are a nuisance to replace. Cracked filter bowls are a common source of problem when you restart in the Spring.